Final Report Summary - BIOROBUR (Biogas robust processing with combined catalytic reformer and trap)
Executive Summary:
The BioRobur project developed and tested a robust and efficient decentralized fuel processor based on the direct autothermal reforming (ATR) of biogas with a nominal production rate of PEM-grade hydrogen of 50 Nm3/h.
Modelling and simulation (CFD and FEM) were carried out to select the innovative catalyst support with promising results for the BioRobur fuel processor and furthermore, 2D CFD analysis was also used to examine flow uniformity issues due to soot trap integration close coupled to the ATR. 15-0.05 wt.% Ni-Rh/MgAl2O4 -SiSiC structured catalyst was selected as a potential catalyst for the conversion of biogas to hydrogen. Homogenous lattice structure composed of cubic rotated cell showed excellent performances, guaranteeing a high reliability of the process. Moreover, LiFeO2 catalyst was selected as the most prominent candidate towards to carbon gasification in a reducing atmosphere. The catalyst was in-situ deposited directly over the wall-flow filter. Tests of the coupled system under realistic conditions at the pilot and demonstration scale have showed satisfactory results in terms of, hydrogen yield and pressure drop in the system, reaching the target with a nominal production rate corresponding to 50 Nm3/h of hydrogen (100 Kg/day), creating a negligible pressure drop during the operation time of the processor. A thermodynamic equilibrium and a methane conversion higher than 98% were achieved.
Besides, Aspen simulation and LCA analysis has demonstrated that BioRobur is the most promising process to hydrogen production compared to other types of reforming process. A comparative LCA analysis of biogas ATR, biogas SR and biogas fueled IC engine followed by Alkaline Electrolyzer was performed, and the results shown that Biorobur process (biogas ATR) presents a high energy sustainability and a high efficiency, so this arises as the best choice among the three scenarios.
Finally, a techno-economic analysis of BioRobur technology for green hydrogen production was performed to provide a basis for comparison between the hydrogen final cost and the European target. Besides, an eventual implementation plan technology was addressed, in which weakness and strengths were identified by SWOT analysis. The cost and supply analysis of biogas-to-hydrogen production via authothermal reforming (ATR) indicates that municipal solid waste (MSW) dominates the low-cost supply of biogas-derived hydrogen. Regarding the market potential, this analysis suggests that at 5€/kg H2 (delivered cost), MSW can provide about 285,536 kg/day. Additionally, in 10 years of amortization, the final cost to produce 100 Nm3/h of H2 would be 3€/kg far lower compared with the European target for the cost of H2 from biogas reforming which is 5€/kg of H2. Moreover, considering an amortization time of 4 years, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
Project Context and Objectives:
The main objective of the BioRobur project was the development and testing of a robust and efficient biogas reformer aimed at covering a wide span of potential applications, from fuel cells feed (both high temperature SOFC or MCFC fuel cells and low temperature PEM ones, requiring a significantly lower inlet CO concentration) up to the production of pure, PEM-grade hydrogen. The nominal production rate of pure hydrogen of the BioRobur fuel processor is 50 Nm3/h with an overall efficiency of the conversion of biogas to green hydrogen of 65%.
The process can be divided in three sections as shown in Figure 1 (see pdf attached). The feed section is the first, it consists in the preheating, compression and mixing of air, steam and biogas streams. In this section the compression of the biogas is provided by a steam ejector, in order to avoid the use of a compressor. The heart of the process is the ATR-Reactor, located in the second process step, in which the biogas is converted in a mixture of gas rich in H2. Close coupled to the ATR unit, there is a wall flow filter to retain the soot produced during the reforming. In the last part of the process take a place the gas purification section. There are two sections of purification: the first step is constituted by two WGS reactors, high-temperature (HT-WGS) and low-temperature water gas shift (LT-WGS) reactor and the second step provides the pressure swing adsorption (PSA) unit treatment at 20 barg.
The BioRobur fuel processor employs a catalytic autothermal reforming (ATR) process using a structured catalyst in order to convert biogas to hydrogen. The peculiar feature of ATR lies in the fact that heat is directly provided within the reactor, through partial oxidation of the biogas. This reduces the need of heat exchangers, and increases the flexibility of the plant.
15-0.05 wt.% Ni-Rh/MgAl2O4 catalyst was identified as a robust catalysts for autothermal reforming of a model biogas (composed of methane and carbon dioxide 60:40 vol:vol) over 350 h time-on-stream with a constant hydrogen production. The catalyst showed better resistance to the problem of carbon deposition and avoid the high cost of the nobles metals.
The Robust Demo-plant developed and tested for hydrogen production is illustrated in Figure 2 (see pdf attached).
In order to ensure a high reliability of the ATR process, new catalyst structures (homogenous lattices composed of Cubic, Octet and Kelvin cells and the Conventional Foam structure) were designed and tested within the research BioRobur project, which are based on high thermal conductivity cellular materials to disperse the heat axially in the reactor (Figure 3 - see pdf attached).
Moreover, all SiSiC-structures were coated with the same amount of catalyst to ensure identical conditions between the supports in the catalytic activity test in the pilot testing campaign. The different catalytic (15-0.05 wt.% Ni-Rh/MgAl2O4) homogenous SiSiC lattice structures were tested in the ATR test-rig, using a space velocity (GHSV) between 2000 and 20000 h-1 in standard conditions. The steam to carbon ratio (S/C) was fixed at 2.0 and the oxygen to carbon ratio (O/C) was 1.0 1.1 and 1.2. Homogenous lattice composed of cubic rotated cells presented the best performance to convert biogas into hydrogen with a CH4 conversion of 95% and H2 yield of 2.2 using an O/C ratio of 1.0 1.1 and 1.2 S/C ratio of 2 and GHSV of 20000 h-1. Besides, this support presents the lower pressure drop (6-40 Pa/m) with the lower specific surface area comparing with the other structures tested. Based on the abovementioned results, a conventional foam and the rotated cubic cell were selected to be tested in the Demo-Biorobur plant.
Moreover, another originality of the project is the adoption of a novel approach to retain particulate matter emissions in a catalytic wall-flow trap based on transition metal catalysts, downstream from a biogas ATR, which could entail effective filtration and gasification of soot particles eventually generated in the inlet part of the reformer during steady or transient operation, or due to the decomposition of traces of incomplete reforming products. LiFeO2 formulation was selected as the most prominent candidate towards to carbon gasification in a reducing atmosphere. The catalyst was in-situ deposited directly over the wall-flow filters. Due to the excellent performance with respect to filtration efficiency and pressure drop development during soot loading, a monolith with 15 μm mean pore size and 45% porosity was selected to be tested in the Biorobur plant. The tests of the coupled system under realistic conditions were first carried out first at the pilot scale at Hysytech premises. A long duration test was also performed principally to see the interaction of the reformer part with the filter part, of which, satisfactory results were obtained in terms of hydrogen yield and pressure drop in the system.
Furthermore, the functionality of the full BioRobur processor has been demonstrated. First, reference tests using a noble metal based coated monolith close coupled with an uncoated filter were performed in the demonstration BioRobur plant. Moreover, tests with the integration of the catalyzed conventional foam and the catalytic trap downstream of the reforming reactor were performed (Figure 4 - see pdf attached). So far, the activation procedure with coated foam support was successful and a long duration test (more than 30 h) was carried out. The boundary conditions were a space velocity of 4000, S/C= 2 and O/C=1.1. A thermodynamic equilibrium and a methane conversion higher than 98% were achieved. The BioRobur plant was able to reach the predicted conversions and concentrations at nominal capacities corresponding to 50 Nm3/h (100 Kg/day) of pure hydrogen, creating a negligible pressure drop during the operation time of the processor. The overall behavior fully corresponds to the predicted in the simulation for an O/C ratio of 1.1 and S/C ratio of 2. For the design condition (GHSV=10000, O/C=1.1 S/C=2.0) and an inlet temperature of 500°C the demo-plant has a plant efficiency of about 65%.
During the foam campaign testing, a kind of catalyst deactivation was observed. During the las t test using the catalytic conventional foam, the methane conversion remained between 99% and 96%, but the hydrogen yield was dropping from 2.2 to 1.7. This could be because the combustion zone was moving down on the catalyst and there was not enough room for the endothermic reaction and so for the syngas production, as was also observed in the powder testing campaign. The cold gas efficiency should be about 92%, but the measurements indicate a cold gas efficiency between 80% and 70%, this is because of the same reason that was already stated; the partial oxidation zone is moving down and the endothermic reaction are not completed, reducing at the same time the hydrogen production and so the cold gas efficiency.
Regarding to the rotated cubic cell catalyst was not possible to tests it in the demonstration plant. A problem with the coating was found, which did not allow the activation of the catalyst and so the biogas reforming.
Besides, the comparison between the foams at small–scale and Demo-plant scale shows that the performance of the Demo-plant are better, because the methane conversion and hydrogen yield are higher. Furthermore, the monolith reference shows also good methane conversion in the tested range. Figure 5 (see pdf attached) shows the comparison of the results between the small and Demo-BioRobur plant.
Finally, the ASPEN simulation and LCA analysis have demonstrated that BioRobur is the most promising process to hydrogen production compared to Steam Reforming and the coupling of internal combustion engine and Electrolyser Besides, Aspen simulation and LCA analysis has demonstrated that BioRobur is the most promising process to hydrogen production compared to other types of reforming process. A comparative LCA analysis of biogas ATR, biogas SR and biogas fueled IC engine followed by Alkaline Electrolyzer was performed, and the results shown that Biorobur process (biogas ATR) presents a high energy sustainability and a high efficiency, so this arises as the best choice among the three scenarios.
Finally, a techno-economic analysis of BioRobur technology for green hydrogen production was performed to provide a basis for comparison between the hydrogen final cost and the European target. Besides, an eventual implementation plan technology was addressed, in which weakness and strengths were identified by SWOT analysis. The cost and supply analysis of biogas-to-hydrogen production via authothermal reforming (ATR) indicates that municipal solid waste (MSW) dominates the low-cost supply of biogas-derived hydrogen. Regarding the market potential, this analysis suggests that at 5€/kg H2 (delivered cost), MSW can provide about 285,536 kg/day. Additionally, in 10 years of amortization, the final cost to produce 100 Nm3/h of H2 would be 3€/kg far lower compared with the European target for the cost of H2 from biogas reforming which is 5€/kg of H2. Moreover, considering an amortization time of 4 years, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
Project Results:
1. Catalysts screening for ATR
Different catalysts were synthesized and tested along with some commercial catalysts in order to select the most appropriate for the BioRobur context. The catalysts must guarantee some important features such as less prone to coking and easier adaptability to the change of biogas composition. Nickel supported on mixed oxides, perovskites and spinels were synthesized for the ATR reaction and tested in a six parallel-flow reactor technology implemented to test simultaneously six different catalysts under a feed consisting of 42% H2O, 14% CH4, 9% CO2, 7% O2 in argon. Tests were performed with quartz reactors at 700°C (oven setpoint) under atmospheric pressure. Reactors had a length of 180 mm and an inner diameter of 4 mm. Catalyst beds were composed of 20 mg of prepared catalyst diluted with quartz powder.
