The ARPA-E REBELS Program: Advances and Challenges after 1.5 Years of Research

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In 2014, the Advanced Research Projects Agency-Energy (ARPA-E) started the Reliable Electricity Based on ELectrochemical Systems (REBELS) program, focusing on fuel cells utilizing natural gas for stationary power production and value-added products generation. The intent of REBELS was twofold: (1) demonstrate that operating fuel cells in an “intermediate” temperature range of 200-500 oC could reduce system cost compared to polymer electrolyte membrane (PEM) fuel cells and higher temperature solid oxide fuel cells (SOFCs), and (2) create new electrochemical functionality such as charge storage in the stack and liquid fuel production to benefit grid applications. REBELS was enabled by more than 15 years of materials research on new electrolytes, such as solid acids, proton-conducting ceramics, and alternative oxygen-conducting ceramics to yttria-stabilized zirconia. This presentation describes the rationale behind the REBELS program, including changes in the U.S. electrical grid and the evolving opportunities for distributed power generation. Technical barriers to intermediate temperature operation such as methane activation at lower temperatures and reduced power density due to electrode overpotentials and electrolyte resistance will be highlighted.In the year and a half since the REBELS program began, teams working on a variety of material systems have made progress on several fronts. New anode compositions and microstructures enabled fuel cells to operate directly on methane at 500 oC without coking. New cathode materials mitigated the increase in electrode overpotential as temperature decreased from higher temperature SOFC operation. New electrocatalyst materials and morphologies allowed solid acid fuel cells to operate around 250 oC with reduced platinum loadings. New electrochemical functions have also been demonstrated, such as power production with internal charge storage (no external fuel) and conversion of methane to products such as methanol and ethylene.This presentation will summarize the performance of technologies within the REBELS program with respect to PEM and SOFCs, and it will revisit the original assumptions that motivated the program. Components of the techno-economic models required to rigorously evaluate the program, such as electrochemical performance, materials cost, stack lifetime, efficiency etc. will be discussed.