Periodic Reporting for period 2 - CLARA (Chemical Looping gAsification foR sustainAble production of biofuels)
Reporting period: 2020-05-01 to 2022-04-30
Reducing the detrimental impact of the energy intensive heavy freight transport and aviation industry on the environment is a key obstacle that needs overcoming on the way towards a carbon-neutral society. Hence, alternatives for these industry sectors heavily relying on fossil fuels have to be established. Due to their great promise, the production of biofuels has been greatly intensified in recent years. However, the large-scale utilization of food crops for fuel production has also drawn substantial criticism, related to food scarcity and prices. To limit the implications of the food vs. fuel issue, the pursuit of efficient and economic pathways for producing so-called 2nd generation biofuels, derived from biogenic residues, is en vogue.
Gasification is a well-known thermochemical conversion strategy, allowing for the production of a high calorific synthesis gas from virtually any solid carbon-based material, which is why it is considered to be a crucial building block in future 2nd generation biofuel process chains. Within the scope of the project CLARA an efficient process chain for the production of liquid fuels based on chemical looping gasification (CLG) of biogenic residues is being developed. In chemical looping, pure oxygen for feedstock conversion is provided through the cyclic reduction and oxidation of a circulating oxygen carrier material (see Fig.1). Hence, CLG facilitates the efficient conversion of biogenic feedstocks into a high-calorific and N2-free synthesis gas, without relying on a costly air separation unit. Moreover, the CO2 formed during the autothermal gasification process can be captured efficiently, allowing for the production of end-products with negative carbon footprints. The advantages of this novel gasification technology are combined with other innovative technologies related to feedstock pre-treatment, enabling the use of low-grade biogenic residues for gasification, and raw gas cleaning, lowering capital and operational expenditures by 30 % compared to state of the art gas cleaning technologies. Consequently, the suggested process chain, schematically shown in Figure 2, allows for significantly reduced biofuel production costs, so that cost-competitive drop-in fuels (0.7 €/l) can be realized.
Gasification is a well-known thermochemical conversion strategy, allowing for the production of a high calorific synthesis gas from virtually any solid carbon-based material, which is why it is considered to be a crucial building block in future 2nd generation biofuel process chains. Within the scope of the project CLARA an efficient process chain for the production of liquid fuels based on chemical looping gasification (CLG) of biogenic residues is being developed. In chemical looping, pure oxygen for feedstock conversion is provided through the cyclic reduction and oxidation of a circulating oxygen carrier material (see Fig.1). Hence, CLG facilitates the efficient conversion of biogenic feedstocks into a high-calorific and N2-free synthesis gas, without relying on a costly air separation unit. Moreover, the CO2 formed during the autothermal gasification process can be captured efficiently, allowing for the production of end-products with negative carbon footprints. The advantages of this novel gasification technology are combined with other innovative technologies related to feedstock pre-treatment, enabling the use of low-grade biogenic residues for gasification, and raw gas cleaning, lowering capital and operational expenditures by 30 % compared to state of the art gas cleaning technologies. Consequently, the suggested process chain, schematically shown in Figure 2, allows for significantly reduced biofuel production costs, so that cost-competitive drop-in fuels (0.7 €/l) can be realized.
During the second reporting period (RP), the focus was laid upon further refining initial findings made with regard to the innovative technologies under investigation in the CLARA project and optimizing the individual process steps. The advances made in terms of biomass pre-treatment, CLG, and the novel gas treatment concept are schematically visualized in Figure 2. On the other hand, the development and demonstration of the entire integrated biomass-to-liquid (BtL) process chain consisting of the individual technologies (see Fig. 3) was progressed using those insights before the process chain was evaluated in terms of risks and economics.
Building on the findings made in lab & bench scale in the previous RP, the novel pre-treatment process for biogenic residues of inferior quality was successfully applied in pilot and industry scale, highlighting the feasibility of utilizing of a wide range of biogenic materials for feedstock production. With the aim of advancing the maturity of the novel CLG technology, insights made in lab scale in the first RP were successfully transferred to small pilots, showing that continuous CLG operation at relevant conditions is achievable. Moreover, further findings, allowing for improved process efficiency and operability were made during continuous pilot testing. Building on this foundation, the very first autothermal CLG operation was achieved in the 1 MW pilot plant, shown in Figure 4, which was extensively adapted in RP 1 & 2 to allow for CLG operation, thus elevating the CLG technology to TRL6. Furthermore, the proposed novel acid gas cleaning technique, i.e. removal of H2S from sour gas via KMnO4 scrubbing, was successfully demonstrated in lab scale prior to its patenting.
