Final Report Summary - COMETHY (Compact Multifuel-Energy To Hydrogen converter)
Executive Summary:
An innovative technology for hydrogen production has been developed in the project CoMETHy (Compact Multi-fuel Energy To Hydrogen converter), co-financed by the European Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and coordinated by ENEA.
The Project, started in December 2011 and concluded in December 2015, has seen 12 organisations between Industries, Research Centres and Universities cooperating in an excellent collaborative environment: ENEA (Italy), Processi Innovativi Srl (Italy), Acktar Ltd. (Israel), Technion (Israel), Fraunhofer Institute (Germany), University of Salerno (Italy), CERTH (Greece), Aristotle University of Thessaloniki (Greece), University “La Sapienza” (Italy), ECN (the Netherlands), GKN Sinter Metals Engineering GmbH (Germany) and University “Campus Bio Medico” (Italy).
The technology developed in CoMETHy allows to combine different types of energy sources, like solar, biomass and fossil fuels, to produce pure hydrogen for various applications, permitting to adapt hydrogen production to the locally available energy mix.
The system has been based on the steam reforming process, a widespread hydrogen production method, which has been revised to exploit renewable energy: the main aim has been to power the process with an energy vector that today is widely used to capture, store and dispatch solar heat in Concentrating Solar plants, i.e. a mixture of molten salts. This fluid, often called “solar salt”, has several outstanding positive features including low cost, high heat transfer/storage capacity and minor implications about environmental and safety issues and toxicity.
The steam reforming process has been specifically tailored and re-designed to be combined with Concentrating Solar plants using “solar salts”: a “low-temperature” steam reforming reactor was developed, operating at temperatures up to 550°C, much lower than the traditional process (usually > 850°C). This result was obtained after extensive research, going from the development of basic components (catalysts and membranes) to their integration in an innovative membrane reformer heated with molten salts, where both hydrogen production and purification occurred in a single stage.
Besides the high degree of compactness, the device developed is also highly flexible as far as the feedstock to be converted to hydrogen is concerned, which can be either clean methane (e.g. from natural gas) or a biomass-derived fuel such as clean biogas (methane/CO2 mixtures) or bioethanol. The steam reforming technology developed in CoMETHy allows for an easy changeover of both the feedstock and the external heat source (solar or fossil/biomass back up) whereas start-up, stand-by and shut-down operations are eased.
The reactors developed in CoMETHy were successfully tested with different prototypes, one of which realized up to the pilot scale (3.5 Nm3/h hydrogen production) and integrated in a molten salt loop, allowing to prove the concept developed and to reach performance figures above the initial targets.
In conclusion, with the input of solar energy, CoMETHy technology allows to substantially save primary fuels and reduce CO2 emissions in hydrogen production (compared to traditional reforming technology), in a process evaluated to be economically attractive for both decentralized (1500 Nm3/h) and centralized (> 5000 Nm3/h) plant schemes. Furthermore, CoMETHy successfully proved a solar reforming process aided by concentrating solar plants using mature thermal energy storage system to increase plant utilization compared to the directly heated solar reformers proposed in the past. Additional advantages would be obtained by the use of biomass-derived feedstocks, including CO2 capture and re-use.
Project Context and Objectives:
CoMETHy (Compact Multi-fuel Energy To Hydrogen converter) is a product-oriented project, which main objective is the development of an innovative compact and modular steam reformer to convert reformable fuels (methane, ethanol, etc.) to pure hydrogen, adaptable to several heat sources (solar, biomass, fossil, etc.) depending on the locally available energy mix.
The system developed within the project is characterized by a high degree of flexibility, both in terms of:
1) the feedstock that is converted to hydrogen;
2) the primary energy source that powers the energy demanding process.
It is clear that the general strategy for hydrogen production is focused on water (or steam) electrolysis powered by Renewable Energy Sources (RES). However, in this scenario, reliable and flexible thermochemical processes can represent complementary hydrogen back up source, especially if the RES input in the process is still high, as proposed in CoMETHy.
The project logo recalls the general concept of the project: combining different sources, depending on the locally available energy mix, to produce hydrogen as the unique output energy vector. The different colours in the left hand side of the picture represent the different combined energy and material resources: solar radiation, biomass, and two reformable molecules of methane (bio-methane or natural gas) and ethanol (bio-ethanol); a water droplet is represented too, in order to recall that CoMETHy is focused on the steam reforming technology and that water is a feedstock converted to hydrogen (half hydrogen produced from water). The circular arrow indicates that all these energy sources are combined together and that most of them are “renewable” and contribute to the production of a single product on the right hand side of the picture: “hydrogen”.
The technology developed in CoMETHy will support in particular the decentralized hydrogen production (i.e. close to the end-user) thus surmounting the actual lack (and costs) of a reliable hydrogen distribution pipeline and infrastructure (distribution, storage, logistics and charging facilities). Besides, solar steam reforming technology is an attracting process route also for centralized hydrogen production plants in countries with satisfactory solar radiation rates, like those belonging to the so-called “sun-belt” (which also includes the Mediterranean area).
CoMETHy proposes a new “low-temperature” steam reforming technology, where a molten salt (molten nitrates mixture) at maximum temperatures of 550°C is used as heat transfer fluid. This concept allows the supply of the process heat to the reformer as recovered from different heat sources like Concentrating Solar Thermal (CST) plants. The hydrogen produced is separated and purified by means of selective membranes.
More in detail, the general process scheme involves main heat collection from a Concentrating Solar Thermal (CST) plant and heat transfer to the thermochemical (steam reforming) plant. The heat transfer fluid is represented by the so-called “solar salt”, i.e. the molten salt mixture NaNO3/KNO3 (60/40 w/w) commonly used in commercial CSP plants as thermal storage medium and, in some cases, as heat transfer fluid up to 565°C. A suitable heat storage system, based on the use of the solar salt mixture, allows a mismatch between the fluctuating solar source and the often steady running chemical plant: in principle, this makes possible to drive the thermochemical plant at steady state, regardless of the effective instantaneous availability of the solar radiation, even overnight and during cloudy periods.
Selective membranes allow recovery of high-grade hydrogen and increase conversion despite the relatively low operating temperatures. In the low-temperature steam reformer the catalyst and the operating conditions also enhance the Water-Gas-Shift (WGS) reaction in a single step with the main steam reforming reaction: therefore, compared to conventional steam reforming at higher temperatures (> 850°C), the overall heat duty of the reformer will be reduced and the outlet retentate (non-permeate) stream will contain a low CO content (< 10%vol.). After cooling and CO2 separation, the residual H2/CH4 stream from the reactor can be recycled to the reformer. In this way, when the thermochemical plant is powered by solar heat, in principle, there will be no combustion in the whole process, nor combustion generated CO2-containing flue gases emitted to the atmosphere: this will result in a substantial reduction, from 40% to more than 50%, of fuel consumption and CO2 emissions, compared to the conventional route.
It is worth to be noted that the capture and recovery of the CO2 produced is also enhanced due to its relatively high concentration in the outlet process stream. Moreover, when bio-fuels (biogas, bioethanol, etc.) are used as feedstock in the membrane reformer, totally green hydrogen production is achieved. Alternatively, the residual H2/CH4 stream can be used as back up fuel when the solar power is not available.
The molten salt stream provides the process heat to the steam reformer, steam generator, feed pre-heating, etc. Methane, either natural gas or biogas, and bioethanol were studied as feedstock in a multi-fuel approach: CoMETHy aims at supporting the transition from a fossil-based to a renewable-based energy economy, providing a flexible technology for different energy scenarios.
The technology developed in CoMETHy leads to potential benefits also on hydrogen production costs, operational flexibility and environment impact. Materials cost is reduced by operating at less than 550°C, and additional process units, such as water-gas-shift reactor(s) and hydrogen purifiers, avoided by the integration with membranes.
The first challenge to be faced in the development of this technology was the development of advanced low-temperature steam reforming catalysts and cost-effective selective membranes in the reference operational range (400-550°C, 1-10 bar). The subsequent technical challenge was related to the coupling of the membrane with the catalyst in a membrane reactor. Finally, the project involved the integration of the membrane reformer in a molten salts loop for proof-of-concept at the 2 Nm3/h hydrogen production scale, and the techno-economical assessment of the whole system.
CoMETHy Work Plan was divided in 5 RTD work packages (WPs 2 to 6) each including several tasks and subtasks contributing to the achievement of specific project milestones. The first project stage was mainly focused on the development of the two key components of the reformer, i.e. the catalyst (WP2) and the membrane (WP3) to provide basic recommendations about the catalyst system and the membrane to be applied (Milestones 1 and 2, respectively). These activities represented an input to the reformer design (Milestone 3) and validation (WP4), a main activity carried out during the second project year. After construction of the 2 Nm3/h prototype, the final project period was mostly dedicated to the proof-of-concept (WP5, Milestones 5) and to the optimization and evaluation of the whole system (WP6, Milestones 6 and 7, respectively). In the perspective of a multi-fuel application, the identification of specific catalysts for bioethanol steam reforming was required too (Milestone 4).
It is noteworthy that the activities carried out in CoMETHy and the results obtained contributed to achieve the following FCH JU targets about hydrogen production:
- Maximizing hydrogen production from Renewable Energy Sources (RES), with CO2 free (or CO2 lean) routes, specifically for the decarbonisation of transport (with up to 50% of the hydrogen energy supplied from RES).
- Lowering the hydrogen production costs.
- Introducing and exploiting of higher performance materials (e.g. reforming catalysts with shift activity and membranes).
- Developing steam reforming processes with efficiencies > 72% (including CO2 capture) for centralized production, and > 67% for decentralized production from biogas (methane).
- Simplifying the reformer design in terms of compactness and scalability (2 to 750 Nm3/h hydrogen production rate) and enhance catalyst replacement in less than 4 hours.
Project Results:
Development of new structured, open foam catalysts (WP2).
Fuel-flexible structured catalysts were first developed for the “low-temperature” (<550°C) steam reforming of methane (natural gas or biogas-like methane/CO2 mixtures) and bioethanol. The catalysts developed are characterized by minor pressure drops, enhanced heat transfer, and the ability to simultaneously promote steam reforming and water gas shift reactions.
In order to optimize the performance of the membrane reformer, ceramic foams were considered as support material for catalysts in the compact steam reformer at 400-550°C. In particular, ceramic foams were specifically developed and adjusted to the requirements of the steam reforming process:
- High radial heat transport in the packed bed reactor: especially in low-temperature steam reforming, thermal gradients should be minimized to avoid temperature performance loss due to low reaction rates in the coldest parts of the catalyst bed.
- Low pressure drop: especially in a membrane reactor, pressure drops should be minimized to maximize the hydrogen flow through the membrane.
- High surface-to-volume ratio to reach a high catalyst loading.
The above properties of the foam are substantially influenced by its macro- and micro-structural properties like type of material, porosity (ceramic content), cell size and cell porosity. Therefore, hundreds of open-celled foam sample were developed and manufactured to be characterized, coated with the catalytic material(s) and then tested in the reformers (in WP2, WP4 and WP5).
The manufacturing process was adapted and expanded in order to obtain the open foam specifications desired, identified as the best compromise between thermal conductivity, high surface for catalyst deposition, pressure drop and for the application of the slurry washcoating method.
The structure and different types of porosity of ceramic foams were characterized in detail by using special light microscopic measurement techniques.
In order to minimize the heat transfer resistance to the reactor wall, foams with different variations of the external cylindrical surface were produced and evaluated too.
Non-catalytic monolithic foam samples with different materials and geometry were experimentally tested to determine relevant heat transport pressure drop characteristics and a mathematical model for heat transport in open cell solid foams was developed
Catalytic materials to be coated on the open foam supports had to be identified.
Initially, an extensive state-of-the-art review on steam reforming catalysts at 400-550°C was made. Based on this, a review paper was published in the International Journal of Hydrogen Energy with the title “State-of-the-art Catalysts for CH4 Steam Reforming at Low Temperature” (ref.: Int. J. Hydrogen Energy, 2014, vol.39 p.1979-1997).
For the steam reforming at 400-550°C of pure methane and CH4/CO2 mixtures (50/50 v/v, to simulate a biogas with high CO2 content, to assess the effect of CO2) the catalysts needed to be active and stable; moreover, the catalyst should promote the water-gas-shift reaction under the same operative conditions, in order to increase the hydrogen concentration, decrease the CO content, and reduce the overall heat demand of the reformer.
Therefore, based on literature and partners’ experience, 16 catalyst formulations were initially proposed, with different active metals (Ni, Rh, Pt) supported on different oxides (Ce, La, Zr, Ca, Al oxides). Fresh catalysts were fully characterized with several methods. Then, all catalysts developed were tested for methane steam reforming, under representative conditions, to evaluate the initial activity. After this pre-screening phase, the catalyst formulations showing best performance were further tested over a wider operational range (1-7 bar, 400-550°C, several space velocities), for the steam reforming of the CH4/CO2 mixtures (50/50 v/v) and in durability tests (up to 250 hours-on-stream).