15-0.05 wt.% Ni-Rh/ MgAl2O4 catalyst is most resistant to deactivation. The catalyst showed full methane conversion over 250 hours with a constant hydrogen production as showed in Figure 1 (see pdf attached). The deactivation process of the catalyst could be related to some carbon deposition, but the main fast final deactivation process is likely associated to nickel oxidation.
1.1. Deactivation study
A deactivation study was performed and the main results are shown here. Some tests of ATR on Ni/MgxAl2O4 were performed changing the Mg:Al ratio to check the catalyst stability. The Figure 2 (see pdf attached) shows that Mg:Al ratio is a very important parameter for the stability of the catalyst. Deactivation rate is higher when Mg:Al ratio < 0.5. The Ni/Mg1.1 Al2O4 was the most stable.
On the other hands, it was dmostrated that Rh enhances the reducibility of nickel (Figure 3 see pdf attached)). Temperature programmed reduction (TPR) analisys over NiRh/MgAl2O4 and Ni/MgAl2O4 were performed.
After one hour of reaction, the temperature throughout the bed was measured to localise the zone of combustion and reforming. The exothermal combustion occurs at the very inlet of the catalytic bed followed by the reforming process. Besides, there is a hot spot formation in the inlet of the catalyst bed. From the results is possible to conclude that the Rh promotes Ni stability.
Figure 4 (see pdf attached) shows the profile measured after 1h of reaction by moving the thermocouple along the bed.
Figure 5 (see pdf attached) shows the temperature profile and the methane conversion along the catalyst bed of 5wt% Ni/Mg0.42Al2O4 during the ATR of biogas.
Deactivation is due to the formation of NiAl2O4 as is demonstrated in the UV-VIS-DRS analyses of the states of Ni species studied (Figure 6 - see pdf attached)). When the spinel is formed, no combustion occurs. The exothermal zone progresses along the bed during reaction until complete deactivation.
Progression of the combustion zone is associated with a change in the states of Ni species. A further study over 5wt% Ni/Mg0.42Al2O4 catalyst was performed to understand the reason why the combustion zone is moved along the catalytic bed as shown before in Figure 5. The reactor was composed of four 5wt% Ni/Mg0.42Al2O4 catalyst sections separated each other with quartz wool as shown in Figure 7 (a) (see pdf attached). From the results is possible to affirm that the progression of the combustion zone is associated with a change in the states of Ni species.
Identification and quantification of NiO and NiAl2O4 is possible by UV-vis-DRS analysis. After each test the sample was analyzed by UV-vis and the results shown that the proportion of NiO is always negligible. After deactivation, only the spinel phase could be observed (Figure 8 and 9 - see pdf attached). Additional test were performed with commercial NiO and prepared NiAl2O4 and the results show that NiO is active for CH4 combustion only, not for reforming and NiAl2O4 is even less active than NiO.
When the reaction is started, Ni is oxidized at the inlet of the bed due to the presence of O2. NiO is active for the combustion of methane. Downstream, the nickel is still metallic and perform the reforming of methane in the absence of O2. At the inlet, the high temperatures reached because of the exothermic combustion lead to a disorder in the crystal structure of the support • Ni2+ ions diffuse into the vacancies of the support, forming inactive NiAl2O4
The deactivation study has demonstrated that during ATR over Ni/MgAl2O4, the formation of NiAl2O4 leads to deactivation. Furthermore, NiRh/MgAl2O4 catalyst is active and is the most resistant to deactivation. The addition of a small quantity of Rh enhances the reducibility of Ni and also stabilizes the combustion zone at the front of the bed.
2. Soot Trap Catalyst
Li-delafossite based catalysts were prepared via a solution combustion synthesis (SCS) method and investigated under realistic conditions as catalysts for the gasification of particulate matter retained in a soot trap downstream from a biogas autothermal reformer (ATR). The activity of the catalysts towards soot gasification was analyzed by temperature programmed reaction (TPRe), which was carried out in a fixed-bed micro-reactor. A flow of 100 ml/min of CO2 (10,92%), CO (10,6%), H2 (26,83%), H2O (24,87%) and N2 (26,76%) was sent to a fixed bed of 50 mg of a mixture of carbon (Printex U) and powdered catalyst (ratio 1:9 on a mass basis) with 150 mg of inert silica (to reduce the specific pressure drop and to prevent thermal runaways). Figure shown an increase in the CO2 and H2 concentrations and a decrease in CO concentration at high temperatures (after 500°C) when LiCrO2, LiCr0.9O2 LiCr0.8O2 and LiFeO2 are used as gasification catalysts. Instead, LiCoO2 and LiNiO2 catalysts at lower temperature (between 400-600 °C) produce high quantity of CO2, CH4 and H2 while CO is consumed. This evidence that methanation and water gas shift reactions are taking a place in this range of temperatures.
During the reaction, species are adsorbed and desorbed influencing the proper data analysis. Furthermore, the presence of several reactions simultaneously during gasification hinders the correct calculations of soot conversion. Then, in order to know exactly the quantity of soot not gasified during the reaction, a flow containing 10% of oxygen diluted in nitrogen was fed to the reactor after the gasification reaction ended to oxidize the amount of soot remained. The soot not gasified was calculated with the concentrations of CO and CO2 obtained during the combustion step. Instead, the quantity of gassified soot was then found by the difference between the initial amount of carbon and the oxidized one. Figure 11 (see pdf attached) shows the CO and CO2 concentration as a product of the oxidation at 850°C of the remaining soot after the gasification. The curve related to non-catalytic gasification of carbon is also reported as a reference, and shows a lower CO2 selectivity, contrary to the catalyzed reactions.
The results obtained are very promising, showing relatively fast gasification of soot. LiFeO2 and LiCoO2 present the best performance to gasification of carbon. The 98% and 99.8% of soot is gasified before 850°C when LiCoO2 and LiFeO2 were used as catalysts while approximately the 30% is just gasified without catalyst before 850°C.
3. Structured catalyst supports to ATR reactor
In order to identify a suitable support structure, which meets the desired demands, i.e. high effective thermal conductivity, open structure to avoid dead zones and plugging by soot build up, strong mixing and high contact time of the fluid with the catalytic surface, high mechanical strength and low pressure drop; numerical simulations of fluid flow, heat transfer and mechanical behavior numerical simulations based on CFD and FEM models have been performed on three different geometries (Figure 12 - see pdf attached)) which are assessed by different effective properties. While conventional catalyst supports like honeycombs and solid bulk material suffer from certain shortcomings such as poor transverse mixing in case of honeycombs or high pressure loss and poor heat transfer in case of packed beds, the 3D printing method employed in the BioRobur project offers the opportunity to produce almost arbitrary designs of catalyst supports.
In order to obtain the isothermal transient flow field, the governing equations for mass and momentum are numerically solved using a CFD code based on the Lattice-Boltzmann method (LBM). For evaluating the effective thermal conductivity of the structures, the heat transfer was solved by using the finite volume method (FVM) under the assumption of a non-conducting fluid phase. To test the mechanical behavior of the supports made of SiSiC lattice structures, an analysis on the basis of the finite element method (FEM) was performed employing the commercial software COMSOL V4.4
Figure 13 (see pdf attached) shows the dispersion as a function of the Reynold numbers for all the structures and it illustrate:
• Low dispersion at low Reynolds numbers due to laminar flow.
• Significant increase of dispersion for the cubic lattice in flow direction (111)
• Good performance of random foam.
3.1. Development and coating of the supports
a) Manufacturing process
Erbicol’s process to manufacture SiSiC ceramics is based on the reactive silicon infiltration of a preform containing α-SiC and carbon. By performing the infiltration at 1500°C in vacuum, carbon and silicon react to β-SiC, while excess silicon densifies the structure. As a result, the final product is a composite of α-SiC (from powders), β-SiC from reaction bonding, and excess silicon. The excess silicon has one main advantage but also one disadvantage. By filling the structure with metallic silicon, it becomes completely dense and impermeable to oxygen. On the other hand, an excessive presence of metallic silicon may limit the adhesion of the wash coating and catalyst on the foam surface, leading to a fast decrease in catalyst performance.
Concerning silicon nitride, usually nitridation of a silicon preform is performed, by letting gaseous nitrogen react with a solid silicon preform between 1100°C and 1350°C. For the present case, silicon nitride was selected for the potentially better adhesion of the wash coat on the material surface, therefore it is important to have the silicon nitride on the surface of the foam. Given this condition, to manufacture the silicon nitride foam, finished SiSiC foams have been nitridized.
Because of the excess silicon present in the SiSiC foams, nitridation has produced a foam with a silicon carbide skeleton and silicon nitride surface, combining the two desired material properties in one product.
For the manufacturing of foams, the replica technique was used (also called Schwarzwalder method), which consists of the impregnation of a sacrificial polymeric template. The green body is then pyrolyzed in inert atmosphere and liquid silicon infiltrated. The products are then machined with diamond tools. For the silicon nitride foams, a further step is added, consisting of a high temperature cycle at 1300°C in nitrogen atmosphere. Following scheme shows the details of the manufacturing process:
Structures for the pilot-plant
Several sample sets were produced, coated and tested at the pilot plant (Figure 15). 15%Ni-0.05%Rh/MgAl2O4 catalyst washcoat were deposited onto the cellular materials by dip-slurry coating:
• Pre-treatment of SiSiC samples. Deposition of early prepared suspension using dip-coating technology
• Drying at 60 °C for 1 hour
• Coating of SiSiC samples with spinel and Calcination at 800 °C for 4 hours
• Impregnation with nickel nitrate solution
• Drying at 60 °C for 1 hour
• Impregnation with nickel (II) nitrate and calcination and Calcination at 550 °C for 4 hours
• Impregnation with rhodium nitrate solution
• Drying at 60 °C for 4 hours
• Impregnation with rhodium (III) nitrate and Calcination at 550°C for 4 hours
All the structures were coated with the same amount of catalyst to ensure identical conditions between the supports in the catalytic activity tests.