Building on the extensive knowledge gathered during advancing of the individual technologies, the defined BtL process chain, developed in the first RP has been further refined and optimized. Through tailored interconnection of existing processes with the novel technologies under investigation, it was established that cold gas efficiencies >80 % are attainable in CLG, at carbon conversions exceeding 98 %. Furthermore, a carbon utilization of 32.5 % and an energetic fuel efficiency of 53.5 % were determined for the entire BtL chain, showing that the set KPIs can be reached via the process route under investigation. Based on the calculated heat & mass balances of the optimized process chain and by using the expertise of the CLARA consortium, the layouts for the pre-treatment unit, the chemical looping gasifier, the gas treatment unit, as well as the fuel synthesis unit were specified for a thermal load of 200 MW. Subsequently, the technological, societal, and environmental risks of the entire scaled BtL chain were investigated in detail and risk mitigation strategies were conceived. Moreover, initial cost structures for the scaled process chain were calculated. The preliminary techno-economic-assessment result shows that the break-even selling points of biofuel production cost range from 0.76-0.80 €/liter without revenues from by-product sales. If the CO2 credit is included, the biofuel production costs are reduced, ranging from 0.63-0.68 €/liter.
Building on the findings made in lab & bench scale in the previous RP, the novel pre-treatment process for biogenic residues of inferior quality was successfully applied in pilot and industry scale, highlighting the feasibility of utilizing of a wide range of biogenic materials for feedstock production. With the aim of advancing the maturity of the novel CLG technology, insights made in lab scale in the first RP were successfully transferred to small pilots, showing that continuous CLG operation at relevant conditions is achievable. Moreover, further findings, allowing for improved process efficiency and operability were made during continuous pilot testing. Building on this foundation, the very first autothermal CLG operation was achieved in the 1 MW pilot plant, shown in Figure 4, which was extensively adapted in RP 1 & 2 to allow for CLG operation, thus elevating the CLG technology to TRL6. Furthermore, the proposed novel acid gas cleaning technique, i.e. removal of H2S from sour gas via KMnO4 scrubbing, was successfully demonstrated in lab scale prior to its patenting.
Building on the extensive knowledge gathered during advancing of the individual technologies, the defined BtL process chain, developed in the first RP has been further refined and optimized. Through tailored interconnection of existing processes with the novel technologies under investigation, it was established that cold gas efficiencies >80 % are attainable in CLG, at carbon conversions exceeding 98 %. Furthermore, a carbon utilization of 32.5 % and an energetic fuel efficiency of 53.5 % were determined for the entire BtL chain, showing that the set KPIs can be reached via the process route under investigation. Based on the calculated heat & mass balances of the optimized process chain and by using the expertise of the CLARA consortium, the layouts for the pre-treatment unit, the chemical looping gasifier, the gas treatment unit, as well as the fuel synthesis unit were specified for a thermal load of 200 MW. Subsequently, the technological, societal, and environmental risks of the entire scaled BtL chain were investigated in detail and risk mitigation strategies were conceived. Moreover, initial cost structures for the scaled process chain were calculated. The preliminary techno-economic-assessment result shows that the break-even selling points of biofuel production cost range from 0.76-0.80 €/liter without revenues from by-product sales. If the CO2 credit is included, the biofuel production costs are reduced, ranging from 0.63-0.68 €/liter.
CLG is a relatively new technology, which has not been studied in great detail prior to the start of the CLARA project. Within the project, the consortium was able to elevate this technology towards technical maturity (TRL 6), thus paving the way towards the edification of large-scale highly efficient next generation gasifiers. Moreover, the novel biomass pre-treatment concept, developed within the project, allows for the exploitation of a wider feedstock range for biomass-to-x process chains, thus promoting the efficient utilization of biogenic waste materials and the development of process chains exhibiting a closed carbon cycle. Lastly, the patented gas cleaning technology, which is being developed within the CLARA project, is expected to significantly reduce syngas post-processing cost, which means that a sound alternative to the state-of-the-art Rectisol process, finding application in a range of different process chains, was formulated.
The integration of these technologies, as suggested in the CLARA project, yields a BtL chain allowing for the production of cost-competitive biofuels, signifying a key pillar in the strive towards a carbon-neutral society. Another issue addressed through the process is the necessity of large-scale deployment of BECCS by 2050 in order to reach the 1.5 °C target. The highly concentrated CO2 stream leaving the gasifier as a side product can be sequestered or further utilized, thus signifying negative CO2 emissions at no substantial additional cost, if sustainably grown biomass is used as feedstock. First calculations indicate that the suggested BtL process will be able to capture 44.7-45.4 % of the carbon contained in the biomass feedstock. Moreover, no detrimental effects regarding food availability or food prices will occur, as the feedstock is limited to biogenic residues. In addition, these biogenic waste materials from agriculture or forestry are valorized, thus diverting profits to rural areas.
The integration of these technologies, as suggested in the CLARA project, yields a BtL chain allowing for the production of cost-competitive biofuels, signifying a key pillar in the strive towards a carbon-neutral society. Another issue addressed through the process is the necessity of large-scale deployment of BECCS by 2050 in order to reach the 1.5 °C target. The highly concentrated CO2 stream leaving the gasifier as a side product can be sequestered or further utilized, thus signifying negative CO2 emissions at no substantial additional cost, if sustainably grown biomass is used as feedstock. First calculations indicate that the suggested BtL process will be able to capture 44.7-45.4 % of the carbon contained in the biomass feedstock. Moreover, no detrimental effects regarding food availability or food prices will occur, as the feedstock is limited to biogenic residues. In addition, these biogenic waste materials from agriculture or forestry are valorized, thus diverting profits to rural areas.