As a result of this process, four possible chemically active species/chemical support combinations were finally selected for the CoMETHy reactor, based on Ni(10%), Rh(1%) or Ni(10%)Pt(3%) (bimetallic) active species on CeO2 or CeZrLa oxide supports.
The catalysts selected showed high activity, allowing to obtain an output gas composition close to the equilibrium condition at Gas Hourly Space Velocity (GHSV) of 30,000 h-1. Since the contact time expected in the designed membrane rector is much higher, these results prove that, in terms of activity, the selected catalysts are suitable for CoMETHy application. These catalysts also showed good activity towards the water-gas-shift reaction, allowing an outlet CO concentration always lower than 3%vol.
Due to the importance of coke formation, this effect was better investigated and hydrogenation was identified as a possible regeneration method.
For the selected catalysts, a suitable kinetic rate expression was validated, suitable to be applied to the design and modelling of the low-temperature catalytic steam reformer.
Several catalyst formulations were proposed, developed and tested also for bioethanol steam reforming. In this case, the bimetallic catalyst Ni(10%)Pt(3%) supported on CeO2 or CeZrLa oxide was identified as the “best” option: despite the higher material cost (due to the minor Pt content) this catalyst proved to be active and stable in ethanol, methane and simulated biogas steam reforming, thus permitting to the CoMETHy reactor to work in the multi-fuel mode. In this case, the possibility to use raw bioethanol (with large water content and contaminants) was also evaluated.
A coating procedure was developed to obtain homogeneous, thin, and stable layers of the selected catalytic materials (developed in the form of powders) on the pressureless Sintered Silicon Carbide (SSiC) foam supports, without blocking the open-celled structure.
For catalytic applications the specific surface of these ceramic foams with less than 0.5 m²/g is too low. In order to give ceramic foams their catalytic properties, they need to be coated with thin layers of highly porous materials, the so called washcoat. This surface-enlarging washcoat layer is then impregnated with the effective amount of above mentioned selected catalytic materials. In this way, the ceramic foam mainly fulfils requirements like mechanical stability and high thermal conductivity, while the washcoat acts as a surface-enlarging support that enables a finely dispersion of the catalytic active particles. The effect special binders and additives was studied too in order to improve adhesion of the washcoat layers on the support material.
Hence, using the developed components, materials and procedures, several catalytic foam samples were manufactured and tested (with respect to stability and catalytic properties) to validate performances in small reactors: a parametric experimental study at different operative conditions (temperature, pressure, space velocity, etc.) was carried out to obtain relevant data for reactor design and modelling. Durability tests (up to 250 hours-on-stream) were carried out too, in order to validate the stability of the system.
In the end, the “best” combinations between catalyst formulation, foam type (SSiC solid foams with a cell density of 30 ppi and 85% total porosity) and deposition method were defined for the CoMETHy reactor. Ni(10%)/CeZrLaOx and Ni(10%)Pt(3%)/CeZrLaOx were identified as the “best” performing systems. The bimetallic Ni-Pt based catalytic foam was finally chosen for the final membrane reformer because of the good catalytic activity showed not only in methane but also in ethanol steam reforming.
Combining the heat transport model obtained with the (non-catalytic) foam, the kinetic expression obtained with the catalytic pellets and the results obtained with the small catalysed samples, it was possible to obtain a complete mathematical model of foam packed fixed bed reactor.
The developed catalysts were also assessed with respect to their performances in a “real” environment, i.e. when the gas feedstock is contaminated with typical contaminants. This is the case of catalyst poisoning due to higher hydrocarbons and/or sulfur compounds in methane/biogas feedstock, or acetaldehyde and higher alcohols in bioethanol. Results showed that methane steam reforming catalysts rapidly deactivate with few ppm of H2S. Therefore, sulfur removal units to << 1 ppm should be applied in any case in order to avoid membrane failure. Moreover, selected catalysts showed high activity towards the alkane feedstock with no apparent deactivation during the experiments. Also in-situ catalyst’s regeneration procedures were defined.
Development, characterization and selection of hydrogen separation membranes (WP3).
Different types of Palladium (Pd) based membranes were initially considered as potential option to be applied in CoMETHy reactor, with different support (ceramic or metal supports, or self-supported ones), selective layer composition (pure Pd or Pd-Ag) and selective layer deposition method (electroless plating, sputtering, roll-to-roll of Pd foils, self-supported membranes).
Considering the final design of CoMETHy membrane reformer, self-supported membranes were considered not suitable for this application because of mechanical issues, scale up implications and costs. Differently, composite membranes with a thin Pd-based layer (2-5 µm) on a porous support tube are considered as the best scale up choice.
The membranes produced by sputtering (PVD technique) did not show sufficiently dense noble metal layers: the roughness of the support significantly affected the densification, but an extra-smooth support led to peeling of effects on the selective Pd-based layer.
Initially, CoMETHy was focusing on the development of Pd-Ag membranes on asymmetrical porous stainless steel supports (APSS). Unfortunately, this development was hindered by technical issues about the preparation of the APSS support (including the intermetallic ceramic layer) with satisfactory quality for Pd-Ag deposition. Specifically, main issues were dealing with the support roughness and the defects caused by the welding procedure in the connection area between the porous tube and the solid metal ends.
As a consequence, the surface smoothness was significantly improved applying an outer compaction technique. The application of the ceramic layer (TiO2, zirconia or TiN) was also improved, introducing the film coating of ZrO2 as deposition technique and optimizing the sputtering procedure for TiN, in order to minimize peeling off and roughness. However, in both cases improvements are still necessary to obtain reliable supports.
Another required improvement on APSS supports was the reduction of defects in the connection area between the porous tube and the solid metal flanges at the end, caused by the welding procedure: the welding area between porous and non-porous metal support parts is still insufficiently smooth.
In conclusion, metal supported membranes showed not to be mature enough to be incorporated into the CoMETHy reactor. In any case, improvements to come to a hydrogen selective membrane are very promising and potentials for further improvements exist.
However, the final readiness level obtained was not satisfactory for application in the membrane reformer and further developments are necessary.
Differently, Pd membranes on a ceramic support by electroless plating were evaluated so far as the “best” option currently available for the membrane reactor. For this reason, membrane reformer prototypes constructed and tested in CoMETHy were equipped with this kind of membranes.
Despite some permeance inhibition effects (about 65%) by other mixture components (basically methane) ceramic supported membranes produced by electroless plating allowed > 20 Nm3/m2/h/bar0.5 hydrogen permeability, above the initial targets (10 Nm3/m2/h/bar0.5). Some selectivity loss (< 20%) was measured over 1,000 hours-on-stream, but still within the project targets.
Commercially available ceramic-supported Pd-based membranes were also purchased and tested for more comprehensive evaluation and benchmarking. It was concluded that the ceramic-supported Pd membranes selected and studied in CoMETHy have a good hydrogen permeance when compared to other available membranes.
Progress in the development of metal-supported membranes shows to be very promising, although it is unclear whether sputtering or electroless plating will be the most preferable deposition method: both methods have advantages and disadvantages, and the suitability of both deposition techniques on metal supports still has to be determined and is considered an essential investigation task for future projects.
Finally, membrane performance results were successfully modelled considering different effects like concentration polarization, competitive adsorption, inhibition effects, etc. The model was validated with experimental results and literature data and applied to understand the results obtained with the prototype and pilot membrane reactors developed in the project: by combining the catalyst models with the membrane transport models it is possible to obtain the integrated membrane reformer model.
Design and laboratory test of the fuel-flexible reformer (WP4).
Different design options for the molten salts heated membrane steam reformer were conceived and evaluated. The first design was based on a Multi-Stage Membrane Reformer (MSMR) where the membrane unit is separated from the catalytic bed, in a multi-stage reactor-membrane train arrangement. The second design was an Integrated Membrane Reformer (IMR) where the membrane is integrated with the catalyst bed and the molten salts heat exchanger.
Besides technical considerations, the selection of the optimal configuration depends on the final application and optimization criteria. The IMR design, also called “closed” reactor, represented a major engineering challenge in CoMETHy. On the one hand, Pd-based membranes are compliant with the reactor temperatures, so an integrated system represented an attractive choice: it is more compact and allows single-pass higher efficiency. On the other hand, challenges such as catalyst/membrane integration and thermal/mechanical integration of components needed thorough consideration and validation in innovative compact reformer prototypes.
Therefore, two IMR were assembled and tested in two dedicated test rigs. These prototypes represented the final outcome of a close cooperation between different project partners involved in the development of catalysts (WP2) and membranes (WP3), each bringing some fundamental elements specifically and jointly developed. Noteworthy, both IMR prototypes developed and tested in WP4 had cross sections with similar size and geometry than the 2 Nm3/h pilot unit developed in WP5: reactor tube inlet (or foam outlet) diameter in the range 34-41 mm and 40-43 mm in the small prototypes and pilot reactor, respectively (membrane outer diameter is always 14 mm). This allowed the study and validation of the basic mechanisms involved in the process.
In preliminary tests, catalysts and membranes developed in CoMETHy were individually studied and compared with commercial options for benchmarking.
Afterwards, both prototypes were successfully tested under representative conditions. Several experimental tests were carried out in order to determine the effect of different operating parameters, mainly the sweep gas flow rate, the steam-to-methane (S/C) feed ratio, methane feed flow rate, and the operating pressures and temperatures on the reaction and permeation zones. In this way it was possible to experimentally determine the IMR performance characteristics. Experimental results showed that methane conversion and hydrogen production rates are highly sensible to the sweep gas flow rate, permeate pressure and the feed methane flow rate. Differently, the S/C ratio has slight effect on the single-pass conversion.
The experimental results obtained in the two laboratories were qualitatively consistent, showing the reliability of the developed system.
Additionally, during the experimental campaigns, no evidence of reactor performance drop were detected over hundreds operational hours: after 8 weeks of consecutive 24 h/24 h operation, no methane conversion efficiency loss (due, for example, to catalyst deactivation) was evidenced. This result suggests the robustness of the reactor assembly and confirms the positive results previously obtained about catalyst and membrane stability over > 250 hours-on-stream.
The fuel-flexible (multi-fuel) approach was successfully proved too with feed methane/ethanol changeover over the same catalyst. Specifically, the open foam supported Pt(3%)Ni(10%)/CeO2 catalyst was applied which, as mentioned above, is active towards both methane and ethanol steam reforming. Therefore, the “multi-fuel” feature of CoMETHy reactor was successfully demonstrated, obtaining complete conversion of ethanol with CO, CO2, CH4, and H2 as the only products.
At the end of this preliminary design and experimental validation stage, it was concluded that the optimal multi-fuel design of the process is a single Integrated Membrane Reactor (IMR) equipped with the multi-fuel catalyst. In the final design a pre-reformer (i.e. a low-temperature steam reformer without membranes) was also introduced, in order to get some hydrogen concentration in the inlet gas feed to the IMR as well as to reduce thermal gradients in this section.
Mathematical models for the membrane reactor were developed to be applied as design and optimization tools, facing the key challenge to synchronize the heat transfer rate with the reaction kinetics and the hydrogen permeation through the membrane. The models developed were validated considering different aspects of the IMR (heat and mass transfer mechanisms, reaction kinetics, hydrogen permeance through the membrane, etc.) and applying the catalyst and membrane performance data obtained in WP2 and WP3 respectively.
One major conclusion is that membrane reformer’s performances are significantly affected by concentration polarization and inhibition of the membrane by other species (that can be amplified at higher pressures).
Based on the results obtained and validation of the IMR design, the detailed engineering design of the pilot steam reformer was developed.
Pilot plant construction and proof of concept (WP5).
According to the design, pilot plant components, including catalysts and membranes, were manufactured and supplied by CoMETHy partners with the defined size and geometry. Then, the pilot plant was built and commissioned at ENEA-Casaccia research centre in Rome, integrated in an existing molten salts loop using electrical heaters to simulate the Concentrating Solar Thermal (CST) plant.
The plant scheme involves two molten salts heated steam reformers connected in series: a pre-reformer and an Integrated Membrane Reformer (IMR). Both reactors are based on a shell-&-tube heat exchangers layout, with the molten salts stream flowing on the shell side.
The membrane reformer includes ten reactor tubes, each including the catalyst and the membrane. The reactor includes six gates: molten salt inlet/exit gates, feed mixture inlet, retentate exit, sweeping steam inlet and the hydrogen permeate exit ports.
The pre-reformer allows the production of a H2-containing gas mixture (roughly corresponding to thermodynamic equilibrium) leading to the following advantages on the process:
- maximizing the utilization of the membranes also at the feed inlet section on the IMR;
- minimizing the thermal stresses on the inlet section of the IMR due to high reaction rates;
- minimizing the risk of fouling of membrane and catalyst in the IMR thanks to higher hydrogen concentration.