Structures for the Demo-plant
Due to big dimension of the ATR support and in order to make a complete and uniformed coating, was decided to make separate flat slices with diameter 260 mm and thickness 50 mm as illustrated in the Figure 16 (see pdf attached). Six slices were produced and coated. The procedure of catalyst deposition for flat slices of structured catalyst was carried out according to the dip-coating technology already explained.
NOT enough space here to cut and paste please see pdf attached
Potential Impact:
Introduction
Nowadays the production of energy and its consumption are becoming a significant issue, therefore research studies on new energy sources and effective technologies able to exploit them are taking great relevance.
In this document is addressed a marketing analysis of Biorobur technologies and the eventual implementation plan technology, with the purpose of identifying its weakness and strengths A techno-economic analysis of BioRobur technology for green hydrogen production of 100 Nm3 H2/h (5.0 grade) was performed to provide a basis for comparison between the hydrogen final cost and the European target. Besides, an eventual implementation plan technology was addressed, in which weakness and strengths were identified by SWOT analysis. The cost and supply analysis of biogas-to-hydrogen production via authothermal reforming (ATR) indicates that municipal solid waste (MSW) dominates the low-cost supply of biogas-derived hydrogen. Regarding the market potential, this analysis suggests that at 5€/kg H2 (delivered cost), MSW can provide about 285,536 kg/day. Additionally, in 10 years of amortization, the final cost to produce 100 Nm3/h of H2 would be 3€/kg far lower compared with the European target for the cost of H2 from biogas reforming which is 5€/kg of H2. Moreover, considering an amortization time of 4 years, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
Evaluation of cost and quality of biomass
In particular, this study aims to analyze the main costs of the BioRobur technology, in order to identify a Hydrogen final cost to compare with the European target. The analysis is divided into four main sections:
evaluation of costs and quality of biogas;
estimation of Capital Expenditure (Capex);
estimation of Operating Expenditure (Opex);
Hydrogen final cost.
Evaluation of cost and quality of biomass
Biogas is defined as a fuel produced by the anaerobic digestion process of the residual biomass from different sources (manure, organic waste, sewage sludge, landfills, etc.). Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen.
Biogas is primarily a mixture of methane (CH4) and carbon dioxide (CO2), associated with traces of other gases such as hydrogen sulfide (H2S), ammonia (NH3), hydrogen (H2), nitrogen (N2), oxygen (O2) and vapor water (H2O). The sulfur content and the methane composition in the biogas mixture depends of the sources of biomass used.
Into the European market is possible to identify four main biological matrices: landfill, energy crops, municipal solid waste (MSW) and agro-industrial scraps.
The landfills
The European Union has determined that the use of landfill sites for waste can be avoided; only materials with low organic carbon content are allowed. For this reason, the landfills will be not considered in the future as source of biogas.
The energy crops
The use of energy crops is increased in the past years; initially obtainable in cases of overproduction, from land marginal, partially cultivated or in set aside land. Thanks to the incentives (green certificates, etc.), the energy crops are always more used.
The strengths of energy crops are mainly related to energetic and commercial aspects. The percentage of volatile solids in the energy crops is higher than other substrates, guaranteeing an increased yield of biogas. The easy cultivation and storage make possible the insertion and adoptability in the farms, facilitating the end- use of the digestate for that cases in which the soils from which they derive are part of the bioenergetic companies.
However, in last years an ethic/environmental controversy arisen. Some people consider immoral the use of food crops to fuel car and in this way the agricultural commodity prices increase. Additionally, the easy adoptability of energy crops subtracts land for the poorest sections of society, who often lose access to land and resources that are essential for their livelihood.
From the environmental point of view, with the intensification of crops, the digestate to be disposed increases and thus the load of nitrogen per unit area. Meanwhile, the extensive use of fertilizers increases the CO2 emissions.
The municipal solid waste (MSW)
The strength of this kind of substrates is mainly related to the enhancement of waste. In this way there is a double benefit: a significant reduction in disposal costs and a strong environmental pollution abatement. Moreover, the recovery of wastes is a service for the community and the citizens typically pay a rate of contribution. In this view, it can be considered as very low/no- cost or, even, a negative cost for the acquisition of these matrices.
However, the necessity of a pre-treatment makes the management and the storage more difficult. Additionally, considering the high potential of the produced biogas, it could be right to attribute an economic value to the biogas produced.
A similar economic consideration can be applied for the active sludge. In fact, not all the water treatment plants have the possibility to exploit the active sludge because do not have the anaerobic digestion plants already existent, but there is a potential opportunity to be exploited.
The valorization of the active sludge through anaerobic digestion does not represent a huge cost for the water treatment plants which have the capability to produce biogas. Meanwhile, considering the real potential of the active sludge, many entrepreneurs have decided to invest in an anaerobic digestion plant, imputing a price for the produced biogas in order to compensate their investment.
Agroindustry scraps
Generalizing the agroindustry scraps are waste for disposal, like MSW. Precisely, the “by-product” is the residue of another producing cycle and has to respect the following criteria:
it has to be generated by a production process, not being the main object;
the by-product must have material properties and quality environment such as to ensure that its use does not generate an environmental impact;
the environmental compatibility characteristics described above must be possessed by the by-product from the time of its production; it is not allowed a prior treatment to reuse;
the by-product must have an economic value of the market.
This category includes also the livestock waste. They are characterized by an extremely variable composition, depending on the animal species that originates and the mode of farming. They can be both shoveled form (manure) that pumpable (sewage) depending on the content of dry substance.
From the energy point of view, the agroindustry scraps, like dedicated cultures, may present percentage of volatile solids higher than wastewater and livestock waste.
In the last decade the incentive policies have encouraged the use of agroindustry scraps to produce biogas, with the consequent increase in the price of raw materials.
In Table 1 (see pdf attached) are compared the most common biomasses, indicating the positive and negative aspects, the price for tons and the percentage of methane (in biogas) for each raw material.
Estimation of Capital Expenditure (CAPEX)
The “capital expenditures” are the assets that a company uses to buy durable goods in order to create or expand their production capacity. The CAPEX represents the initial investment. The costs take into account the direct costs (DC) and indirect costs (IC).
The DC are those cost which can be granted to the objects cost, for example the equipment, the raw materials or the instrumentations. Meanwhile the IC are those costs which are derived from the control and management of the company, for example the supervision or the construction.
In order to establish a methodology to evaluate the capital costs, the AACE International is taken as a reference.
There are five cost estimate classes defined in function of the level of project definition. The level of project definition establishes the information available to the estimating costs. The Class 5 estimate is based on the lowest level of project definition, meanwhile the Class 1 estimate is relative to the full project definition.
For this analysis has been used the AACE Class 5 Cost Estimation Methodology based on the cost of the total purchased price of major equipment. The range of error assigned for this kind of methodology is 20% and 33%.
Major equipment
To estimate the cost of each equipment, commercial references were used.
In the Table 2 (see pdf attached) are summarized the direct and indirect costs for the BioRobur’s Plant.
Estimation of Operational expenditure (OPEX)
In this evaluation are included all the costs necessary to manage the plant. Those are called Operation and Maintenance cost (O&M). It can comprise also the cost of manpower and the rent of the site.
Table 3. OPEX estimation.
The operational expenditures were divided into three main sections:
streams: including biogas and service fluids
services: including thermic and electrical consumptions
items: including maintenance, spare parts, catalyst and adsorbent materials.
In the Table 3 (see pdf attached) are summarized the operational costs of the BioRobur’s Plant.
Hydrogen Final Cost
The study carried out was focused on a commercial plant which produces 100 Nm3/h of hydrogen (5.0 grade) from the biogas obtained from MSW. The final purpose of this analysis is the assessment of the real cost of the hydrogen’s production. In order to reach our target, we have to include other considerations:
the European target: how far are we from the EU target?
the amortization time: what is the impact of the average plant life on hydrogen final cost?
the size of the plant: what is the impact of the plant size on hydrogen final cost?
the raw materials: what is the impact of the different sources of biogas on hydrogen final cost?
The European target
The European target for the cost of hydrogen from biogas is 5€/kg of H2. But, considering 10 years of amortization, the final cost to produce 100 Nm3/h of hydrogen using the BioRobur technology is 3€/kg of H2.
Table 4. CAPEX and OPEX estimation in 10 years of amortization time.(see pdf attached)
The amortization time
The amortization time represents the average cycle of life of the commercial plant. The cost of hydrogen is calculated for five different periods of amortization and compared with the European target.
Table 5. Amortization time (see pdf attached) The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase The size of the plant
The impact of the size plant on the final costs was evaluated. The capital and operational costs change with the dimension of the plant. A small plant has lower direct and operational costs, but, at the same time, it has also a lower production; in this way the final cost of the product increases. Moreover, increasing the volume of the plant (for example twice), the surface increases proportionally lower (i.e. less than twice). In general, in the production processes, the investment costs increase in proportion to the surface, while the operating costs vary in proportion to the volume of the plant. The raw materials
The influence of the different substrates for the biogas production on the hydrogen cost was also calculated. The biogas from MSW is characterized by a medium- high content of H2S, nearly 900 mg for Sm3 of biogas; it means 757 kg/y of H2S to dispose and nearly 1000 kg of activate carbon for year (Hysytech company). A biogas poor of sulphur allows to save on the desulphurization costs, but it goes to the detriment of the cost of biogas which is higher.
Considering 4 years of amortization, the operational costs are estimated in order to assess the impact of different matrices on hydrogen final cost.
In the Table 7 are compared the H2S content in the biogas, the biogas price and the respective operational costs for three different sources of biogas.
Table 7. Hydrogen final cost for different substrates.(see pdf attached) Figure 41. Hydrogen final cost for different substrates.
For simplicity, the quality of biogas from MSW and agroindustry scraps is considered the same, because the methane content in biogas is similar (60% CH4). The agroindustry scraps can be divided into three sub-cases:
I. the sewages are in the same site in which is present the AD; in this case, it is convenient to use the manure to produce biogas, there aren’t additional costs and other solutions would be more expensive.
II. the sewages are in a site near the biogas plant; in this case, the costs of biomass and its transport are about 10 €/tontq
III. the sewages are purchased, transported and stored in the AD site; in this case, the cost of biomass has to be integrated with the cost of transport and storage, about 55 €/tontq.
The active sludge is characterized by a higher H2S content and lower CH4 content (53% CH4), therefore the yield of biogas is less. The estimated hydrogen’s production is nearly 83 Nm3/h.
