Periodic Reporting for period 2 - WASTE2WATTS (Unlocking unused bio-WASTE resources with loW cost cleAning and Thermal inTegration with Solid oxide fuel cells)
Período documentado: 2020-07-01 hasta 2021-12-31
WASTE2WATTS (W2W) designs an integrated biogas-SOFC CHP system with targeted gas processing, focusing on low-cost biogas pollutant removal, for SOFC system compatibility (catalyst tolerances), and a proper thermal integration based on stack technology and gas feed.
Biogas is a resource available across all Europe which is largely underexploited (<20% of the potential). One reason is that it is dispersed (distribution density represents 30-50 kW_CH4 per km2) and thus needs small systems. Another bottleneck is lack of policy, incentive, reglementations, and of standardisation in product offers and sizes. SOFCs can exploit the resource on the local small-scale (25-50 kWe) owing to high electrical efficiency (>50%) and absence of polluting and noise emissions. They can provide base load in winter. Biogases contain traces that hamper the downstream gas use, in engines (corrosion), gas grid injection (limits to respect) or fuel cell system catalysts (reformer and anodes, Ni-based), and which must be removed, in a cheap way, to about 1 ppm level, taking into account specifics (humidity, gas matrix, competitive removal, variations based on waste input and season).
Two cleaning approaches are developed:
(1) one for small-scale units (25-50 kWe), where H2S and organic S are removed by a solid sorbent mix that the project research identified through testing.
(2) one for medium-to-large scale units (multi-100 kWe), where sulfur compounds and siloxanes are removed by a deep gas cooling approach (-100°C).
For both cases the hardware is built and installed on biogas sites treating different wastes. A kWe-size small-scale SOFC system from SOLIDpower will run on an agro-biogas site in Switzerland, connected to a sorbent gas cleaning unit. A 100 m3/h sized gas cleaning system will be installed on a mixed biowaste digestion site in Lithuania to demonstrate the deep cooling approach.
Cost projections for high volume production for both the cleaning and SOFC systems have been conducted. SOFC production of 25-50 MWe/yr will drop cost to a few k€/kWe.
A detailed full system model is defined, with the targets to maximise net electrical efficiency (>55%) and minimise cost (<3500€/kWe for the combined cost of SOFC CHP (max 2500€/kWe) and biogas cleaning (max 1000€/kWe)).
SOFC cell/stacks and reformer catalysts are evaluated with selected and relevant gas mixtures, containing H2S, CH3-S-CH3, COS, CH3-SH at 1-30 ppm level.
The unused biowaste potential in EU-27 agriculture amounts to 3000 PJ. This represents 47 GWe power, distributed as around 110'000 units of 200 kWe, 330'000 units of 50 kWe and 340'000 units of 25 kWe.
Biogas is a resource available across all Europe which is largely underexploited (<20% of the potential). One reason is that it is dispersed (distribution density represents 30-50 kW_CH4 per km2) and thus needs small systems. Another bottleneck is lack of policy, incentive, reglementations, and of standardisation in product offers and sizes. SOFCs can exploit the resource on the local small-scale (25-50 kWe) owing to high electrical efficiency (>50%) and absence of polluting and noise emissions. They can provide base load in winter. Biogases contain traces that hamper the downstream gas use, in engines (corrosion), gas grid injection (limits to respect) or fuel cell system catalysts (reformer and anodes, Ni-based), and which must be removed, in a cheap way, to about 1 ppm level, taking into account specifics (humidity, gas matrix, competitive removal, variations based on waste input and season).
Two cleaning approaches are developed:
(1) one for small-scale units (25-50 kWe), where H2S and organic S are removed by a solid sorbent mix that the project research identified through testing.
(2) one for medium-to-large scale units (multi-100 kWe), where sulfur compounds and siloxanes are removed by a deep gas cooling approach (-100°C).
For both cases the hardware is built and installed on biogas sites treating different wastes. A kWe-size small-scale SOFC system from SOLIDpower will run on an agro-biogas site in Switzerland, connected to a sorbent gas cleaning unit. A 100 m3/h sized gas cleaning system will be installed on a mixed biowaste digestion site in Lithuania to demonstrate the deep cooling approach.
Cost projections for high volume production for both the cleaning and SOFC systems have been conducted. SOFC production of 25-50 MWe/yr will drop cost to a few k€/kWe.
A detailed full system model is defined, with the targets to maximise net electrical efficiency (>55%) and minimise cost (<3500€/kWe for the combined cost of SOFC CHP (max 2500€/kWe) and biogas cleaning (max 1000€/kWe)).