Process steam from a steam generator is first pre-heated at the desired temperature and then split in two streams:
- sweep steam directly injected on the permeate side of the IMR;
- process steam to be mixed with the CH4 feed (from gas cylinders) and pre-heated to reactors’ inlet temperature, usually in the range 420-480°C.
The produced permeate and retentate streams are recovered and analysed after excess steam condensation. Molten salts are counter-currently flowed through the two reactors, entering firstly in the IMR reactor at the desired temperature and flow rate from the MO.S.E. plant facility at ENEA-Casaccia research center in Rome.
The pilot plant operation included a preliminary phase with the validation of start-up, shut down and stand-by strategies. The study also included an assessment of plant performances and a macroscopic analysis of the experimental results.
In total, including the start-up, stand-by and shut down stages, the plant was operated with molten salts for about 700 hours. Continuous operation of the plant was achieved for about 150 hours. During this period the plant performances were assessed under several operative conditions: molten salts inlet temperature, sweep steam flow rate and steam-to-carbon feed ratio. A macroscopic result analysis was carried out too.
Results can be summarized as follows:
- the application of the membrane reformer following a pre-reformer allows to get more than double the conversion that can be obtained with a non-membrane reformer under the same conditions;
- proof-of-concept of CoMETHy technology was successfully achieved at the pilot scale in relevant environment, obtaining up to 3.5 Nm3/h pure hydrogen production under design conditions, higher than the project quantitative target of 2.0 Nm3/h;
- > 99.8% hydrogen permeate was produced with < 100 ppm CO content and the conditions to minimize CO concentration in the permeate were identified;
- catalysts and membranes were assembled and replaced in the reactor(s) in less than 4 hours;
- no macroscopical signs of reactor performance loss were evidenced over the experimental operation period, despite the above mentioned handling of catalysts and membranes (the reactor was opened during the experimental phase) and the several switches of operative conditions;
- start-up, shut down and stand-by strategies were validated and the good practice (for full-scale plants) to keep reactor(s) “hot” during stand-by periods, by the use of molten salts as thermostatic fluid, was assessed, thus facilitating start-up and extend lifetime of components (e.g. membranes);
- the effectiveness of the WGS reaction in the reactor(s) resulted in an outlet retentate stream with low CO concentration (< 2%);
- a relatively high CO2 concentration (32-39%) was obtained in the outlet retentate stream at 9.5 bar, enhancing CO2 capture for its recovery and/or reuse, demonstrating the application of CoMETHy technology to fuels pre-combustion decarbonisation.
Techno-Economical assessment of the process (WP6).
Based on the results obtained with the pilot reformer, the best strategies to couple this reformer with a CST plant were studied and evaluated from a techno-economic perspective. Several process schemes were conceived, simulated and evaluated, under different scenarios. Specifically, decentralized and centralized solar steam reforming plant schemes (1500 and 5000 Nm3/h, respectively) were developed and evaluated. Results were compared to a conventional steam reforming process with the same capacity and scenarios, including CO2 recovery.
In general, two process options were considered:
- “full solar” steam reforming process, where the process heat is entirely provided by the CST plant, with or without electrical power co-generation;
- “hybrid” steam reforming process, where part of the process heat is provided by retentate off-gas combustion with oxygen or air, and partly by the CST plant.
In both cases, the continuous operation of the steam reforming plant is primarily ensured by means of a molten salts based heat storage system and then by a gas fired back-up heater to drive the process when the solar heat is no longer available.
For larger scale plants with hydrogen production capacity of 5,000 Nm3/h (or more) a Multi-Stage Membrane Reformer (MSMR) was considered for the evaluation, provided that this arrangement is considered more suitable for larger scale plants. However, the general conclusions of this study were not affected by the membrane reactor design type (either integrated or not).
Since the results obtained were strictly related to the economic assumptions, a sensitivity analysis was carried out too, changing different economic input parameters like the depreciation factor or unit costs of feedstock/fuel (NG), catalysts, membranes, CST plant, by-products, etc.
In general, integration of solar energy through a CST system based on molten salts in a steam reforming process seems to be a promising approach to minimize hydrogen production costs and the CO2 emitted.
Compared to conventional steam reforming processes, the solar processes developed in CoMETHy require higher initial investment costs (CAPEX) due to the rather relevant investment for the CST plant and ancillary items: the CAPEX impact on the hydrogen cost is, in most cases, > 45%, while the CAPEX impact in conventional steam reforming routes is usually < 25%. This larger CAPEX is however balanced by savings in operative costs for the feedstock and the fuel in the solar process. As a result, the overall hydrogen production cost obtained by CoMETHy solar steam reforming technology does not significantly differ from conventional routes.
In the 5,000 Nm3/h solar steam reforming schemes, hydrogen COP is within the range of 1.09-1.22 €/kg, considering a 5,000 hours/year full-solar operation. These values are rather close (< ±10% difference) to the value of 1.19 €/kg estimated for a conventional steam reforming process (i.e. without solar input) under similar assumptions (including CO2 recovery).
Considering that CoMETHy process is highly capital intensive, the impact of the annual depreciation factor was evaluated too.
After preliminary evaluation of different solar steam reforming schemes with 5,000 Nm3/h hydrogen production capacity, based on the MSMR design, a process scheme with 1,500 Nm3/h hydrogen production capacity was evaluated. In this case, the Integrated Membrane Reformer (IMR) design successfully proved in CoMETHy pilot plant was considered, and a more detailed analysis carried out.
First, the relationship between the size of the solar field, the Thermal Energy Storage (TES) capacity and the annual operational hours when the process is fully powered by solar energy was determined by increasing the number of hours/year operated with solar power the back-up fuel demand proportionally drops and the energy efficiency (produced H2 energy (LHV) divided by NG feed + fuel + power input) increases up to 80%.
Merging these results with those from the sensitivity study (by changing the economic parameters) the hydrogen production costs obtained were always within the range of 2.02-3.36 €/kg, a cost that is rather close to the one obtained in conventional steam reforming of 1.74 €/kg. The higher hydrogen production costs are mainly due to the above mentioned higher CAPEX impact (in the range of 46-58%) on COP compared to the 21% CAPEX in conventional steam reforming.
The contribution of the different cost items to the overall hydrogen production cost was identified. The CST plant represents the package with the largest impact (49%) on the total equipment cost, followed by the membrane steam reformers (23%). Therefore, a trade-off should be identified to minimize the hydrogen production costs while maintaining high the solar power impact in the process. Differently, membranes, catalysts and maintenance costs have a minor impact (< 11%) on production costs. As for the impact of feedstock and fuel (NG), different scenarios were considered, referring to the NG market price in Europe and USA.
It is noteworthy that, in CoMETHy’s “multi-fuel” approach, biogas and/or bioethanol were envisaged as feedstock too. In both cases, the biomass-derived feedstock is usually derived by low-cost refuses, but a biogas up-grading unit or a bioethanol pre-reformer should be introduced in the process, affecting the cost of the methane-rich gas effectively fed to the main membrane reformer. Therefore, the sensitivity analysis of the impact of feedstock cost will be helpful to predict also the effect of alternative fuels in the multi-fuel cases.
Potential Impact:
CoMETHy is a product-oriented project which main objective is the development of an innovative compact and modular steam reformer. As such, the potential impact of the technology developed, as well as the exploitation scenarios, can be analysed at the end of the project, when measurable and final results are available, concretely showing the outcomes of the research and of the technological activities carried out. All the starting assumptions, declared objectives and expected outcomes can be measured against concrete results. The approach to the project can thus be innovative and pioneering, and the achievements of the 4 year work can be looked through the lenses of concrete exploitation.
In the second part of this section the dissemination activities aimed at fostering the exploitation of the results are reported.
Impact of CoMETHy results
Steam reforming is the leading technology for large scale hydrogen production: today, more than 25 million tons of hydrogen per year are produced primarily by steam reforming of natural gas.
CoMETHy developed and proved a new steam reforming process characterized by several innovative features compared with the traditional route, including:
- compact layout of the reactor;
- operation at lower temperatures (< 550°C, compared to traditional SMR > 850°C);
- possibility to power the process with solar energy, reducing CO2 emissions and save primary fuel;
- flexibility of operation in terms of rapid start-up and shut down;
- flexibility of application in terms of primary fuel and feedstock to be converted to hydrogen (natural gas, biogas, bioethanol, etc.).
The reactor developed in CoMETHy is by itself the first of its kind, based on a membrane reformer and molten salts as heat transfer fluid. Moreover, new plant schemes were conceived and positively evaluated from technical and economical perspectives, adaptable to different industrial and energy scenarios, for both centralized and decentralized hydrogen production.
With these results and the activities implemented, it is noteworthy that CoMETHy contributed to achieve some of the FCH JU Programme objectives and targets dealing with “Hydrogen Production and Distribution”. In the following paragraphs it is reported how CoMETHy’s results would endorse the implementation of the FCH JU Programme and its roadmap.
Hydrogen production processes from Renewable Energy Sources.
The general strategy on hydrogen production aims at maximizing the production from Renewable Energy Sources (RES), with CO2 free (or CO2 lean) routes, in particular for the decarbonisation of transport. Specifically, the FCH JU MAIP published for 2008-2013 targeted up to 50% of the hydrogen energy supplied from RES.
CoMETHy’s reactor prototypes and pilot plant proved the feasibility of the solar steam reforming of methane, resulting in a 38-53% reduction of CO2 emissions and equivalent methane savings compared to the traditional process.
Additionally, considering the energy balance of developed Natural Gas (NG) steam reforming plant schemes developed in CoMETHy, more than 40% of total energy input in the process derives from solar heat.
Reforming of biofuels (biogas, bioethanol) was proved too, obtaining 100% renewable hydrogen.
Current strategies for future hydrogen production are chiefly focused on the exploitation of electrolysis mainly powered by renewable sources (e.g. PV and wind). This trend is supported by the growing impact of renewable sources in the electrical grid mix. However, it is important to notice that energy systems with major impact of intermittent renewable sources (e.g. PV and wind) need some extent of “predictable” back-up sources and technologies available to compensate fluctuations and satisfy power demand. In electrical power systems this is usually achieved by NG and/or biomass power plants. Similarly, in hydrogen production the back-up option can be represented by decentralized steam reforming plants powered by NG and/or renewable sources: in this context, CoMETHy offers a technological solution: the novel membrane steam reforming reactor made available by CoMETHy is expected to pave the way to new opportunities for distributed hydrogen generation, alternative to electrolysis and allowing the use of different fuels and energy sources depending on local availability.
Reduction of hydrogen production costs.
Lowering the hydrogen production costs represents a key target for hydrogen production technologies (MAIP 2008-13).
Compared to traditional steam reforming, the reduction of operating temperatures obtained allows savings in construction material costs for the reactor.
The techno-economic assessment of CoMETHy solar steam reforming technology demonstrated that the hydrogen production costs reached are close to the hydrogen production costs of traditional steam reforming processes on the 1,500-5,000 Nm3/h scale. Though, the environmental benefits and the lower impact of primary fuel cost should be considered in the balance.
Additionally, by increasing the solar energy share in the process, the cost of hydrogen is less subject to the cost of fossil source compared to the traditional process.
Development of higher performance materials.
The introduction and exploitation of higher performance materials (e.g. reforming catalysts with shift activity and membranes) represent another key target in hydrogen production technologies (MAIP 2008-13).
The catalysts developed in CoMETHy were proved to be stable over 250 hours-on-stream, with combined steam reforming and water-gas-shift activity: these steam reforming catalysts lead to CO content < 5%vol, thus avoiding the need of water gas shift reactors and reducing the reformer heat duty.
The effectiveness of the WGS reaction has also been demonstrated in the pilot reactor where < 2% CO concentration was obtained in the outlet retentate stream.
As for the membranes, solutions were identified and significant advancement has been achieved on metal supported membranes. Nevertheless, ceramic-supported palladium membranes represented an alternative option successfully demonstrated in CoMETHy up to the pilot scale. However, long-term durability of membranes needs to be further assessed in future projects
Process performances.
The FCH JU implementation plan for 2008-2013 targeted the development of steam reforming processes including CO2 capture with efficiencies > 72% for centralized production and > 67% for decentralized production from biogas (methane).
CoMETHy process evaluations and experimental results lead to steam reforming thermal efficiency in the range of 68-80% (produced H2 thermal power, LHV, divided by feed + fuel + thermal power input) for a 1,500 Nm3/h methane steam reforming plant (decentralized production) including CO2 capture.
Simplification of the plant and the process.
The FCH JU implementation plan published in 2010 called for a simplification of reformer design in terms of compactness and scalability (2 to 750 Nm3/h hydrogen production rate). Additionally, catalyst replacement should be easily achieved in < 4 hours (AIP 2010).