2.5. The SWOT Analysis
The SWOT analysis summarizes Strengths, Weakness, Opportunity and Threats of a project. This is an important instrument used for the strategic and commercial business planning.
First of all, a target needs to be define in order to realize s SWOT analysis. Our target is the BioRobur’s technology. Two main categories constitute the matrix SWOT:
➢ Internal factors: here are included the strengths and weaknesses internal to the BioRobur technology
➢ External factors: here are included the opportunities and threats presented by the environment external to the BioRobur’s technology.
Strengths
This square includes the internal aspects that are helpful to achieving the objective.
The strengths of BioRobur’s technology are:
• Low environmental impact: the main feeding of BioRobur’s technology is the biogas which allows to dispose waste producing energy. Also, the energy recovery, aimed to heat the process water, permits to reduce the thermal consumptions.
• Competitive on European market: in 5 years of amortization the estimated hydrogen’s cost is 4 € for kilograms of hydrogen, meanwhile the European target is 5 € for kilograms of hydrogen.
• High energy efficiency: the heart of the process is an auto thermal reaction; it means that the heat required from the reforming reaction is balanced with the heat released by the partial oxidation, guarantying an auto sustainable process.
Weakness
This square includes the internal negative aspects that harm the objective.
The weakness of BioRobur’s technology are:
• High cost of PSA unit: the gas purification is crucial to reach the final specification and the high grade required. The PSA unit guarantees these results but the overall costs of this technology (the equipment, the materials and the energy consumptions) are very high, nearly the 22% of total costs.
Opportunities
This square includes the external conditions that are helpful to reach the target.
• Policy incentives: there has been a wide diffusion of plants to produce biogas in the last years. In fact, the government incentives have promoted the use of biomass in order to produce energy as alternative to the use of fossil fuels.
• The research of new energy sources: the world is occupied to research alternative energy sources in order to reduce the pollution and defend the environment, especially for future generations. There is more sensibility and interest for the environmental protection.
Threats
This square includes the external conditions that hinder to reach the target.
• Difficult final applications: the hydrogen technology is not really diffuse yet and its final applications are not easy.
• Fossil fuels: the future scenarios expect that, for the next thirty years, the fossil sources will remain the most used.
• The time: the “hydrogen economy” is not expected before many years. In this contest, characterized by a strong technological competition, the BioRobur’s technology will compete with technologies more consolidated.
3. Conclusion
The techno-economic analysis showed that the BioRobur technology plays an important role to create a more sustainable scenario and it could have a crucial role in the European market. The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase with the years, the capital costs do not change and they are distributed on the entire cycle life. Moreover, in 10 years of amortization, the final cost to produce 100 Nm3/h of hydrogen from biogas is 3€/Kg H2, lower than the European target (5€/kg H2). The raw material for the biogas production is a key for the final hydrogen cost.
Additional, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
In the other hand, Strengths, Weakness, Opportunity and Threats of a technology were identified by a SWOT analysis. Finally, the route to implement and spread these bio-technologies is still long. For this reason, there is the need for constant incentives in order to deepen, improve and implement the new bio-technologies such as the production of biogas and the hydrogen technology.
With the years, the capital costs do not change and they are distributed on the entire cycle life. The results are showed in Figure 39 (see pdf attached)
The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase with the years, the capital costs do not change and they are distributed on the entire cycle life. The results are showed in Figure 4.
Figure 3. Hydrogen final cost vs. amortization time, compared with the EU target.
The size of the plant
The impact of the size plant on the final costs was evaluated. The capital and operational costs change with the dimension of the plant. A small plant has lower direct and operational costs, but, at the same time, it has also a lower production; in this way the final cost of the product increases. Moreover, increasing the volume of the plant (for example twice), the surface increases proportionally lower (i.e. less than twice). In general, in the production processes, the investment costs increase in proportion to the surface, while the operating costs vary in proportion to the volume of the plant.
Capex estimation: the ratio between the new Capex and the Capex for the reference size (rf) is equal to the ratio between the new size and the reference size (rf), elevated to 0,6 (eq. [1]).
Capex/〖Capex〗_rf = (Size/〖Size〗_rf )^0.6 [1]
Opex estimation: the variation between the ratio of Opex on reference Opex (rf) and size on reference size (rf) is linear (eq. [2]).
Opex/Opex_rf = (Size/Size_rf ) [2]
For the H2 production cost calculation in function of the size of the plant, an amortization time of 4 years was considered. The results are displayed in Table 6.
Table 6. Hydrogen cost based on the plant size.
SIZE
[Nm3H2/h] CAPEX
[€] OPEX
[€] H2 Produced
[kg] H2 cost
[€/kgH2]
50 € 575.305 € 186.800 142.768 6
100 € 872.000 € 373.600 285.536 5
150 € 1.112.170 € 560.400 428.304 4
200 € 1.321.705 € 747.200 571.072 3,7
250 € 1.511.056 € 934.000 713.840 3,5
500 € 2.290.332 € 1.868.000 1.427.679 3
700(*) € 2.802.692 € 2.615.200 1.998.751 2,8
(*) Typically, the plant with a large production of hydrogen (500-700 Nm3/h) are fed with biogas from MSW.
The results are illustrated in Figure 5.
Figure 4. Hydrogen cost vs. plant size, compared with the EU target.
The Figure shows that for a low production of hydrogen (50 Nm3/h) the H2 costs are unfavourable compared with the European target.
The raw materials
The influence of the different substrates for the biogas production on the hydrogen cost was also calculated. The biogas from MSW is characterized by a medium- high content of H2S, nearly 900 mg for Sm3 of biogas; it means 757 kg/y of H2S to dispose and nearly 1000 kg of activate carbon for year (Hysytech company). A biogas poor of sulphur allows to save on the desulphurization costs, but it goes to the detriment of the cost of biogas which is higher.
Considering 4 years of amortization, the operational costs are estimated in order to assess the impact of different matrices on hydrogen final cost.
In the Table 7 are compared the H2S content in the biogas, the biogas price and the respective operational costs for three different sources of biogas.
Table 7. Hydrogen final cost for different substrates.
SUBSTRATE H2S CONTENT [mg/Sm3biogas] PRICE
[€/tontq] OPEX
[€] H2 COST [€/kgH2] H2 Produced
[Nm3/h]
MSW 900 0 € 373.600 5,0 100
Active Sludge 4000 15 € 539.477 6,0 83
I. Agroindustry scraps 400 0 € 355.051 4,3 100
II. Agroindustry scraps 400 10 € 397.292 4,4 100
III. Agroindustry scraps 400 55 € 587.372 5,1 100
Figure 6. Hydrogen final cost for different substrates.
For simplicity, the quality of biogas from MSW and agroindustry scraps is considered the same, because the methane content in biogas is similar (60% CH4). The agroindustry scraps can be divided into three sub-cases:
the sewages are in the same site in which is present the AD; in this case, it is convenient to use the manure to produce biogas, there aren’t additional costs and other solutions would be more expensive.
the sewages are in a site near the biogas plant; in this case, the costs of biomass and its transport are about 10 €/tontq
the sewages are purchased, transported and stored in the AD site; in this case, the cost of biomass has to be integrated with the cost of transport and storage, about 55 €/tontq.
The active sludge is characterized by a higher H2S content and lower CH4 content (53% CH4), therefore the yield of biogas is less. The estimated hydrogen’s production is nearly 83 Nm3/h.
The SWOT Analysis
The SWOT analysis summarizes Strengths, Weakness, Opportunity and Threats of a project. This is an important instrument used for the strategic and commercial business planning.
First of all, a target needs to be define in order to realize s SWOT analysis. Our target is the BioRobur’s technology. Two main categories constitute the matrix SWOT:
Internal factors: here are included the strengths and weaknesses internal to the BioRobur technology
External factors: here are included the opportunities and threats presented by the environment external to the BioRobur’s technology.
Strengths
This square includes the internal aspects that are helpful to achieving the objective.
The strengths of BioRobur’s technology are:
Low environmental impact: the main feeding of BioRobur’s technology is the biogas which allows to dispose waste producing energy. Also, the energy recovery, aimed to heat the process water, permits to reduce the thermal consumptions.
Competitive on European market: in 5 years of amortization the estimated hydrogen’s cost is 4 € for kilograms of hydrogen, meanwhile the European target is 5 € for kilograms of hydrogen.
High energy efficiency: the heart of the process is an auto thermal reaction; it means that the heat required from the reforming reaction is balanced with the heat released by the partial oxidation, guarantying an auto sustainable process.
Weakness
This square includes the internal negative aspects that harm the objective.
The weakness of BioRobur’s technology are:
High cost of PSA unit: the gas purification is crucial to reach the final specification and the high grade required. The PSA unit guarantees these results but the overall costs of this technology (the equipment, the materials and the energy consumptions) are very high, nearly the 22% of total costs.
Opportunities
This square includes the external conditions that are helpful to reach the target.
Policy incentives: there has been a wide diffusion of plants to produce biogas in the last years. In fact, the government incentives have promoted the use of biomass in order to produce energy as alternative to the use of fossil fuels.
The research of new energy sources: the world is occupied to research alternative energy sources in order to reduce the pollution and defend the environment, especially for future generations. There is more sensibility and interest for the environmental protection.
Threats
This square includes the external conditions that hinder to reach the target.
Difficult final applications: the hydrogen technology is not really diffuse yet and its final applications are not easy.
Fossil fuels: the future scenarios expect that, for the next thirty years, the fossil sources will remain the most used.
The time: the “hydrogen economy” is not expected before many years. In this contest, characterized by a strong technological competition, the BioRobur’s technology will compete with technologies more consolidated.
Conclusion
The techno-economic analysis showed that the BioRobur technology plays an important role to create a more sustainable scenario and it could have a crucial role in the European market. The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase with the years, the capital costs do not change and they are distributed on the entire cycle life. Moreover, in 10 years of amortization, the final cost to produce 100 Nm3/h of hydrogen from biogas is 3€/Kg H2, lower than the European target (5€/kg H2). The raw material for the biogas production is a key for the final hydrogen cost.
Additional, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
In the other hand, Strengths, Weakness, Opportunity and Threats of a technology were identified by a SWOT analysis. Finally, the route to implement and spread these bio-technologies is still long. For this reason, there is the need for constant incentives in order to deepen, improve and implement the new bio-technologies such as the production of biogas and the hydrogen technology.