SOFC cell/stacks and reformer catalysts are evaluated with selected and relevant gas mixtures, containing H2S, CH3-S-CH3, COS, CH3-SH at 1-30 ppm level.
The unused biowaste potential in EU-27 agriculture amounts to 3000 PJ. This represents 47 GWe power, distributed as around 110'000 units of 200 kWe, 330'000 units of 50 kWe and 340'000 units of 25 kWe.
Main results in Period 1 and Period 2 (M1-M36, Jan2019-Dec2021):
1. Bio-waste potential (WP1)
Currently unused biogas resources are 3000PJ (20% of EU natural gas use), and classified into small scale (5/50 kWe) and medium/large scale (500 kWe and larger). They reside almost entirely in agriculture (manure and crops residues, in a proportion of 35%-65%); the OFMSW-biogas potential is just 2% of that in agriculture.
Over half (53%) is available for exploitation on 50 kWe scale per site (15 m3/h of biogas), amounting to 0.5 million SOFC units deployed over Europe, for total installed power of 25 GWe, for a generation of 220 TWhe/yr, or 7% of EU electricity.
2. Biogas cleaning (WP2)
Agro-biogas is dominated by sulfur contaminants: hundreds of ppm H2S, and a few ppm of difficult traces such as CH3-S-CH3 (DMS dimethyl-sulfide), CH3-SH, COS.
The other critical contaminant is siloxanes, especially in landfill (116 PJ use in Europe, large ICE sites), and wastewater treatment plants WWTP (59 PJ use in Europe).
About 20 solid sorbents have been selected, sourced and tested for S-removal in 3 labs on different S-compounds, in variable conditions (gas matrix, humidity, O2 presence, flow velocity). Moreover, sorbents have been tested in the field on real biogas. Sorption capacity is sensitive to the combination of all parameters. A solution was identified by first removing H2S from wet biogas, chilling the gas, and performing a polish with dry gas to remove the rest of the sulfur. COS will fix the amount of sorbent to be used for a given application. 1 kg of sorbent can remove 200 g H2S, 18 g CH3-SH, 3 g DMS and 1 g COS and can cost <100€/kWe for the sorbent.
SOLIDpower has validated in-house a 6.8 kWe system (64% dc efficiency on natural gas).
3. Biogas composition definition, and testing on SOFC (WP3, WP4)
8400 biogas-SOFC-system configurations were computed. This led to the choice of 4 gas compositions used in testing, 2 each for SOLIDpower and Sunfire SOFC technologies, 1 with dry-dominant reforming, 1 with mixed CO2/steam reforming. Theoretical electrical efficiencies of 57-64% result from the computations.
4 reforming catalysts were characterised. Exposure to 10 ppm H2S for 100h has been performed and partial regeneration demonstrated.
Cells were tested up to 2400h, and resilience to 3 and 5 ppm S was shown with only 1-2% performance loss. A similar result was obtained on stacks. A SOLIDpower stack in simulated reformed biogas (without S) achieved 66% dc LHV efficiency.
Techno-economic analyses were performed for 20-200 kWe systems. LCOE of 9-14 cts€/kWhe is achieved for systems reaching TCO of 10 k€/kWe (with stacks of 10 yrs life time), where the biogas cost remains dominant (50%), the SOFC 35% and the cleaning section 15%. Sensitivity analyses showed stack cost and stack lifetime as important; hence high volume manufacturing to bring down this cost is essential.
4. Dissemination, management, amendment (WP5, WP6)
A project website and project templates were set up, 2 project flyers and 2 project newsletters circulated, and W2W presented at a biogas seminar and 2 open door day events. 6 oral presentations at conferences were given and multiple journal articles published. Many results have been gathered for further publications. Data have been collected on sorbents, biogas compositions and trace concentrations, on the bio-waste resource potential. A biogas market entry for SOFC was carried out, considering the replacement of ICEs on existing biogas installations until 2030: this would amount to ~40’000 units of 50 kWe SOFC or ~2 GWe.
1. Bio-waste potential (WP1)
Currently unused biogas resources are 3000PJ (20% of EU natural gas use), and classified into small scale (5/50 kWe) and medium/large scale (500 kWe and larger). They reside almost entirely in agriculture (manure and crops residues, in a proportion of 35%-65%); the OFMSW-biogas potential is just 2% of that in agriculture.
Over half (53%) is available for exploitation on 50 kWe scale per site (15 m3/h of biogas), amounting to 0.5 million SOFC units deployed over Europe, for total installed power of 25 GWe, for a generation of 220 TWhe/yr, or 7% of EU electricity.
2. Biogas cleaning (WP2)
Agro-biogas is dominated by sulfur contaminants: hundreds of ppm H2S, and a few ppm of difficult traces such as CH3-S-CH3 (DMS dimethyl-sulfide), CH3-SH, COS.