In CoMETHy a highly compact reactor has been developed and demonstrated, with steam reforming, water-gas shift and hydrogen separation achieved in a single unit. The use of a liquid heat carrier like molten salts (with high heat capacity per unit volume) allows further reduction of reformer volumes compared to conventional furnaces. The concept has been proved with a pilot plant producing from 1.5 to more than 3.5 Nm3/h of pure hydrogen.
Modular and scalable reactor designs were conceived. The shell-and-tube heat exchanger configuration will ease scalability from the 2 Nm3/h (as in the pilot unit experimentally proved in CoMETHy) to 1,500 Nm3/h or more: increasing or decreasing the number of tubular reactors and membranes is enough to obtain different plant sizes. An alternative “multi-stage” (or “one”) configuration has been designed too, suitable for larger scale applications.
Therefore, CoMETHy technology could be applied in small-medium-large scales and the reformer used in various operational fields, from an industrial plant to produce large amount of hydrogen to decentralized small users.
As for the reactor maintenance, in CoMETHy it has been demonstrated the replaceability of catalysts and membranes in the reactor(s) in less than 4 hours, thus achieving another specific target set by the FCH JU in the field of hydrogen production.
Socio-economic impact.
The success of CoMETHy process will support the opening of new industrial production lines in the fields of advanced catalyst systems, hydrogen separation membranes, new reactor and chemical technologies and new concentrating solar power applications.
The worldwide growth of the “green economy”, with the actual implementation of the FCH JU plan up to market penetration of developed technologies and the wide application scenarios for steam reforming, will result in a socio-economic impact: CoMETHy proposes new products and solutions well aligned with the common strategies on sustainable development, thus supporting job creation, energy safety and welfare.
Exploitation of CoMETHy results
The foregrounds generated in CoMETHy potentially pave the way to different exploitation scenarios, mainly thanks to the inherent innovation proposed by the technology.
In general, the steam reforming technology developed in CoMETHy is considered innovative compared to the state of the art for different reasons.
First of all, the adoption of a multi-fuel approach, i.e. the possibility to convert either methane (concentrated or mixed with CO2) or bioethanol in the same reactor, is by itself a new concept.
Moreover, a new solar steam reforming process has been conceived and successfully proved, featured by the use of molten salts as heat transfer fluid from the CST plant and solar heat storage medium. Indeed, solar reforming has been studied in previous projects, using solar-receiver reactors directly heated by the concentrated solar radiation, with full-solar operation limited to 2,000 hours/year. In CoMETHy, the application of CST molten salts technology with thermal storage allows to increase the full-solar operation of the reformer to > 4,000 hours/year. In this way it is possible to maximize the utilization of the solar thermal power.
Furthermore, a new knowledge has been generated in the development of structured heterogeneous catalysts with enhanced heat transfer properties and reduced pressure drops. Some advancement has been achieved also in the production of SS-supported Pd-based membranes, although further research and development is needed to obtain a reliable product.
The exploitable foreground generated in a RTD project like CoMETHy in most cases consists of a “general advancement of knowledge”, and RTD results are not considered ready for commercial exploitation, yet. To measure such knowledge advancement, it is convenient to use the Technology Readiness Level (TRL). In terms of TRL, CoMETHy has taken a technology concept initially formulated with basic studies (corresponding to TRL = 2) to demonstration of the technology in relevant environment (TRL = 6). Demonstration and qualification in a full-scale operational (industrial) environment (TRL = 7 up to 8) is still needed before commercial exploitation. Therefore, despite the successful results, this innovative technology is not ready for market penetration, yet: further work would be needed to further develop and test the knowledge generated in a follow-up demonstration project (in a real industrial and end-user context) to get to the market stage.
CoMETHy follow up opportunities, exploitable foreground and the exploitation lines were widely discussed between project partners during the final project meeting (December 2015). Some conclusions of this analysis are summarized in the following paragraphs.
Application of developed new materials and components.
Some components studied and developed in CoMETHy, such as structured (open foam) catalysts, hydrogen separation membranes, integrated membrane reactors, etc., can lead to potential spin-off for advanced component manufacturing (catalysts, membranes, hydrogen purification units, reactor assembly, heat recovery units, etc.) and engineering.
This is the case of structured open foam catalysts, developed specifically for low-temperature steam reforming of methane and/or ethanol. This catalyst is characterized by enhanced heat transfer, minor pressure drops, and the capability to simultaneously promote steam reforming and water-gas-shift reactions in the temperature range of 400-550°C. This has been positively proved in several tests in CoMETHy, so it can be commercially exploited, provided that the performances are validated over longer times on stream (> 1,000 hours).
Considerable effort has been addressed to palladium based membranes on porous metal supports. Significant advancement has been achieved, specifically on the porous metal substrate quality and the deposition of the inter-metallic ceramic barrier layer. Nevertheless, further RTD activities are required to obtain a reliable product. Therefore, the knowledge generated in CoMETHy can foster next RTD projects aimed to launch this new product on the market.
Application of CoMETHy reactor concept.
In CoMETHy, two different membrane reformer designs were developed: Integrated Membrane Reformer (IMR) and non-integrated Multi-Stage Membrane Reformer (MSMR).
The IMR design, also called “closed” reactor, represented a major engineering challenge. It has been successfully proved up to the pilot scale in a representing unique prototype of this kind, heated by molten salts up to 550°C. All project partners participated to the development of this reactor. Before commercial exploitation, it is necessary to validate the performances over longer operational periods (> 1,000 hours).
The MSMR design, also called “open” reactor, has been evaluated to be most suitable for larger scale applications (> 5,000 Nm3/h hydrogen production). This reactor layout has been designed but not experimentally proved in CoMETHy.
Application of CoMETHy solar steam reforming process.
After the experimental validation of CoMETHy technology at the pilot scale, different process schemes have been developed and evaluated from the techno-economical perspective, considering different scenarios and plant capacity (1,500 and 5,000 Nm3/h hydrogen production). Moreover, the strategies and best practices to couple the steam reforming plant with the Concentrating Solar Thermal (CST) plant have been identified, showing the competitiveness of the developed process with conventional steam reforming routes.
Application of CoMETHy multi-fuel reformer for decentralized hydrogen production.
Besides the possibility to power the steam reforming process by solar energy, other process schemes have been developed in CoMETHy for distributed hydrogen production.
Based on the solar reforming scheme, mostly suitable for medium-large scale applications (> 1,500 Nm3/h production scale) an “autothermal” process has been developed for smaller scales (e.g. 750 Nm3/h), for example for refuelling stations. In this case, CoMETHy reformer can be applied to hydrogen production from natural gas or biogas, using the residual heat value of the retentate stream to sustain the process. It is noteworthy that this small reformer would be the first commercial product of this kind in Europe.
Furthermore, a process to convert bioethanol to hydrogen has been developed, with the same multi-fuelled membrane reformer as above, but with the pre-reformer to convert the diluted ethanol to methane before feeding the membrane reformer. Considering the multi-fuel feature of the reformer, this approach allows a full renewable back up of the gas fuel reformer, to “on demand” allow hydrogen generation.
Possible exploitation burdens and limitations.
In assessing the exploitation potentials of the technology developed, possible burdens should be also taken into account.
Intellectual Property (IP) issues do not represent a significant limitation to the diffusion of the developed technology. Clearly, CoMETHy is a product-oriented RTD project with a deep industrial footprint and a specific know-how was developed in the project. CoMETHy partners obtained the necessary skills to implement further technical projects. Otherwise, the exploitation can pass through technology transfer from CoMETHy partners to final users. In any case, the developed know-how can be transferred to support its wide diffusion.
As far as the technology maturity and readiness is concerned, CoMETHy reactor has been successfully proved at the pilot scale, but for a limited number of operational hours. In order to validate the technology, the process performance over a longer operation time (> 1,000 hours), would be necessary.
As for the application scenarios, different exploitation cases have been investigated in CoMETHy and some limitations identified: the wide exploitation of solar reforming is limited to countries with satisfactory solar radiation intensity for the convenient installation of CSP plants, i.e. those belonging to the so-called “sun-belt”. Additionally, according to CoMETHy results, the solar reforming route is applicable for reforming plant scales of 1,500 Nm3/h or more. Although this minimum solar reforming plant size can still be considered for distributed hydrogen production, at least 20,000-30,000 m2 area should be available nearby the plant to allocate the solar collectors. This can represent a limitation for the implementation of the technology in some cases (e.g. for refuelling stations in urban areas). For more decentralized applications (< 1,500 Nm3/h) the non-solar CoMETHy process can be applied, either for methane, biogas and/or bioethanol steam reforming. In this last case, the low-temperature steam reforming technology developed in CoMETHy will compete with alternative small reforming technologies like compact autothermal reformers.
Future developments.
Considering the technical success of the project and the Technology Readiness Level achieved, CoMETHy partners agreed to carry out follow-up activities at the demonstration level, as detailed below.
First, the pilot plant constructed in CoMETHy can be further used, with some adaptations, in new projects aimed at consolidating results and paving the way for the commercial exploitation of the technology, for example:
- Plant performance analysis for longer periods (> 1,000 hours).
- Bio-ethanol steam reforming tests.
- Plant integration with CO2 separation membranes and recirculation of the residual H2/CH4 from the retentate to the membrane reactor.
- Support a demonstration project with a preliminary test campaign to test the plant under specific representative working conditions useful for the design.
Otherwise, new demonstration plants to prove the technology in real industrial or end-user’s environment can be built.
A first option (for non-solar CoMETHy reformer) is the installation of the methane/biogas steam reformer in a “biomass-to-hydrogen” context, in the framework of a demonstration project, possibly directly coupled to a fermentation plant and biogas clean-up unit. In this case, the reformer would not necessarily be powered by a CSP plant, but the “autothermal” layout is most likely to be used. Additionally, the membrane reformer can be combined with a dry reformer, operating at higher temperatures (usually > 650°C) as pre-reformer: CoMETHy membrane reformer will complete the conversion of bio-methane to pure hydrogen. A small scale methane/bioethanol steam reformer (eventually in the multi-fuel configuration) can also be integrated in a hydrogen refuelling station.
An interesting perspective is the application of the solar steam reforming process to ammonia plants. Ammonia synthesis plants require large amount of pure hydrogen usually produced by Natural Gas (NG) steam reforming. A project can be implemented integrating the CoMETHy solar methane steam reforming technology with an ammonia plant in a “sun belt” region. The advantage of this approach lays in the replacement of conventional reforming with a solar reformer (> 40% savings in methane consumption and CO2 emissions during solar operation) combined with the possibility to use nitrogen as sweep gas in the reactor in order to directly produce the H2/N2 feed mixture for ammonia synthesis, thus saving the sweeping steam generation.
It is possible that CoMETHy reformer prototypes will also find applications integrated in more complex process schemes. This is the case, for example, of refinery processing where heat is available for recovery at 500-600°C.
Finally, CoMETHy reformer can be applied to maximize hydrogen recovery from partially converted syngas streams produced in higher temperature reforming units.
Dissemination activities
Dissemination activities undertaken from the beginning and beyond the end of the project represent a tool to boost exploitation potential and identify new scenarios, perspectives and stakeholders.
CoMETHy results have been presented in several international journals, conferences and workshops dealing with chemical reactor engineering, membrane reactors, renewable energy, hydrogen production, etc.
Two international workshops have been organized in cooperation with other 7FP projects dealing with palladium membranes and membrane reactors in November 2012 (Italy) and November 2014 (the Netherlands). The two workshops gathered world players in this field. Booklets have been produced and distributed after the events.
In October 2013 a summer school titled “Engineering of membrane reactors for the process industry” has been organized with several CoMETHy lectures; during the same period, a CoMETHy session has been organized within the PRES’13 Conference in Rhodes.
Moreover, CoMETHy results have been widely presented in tens of papers published in international peer reviewed journals and conference proceedings.
It is planned to continue dissemination actions beyond the end of the project in order to promote the exploitation of the developed technology: dissemination actions planned after the end of the project will mainly look for the exploitation of results, outlining the potentials of CoMETHy based applications, with an “end-user” oriented message. Furthermore, the pilot plant operated during the final project year at the ENEA-Casaccia research center in Rome has been visited by several groups, and will be available for external visitors to show the developed technology.
The target group comprises potential stakeholders, developers and potential end-users of the technology developed, who have been identified among those who have already been in contact with the project, such as participants to dissemination events, components’ producers and scientific and technological partners internal and external to the project as well as newly identified final users.
In general, CoMETHy stakeholders, developers and end-users belong to the following focus areas: renewable energy, hydrogen production, fuel cells, hydrogen refuelling, CSP, solar fuels, pre-combustion decarbonisation, NG pipeline, catalysis, hydrogen purification, process intensification, etc. End-users and developers together draw the picture of a potential production chain, getting the innovation to the market/to a further development step.