List of Websites:
www.biorobur.org
The BioRobur project developed and tested a robust and efficient decentralized fuel processor based on the direct autothermal reforming (ATR) of biogas with a nominal production rate of PEM-grade hydrogen of 50 Nm3/h.
Modelling and simulation (CFD and FEM) were carried out to select the innovative catalyst support with promising results for the BioRobur fuel processor and furthermore, 2D CFD analysis was also used to examine flow uniformity issues due to soot trap integration close coupled to the ATR. 15-0.05 wt.% Ni-Rh/MgAl2O4 -SiSiC structured catalyst was selected as a potential catalyst for the conversion of biogas to hydrogen. Homogenous lattice structure composed of cubic rotated cell showed excellent performances, guaranteeing a high reliability of the process. Moreover, LiFeO2 catalyst was selected as the most prominent candidate towards to carbon gasification in a reducing atmosphere. The catalyst was in-situ deposited directly over the wall-flow filter. Tests of the coupled system under realistic conditions at the pilot and demonstration scale have showed satisfactory results in terms of, hydrogen yield and pressure drop in the system, reaching the target with a nominal production rate corresponding to 50 Nm3/h of hydrogen (100 Kg/day), creating a negligible pressure drop during the operation time of the processor. A thermodynamic equilibrium and a methane conversion higher than 98% were achieved.
Besides, Aspen simulation and LCA analysis has demonstrated that BioRobur is the most promising process to hydrogen production compared to other types of reforming process. A comparative LCA analysis of biogas ATR, biogas SR and biogas fueled IC engine followed by Alkaline Electrolyzer was performed, and the results shown that Biorobur process (biogas ATR) presents a high energy sustainability and a high efficiency, so this arises as the best choice among the three scenarios.
Finally, a techno-economic analysis of BioRobur technology for green hydrogen production was performed to provide a basis for comparison between the hydrogen final cost and the European target. Besides, an eventual implementation plan technology was addressed, in which weakness and strengths were identified by SWOT analysis. The cost and supply analysis of biogas-to-hydrogen production via authothermal reforming (ATR) indicates that municipal solid waste (MSW) dominates the low-cost supply of biogas-derived hydrogen. Regarding the market potential, this analysis suggests that at 5€/kg H2 (delivered cost), MSW can provide about 285,536 kg/day. Additionally, in 10 years of amortization, the final cost to produce 100 Nm3/h of H2 would be 3€/kg far lower compared with the European target for the cost of H2 from biogas reforming which is 5€/kg of H2. Moreover, considering an amortization time of 4 years, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
Project Context and Objectives:
The main objective of the BioRobur project was the development and testing of a robust and efficient biogas reformer aimed at covering a wide span of potential applications, from fuel cells feed (both high temperature SOFC or MCFC fuel cells and low temperature PEM ones, requiring a significantly lower inlet CO concentration) up to the production of pure, PEM-grade hydrogen. The nominal production rate of pure hydrogen of the BioRobur fuel processor is 50 Nm3/h with an overall efficiency of the conversion of biogas to green hydrogen of 65%.
The process can be divided in three sections as shown in Figure 1 (see pdf attached). The feed section is the first, it consists in the preheating, compression and mixing of air, steam and biogas streams. In this section the compression of the biogas is provided by a steam ejector, in order to avoid the use of a compressor. The heart of the process is the ATR-Reactor, located in the second process step, in which the biogas is converted in a mixture of gas rich in H2. Close coupled to the ATR unit, there is a wall flow filter to retain the soot produced during the reforming. In the last part of the process take a place the gas purification section. There are two sections of purification: the first step is constituted by two WGS reactors, high-temperature (HT-WGS) and low-temperature water gas shift (LT-WGS) reactor and the second step provides the pressure swing adsorption (PSA) unit treatment at 20 barg.
The BioRobur fuel processor employs a catalytic autothermal reforming (ATR) process using a structured catalyst in order to convert biogas to hydrogen. The peculiar feature of ATR lies in the fact that heat is directly provided within the reactor, through partial oxidation of the biogas. This reduces the need of heat exchangers, and increases the flexibility of the plant.
15-0.05 wt.% Ni-Rh/MgAl2O4 catalyst was identified as a robust catalysts for autothermal reforming of a model biogas (composed of methane and carbon dioxide 60:40 vol:vol) over 350 h time-on-stream with a constant hydrogen production. The catalyst showed better resistance to the problem of carbon deposition and avoid the high cost of the nobles metals.
The Robust Demo-plant developed and tested for hydrogen production is illustrated in Figure 2 (see pdf attached).
In order to ensure a high reliability of the ATR process, new catalyst structures (homogenous lattices composed of Cubic, Octet and Kelvin cells and the Conventional Foam structure) were designed and tested within the research BioRobur project, which are based on high thermal conductivity cellular materials to disperse the heat axially in the reactor (Figure 3 - see pdf attached).
Moreover, all SiSiC-structures were coated with the same amount of catalyst to ensure identical conditions between the supports in the catalytic activity test in the pilot testing campaign. The different catalytic (15-0.05 wt.% Ni-Rh/MgAl2O4) homogenous SiSiC lattice structures were tested in the ATR test-rig, using a space velocity (GHSV) between 2000 and 20000 h-1 in standard conditions. The steam to carbon ratio (S/C) was fixed at 2.0 and the oxygen to carbon ratio (O/C) was 1.0 1.1 and 1.2. Homogenous lattice composed of cubic rotated cells presented the best performance to convert biogas into hydrogen with a CH4 conversion of 95% and H2 yield of 2.2 using an O/C ratio of 1.0 1.1 and 1.2 S/C ratio of 2 and GHSV of 20000 h-1. Besides, this support presents the lower pressure drop (6-40 Pa/m) with the lower specific surface area comparing with the other structures tested. Based on the abovementioned results, a conventional foam and the rotated cubic cell were selected to be tested in the Demo-Biorobur plant.
Moreover, another originality of the project is the adoption of a novel approach to retain particulate matter emissions in a catalytic wall-flow trap based on transition metal catalysts, downstream from a biogas ATR, which could entail effective filtration and gasification of soot particles eventually generated in the inlet part of the reformer during steady or transient operation, or due to the decomposition of traces of incomplete reforming products. LiFeO2 formulation was selected as the most prominent candidate towards to carbon gasification in a reducing atmosphere. The catalyst was in-situ deposited directly over the wall-flow filters. Due to the excellent performance with respect to filtration efficiency and pressure drop development during soot loading, a monolith with 15 μm mean pore size and 45% porosity was selected to be tested in the Biorobur plant. The tests of the coupled system under realistic conditions were first carried out first at the pilot scale at Hysytech premises. A long duration test was also performed principally to see the interaction of the reformer part with the filter part, of which, satisfactory results were obtained in terms of hydrogen yield and pressure drop in the system.
Furthermore, the functionality of the full BioRobur processor has been demonstrated. First, reference tests using a noble metal based coated monolith close coupled with an uncoated filter were performed in the demonstration BioRobur plant. Moreover, tests with the integration of the catalyzed conventional foam and the catalytic trap downstream of the reforming reactor were performed (Figure 4 - see pdf attached). So far, the activation procedure with coated foam support was successful and a long duration test (more than 30 h) was carried out. The boundary conditions were a space velocity of 4000, S/C= 2 and O/C=1.1. A thermodynamic equilibrium and a methane conversion higher than 98% were achieved. The BioRobur plant was able to reach the predicted conversions and concentrations at nominal capacities corresponding to 50 Nm3/h (100 Kg/day) of pure hydrogen, creating a negligible pressure drop during the operation time of the processor. The overall behavior fully corresponds to the predicted in the simulation for an O/C ratio of 1.1 and S/C ratio of 2. For the design condition (GHSV=10000, O/C=1.1 S/C=2.0) and an inlet temperature of 500°C the demo-plant has a plant efficiency of about 65%.
During the foam campaign testing, a kind of catalyst deactivation was observed. During the las t test using the catalytic conventional foam, the methane conversion remained between 99% and 96%, but the hydrogen yield was dropping from 2.2 to 1.7. This could be because the combustion zone was moving down on the catalyst and there was not enough room for the endothermic reaction and so for the syngas production, as was also observed in the powder testing campaign. The cold gas efficiency should be about 92%, but the measurements indicate a cold gas efficiency between 80% and 70%, this is because of the same reason that was already stated; the partial oxidation zone is moving down and the endothermic reaction are not completed, reducing at the same time the hydrogen production and so the cold gas efficiency.
Regarding to the rotated cubic cell catalyst was not possible to tests it in the demonstration plant. A problem with the coating was found, which did not allow the activation of the catalyst and so the biogas reforming.
Besides, the comparison between the foams at small–scale and Demo-plant scale shows that the performance of the Demo-plant are better, because the methane conversion and hydrogen yield are higher. Furthermore, the monolith reference shows also good methane conversion in the tested range. Figure 5 (see pdf attached) shows the comparison of the results between the small and Demo-BioRobur plant.
Finally, the ASPEN simulation and LCA analysis have demonstrated that BioRobur is the most promising process to hydrogen production compared to Steam Reforming and the coupling of internal combustion engine and Electrolyser Besides, Aspen simulation and LCA analysis has demonstrated that BioRobur is the most promising process to hydrogen production compared to other types of reforming process. A comparative LCA analysis of biogas ATR, biogas SR and biogas fueled IC engine followed by Alkaline Electrolyzer was performed, and the results shown that Biorobur process (biogas ATR) presents a high energy sustainability and a high efficiency, so this arises as the best choice among the three scenarios.
Finally, a techno-economic analysis of BioRobur technology for green hydrogen production was performed to provide a basis for comparison between the hydrogen final cost and the European target. Besides, an eventual implementation plan technology was addressed, in which weakness and strengths were identified by SWOT analysis. The cost and supply analysis of biogas-to-hydrogen production via authothermal reforming (ATR) indicates that municipal solid waste (MSW) dominates the low-cost supply of biogas-derived hydrogen. Regarding the market potential, this analysis suggests that at 5€/kg H2 (delivered cost), MSW can provide about 285,536 kg/day. Additionally, in 10 years of amortization, the final cost to produce 100 Nm3/h of H2 would be 3€/kg far lower compared with the European target for the cost of H2 from biogas reforming which is 5€/kg of H2. Moreover, considering an amortization time of 4 years, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
Project Results:
1. Catalysts screening for ATR
Different catalysts were synthesized and tested along with some commercial catalysts in order to select the most appropriate for the BioRobur context. The catalysts must guarantee some important features such as less prone to coking and easier adaptability to the change of biogas composition. Nickel supported on mixed oxides, perovskites and spinels were synthesized for the ATR reaction and tested in a six parallel-flow reactor technology implemented to test simultaneously six different catalysts under a feed consisting of 42% H2O, 14% CH4, 9% CO2, 7% O2 in argon. Tests were performed with quartz reactors at 700°C (oven setpoint) under atmospheric pressure. Reactors had a length of 180 mm and an inner diameter of 4 mm. Catalyst beds were composed of 20 mg of prepared catalyst diluted with quartz powder.
