Excess Electric Power-Driven Conversion of Carbon Dioxide to Chemicals
- Precision Combustion, Inc.
Our process features a PCI proprietary regenerable solid-oxide fuel cell stack operating in electrolysis mode (SOEC) using low value off-peak (excess) power from wind or solar renewable electricity sources, producing syngas, from zero-value carbon dioxide and water feed stocks, that is then upgraded in a novel Fischer-Tropsch (FT) reactor design. The products are a range of hydrocarbon chemicals and / or fuels that are drop-in replacements from the equivalent products produced from crude oil. During off-power time intervals, the stack is operated in solid-oxide fuel cell (SOFC) mode, employing energy-containing byproducts from the FT unit. Production and storage of excess syngas in SOEC mode permits continuous operation of the FT unit and avoids system shutdowns and eliminates harmful thermal cycling in both the SOEC/SOFC and FT units. During the course of this Phase I project, we determined that our approach to FT can enable a compact reactor that takes advantage of the benefits of Microlith® mesh catalyst substrates. Specifically, we found that when a catalyst is supported on mesh, greater productivity to higher hydrocarbons is achievable. Mesh enables operating at faster reaction kinetics without changing the reaction rate determining mechanism, minimizing or eliminating methane production and improving desired product yields; in comparison, pellet-supported catalysts need to operate in a kinetics constrained mode to avoid overheating, limiting possible higher hydrocarbon yields. We identified a novel catalyst composition that produces very low methane yields while producing higher hydrocarbons from CO2, enabling operational flexibility, with the advantages of this class of catalysts remains to be fully explored. Additionally, our regenerable SOEC stack can produce syngas via co-electrolysis of CO2 and H2O in the correct H2/COx ratio for optimum FT operation while also operable in SOFC for process flexibility. Provided that we can achieve optimized performance, we can produced diesel fuel at a producer price of $3.85/gal, corresponding to $3.57/GGE (gallon gasoline equivalent), with an overall carbon efficiency of 53% and power efficiency of 32%. These values compare favorably with DOE’s goals of $3.00/GGE, 40% carbon efficiency, and 40 % power efficiency. We expect to improve power efficiency upon optimization of the process, including identification of opportunities for reuse of waste energy from the process and SOFC-based power co-generation from H2 and CO-rich tail gas.
- Research Organization:
- Precision Combustion, Inc., North Haven, CT (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0018620
- OSTI ID:
- 1491756
- Type / Phase:
- SBIR (Phase I)
- Report Number(s):
- PCI-SC0018620-PhI
- Country of Publication:
- United States
- Language:
- English
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