List of Websites:
www.comethy.enea.it
An innovative technology for hydrogen production has been developed in the project CoMETHy (Compact Multi-fuel Energy To Hydrogen converter), co-financed by the European Fuel Cells and Hydrogen Joint Undertaking (FCH JU) and coordinated by ENEA.
The Project, started in December 2011 and concluded in December 2015, has seen 12 organisations between Industries, Research Centres and Universities cooperating in an excellent collaborative environment: ENEA (Italy), Processi Innovativi Srl (Italy), Acktar Ltd. (Israel), Technion (Israel), Fraunhofer Institute (Germany), University of Salerno (Italy), CERTH (Greece), Aristotle University of Thessaloniki (Greece), University “La Sapienza” (Italy), ECN (the Netherlands), GKN Sinter Metals Engineering GmbH (Germany) and University “Campus Bio Medico” (Italy).
The technology developed in CoMETHy allows to combine different types of energy sources, like solar, biomass and fossil fuels, to produce pure hydrogen for various applications, permitting to adapt hydrogen production to the locally available energy mix.
The system has been based on the steam reforming process, a widespread hydrogen production method, which has been revised to exploit renewable energy: the main aim has been to power the process with an energy vector that today is widely used to capture, store and dispatch solar heat in Concentrating Solar plants, i.e. a mixture of molten salts. This fluid, often called “solar salt”, has several outstanding positive features including low cost, high heat transfer/storage capacity and minor implications about environmental and safety issues and toxicity.
The steam reforming process has been specifically tailored and re-designed to be combined with Concentrating Solar plants using “solar salts”: a “low-temperature” steam reforming reactor was developed, operating at temperatures up to 550°C, much lower than the traditional process (usually > 850°C). This result was obtained after extensive research, going from the development of basic components (catalysts and membranes) to their integration in an innovative membrane reformer heated with molten salts, where both hydrogen production and purification occurred in a single stage.
Besides the high degree of compactness, the device developed is also highly flexible as far as the feedstock to be converted to hydrogen is concerned, which can be either clean methane (e.g. from natural gas) or a biomass-derived fuel such as clean biogas (methane/CO2 mixtures) or bioethanol. The steam reforming technology developed in CoMETHy allows for an easy changeover of both the feedstock and the external heat source (solar or fossil/biomass back up) whereas start-up, stand-by and shut-down operations are eased.
The reactors developed in CoMETHy were successfully tested with different prototypes, one of which realized up to the pilot scale (3.5 Nm3/h hydrogen production) and integrated in a molten salt loop, allowing to prove the concept developed and to reach performance figures above the initial targets.
In conclusion, with the input of solar energy, CoMETHy technology allows to substantially save primary fuels and reduce CO2 emissions in hydrogen production (compared to traditional reforming technology), in a process evaluated to be economically attractive for both decentralized (1500 Nm3/h) and centralized (> 5000 Nm3/h) plant schemes. Furthermore, CoMETHy successfully proved a solar reforming process aided by concentrating solar plants using mature thermal energy storage system to increase plant utilization compared to the directly heated solar reformers proposed in the past. Additional advantages would be obtained by the use of biomass-derived feedstocks, including CO2 capture and re-use.
Project Context and Objectives:
CoMETHy (Compact Multi-fuel Energy To Hydrogen converter) is a product-oriented project, which main objective is the development of an innovative compact and modular steam reformer to convert reformable fuels (methane, ethanol, etc.) to pure hydrogen, adaptable to several heat sources (solar, biomass, fossil, etc.) depending on the locally available energy mix.
The system developed within the project is characterized by a high degree of flexibility, both in terms of:
1) the feedstock that is converted to hydrogen;
2) the primary energy source that powers the energy demanding process.
It is clear that the general strategy for hydrogen production is focused on water (or steam) electrolysis powered by Renewable Energy Sources (RES). However, in this scenario, reliable and flexible thermochemical processes can represent complementary hydrogen back up source, especially if the RES input in the process is still high, as proposed in CoMETHy.
The project logo recalls the general concept of the project: combining different sources, depending on the locally available energy mix, to produce hydrogen as the unique output energy vector. The different colours in the left hand side of the picture represent the different combined energy and material resources: solar radiation, biomass, and two reformable molecules of methane (bio-methane or natural gas) and ethanol (bio-ethanol); a water droplet is represented too, in order to recall that CoMETHy is focused on the steam reforming technology and that water is a feedstock converted to hydrogen (half hydrogen produced from water). The circular arrow indicates that all these energy sources are combined together and that most of them are “renewable” and contribute to the production of a single product on the right hand side of the picture: “hydrogen”.
The technology developed in CoMETHy will support in particular the decentralized hydrogen production (i.e. close to the end-user) thus surmounting the actual lack (and costs) of a reliable hydrogen distribution pipeline and infrastructure (distribution, storage, logistics and charging facilities). Besides, solar steam reforming technology is an attracting process route also for centralized hydrogen production plants in countries with satisfactory solar radiation rates, like those belonging to the so-called “sun-belt” (which also includes the Mediterranean area).
CoMETHy proposes a new “low-temperature” steam reforming technology, where a molten salt (molten nitrates mixture) at maximum temperatures of 550°C is used as heat transfer fluid. This concept allows the supply of the process heat to the reformer as recovered from different heat sources like Concentrating Solar Thermal (CST) plants. The hydrogen produced is separated and purified by means of selective membranes.
More in detail, the general process scheme involves main heat collection from a Concentrating Solar Thermal (CST) plant and heat transfer to the thermochemical (steam reforming) plant. The heat transfer fluid is represented by the so-called “solar salt”, i.e. the molten salt mixture NaNO3/KNO3 (60/40 w/w) commonly used in commercial CSP plants as thermal storage medium and, in some cases, as heat transfer fluid up to 565°C. A suitable heat storage system, based on the use of the solar salt mixture, allows a mismatch between the fluctuating solar source and the often steady running chemical plant: in principle, this makes possible to drive the thermochemical plant at steady state, regardless of the effective instantaneous availability of the solar radiation, even overnight and during cloudy periods.
Selective membranes allow recovery of high-grade hydrogen and increase conversion despite the relatively low operating temperatures. In the low-temperature steam reformer the catalyst and the operating conditions also enhance the Water-Gas-Shift (WGS) reaction in a single step with the main steam reforming reaction: therefore, compared to conventional steam reforming at higher temperatures (> 850°C), the overall heat duty of the reformer will be reduced and the outlet retentate (non-permeate) stream will contain a low CO content (< 10%vol.). After cooling and CO2 separation, the residual H2/CH4 stream from the reactor can be recycled to the reformer. In this way, when the thermochemical plant is powered by solar heat, in principle, there will be no combustion in the whole process, nor combustion generated CO2-containing flue gases emitted to the atmosphere: this will result in a substantial reduction, from 40% to more than 50%, of fuel consumption and CO2 emissions, compared to the conventional route.
It is worth to be noted that the capture and recovery of the CO2 produced is also enhanced due to its relatively high concentration in the outlet process stream. Moreover, when bio-fuels (biogas, bioethanol, etc.) are used as feedstock in the membrane reformer, totally green hydrogen production is achieved. Alternatively, the residual H2/CH4 stream can be used as back up fuel when the solar power is not available.
The molten salt stream provides the process heat to the steam reformer, steam generator, feed pre-heating, etc. Methane, either natural gas or biogas, and bioethanol were studied as feedstock in a multi-fuel approach: CoMETHy aims at supporting the transition from a fossil-based to a renewable-based energy economy, providing a flexible technology for different energy scenarios.
The technology developed in CoMETHy leads to potential benefits also on hydrogen production costs, operational flexibility and environment impact. Materials cost is reduced by operating at less than 550°C, and additional process units, such as water-gas-shift reactor(s) and hydrogen purifiers, avoided by the integration with membranes.
The first challenge to be faced in the development of this technology was the development of advanced low-temperature steam reforming catalysts and cost-effective selective membranes in the reference operational range (400-550°C, 1-10 bar). The subsequent technical challenge was related to the coupling of the membrane with the catalyst in a membrane reactor. Finally, the project involved the integration of the membrane reformer in a molten salts loop for proof-of-concept at the 2 Nm3/h hydrogen production scale, and the techno-economical assessment of the whole system.
CoMETHy Work Plan was divided in 5 RTD work packages (WPs 2 to 6) each including several tasks and subtasks contributing to the achievement of specific project milestones. The first project stage was mainly focused on the development of the two key components of the reformer, i.e. the catalyst (WP2) and the membrane (WP3) to provide basic recommendations about the catalyst system and the membrane to be applied (Milestones 1 and 2, respectively). These activities represented an input to the reformer design (Milestone 3) and validation (WP4), a main activity carried out during the second project year. After construction of the 2 Nm3/h prototype, the final project period was mostly dedicated to the proof-of-concept (WP5, Milestones 5) and to the optimization and evaluation of the whole system (WP6, Milestones 6 and 7, respectively). In the perspective of a multi-fuel application, the identification of specific catalysts for bioethanol steam reforming was required too (Milestone 4).
It is noteworthy that the activities carried out in CoMETHy and the results obtained contributed to achieve the following FCH JU targets about hydrogen production:
- Maximizing hydrogen production from Renewable Energy Sources (RES), with CO2 free (or CO2 lean) routes, specifically for the decarbonisation of transport (with up to 50% of the hydrogen energy supplied from RES).
- Lowering the hydrogen production costs.
- Introducing and exploiting of higher performance materials (e.g. reforming catalysts with shift activity and membranes).
- Developing steam reforming processes with efficiencies > 72% (including CO2 capture) for centralized production, and > 67% for decentralized production from biogas (methane).
- Simplifying the reformer design in terms of compactness and scalability (2 to 750 Nm3/h hydrogen production rate) and enhance catalyst replacement in less than 4 hours.
Project Results:
Development of new structured, open foam catalysts (WP2).
Fuel-flexible structured catalysts were first developed for the “low-temperature” (<550°C) steam reforming of methane (natural gas or biogas-like methane/CO2 mixtures) and bioethanol. The catalysts developed are characterized by minor pressure drops, enhanced heat transfer, and the ability to simultaneously promote steam reforming and water gas shift reactions.
In order to optimize the performance of the membrane reformer, ceramic foams were considered as support material for catalysts in the compact steam reformer at 400-550°C. In particular, ceramic foams were specifically developed and adjusted to the requirements of the steam reforming process:
- High radial heat transport in the packed bed reactor: especially in low-temperature steam reforming, thermal gradients should be minimized to avoid temperature performance loss due to low reaction rates in the coldest parts of the catalyst bed.
- Low pressure drop: especially in a membrane reactor, pressure drops should be minimized to maximize the hydrogen flow through the membrane.
- High surface-to-volume ratio to reach a high catalyst loading.
The above properties of the foam are substantially influenced by its macro- and micro-structural properties like type of material, porosity (ceramic content), cell size and cell porosity. Therefore, hundreds of open-celled foam sample were developed and manufactured to be characterized, coated with the catalytic material(s) and then tested in the reformers (in WP2, WP4 and WP5).
The manufacturing process was adapted and expanded in order to obtain the open foam specifications desired, identified as the best compromise between thermal conductivity, high surface for catalyst deposition, pressure drop and for the application of the slurry washcoating method.
The structure and different types of porosity of ceramic foams were characterized in detail by using special light microscopic measurement techniques.
In order to minimize the heat transfer resistance to the reactor wall, foams with different variations of the external cylindrical surface were produced and evaluated too.
Non-catalytic monolithic foam samples with different materials and geometry were experimentally tested to determine relevant heat transport pressure drop characteristics and a mathematical model for heat transport in open cell solid foams was developed
Catalytic materials to be coated on the open foam supports had to be identified.
Initially, an extensive state-of-the-art review on steam reforming catalysts at 400-550°C was made. Based on this, a review paper was published in the International Journal of Hydrogen Energy with the title “State-of-the-art Catalysts for CH4 Steam Reforming at Low Temperature” (ref.: Int. J. Hydrogen Energy, 2014, vol.39 p.1979-1997).
For the steam reforming at 400-550°C of pure methane and CH4/CO2 mixtures (50/50 v/v, to simulate a biogas with high CO2 content, to assess the effect of CO2) the catalysts needed to be active and stable; moreover, the catalyst should promote the water-gas-shift reaction under the same operative conditions, in order to increase the hydrogen concentration, decrease the CO content, and reduce the overall heat demand of the reformer.
Therefore, based on literature and partners’ experience, 16 catalyst formulations were initially proposed, with different active metals (Ni, Rh, Pt) supported on different oxides (Ce, La, Zr, Ca, Al oxides). Fresh catalysts were fully characterized with several methods. Then, all catalysts developed were tested for methane steam reforming, under representative conditions, to evaluate the initial activity. After this pre-screening phase, the catalyst formulations showing best performance were further tested over a wider operational range (1-7 bar, 400-550°C, several space velocities), for the steam reforming of the CH4/CO2 mixtures (50/50 v/v) and in durability tests (up to 250 hours-on-stream).