15-0.05 wt.% Ni-Rh/ MgAl2O4 catalyst is most resistant to deactivation. The catalyst showed full methane conversion over 250 hours with a constant hydrogen production as showed in Figure 1 (see pdf attached). The deactivation process of the catalyst could be related to some carbon deposition, but the main fast final deactivation process is likely associated to nickel oxidation.
1.1. Deactivation study
A deactivation study was performed and the main results are shown here. Some tests of ATR on Ni/MgxAl2O4 were performed changing the Mg:Al ratio to check the catalyst stability. The Figure 2 (see pdf attached) shows that Mg:Al ratio is a very important parameter for the stability of the catalyst. Deactivation rate is higher when Mg:Al ratio < 0.5. The Ni/Mg1.1 Al2O4 was the most stable.
On the other hands, it was dmostrated that Rh enhances the reducibility of nickel (Figure 3 see pdf attached)). Temperature programmed reduction (TPR) analisys over NiRh/MgAl2O4 and Ni/MgAl2O4 were performed.
After one hour of reaction, the temperature throughout the bed was measured to localise the zone of combustion and reforming. The exothermal combustion occurs at the very inlet of the catalytic bed followed by the reforming process. Besides, there is a hot spot formation in the inlet of the catalyst bed. From the results is possible to conclude that the Rh promotes Ni stability.
Figure 4 (see pdf attached) shows the profile measured after 1h of reaction by moving the thermocouple along the bed.
Figure 5 (see pdf attached) shows the temperature profile and the methane conversion along the catalyst bed of 5wt% Ni/Mg0.42Al2O4 during the ATR of biogas.
Deactivation is due to the formation of NiAl2O4 as is demonstrated in the UV-VIS-DRS analyses of the states of Ni species studied (Figure 6 - see pdf attached)). When the spinel is formed, no combustion occurs. The exothermal zone progresses along the bed during reaction until complete deactivation.
Progression of the combustion zone is associated with a change in the states of Ni species. A further study over 5wt% Ni/Mg0.42Al2O4 catalyst was performed to understand the reason why the combustion zone is moved along the catalytic bed as shown before in Figure 5. The reactor was composed of four 5wt% Ni/Mg0.42Al2O4 catalyst sections separated each other with quartz wool as shown in Figure 7 (a) (see pdf attached). From the results is possible to affirm that the progression of the combustion zone is associated with a change in the states of Ni species.
Identification and quantification of NiO and NiAl2O4 is possible by UV-vis-DRS analysis. After each test the sample was analyzed by UV-vis and the results shown that the proportion of NiO is always negligible. After deactivation, only the spinel phase could be observed (Figure 8 and 9 - see pdf attached). Additional test were performed with commercial NiO and prepared NiAl2O4 and the results show that NiO is active for CH4 combustion only, not for reforming and NiAl2O4 is even less active than NiO.
When the reaction is started, Ni is oxidized at the inlet of the bed due to the presence of O2. NiO is active for the combustion of methane. Downstream, the nickel is still metallic and perform the reforming of methane in the absence of O2. At the inlet, the high temperatures reached because of the exothermic combustion lead to a disorder in the crystal structure of the support • Ni2+ ions diffuse into the vacancies of the support, forming inactive NiAl2O4
The deactivation study has demonstrated that during ATR over Ni/MgAl2O4, the formation of NiAl2O4 leads to deactivation. Furthermore, NiRh/MgAl2O4 catalyst is active and is the most resistant to deactivation. The addition of a small quantity of Rh enhances the reducibility of Ni and also stabilizes the combustion zone at the front of the bed.
2. Soot Trap Catalyst
Li-delafossite based catalysts were prepared via a solution combustion synthesis (SCS) method and investigated under realistic conditions as catalysts for the gasification of particulate matter retained in a soot trap downstream from a biogas autothermal reformer (ATR). The activity of the catalysts towards soot gasification was analyzed by temperature programmed reaction (TPRe), which was carried out in a fixed-bed micro-reactor. A flow of 100 ml/min of CO2 (10,92%), CO (10,6%), H2 (26,83%), H2O (24,87%) and N2 (26,76%) was sent to a fixed bed of 50 mg of a mixture of carbon (Printex U) and powdered catalyst (ratio 1:9 on a mass basis) with 150 mg of inert silica (to reduce the specific pressure drop and to prevent thermal runaways). Figure shown an increase in the CO2 and H2 concentrations and a decrease in CO concentration at high temperatures (after 500°C) when LiCrO2, LiCr0.9O2 LiCr0.8O2 and LiFeO2 are used as gasification catalysts. Instead, LiCoO2 and LiNiO2 catalysts at lower temperature (between 400-600 °C) produce high quantity of CO2, CH4 and H2 while CO is consumed. This evidence that methanation and water gas shift reactions are taking a place in this range of temperatures.
During the reaction, species are adsorbed and desorbed influencing the proper data analysis. Furthermore, the presence of several reactions simultaneously during gasification hinders the correct calculations of soot conversion. Then, in order to know exactly the quantity of soot not gasified during the reaction, a flow containing 10% of oxygen diluted in nitrogen was fed to the reactor after the gasification reaction ended to oxidize the amount of soot remained. The soot not gasified was calculated with the concentrations of CO and CO2 obtained during the combustion step. Instead, the quantity of gassified soot was then found by the difference between the initial amount of carbon and the oxidized one. Figure 11 (see pdf attached) shows the CO and CO2 concentration as a product of the oxidation at 850°C of the remaining soot after the gasification. The curve related to non-catalytic gasification of carbon is also reported as a reference, and shows a lower CO2 selectivity, contrary to the catalyzed reactions.
The results obtained are very promising, showing relatively fast gasification of soot. LiFeO2 and LiCoO2 present the best performance to gasification of carbon. The 98% and 99.8% of soot is gasified before 850°C when LiCoO2 and LiFeO2 were used as catalysts while approximately the 30% is just gasified without catalyst before 850°C.
3. Structured catalyst supports to ATR reactor
In order to identify a suitable support structure, which meets the desired demands, i.e. high effective thermal conductivity, open structure to avoid dead zones and plugging by soot build up, strong mixing and high contact time of the fluid with the catalytic surface, high mechanical strength and low pressure drop; numerical simulations of fluid flow, heat transfer and mechanical behavior numerical simulations based on CFD and FEM models have been performed on three different geometries (Figure 12 - see pdf attached)) which are assessed by different effective properties. While conventional catalyst supports like honeycombs and solid bulk material suffer from certain shortcomings such as poor transverse mixing in case of honeycombs or high pressure loss and poor heat transfer in case of packed beds, the 3D printing method employed in the BioRobur project offers the opportunity to produce almost arbitrary designs of catalyst supports.
In order to obtain the isothermal transient flow field, the governing equations for mass and momentum are numerically solved using a CFD code based on the Lattice-Boltzmann method (LBM). For evaluating the effective thermal conductivity of the structures, the heat transfer was solved by using the finite volume method (FVM) under the assumption of a non-conducting fluid phase. To test the mechanical behavior of the supports made of SiSiC lattice structures, an analysis on the basis of the finite element method (FEM) was performed employing the commercial software COMSOL V4.4
Figure 13 (see pdf attached) shows the dispersion as a function of the Reynold numbers for all the structures and it illustrate:
• Low dispersion at low Reynolds numbers due to laminar flow.
• Significant increase of dispersion for the cubic lattice in flow direction (111)
• Good performance of random foam.
3.1. Development and coating of the supports
a) Manufacturing process
Erbicol’s process to manufacture SiSiC ceramics is based on the reactive silicon infiltration of a preform containing α-SiC and carbon. By performing the infiltration at 1500°C in vacuum, carbon and silicon react to β-SiC, while excess silicon densifies the structure. As a result, the final product is a composite of α-SiC (from powders), β-SiC from reaction bonding, and excess silicon. The excess silicon has one main advantage but also one disadvantage. By filling the structure with metallic silicon, it becomes completely dense and impermeable to oxygen. On the other hand, an excessive presence of metallic silicon may limit the adhesion of the wash coating and catalyst on the foam surface, leading to a fast decrease in catalyst performance.
Concerning silicon nitride, usually nitridation of a silicon preform is performed, by letting gaseous nitrogen react with a solid silicon preform between 1100°C and 1350°C. For the present case, silicon nitride was selected for the potentially better adhesion of the wash coat on the material surface, therefore it is important to have the silicon nitride on the surface of the foam. Given this condition, to manufacture the silicon nitride foam, finished SiSiC foams have been nitridized.
Because of the excess silicon present in the SiSiC foams, nitridation has produced a foam with a silicon carbide skeleton and silicon nitride surface, combining the two desired material properties in one product.
For the manufacturing of foams, the replica technique was used (also called Schwarzwalder method), which consists of the impregnation of a sacrificial polymeric template. The green body is then pyrolyzed in inert atmosphere and liquid silicon infiltrated. The products are then machined with diamond tools. For the silicon nitride foams, a further step is added, consisting of a high temperature cycle at 1300°C in nitrogen atmosphere. Following scheme shows the details of the manufacturing process:
Structures for the pilot-plant
Several sample sets were produced, coated and tested at the pilot plant (Figure 15). 15%Ni-0.05%Rh/MgAl2O4 catalyst washcoat were deposited onto the cellular materials by dip-slurry coating:
• Pre-treatment of SiSiC samples. Deposition of early prepared suspension using dip-coating technology
• Drying at 60 °C for 1 hour
• Coating of SiSiC samples with spinel and Calcination at 800 °C for 4 hours
• Impregnation with nickel nitrate solution
• Drying at 60 °C for 1 hour
• Impregnation with nickel (II) nitrate and calcination and Calcination at 550 °C for 4 hours
• Impregnation with rhodium nitrate solution
• Drying at 60 °C for 4 hours
• Impregnation with rhodium (III) nitrate and Calcination at 550°C for 4 hours
All the structures were coated with the same amount of catalyst to ensure identical conditions between the supports in the catalytic activity tests.