The other critical contaminant is siloxanes, especially in landfill (116 PJ use in Europe, large ICE sites), and wastewater treatment plants WWTP (59 PJ use in Europe).
About 20 solid sorbents have been selected, sourced and tested for S-removal in 3 labs on different S-compounds, in variable conditions (gas matrix, humidity, O2 presence, flow velocity). Moreover, sorbents have been tested in the field on real biogas. Sorption capacity is sensitive to the combination of all parameters. A solution was identified by first removing H2S from wet biogas, chilling the gas, and performing a polish with dry gas to remove the rest of the sulfur. COS will fix the amount of sorbent to be used for a given application. 1 kg of sorbent can remove 200 g H2S, 18 g CH3-SH, 3 g DMS and 1 g COS and can cost <100€/kWe for the sorbent.
SOLIDpower has validated in-house a 6.8 kWe system (64% dc efficiency on natural gas).
3. Biogas composition definition, and testing on SOFC (WP3, WP4)
8400 biogas-SOFC-system configurations were computed. This led to the choice of 4 gas compositions used in testing, 2 each for SOLIDpower and Sunfire SOFC technologies, 1 with dry-dominant reforming, 1 with mixed CO2/steam reforming. Theoretical electrical efficiencies of 57-64% result from the computations.
4 reforming catalysts were characterised. Exposure to 10 ppm H2S for 100h has been performed and partial regeneration demonstrated.
Cells were tested up to 2400h, and resilience to 3 and 5 ppm S was shown with only 1-2% performance loss. A similar result was obtained on stacks. A SOLIDpower stack in simulated reformed biogas (without S) achieved 66% dc LHV efficiency.
Techno-economic analyses were performed for 20-200 kWe systems. LCOE of 9-14 cts€/kWhe is achieved for systems reaching TCO of 10 k€/kWe (with stacks of 10 yrs life time), where the biogas cost remains dominant (50%), the SOFC 35% and the cleaning section 15%. Sensitivity analyses showed stack cost and stack lifetime as important; hence high volume manufacturing to bring down this cost is essential.
4. Dissemination, management, amendment (WP5, WP6)
A project website and project templates were set up, 2 project flyers and 2 project newsletters circulated, and W2W presented at a biogas seminar and 2 open door day events. 6 oral presentations at conferences were given and multiple journal articles published. Many results have been gathered for further publications. Data have been collected on sorbents, biogas compositions and trace concentrations, on the bio-waste resource potential. A biogas market entry for SOFC was carried out, considering the replacement of ICEs on existing biogas installations until 2030: this would amount to ~40’000 units of 50 kWe SOFC or ~2 GWe.
Biogas potential according to power size in 5/50/500kWe, for agro-wastes and OFMSW, per courntry.
Novel small scale cleaning solution based on the best sorbents for the specific contaminants has been identified and will be tested on a farm site.
A new cryocooling cleaning hardware will be tested on a medium sized existing biogas site (>100 m3/h biogas flow).
Catalysts specific for dry and mixed reforming have been tested and validated.
The sulfur robustness of stacks, cells and catalysts is higher than believed. Tolerance up to 3-5 ppm S is possible, which can simplify the cleaning cost and requirement.
Systems were computed to select operating strategies and conditions for a biogas SOFC CHP system.
A new consortium consisting of mainly SME has been created that will implant a complete new agricultural biogas installation including a fuel cell, after W2W.
Policy makers and funding should realize that there lies large potential in biogas on small scale in agriculture (5% of electricity supply), which needs to be supported and incentivised. The standardisation and volume manufacturing of small scale digesters must increase and hence their cost must come down, in parallel to the fuel cells and cleaning cost.
Novel small scale cleaning solution based on the best sorbents for the specific contaminants has been identified and will be tested on a farm site.
A new cryocooling cleaning hardware will be tested on a medium sized existing biogas site (>100 m3/h biogas flow).
Catalysts specific for dry and mixed reforming have been tested and validated.
The sulfur robustness of stacks, cells and catalysts is higher than believed. Tolerance up to 3-5 ppm S is possible, which can simplify the cleaning cost and requirement.
Systems were computed to select operating strategies and conditions for a biogas SOFC CHP system.
A new consortium consisting of mainly SME has been created that will implant a complete new agricultural biogas installation including a fuel cell, after W2W.
Policy makers and funding should realize that there lies large potential in biogas on small scale in agriculture (5% of electricity supply), which needs to be supported and incentivised. The standardisation and volume manufacturing of small scale digesters must increase and hence their cost must come down, in parallel to the fuel cells and cleaning cost.