As a result of this process, four possible chemically active species/chemical support combinations were finally selected for the CoMETHy reactor, based on Ni(10%), Rh(1%) or Ni(10%)Pt(3%) (bimetallic) active species on CeO2 or CeZrLa oxide supports.
The catalysts selected showed high activity, allowing to obtain an output gas composition close to the equilibrium condition at Gas Hourly Space Velocity (GHSV) of 30,000 h-1. Since the contact time expected in the designed membrane rector is much higher, these results prove that, in terms of activity, the selected catalysts are suitable for CoMETHy application. These catalysts also showed good activity towards the water-gas-shift reaction, allowing an outlet CO concentration always lower than 3%vol.
Due to the importance of coke formation, this effect was better investigated and hydrogenation was identified as a possible regeneration method.
For the selected catalysts, a suitable kinetic rate expression was validated, suitable to be applied to the design and modelling of the low-temperature catalytic steam reformer.
Several catalyst formulations were proposed, developed and tested also for bioethanol steam reforming. In this case, the bimetallic catalyst Ni(10%)Pt(3%) supported on CeO2 or CeZrLa oxide was identified as the “best” option: despite the higher material cost (due to the minor Pt content) this catalyst proved to be active and stable in ethanol, methane and simulated biogas steam reforming, thus permitting to the CoMETHy reactor to work in the multi-fuel mode. In this case, the possibility to use raw bioethanol (with large water content and contaminants) was also evaluated.
A coating procedure was developed to obtain homogeneous, thin, and stable layers of the selected catalytic materials (developed in the form of powders) on the pressureless Sintered Silicon Carbide (SSiC) foam supports, without blocking the open-celled structure.
For catalytic applications the specific surface of these ceramic foams with less than 0.5 m²/g is too low. In order to give ceramic foams their catalytic properties, they need to be coated with thin layers of highly porous materials, the so called washcoat. This surface-enlarging washcoat layer is then impregnated with the effective amount of above mentioned selected catalytic materials. In this way, the ceramic foam mainly fulfils requirements like mechanical stability and high thermal conductivity, while the washcoat acts as a surface-enlarging support that enables a finely dispersion of the catalytic active particles. The effect special binders and additives was studied too in order to improve adhesion of the washcoat layers on the support material.
Hence, using the developed components, materials and procedures, several catalytic foam samples were manufactured and tested (with respect to stability and catalytic properties) to validate performances in small reactors: a parametric experimental study at different operative conditions (temperature, pressure, space velocity, etc.) was carried out to obtain relevant data for reactor design and modelling. Durability tests (up to 250 hours-on-stream) were carried out too, in order to validate the stability of the system.
In the end, the “best” combinations between catalyst formulation, foam type (SSiC solid foams with a cell density of 30 ppi and 85% total porosity) and deposition method were defined for the CoMETHy reactor. Ni(10%)/CeZrLaOx and Ni(10%)Pt(3%)/CeZrLaOx were identified as the “best” performing systems. The bimetallic Ni-Pt based catalytic foam was finally chosen for the final membrane reformer because of the good catalytic activity showed not only in methane but also in ethanol steam reforming.
Combining the heat transport model obtained with the (non-catalytic) foam, the kinetic expression obtained with the catalytic pellets and the results obtained with the small catalysed samples, it was possible to obtain a complete mathematical model of foam packed fixed bed reactor.
The developed catalysts were also assessed with respect to their performances in a “real” environment, i.e. when the gas feedstock is contaminated with typical contaminants. This is the case of catalyst poisoning due to higher hydrocarbons and/or sulfur compounds in methane/biogas feedstock, or acetaldehyde and higher alcohols in bioethanol. Results showed that methane steam reforming catalysts rapidly deactivate with few ppm of H2S. Therefore, sulfur removal units to << 1 ppm should be applied in any case in order to avoid membrane failure. Moreover, selected catalysts showed high activity towards the alkane feedstock with no apparent deactivation during the experiments. Also in-situ catalyst’s regeneration procedures were defined.
Development, characterization and selection of hydrogen separation membranes (WP3).
Different types of Palladium (Pd) based membranes were initially considered as potential option to be applied in CoMETHy reactor, with different support (ceramic or metal supports, or self-supported ones), selective layer composition (pure Pd or Pd-Ag) and selective layer deposition method (electroless plating, sputtering, roll-to-roll of Pd foils, self-supported membranes).
Considering the final design of CoMETHy membrane reformer, self-supported membranes were considered not suitable for this application because of mechanical issues, scale up implications and costs. Differently, composite membranes with a thin Pd-based layer (2-5 µm) on a porous support tube are considered as the best scale up choice.
The membranes produced by sputtering (PVD technique) did not show sufficiently dense noble metal layers: the roughness of the support significantly affected the densification, but an extra-smooth support led to peeling of effects on the selective Pd-based layer.
Initially, CoMETHy was focusing on the development of Pd-Ag membranes on asymmetrical porous stainless steel supports (APSS). Unfortunately, this development was hindered by technical issues about the preparation of the APSS support (including the intermetallic ceramic layer) with satisfactory quality for Pd-Ag deposition. Specifically, main issues were dealing with the support roughness and the defects caused by the welding procedure in the connection area between the porous tube and the solid metal ends.
As a consequence, the surface smoothness was significantly improved applying an outer compaction technique. The application of the ceramic layer (TiO2, zirconia or TiN) was also improved, introducing the film coating of ZrO2 as deposition technique and optimizing the sputtering procedure for TiN, in order to minimize peeling off and roughness. However, in both cases improvements are still necessary to obtain reliable supports.
Another required improvement on APSS supports was the reduction of defects in the connection area between the porous tube and the solid metal flanges at the end, caused by the welding procedure: the welding area between porous and non-porous metal support parts is still insufficiently smooth.
In conclusion, metal supported membranes showed not to be mature enough to be incorporated into the CoMETHy reactor. In any case, improvements to come to a hydrogen selective membrane are very promising and potentials for further improvements exist.
However, the final readiness level obtained was not satisfactory for application in the membrane reformer and further developments are necessary.
Differently, Pd membranes on a ceramic support by electroless plating were evaluated so far as the “best” option currently available for the membrane reactor. For this reason, membrane reformer prototypes constructed and tested in CoMETHy were equipped with this kind of membranes.
Despite some permeance inhibition effects (about 65%) by other mixture components (basically methane) ceramic supported membranes produced by electroless plating allowed > 20 Nm3/m2/h/bar0.5 hydrogen permeability, above the initial targets (10 Nm3/m2/h/bar0.5). Some selectivity loss (< 20%) was measured over 1,000 hours-on-stream, but still within the project targets.
Commercially available ceramic-supported Pd-based membranes were also purchased and tested for more comprehensive evaluation and benchmarking. It was concluded that the ceramic-supported Pd membranes selected and studied in CoMETHy have a good hydrogen permeance when compared to other available membranes.
Progress in the development of metal-supported membranes shows to be very promising, although it is unclear whether sputtering or electroless plating will be the most preferable deposition method: both methods have advantages and disadvantages, and the suitability of both deposition techniques on metal supports still has to be determined and is considered an essential investigation task for future projects.
Finally, membrane performance results were successfully modelled considering different effects like concentration polarization, competitive adsorption, inhibition effects, etc. The model was validated with experimental results and literature data and applied to understand the results obtained with the prototype and pilot membrane reactors developed in the project: by combining the catalyst models with the membrane transport models it is possible to obtain the integrated membrane reformer model.
Design and laboratory test of the fuel-flexible reformer (WP4).
Different design options for the molten salts heated membrane steam reformer were conceived and evaluated. The first design was based on a Multi-Stage Membrane Reformer (MSMR) where the membrane unit is separated from the catalytic bed, in a multi-stage reactor-membrane train arrangement. The second design was an Integrated Membrane Reformer (IMR) where the membrane is integrated with the catalyst bed and the molten salts heat exchanger.
Besides technical considerations, the selection of the optimal configuration depends on the final application and optimization criteria. The IMR design, also called “closed” reactor, represented a major engineering challenge in CoMETHy. On the one hand, Pd-based membranes are compliant with the reactor temperatures, so an integrated system represented an attractive choice: it is more compact and allows single-pass higher efficiency. On the other hand, challenges such as catalyst/membrane integration and thermal/mechanical integration of components needed thorough consideration and validation in innovative compact reformer prototypes.
Therefore, two IMR were assembled and tested in two dedicated test rigs. These prototypes represented the final outcome of a close cooperation between different project partners involved in the development of catalysts (WP2) and membranes (WP3), each bringing some fundamental elements specifically and jointly developed. Noteworthy, both IMR prototypes developed and tested in WP4 had cross sections with similar size and geometry than the 2 Nm3/h pilot unit developed in WP5: reactor tube inlet (or foam outlet) diameter in the range 34-41 mm and 40-43 mm in the small prototypes and pilot reactor, respectively (membrane outer diameter is always 14 mm). This allowed the study and validation of the basic mechanisms involved in the process.
In preliminary tests, catalysts and membranes developed in CoMETHy were individually studied and compared with commercial options for benchmarking.
Afterwards, both prototypes were successfully tested under representative conditions. Several experimental tests were carried out in order to determine the effect of different operating parameters, mainly the sweep gas flow rate, the steam-to-methane (S/C) feed ratio, methane feed flow rate, and the operating pressures and temperatures on the reaction and permeation zones. In this way it was possible to experimentally determine the IMR performance characteristics. Experimental results showed that methane conversion and hydrogen production rates are highly sensible to the sweep gas flow rate, permeate pressure and the feed methane flow rate. Differently, the S/C ratio has slight effect on the single-pass conversion.
The experimental results obtained in the two laboratories were qualitatively consistent, showing the reliability of the developed system.
Additionally, during the experimental campaigns, no evidence of reactor performance drop were detected over hundreds operational hours: after 8 weeks of consecutive 24 h/24 h operation, no methane conversion efficiency loss (due, for example, to catalyst deactivation) was evidenced. This result suggests the robustness of the reactor assembly and confirms the positive results previously obtained about catalyst and membrane stability over > 250 hours-on-stream.
The fuel-flexible (multi-fuel) approach was successfully proved too with feed methane/ethanol changeover over the same catalyst. Specifically, the open foam supported Pt(3%)Ni(10%)/CeO2 catalyst was applied which, as mentioned above, is active towards both methane and ethanol steam reforming. Therefore, the “multi-fuel” feature of CoMETHy reactor was successfully demonstrated, obtaining complete conversion of ethanol with CO, CO2, CH4, and H2 as the only products.
At the end of this preliminary design and experimental validation stage, it was concluded that the optimal multi-fuel design of the process is a single Integrated Membrane Reactor (IMR) equipped with the multi-fuel catalyst. In the final design a pre-reformer (i.e. a low-temperature steam reformer without membranes) was also introduced, in order to get some hydrogen concentration in the inlet gas feed to the IMR as well as to reduce thermal gradients in this section.
Mathematical models for the membrane reactor were developed to be applied as design and optimization tools, facing the key challenge to synchronize the heat transfer rate with the reaction kinetics and the hydrogen permeation through the membrane. The models developed were validated considering different aspects of the IMR (heat and mass transfer mechanisms, reaction kinetics, hydrogen permeance through the membrane, etc.) and applying the catalyst and membrane performance data obtained in WP2 and WP3 respectively.
One major conclusion is that membrane reformer’s performances are significantly affected by concentration polarization and inhibition of the membrane by other species (that can be amplified at higher pressures).
Based on the results obtained and validation of the IMR design, the detailed engineering design of the pilot steam reformer was developed.
Pilot plant construction and proof of concept (WP5).
According to the design, pilot plant components, including catalysts and membranes, were manufactured and supplied by CoMETHy partners with the defined size and geometry. Then, the pilot plant was built and commissioned at ENEA-Casaccia research centre in Rome, integrated in an existing molten salts loop using electrical heaters to simulate the Concentrating Solar Thermal (CST) plant.
The plant scheme involves two molten salts heated steam reformers connected in series: a pre-reformer and an Integrated Membrane Reformer (IMR). Both reactors are based on a shell-&-tube heat exchangers layout, with the molten salts stream flowing on the shell side.
The membrane reformer includes ten reactor tubes, each including the catalyst and the membrane. The reactor includes six gates: molten salt inlet/exit gates, feed mixture inlet, retentate exit, sweeping steam inlet and the hydrogen permeate exit ports.
The pre-reformer allows the production of a H2-containing gas mixture (roughly corresponding to thermodynamic equilibrium) leading to the following advantages on the process:
- maximizing the utilization of the membranes also at the feed inlet section on the IMR;
- minimizing the thermal stresses on the inlet section of the IMR due to high reaction rates;
- minimizing the risk of fouling of membrane and catalyst in the IMR thanks to higher hydrogen concentration.