Structures for the Demo-plant
Due to big dimension of the ATR support and in order to make a complete and uniformed coating, was decided to make separate flat slices with diameter 260 mm and thickness 50 mm as illustrated in the Figure 16 (see pdf attached). Six slices were produced and coated. The procedure of catalyst deposition for flat slices of structured catalyst was carried out according to the dip-coating technology already explained.
NOT enough space here to cut and paste please see pdf attached
Potential Impact:
Introduction
Nowadays the production of energy and its consumption are becoming a significant issue, therefore research studies on new energy sources and effective technologies able to exploit them are taking great relevance.
In this document is addressed a marketing analysis of Biorobur technologies and the eventual implementation plan technology, with the purpose of identifying its weakness and strengths A techno-economic analysis of BioRobur technology for green hydrogen production of 100 Nm3 H2/h (5.0 grade) was performed to provide a basis for comparison between the hydrogen final cost and the European target. Besides, an eventual implementation plan technology was addressed, in which weakness and strengths were identified by SWOT analysis. The cost and supply analysis of biogas-to-hydrogen production via authothermal reforming (ATR) indicates that municipal solid waste (MSW) dominates the low-cost supply of biogas-derived hydrogen. Regarding the market potential, this analysis suggests that at 5€/kg H2 (delivered cost), MSW can provide about 285,536 kg/day. Additionally, in 10 years of amortization, the final cost to produce 100 Nm3/h of H2 would be 3€/kg far lower compared with the European target for the cost of H2 from biogas reforming which is 5€/kg of H2. Moreover, considering an amortization time of 4 years, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
Evaluation of cost and quality of biomass
In particular, this study aims to analyze the main costs of the BioRobur technology, in order to identify a Hydrogen final cost to compare with the European target. The analysis is divided into four main sections:
evaluation of costs and quality of biogas;
estimation of Capital Expenditure (Capex);
estimation of Operating Expenditure (Opex);
Hydrogen final cost.
Evaluation of cost and quality of biomass
Biogas is defined as a fuel produced by the anaerobic digestion process of the residual biomass from different sources (manure, organic waste, sewage sludge, landfills, etc.). Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen.
Biogas is primarily a mixture of methane (CH4) and carbon dioxide (CO2), associated with traces of other gases such as hydrogen sulfide (H2S), ammonia (NH3), hydrogen (H2), nitrogen (N2), oxygen (O2) and vapor water (H2O). The sulfur content and the methane composition in the biogas mixture depends of the sources of biomass used.
Into the European market is possible to identify four main biological matrices: landfill, energy crops, municipal solid waste (MSW) and agro-industrial scraps.
The landfills
The European Union has determined that the use of landfill sites for waste can be avoided; only materials with low organic carbon content are allowed. For this reason, the landfills will be not considered in the future as source of biogas.
The energy crops
The use of energy crops is increased in the past years; initially obtainable in cases of overproduction, from land marginal, partially cultivated or in set aside land. Thanks to the incentives (green certificates, etc.), the energy crops are always more used.
The strengths of energy crops are mainly related to energetic and commercial aspects. The percentage of volatile solids in the energy crops is higher than other substrates, guaranteeing an increased yield of biogas. The easy cultivation and storage make possible the insertion and adoptability in the farms, facilitating the end- use of the digestate for that cases in which the soils from which they derive are part of the bioenergetic companies.
However, in last years an ethic/environmental controversy arisen. Some people consider immoral the use of food crops to fuel car and in this way the agricultural commodity prices increase. Additionally, the easy adoptability of energy crops subtracts land for the poorest sections of society, who often lose access to land and resources that are essential for their livelihood.
From the environmental point of view, with the intensification of crops, the digestate to be disposed increases and thus the load of nitrogen per unit area. Meanwhile, the extensive use of fertilizers increases the CO2 emissions.
The municipal solid waste (MSW)
The strength of this kind of substrates is mainly related to the enhancement of waste. In this way there is a double benefit: a significant reduction in disposal costs and a strong environmental pollution abatement. Moreover, the recovery of wastes is a service for the community and the citizens typically pay a rate of contribution. In this view, it can be considered as very low/no- cost or, even, a negative cost for the acquisition of these matrices.
However, the necessity of a pre-treatment makes the management and the storage more difficult. Additionally, considering the high potential of the produced biogas, it could be right to attribute an economic value to the biogas produced.
A similar economic consideration can be applied for the active sludge. In fact, not all the water treatment plants have the possibility to exploit the active sludge because do not have the anaerobic digestion plants already existent, but there is a potential opportunity to be exploited.
The valorization of the active sludge through anaerobic digestion does not represent a huge cost for the water treatment plants which have the capability to produce biogas. Meanwhile, considering the real potential of the active sludge, many entrepreneurs have decided to invest in an anaerobic digestion plant, imputing a price for the produced biogas in order to compensate their investment.
Agroindustry scraps
Generalizing the agroindustry scraps are waste for disposal, like MSW. Precisely, the “by-product” is the residue of another producing cycle and has to respect the following criteria:
it has to be generated by a production process, not being the main object;
the by-product must have material properties and quality environment such as to ensure that its use does not generate an environmental impact;
the environmental compatibility characteristics described above must be possessed by the by-product from the time of its production; it is not allowed a prior treatment to reuse;
the by-product must have an economic value of the market.
This category includes also the livestock waste. They are characterized by an extremely variable composition, depending on the animal species that originates and the mode of farming. They can be both shoveled form (manure) that pumpable (sewage) depending on the content of dry substance.
From the energy point of view, the agroindustry scraps, like dedicated cultures, may present percentage of volatile solids higher than wastewater and livestock waste.
In the last decade the incentive policies have encouraged the use of agroindustry scraps to produce biogas, with the consequent increase in the price of raw materials.
In Table 1 (see pdf attached) are compared the most common biomasses, indicating the positive and negative aspects, the price for tons and the percentage of methane (in biogas) for each raw material.
Estimation of Capital Expenditure (CAPEX)
The “capital expenditures” are the assets that a company uses to buy durable goods in order to create or expand their production capacity. The CAPEX represents the initial investment. The costs take into account the direct costs (DC) and indirect costs (IC).
The DC are those cost which can be granted to the objects cost, for example the equipment, the raw materials or the instrumentations. Meanwhile the IC are those costs which are derived from the control and management of the company, for example the supervision or the construction.
In order to establish a methodology to evaluate the capital costs, the AACE International is taken as a reference.
There are five cost estimate classes defined in function of the level of project definition. The level of project definition establishes the information available to the estimating costs. The Class 5 estimate is based on the lowest level of project definition, meanwhile the Class 1 estimate is relative to the full project definition.
For this analysis has been used the AACE Class 5 Cost Estimation Methodology based on the cost of the total purchased price of major equipment. The range of error assigned for this kind of methodology is 20% and 33%.
Major equipment
To estimate the cost of each equipment, commercial references were used.
In the Table 2 (see pdf attached) are summarized the direct and indirect costs for the BioRobur’s Plant.
Estimation of Operational expenditure (OPEX)
In this evaluation are included all the costs necessary to manage the plant. Those are called Operation and Maintenance cost (O&M). It can comprise also the cost of manpower and the rent of the site.
Table 3. OPEX estimation.
The operational expenditures were divided into three main sections:
streams: including biogas and service fluids
services: including thermic and electrical consumptions
items: including maintenance, spare parts, catalyst and adsorbent materials.
In the Table 3 (see pdf attached) are summarized the operational costs of the BioRobur’s Plant.
Hydrogen Final Cost
The study carried out was focused on a commercial plant which produces 100 Nm3/h of hydrogen (5.0 grade) from the biogas obtained from MSW. The final purpose of this analysis is the assessment of the real cost of the hydrogen’s production. In order to reach our target, we have to include other considerations:
the European target: how far are we from the EU target?
the amortization time: what is the impact of the average plant life on hydrogen final cost?
the size of the plant: what is the impact of the plant size on hydrogen final cost?
the raw materials: what is the impact of the different sources of biogas on hydrogen final cost?
The European target
The European target for the cost of hydrogen from biogas is 5€/kg of H2. But, considering 10 years of amortization, the final cost to produce 100 Nm3/h of hydrogen using the BioRobur technology is 3€/kg of H2.
Table 4. CAPEX and OPEX estimation in 10 years of amortization time.(see pdf attached)
The amortization time
The amortization time represents the average cycle of life of the commercial plant. The cost of hydrogen is calculated for five different periods of amortization and compared with the European target.
Table 5. Amortization time (see pdf attached) The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase The size of the plant
The impact of the size plant on the final costs was evaluated. The capital and operational costs change with the dimension of the plant. A small plant has lower direct and operational costs, but, at the same time, it has also a lower production; in this way the final cost of the product increases. Moreover, increasing the volume of the plant (for example twice), the surface increases proportionally lower (i.e. less than twice). In general, in the production processes, the investment costs increase in proportion to the surface, while the operating costs vary in proportion to the volume of the plant. The raw materials
The influence of the different substrates for the biogas production on the hydrogen cost was also calculated. The biogas from MSW is characterized by a medium- high content of H2S, nearly 900 mg for Sm3 of biogas; it means 757 kg/y of H2S to dispose and nearly 1000 kg of activate carbon for year (Hysytech company). A biogas poor of sulphur allows to save on the desulphurization costs, but it goes to the detriment of the cost of biogas which is higher.
Considering 4 years of amortization, the operational costs are estimated in order to assess the impact of different matrices on hydrogen final cost.
In the Table 7 are compared the H2S content in the biogas, the biogas price and the respective operational costs for three different sources of biogas.
Table 7. Hydrogen final cost for different substrates.(see pdf attached) Figure 41. Hydrogen final cost for different substrates.
For simplicity, the quality of biogas from MSW and agroindustry scraps is considered the same, because the methane content in biogas is similar (60% CH4). The agroindustry scraps can be divided into three sub-cases:
I. the sewages are in the same site in which is present the AD; in this case, it is convenient to use the manure to produce biogas, there aren’t additional costs and other solutions would be more expensive.
II. the sewages are in a site near the biogas plant; in this case, the costs of biomass and its transport are about 10 €/tontq
III. the sewages are purchased, transported and stored in the AD site; in this case, the cost of biomass has to be integrated with the cost of transport and storage, about 55 €/tontq.
The active sludge is characterized by a higher H2S content and lower CH4 content (53% CH4), therefore the yield of biogas is less. The estimated hydrogen’s production is nearly 83 Nm3/h.