Process steam from a steam generator is first pre-heated at the desired temperature and then split in two streams:
- sweep steam directly injected on the permeate side of the IMR;
- process steam to be mixed with the CH4 feed (from gas cylinders) and pre-heated to reactors’ inlet temperature, usually in the range 420-480°C.
The produced permeate and retentate streams are recovered and analysed after excess steam condensation. Molten salts are counter-currently flowed through the two reactors, entering firstly in the IMR reactor at the desired temperature and flow rate from the MO.S.E. plant facility at ENEA-Casaccia research center in Rome.
The pilot plant operation included a preliminary phase with the validation of start-up, shut down and stand-by strategies. The study also included an assessment of plant performances and a macroscopic analysis of the experimental results.
In total, including the start-up, stand-by and shut down stages, the plant was operated with molten salts for about 700 hours. Continuous operation of the plant was achieved for about 150 hours. During this period the plant performances were assessed under several operative conditions: molten salts inlet temperature, sweep steam flow rate and steam-to-carbon feed ratio. A macroscopic result analysis was carried out too.
Results can be summarized as follows:
- the application of the membrane reformer following a pre-reformer allows to get more than double the conversion that can be obtained with a non-membrane reformer under the same conditions;
- proof-of-concept of CoMETHy technology was successfully achieved at the pilot scale in relevant environment, obtaining up to 3.5 Nm3/h pure hydrogen production under design conditions, higher than the project quantitative target of 2.0 Nm3/h;
- > 99.8% hydrogen permeate was produced with < 100 ppm CO content and the conditions to minimize CO concentration in the permeate were identified;
- catalysts and membranes were assembled and replaced in the reactor(s) in less than 4 hours;
- no macroscopical signs of reactor performance loss were evidenced over the experimental operation period, despite the above mentioned handling of catalysts and membranes (the reactor was opened during the experimental phase) and the several switches of operative conditions;
- start-up, shut down and stand-by strategies were validated and the good practice (for full-scale plants) to keep reactor(s) “hot” during stand-by periods, by the use of molten salts as thermostatic fluid, was assessed, thus facilitating start-up and extend lifetime of components (e.g. membranes);
- the effectiveness of the WGS reaction in the reactor(s) resulted in an outlet retentate stream with low CO concentration (< 2%);
- a relatively high CO2 concentration (32-39%) was obtained in the outlet retentate stream at 9.5 bar, enhancing CO2 capture for its recovery and/or reuse, demonstrating the application of CoMETHy technology to fuels pre-combustion decarbonisation.
Techno-Economical assessment of the process (WP6).
Based on the results obtained with the pilot reformer, the best strategies to couple this reformer with a CST plant were studied and evaluated from a techno-economic perspective. Several process schemes were conceived, simulated and evaluated, under different scenarios. Specifically, decentralized and centralized solar steam reforming plant schemes (1500 and 5000 Nm3/h, respectively) were developed and evaluated. Results were compared to a conventional steam reforming process with the same capacity and scenarios, including CO2 recovery.
In general, two process options were considered:
- “full solar” steam reforming process, where the process heat is entirely provided by the CST plant, with or without electrical power co-generation;
- “hybrid” steam reforming process, where part of the process heat is provided by retentate off-gas combustion with oxygen or air, and partly by the CST plant.
In both cases, the continuous operation of the steam reforming plant is primarily ensured by means of a molten salts based heat storage system and then by a gas fired back-up heater to drive the process when the solar heat is no longer available.
For larger scale plants with hydrogen production capacity of 5,000 Nm3/h (or more) a Multi-Stage Membrane Reformer (MSMR) was considered for the evaluation, provided that this arrangement is considered more suitable for larger scale plants. However, the general conclusions of this study were not affected by the membrane reactor design type (either integrated or not).
Since the results obtained were strictly related to the economic assumptions, a sensitivity analysis was carried out too, changing different economic input parameters like the depreciation factor or unit costs of feedstock/fuel (NG), catalysts, membranes, CST plant, by-products, etc.
In general, integration of solar energy through a CST system based on molten salts in a steam reforming process seems to be a promising approach to minimize hydrogen production costs and the CO2 emitted.
Compared to conventional steam reforming processes, the solar processes developed in CoMETHy require higher initial investment costs (CAPEX) due to the rather relevant investment for the CST plant and ancillary items: the CAPEX impact on the hydrogen cost is, in most cases, > 45%, while the CAPEX impact in conventional steam reforming routes is usually < 25%. This larger CAPEX is however balanced by savings in operative costs for the feedstock and the fuel in the solar process. As a result, the overall hydrogen production cost obtained by CoMETHy solar steam reforming technology does not significantly differ from conventional routes.
In the 5,000 Nm3/h solar steam reforming schemes, hydrogen COP is within the range of 1.09-1.22 €/kg, considering a 5,000 hours/year full-solar operation. These values are rather close (< ±10% difference) to the value of 1.19 €/kg estimated for a conventional steam reforming process (i.e. without solar input) under similar assumptions (including CO2 recovery).
Considering that CoMETHy process is highly capital intensive, the impact of the annual depreciation factor was evaluated too.
After preliminary evaluation of different solar steam reforming schemes with 5,000 Nm3/h hydrogen production capacity, based on the MSMR design, a process scheme with 1,500 Nm3/h hydrogen production capacity was evaluated. In this case, the Integrated Membrane Reformer (IMR) design successfully proved in CoMETHy pilot plant was considered, and a more detailed analysis carried out.
First, the relationship between the size of the solar field, the Thermal Energy Storage (TES) capacity and the annual operational hours when the process is fully powered by solar energy was determined by increasing the number of hours/year operated with solar power the back-up fuel demand proportionally drops and the energy efficiency (produced H2 energy (LHV) divided by NG feed + fuel + power input) increases up to 80%.
Merging these results with those from the sensitivity study (by changing the economic parameters) the hydrogen production costs obtained were always within the range of 2.02-3.36 €/kg, a cost that is rather close to the one obtained in conventional steam reforming of 1.74 €/kg. The higher hydrogen production costs are mainly due to the above mentioned higher CAPEX impact (in the range of 46-58%) on COP compared to the 21% CAPEX in conventional steam reforming.
The contribution of the different cost items to the overall hydrogen production cost was identified. The CST plant represents the package with the largest impact (49%) on the total equipment cost, followed by the membrane steam reformers (23%). Therefore, a trade-off should be identified to minimize the hydrogen production costs while maintaining high the solar power impact in the process. Differently, membranes, catalysts and maintenance costs have a minor impact (< 11%) on production costs. As for the impact of feedstock and fuel (NG), different scenarios were considered, referring to the NG market price in Europe and USA.
It is noteworthy that, in CoMETHy’s “multi-fuel” approach, biogas and/or bioethanol were envisaged as feedstock too. In both cases, the biomass-derived feedstock is usually derived by low-cost refuses, but a biogas up-grading unit or a bioethanol pre-reformer should be introduced in the process, affecting the cost of the methane-rich gas effectively fed to the main membrane reformer. Therefore, the sensitivity analysis of the impact of feedstock cost will be helpful to predict also the effect of alternative fuels in the multi-fuel cases.
Potential Impact:
CoMETHy is a product-oriented project which main objective is the development of an innovative compact and modular steam reformer. As such, the potential impact of the technology developed, as well as the exploitation scenarios, can be analysed at the end of the project, when measurable and final results are available, concretely showing the outcomes of the research and of the technological activities carried out. All the starting assumptions, declared objectives and expected outcomes can be measured against concrete results. The approach to the project can thus be innovative and pioneering, and the achievements of the 4 year work can be looked through the lenses of concrete exploitation.
In the second part of this section the dissemination activities aimed at fostering the exploitation of the results are reported.
Impact of CoMETHy results
Steam reforming is the leading technology for large scale hydrogen production: today, more than 25 million tons of hydrogen per year are produced primarily by steam reforming of natural gas.
CoMETHy developed and proved a new steam reforming process characterized by several innovative features compared with the traditional route, including:
- compact layout of the reactor;
- operation at lower temperatures (< 550°C, compared to traditional SMR > 850°C);
- possibility to power the process with solar energy, reducing CO2 emissions and save primary fuel;
- flexibility of operation in terms of rapid start-up and shut down;
- flexibility of application in terms of primary fuel and feedstock to be converted to hydrogen (natural gas, biogas, bioethanol, etc.).
The reactor developed in CoMETHy is by itself the first of its kind, based on a membrane reformer and molten salts as heat transfer fluid. Moreover, new plant schemes were conceived and positively evaluated from technical and economical perspectives, adaptable to different industrial and energy scenarios, for both centralized and decentralized hydrogen production.
With these results and the activities implemented, it is noteworthy that CoMETHy contributed to achieve some of the FCH JU Programme objectives and targets dealing with “Hydrogen Production and Distribution”. In the following paragraphs it is reported how CoMETHy’s results would endorse the implementation of the FCH JU Programme and its roadmap.
Hydrogen production processes from Renewable Energy Sources.
The general strategy on hydrogen production aims at maximizing the production from Renewable Energy Sources (RES), with CO2 free (or CO2 lean) routes, in particular for the decarbonisation of transport. Specifically, the FCH JU MAIP published for 2008-2013 targeted up to 50% of the hydrogen energy supplied from RES.
CoMETHy’s reactor prototypes and pilot plant proved the feasibility of the solar steam reforming of methane, resulting in a 38-53% reduction of CO2 emissions and equivalent methane savings compared to the traditional process.
Additionally, considering the energy balance of developed Natural Gas (NG) steam reforming plant schemes developed in CoMETHy, more than 40% of total energy input in the process derives from solar heat.
Reforming of biofuels (biogas, bioethanol) was proved too, obtaining 100% renewable hydrogen.
Current strategies for future hydrogen production are chiefly focused on the exploitation of electrolysis mainly powered by renewable sources (e.g. PV and wind). This trend is supported by the growing impact of renewable sources in the electrical grid mix. However, it is important to notice that energy systems with major impact of intermittent renewable sources (e.g. PV and wind) need some extent of “predictable” back-up sources and technologies available to compensate fluctuations and satisfy power demand. In electrical power systems this is usually achieved by NG and/or biomass power plants. Similarly, in hydrogen production the back-up option can be represented by decentralized steam reforming plants powered by NG and/or renewable sources: in this context, CoMETHy offers a technological solution: the novel membrane steam reforming reactor made available by CoMETHy is expected to pave the way to new opportunities for distributed hydrogen generation, alternative to electrolysis and allowing the use of different fuels and energy sources depending on local availability.
Reduction of hydrogen production costs.
Lowering the hydrogen production costs represents a key target for hydrogen production technologies (MAIP 2008-13).
Compared to traditional steam reforming, the reduction of operating temperatures obtained allows savings in construction material costs for the reactor.
The techno-economic assessment of CoMETHy solar steam reforming technology demonstrated that the hydrogen production costs reached are close to the hydrogen production costs of traditional steam reforming processes on the 1,500-5,000 Nm3/h scale. Though, the environmental benefits and the lower impact of primary fuel cost should be considered in the balance.
Additionally, by increasing the solar energy share in the process, the cost of hydrogen is less subject to the cost of fossil source compared to the traditional process.
Development of higher performance materials.
The introduction and exploitation of higher performance materials (e.g. reforming catalysts with shift activity and membranes) represent another key target in hydrogen production technologies (MAIP 2008-13).
The catalysts developed in CoMETHy were proved to be stable over 250 hours-on-stream, with combined steam reforming and water-gas-shift activity: these steam reforming catalysts lead to CO content < 5%vol, thus avoiding the need of water gas shift reactors and reducing the reformer heat duty.
The effectiveness of the WGS reaction has also been demonstrated in the pilot reactor where < 2% CO concentration was obtained in the outlet retentate stream.
As for the membranes, solutions were identified and significant advancement has been achieved on metal supported membranes. Nevertheless, ceramic-supported palladium membranes represented an alternative option successfully demonstrated in CoMETHy up to the pilot scale. However, long-term durability of membranes needs to be further assessed in future projects
Process performances.
The FCH JU implementation plan for 2008-2013 targeted the development of steam reforming processes including CO2 capture with efficiencies > 72% for centralized production and > 67% for decentralized production from biogas (methane).
CoMETHy process evaluations and experimental results lead to steam reforming thermal efficiency in the range of 68-80% (produced H2 thermal power, LHV, divided by feed + fuel + thermal power input) for a 1,500 Nm3/h methane steam reforming plant (decentralized production) including CO2 capture.
Simplification of the plant and the process.
The FCH JU implementation plan published in 2010 called for a simplification of reformer design in terms of compactness and scalability (2 to 750 Nm3/h hydrogen production rate). Additionally, catalyst replacement should be easily achieved in < 4 hours (AIP 2010).
In CoMETHy a highly compact reactor has been developed and demonstrated, with steam reforming, water-gas shift and hydrogen separation achieved in a single unit. The use of a liquid heat carrier like molten salts (with high heat capacity per unit volume) allows further reduction of reformer volumes compared to conventional furnaces. The concept has been proved with a pilot plant producing from 1.5 to more than 3.5 Nm3/h of pure hydrogen.
Modular and scalable reactor designs were conceived. The shell-and-tube heat exchanger configuration will ease scalability from the 2 Nm3/h (as in the pilot unit experimentally proved in CoMETHy) to 1,500 Nm3/h or more: increasing or decreasing the number of tubular reactors and membranes is enough to obtain different plant sizes. An alternative “multi-stage” (or “one”) configuration has been designed too, suitable for larger scale applications.
Therefore, CoMETHy technology could be applied in small-medium-large scales and the reformer used in various operational fields, from an industrial plant to produce large amount of hydrogen to decentralized small users.
As for the reactor maintenance, in CoMETHy it has been demonstrated the replaceability of catalysts and membranes in the reactor(s) in less than 4 hours, thus achieving another specific target set by the FCH JU in the field of hydrogen production.
Socio-economic impact.
The success of CoMETHy process will support the opening of new industrial production lines in the fields of advanced catalyst systems, hydrogen separation membranes, new reactor and chemical technologies and new concentrating solar power applications.
The worldwide growth of the “green economy”, with the actual implementation of the FCH JU plan up to market penetration of developed technologies and the wide application scenarios for steam reforming, will result in a socio-economic impact: CoMETHy proposes new products and solutions well aligned with the common strategies on sustainable development, thus supporting job creation, energy safety and welfare.
Exploitation of CoMETHy results
The foregrounds generated in CoMETHy potentially pave the way to different exploitation scenarios, mainly thanks to the inherent innovation proposed by the technology.
In general, the steam reforming technology developed in CoMETHy is considered innovative compared to the state of the art for different reasons.
First of all, the adoption of a multi-fuel approach, i.e. the possibility to convert either methane (concentrated or mixed with CO2) or bioethanol in the same reactor, is by itself a new concept.
Moreover, a new solar steam reforming process has been conceived and successfully proved, featured by the use of molten salts as heat transfer fluid from the CST plant and solar heat storage medium. Indeed, solar reforming has been studied in previous projects, using solar-receiver reactors directly heated by the concentrated solar radiation, with full-solar operation limited to 2,000 hours/year. In CoMETHy, the application of CST molten salts technology with thermal storage allows to increase the full-solar operation of the reformer to > 4,000 hours/year. In this way it is possible to maximize the utilization of the solar thermal power.
Furthermore, a new knowledge has been generated in the development of structured heterogeneous catalysts with enhanced heat transfer properties and reduced pressure drops. Some advancement has been achieved also in the production of SS-supported Pd-based membranes, although further research and development is needed to obtain a reliable product.
The exploitable foreground generated in a RTD project like CoMETHy in most cases consists of a “general advancement of knowledge”, and RTD results are not considered ready for commercial exploitation, yet. To measure such knowledge advancement, it is convenient to use the Technology Readiness Level (TRL). In terms of TRL, CoMETHy has taken a technology concept initially formulated with basic studies (corresponding to TRL = 2) to demonstration of the technology in relevant environment (TRL = 6). Demonstration and qualification in a full-scale operational (industrial) environment (TRL = 7 up to 8) is still needed before commercial exploitation. Therefore, despite the successful results, this innovative technology is not ready for market penetration, yet: further work would be needed to further develop and test the knowledge generated in a follow-up demonstration project (in a real industrial and end-user context) to get to the market stage.
CoMETHy follow up opportunities, exploitable foreground and the exploitation lines were widely discussed between project partners during the final project meeting (December 2015). Some conclusions of this analysis are summarized in the following paragraphs.
Application of developed new materials and components.
Some components studied and developed in CoMETHy, such as structured (open foam) catalysts, hydrogen separation membranes, integrated membrane reactors, etc., can lead to potential spin-off for advanced component manufacturing (catalysts, membranes, hydrogen purification units, reactor assembly, heat recovery units, etc.) and engineering.
This is the case of structured open foam catalysts, developed specifically for low-temperature steam reforming of methane and/or ethanol. This catalyst is characterized by enhanced heat transfer, minor pressure drops, and the capability to simultaneously promote steam reforming and water-gas-shift reactions in the temperature range of 400-550°C. This has been positively proved in several tests in CoMETHy, so it can be commercially exploited, provided that the performances are validated over longer times on stream (> 1,000 hours).
Considerable effort has been addressed to palladium based membranes on porous metal supports. Significant advancement has been achieved, specifically on the porous metal substrate quality and the deposition of the inter-metallic ceramic barrier layer. Nevertheless, further RTD activities are required to obtain a reliable product. Therefore, the knowledge generated in CoMETHy can foster next RTD projects aimed to launch this new product on the market.
Application of CoMETHy reactor concept.
In CoMETHy, two different membrane reformer designs were developed: Integrated Membrane Reformer (IMR) and non-integrated Multi-Stage Membrane Reformer (MSMR).
The IMR design, also called “closed” reactor, represented a major engineering challenge. It has been successfully proved up to the pilot scale in a representing unique prototype of this kind, heated by molten salts up to 550°C. All project partners participated to the development of this reactor. Before commercial exploitation, it is necessary to validate the performances over longer operational periods (> 1,000 hours).
The MSMR design, also called “open” reactor, has been evaluated to be most suitable for larger scale applications (> 5,000 Nm3/h hydrogen production). This reactor layout has been designed but not experimentally proved in CoMETHy.
Application of CoMETHy solar steam reforming process.
After the experimental validation of CoMETHy technology at the pilot scale, different process schemes have been developed and evaluated from the techno-economical perspective, considering different scenarios and plant capacity (1,500 and 5,000 Nm3/h hydrogen production). Moreover, the strategies and best practices to couple the steam reforming plant with the Concentrating Solar Thermal (CST) plant have been identified, showing the competitiveness of the developed process with conventional steam reforming routes.
Application of CoMETHy multi-fuel reformer for decentralized hydrogen production.
Besides the possibility to power the steam reforming process by solar energy, other process schemes have been developed in CoMETHy for distributed hydrogen production.
Based on the solar reforming scheme, mostly suitable for medium-large scale applications (> 1,500 Nm3/h production scale) an “autothermal” process has been developed for smaller scales (e.g. 750 Nm3/h), for example for refuelling stations. In this case, CoMETHy reformer can be applied to hydrogen production from natural gas or biogas, using the residual heat value of the retentate stream to sustain the process. It is noteworthy that this small reformer would be the first commercial product of this kind in Europe.
Furthermore, a process to convert bioethanol to hydrogen has been developed, with the same multi-fuelled membrane reformer as above, but with the pre-reformer to convert the diluted ethanol to methane before feeding the membrane reformer. Considering the multi-fuel feature of the reformer, this approach allows a full renewable back up of the gas fuel reformer, to “on demand” allow hydrogen generation.
Possible exploitation burdens and limitations.
In assessing the exploitation potentials of the technology developed, possible burdens should be also taken into account.
Intellectual Property (IP) issues do not represent a significant limitation to the diffusion of the developed technology. Clearly, CoMETHy is a product-oriented RTD project with a deep industrial footprint and a specific know-how was developed in the project. CoMETHy partners obtained the necessary skills to implement further technical projects. Otherwise, the exploitation can pass through technology transfer from CoMETHy partners to final users. In any case, the developed know-how can be transferred to support its wide diffusion.
As far as the technology maturity and readiness is concerned, CoMETHy reactor has been successfully proved at the pilot scale, but for a limited number of operational hours. In order to validate the technology, the process performance over a longer operation time (> 1,000 hours), would be necessary.
As for the application scenarios, different exploitation cases have been investigated in CoMETHy and some limitations identified: the wide exploitation of solar reforming is limited to countries with satisfactory solar radiation intensity for the convenient installation of CSP plants, i.e. those belonging to the so-called “sun-belt”. Additionally, according to CoMETHy results, the solar reforming route is applicable for reforming plant scales of 1,500 Nm3/h or more. Although this minimum solar reforming plant size can still be considered for distributed hydrogen production, at least 20,000-30,000 m2 area should be available nearby the plant to allocate the solar collectors. This can represent a limitation for the implementation of the technology in some cases (e.g. for refuelling stations in urban areas). For more decentralized applications (< 1,500 Nm3/h) the non-solar CoMETHy process can be applied, either for methane, biogas and/or bioethanol steam reforming. In this last case, the low-temperature steam reforming technology developed in CoMETHy will compete with alternative small reforming technologies like compact autothermal reformers.
Future developments.
Considering the technical success of the project and the Technology Readiness Level achieved, CoMETHy partners agreed to carry out follow-up activities at the demonstration level, as detailed below.
First, the pilot plant constructed in CoMETHy can be further used, with some adaptations, in new projects aimed at consolidating results and paving the way for the commercial exploitation of the technology, for example:
- Plant performance analysis for longer periods (> 1,000 hours).
- Bio-ethanol steam reforming tests.
- Plant integration with CO2 separation membranes and recirculation of the residual H2/CH4 from the retentate to the membrane reactor.
- Support a demonstration project with a preliminary test campaign to test the plant under specific representative working conditions useful for the design.
Otherwise, new demonstration plants to prove the technology in real industrial or end-user’s environment can be built.
A first option (for non-solar CoMETHy reformer) is the installation of the methane/biogas steam reformer in a “biomass-to-hydrogen” context, in the framework of a demonstration project, possibly directly coupled to a fermentation plant and biogas clean-up unit. In this case, the reformer would not necessarily be powered by a CSP plant, but the “autothermal” layout is most likely to be used. Additionally, the membrane reformer can be combined with a dry reformer, operating at higher temperatures (usually > 650°C) as pre-reformer: CoMETHy membrane reformer will complete the conversion of bio-methane to pure hydrogen. A small scale methane/bioethanol steam reformer (eventually in the multi-fuel configuration) can also be integrated in a hydrogen refuelling station.
An interesting perspective is the application of the solar steam reforming process to ammonia plants. Ammonia synthesis plants require large amount of pure hydrogen usually produced by Natural Gas (NG) steam reforming. A project can be implemented integrating the CoMETHy solar methane steam reforming technology with an ammonia plant in a “sun belt” region. The advantage of this approach lays in the replacement of conventional reforming with a solar reformer (> 40% savings in methane consumption and CO2 emissions during solar operation) combined with the possibility to use nitrogen as sweep gas in the reactor in order to directly produce the H2/N2 feed mixture for ammonia synthesis, thus saving the sweeping steam generation.
It is possible that CoMETHy reformer prototypes will also find applications integrated in more complex process schemes. This is the case, for example, of refinery processing where heat is available for recovery at 500-600°C.
Finally, CoMETHy reformer can be applied to maximize hydrogen recovery from partially converted syngas streams produced in higher temperature reforming units.
Dissemination activities
Dissemination activities undertaken from the beginning and beyond the end of the project represent a tool to boost exploitation potential and identify new scenarios, perspectives and stakeholders.
CoMETHy results have been presented in several international journals, conferences and workshops dealing with chemical reactor engineering, membrane reactors, renewable energy, hydrogen production, etc.
Two international workshops have been organized in cooperation with other 7FP projects dealing with palladium membranes and membrane reactors in November 2012 (Italy) and November 2014 (the Netherlands). The two workshops gathered world players in this field. Booklets have been produced and distributed after the events.
In October 2013 a summer school titled “Engineering of membrane reactors for the process industry” has been organized with several CoMETHy lectures; during the same period, a CoMETHy session has been organized within the PRES’13 Conference in Rhodes.
Moreover, CoMETHy results have been widely presented in tens of papers published in international peer reviewed journals and conference proceedings.
It is planned to continue dissemination actions beyond the end of the project in order to promote the exploitation of the developed technology: dissemination actions planned after the end of the project will mainly look for the exploitation of results, outlining the potentials of CoMETHy based applications, with an “end-user” oriented message. Furthermore, the pilot plant operated during the final project year at the ENEA-Casaccia research center in Rome has been visited by several groups, and will be available for external visitors to show the developed technology.
The target group comprises potential stakeholders, developers and potential end-users of the technology developed, who have been identified among those who have already been in contact with the project, such as participants to dissemination events, components’ producers and scientific and technological partners internal and external to the project as well as newly identified final users.
In general, CoMETHy stakeholders, developers and end-users belong to the following focus areas: renewable energy, hydrogen production, fuel cells, hydrogen refuelling, CSP, solar fuels, pre-combustion decarbonisation, NG pipeline, catalysis, hydrogen purification, process intensification, etc. End-users and developers together draw the picture of a potential production chain, getting the innovation to the market/to a further development step.
List of Websites:
www.comethy.enea.it