2.5. The SWOT Analysis
The SWOT analysis summarizes Strengths, Weakness, Opportunity and Threats of a project. This is an important instrument used for the strategic and commercial business planning.
First of all, a target needs to be define in order to realize s SWOT analysis. Our target is the BioRobur’s technology. Two main categories constitute the matrix SWOT:
➢ Internal factors: here are included the strengths and weaknesses internal to the BioRobur technology
➢ External factors: here are included the opportunities and threats presented by the environment external to the BioRobur’s technology.
Strengths
This square includes the internal aspects that are helpful to achieving the objective.
The strengths of BioRobur’s technology are:
• Low environmental impact: the main feeding of BioRobur’s technology is the biogas which allows to dispose waste producing energy. Also, the energy recovery, aimed to heat the process water, permits to reduce the thermal consumptions.
• Competitive on European market: in 5 years of amortization the estimated hydrogen’s cost is 4 € for kilograms of hydrogen, meanwhile the European target is 5 € for kilograms of hydrogen.
• High energy efficiency: the heart of the process is an auto thermal reaction; it means that the heat required from the reforming reaction is balanced with the heat released by the partial oxidation, guarantying an auto sustainable process.
Weakness
This square includes the internal negative aspects that harm the objective.
The weakness of BioRobur’s technology are:
• High cost of PSA unit: the gas purification is crucial to reach the final specification and the high grade required. The PSA unit guarantees these results but the overall costs of this technology (the equipment, the materials and the energy consumptions) are very high, nearly the 22% of total costs.
Opportunities
This square includes the external conditions that are helpful to reach the target.
• Policy incentives: there has been a wide diffusion of plants to produce biogas in the last years. In fact, the government incentives have promoted the use of biomass in order to produce energy as alternative to the use of fossil fuels.
• The research of new energy sources: the world is occupied to research alternative energy sources in order to reduce the pollution and defend the environment, especially for future generations. There is more sensibility and interest for the environmental protection.
Threats
This square includes the external conditions that hinder to reach the target.
• Difficult final applications: the hydrogen technology is not really diffuse yet and its final applications are not easy.
• Fossil fuels: the future scenarios expect that, for the next thirty years, the fossil sources will remain the most used.
• The time: the “hydrogen economy” is not expected before many years. In this contest, characterized by a strong technological competition, the BioRobur’s technology will compete with technologies more consolidated.
3. Conclusion
The techno-economic analysis showed that the BioRobur technology plays an important role to create a more sustainable scenario and it could have a crucial role in the European market. The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase with the years, the capital costs do not change and they are distributed on the entire cycle life. Moreover, in 10 years of amortization, the final cost to produce 100 Nm3/h of hydrogen from biogas is 3€/Kg H2, lower than the European target (5€/kg H2). The raw material for the biogas production is a key for the final hydrogen cost.
Additional, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
In the other hand, Strengths, Weakness, Opportunity and Threats of a technology were identified by a SWOT analysis. Finally, the route to implement and spread these bio-technologies is still long. For this reason, there is the need for constant incentives in order to deepen, improve and implement the new bio-technologies such as the production of biogas and the hydrogen technology.
With the years, the capital costs do not change and they are distributed on the entire cycle life. The results are showed in Figure 39 (see pdf attached)
The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase with the years, the capital costs do not change and they are distributed on the entire cycle life. The results are showed in Figure 4.
Figure 3. Hydrogen final cost vs. amortization time, compared with the EU target.
The size of the plant
The impact of the size plant on the final costs was evaluated. The capital and operational costs change with the dimension of the plant. A small plant has lower direct and operational costs, but, at the same time, it has also a lower production; in this way the final cost of the product increases. Moreover, increasing the volume of the plant (for example twice), the surface increases proportionally lower (i.e. less than twice). In general, in the production processes, the investment costs increase in proportion to the surface, while the operating costs vary in proportion to the volume of the plant.
Capex estimation: the ratio between the new Capex and the Capex for the reference size (rf) is equal to the ratio between the new size and the reference size (rf), elevated to 0,6 (eq. [1]).
Capex/〖Capex〗_rf = (Size/〖Size〗_rf )^0.6 [1]
Opex estimation: the variation between the ratio of Opex on reference Opex (rf) and size on reference size (rf) is linear (eq. [2]).
Opex/Opex_rf = (Size/Size_rf ) [2]
For the H2 production cost calculation in function of the size of the plant, an amortization time of 4 years was considered. The results are displayed in Table 6.
Table 6. Hydrogen cost based on the plant size.
SIZE
[Nm3H2/h] CAPEX
[€] OPEX
[€] H2 Produced
[kg] H2 cost
[€/kgH2]
50 € 575.305 € 186.800 142.768 6
100 € 872.000 € 373.600 285.536 5
150 € 1.112.170 € 560.400 428.304 4
200 € 1.321.705 € 747.200 571.072 3,7
250 € 1.511.056 € 934.000 713.840 3,5
500 € 2.290.332 € 1.868.000 1.427.679 3
700(*) € 2.802.692 € 2.615.200 1.998.751 2,8
(*) Typically, the plant with a large production of hydrogen (500-700 Nm3/h) are fed with biogas from MSW.
The results are illustrated in Figure 5.
Figure 4. Hydrogen cost vs. plant size, compared with the EU target.
The Figure shows that for a low production of hydrogen (50 Nm3/h) the H2 costs are unfavourable compared with the European target.
The raw materials
The influence of the different substrates for the biogas production on the hydrogen cost was also calculated. The biogas from MSW is characterized by a medium- high content of H2S, nearly 900 mg for Sm3 of biogas; it means 757 kg/y of H2S to dispose and nearly 1000 kg of activate carbon for year (Hysytech company). A biogas poor of sulphur allows to save on the desulphurization costs, but it goes to the detriment of the cost of biogas which is higher.
Considering 4 years of amortization, the operational costs are estimated in order to assess the impact of different matrices on hydrogen final cost.
In the Table 7 are compared the H2S content in the biogas, the biogas price and the respective operational costs for three different sources of biogas.
Table 7. Hydrogen final cost for different substrates.
SUBSTRATE H2S CONTENT [mg/Sm3biogas] PRICE
[€/tontq] OPEX
[€] H2 COST [€/kgH2] H2 Produced
[Nm3/h]
MSW 900 0 € 373.600 5,0 100
Active Sludge 4000 15 € 539.477 6,0 83
I. Agroindustry scraps 400 0 € 355.051 4,3 100
II. Agroindustry scraps 400 10 € 397.292 4,4 100
III. Agroindustry scraps 400 55 € 587.372 5,1 100
Figure 6. Hydrogen final cost for different substrates.
For simplicity, the quality of biogas from MSW and agroindustry scraps is considered the same, because the methane content in biogas is similar (60% CH4). The agroindustry scraps can be divided into three sub-cases:
the sewages are in the same site in which is present the AD; in this case, it is convenient to use the manure to produce biogas, there aren’t additional costs and other solutions would be more expensive.
the sewages are in a site near the biogas plant; in this case, the costs of biomass and its transport are about 10 €/tontq
the sewages are purchased, transported and stored in the AD site; in this case, the cost of biomass has to be integrated with the cost of transport and storage, about 55 €/tontq.
The active sludge is characterized by a higher H2S content and lower CH4 content (53% CH4), therefore the yield of biogas is less. The estimated hydrogen’s production is nearly 83 Nm3/h.
The SWOT Analysis
The SWOT analysis summarizes Strengths, Weakness, Opportunity and Threats of a project. This is an important instrument used for the strategic and commercial business planning.
First of all, a target needs to be define in order to realize s SWOT analysis. Our target is the BioRobur’s technology. Two main categories constitute the matrix SWOT:
Internal factors: here are included the strengths and weaknesses internal to the BioRobur technology
External factors: here are included the opportunities and threats presented by the environment external to the BioRobur’s technology.
Strengths
This square includes the internal aspects that are helpful to achieving the objective.
The strengths of BioRobur’s technology are:
Low environmental impact: the main feeding of BioRobur’s technology is the biogas which allows to dispose waste producing energy. Also, the energy recovery, aimed to heat the process water, permits to reduce the thermal consumptions.
Competitive on European market: in 5 years of amortization the estimated hydrogen’s cost is 4 € for kilograms of hydrogen, meanwhile the European target is 5 € for kilograms of hydrogen.
High energy efficiency: the heart of the process is an auto thermal reaction; it means that the heat required from the reforming reaction is balanced with the heat released by the partial oxidation, guarantying an auto sustainable process.
Weakness
This square includes the internal negative aspects that harm the objective.
The weakness of BioRobur’s technology are:
High cost of PSA unit: the gas purification is crucial to reach the final specification and the high grade required. The PSA unit guarantees these results but the overall costs of this technology (the equipment, the materials and the energy consumptions) are very high, nearly the 22% of total costs.
Opportunities
This square includes the external conditions that are helpful to reach the target.
Policy incentives: there has been a wide diffusion of plants to produce biogas in the last years. In fact, the government incentives have promoted the use of biomass in order to produce energy as alternative to the use of fossil fuels.
The research of new energy sources: the world is occupied to research alternative energy sources in order to reduce the pollution and defend the environment, especially for future generations. There is more sensibility and interest for the environmental protection.
Threats
This square includes the external conditions that hinder to reach the target.
Difficult final applications: the hydrogen technology is not really diffuse yet and its final applications are not easy.
Fossil fuels: the future scenarios expect that, for the next thirty years, the fossil sources will remain the most used.
The time: the “hydrogen economy” is not expected before many years. In this contest, characterized by a strong technological competition, the BioRobur’s technology will compete with technologies more consolidated.
Conclusion
The techno-economic analysis showed that the BioRobur technology plays an important role to create a more sustainable scenario and it could have a crucial role in the European market. The results demonstrate that longer is the plant life and more affordable is the initial investment. In fact, although the operational expenditures increase with the years, the capital costs do not change and they are distributed on the entire cycle life. Moreover, in 10 years of amortization, the final cost to produce 100 Nm3/h of hydrogen from biogas is 3€/Kg H2, lower than the European target (5€/kg H2). The raw material for the biogas production is a key for the final hydrogen cost.
Additional, the analysis showed that low production of hydrogen (50 Nm3/h) results unfavourable compared with the European target.
In the other hand, Strengths, Weakness, Opportunity and Threats of a technology were identified by a SWOT analysis. Finally, the route to implement and spread these bio-technologies is still long. For this reason, there is the need for constant incentives in order to deepen, improve and implement the new bio-technologies such as the production of biogas and the hydrogen technology.
List of Websites:
www.biorobur.org