The projects funded within ARPA-E’s Reliable Electricity Based on Electrochemical Systems (REBELS) program are meant to produce fuel cell devices that will be cost-efficient and create new functionality for grid stability and integration of renewables such as wind and solar. One particular REBELS project, developed by the Mines Colorado Fuel Cell Center (CFCC) and led by Mechanical Engineering Associate Professor Neal Sullivan, focused on protonic ceramic fuel cells (PCFCs) for distributed power generation applications that could increase the stability of the grid, provide significant cost savings, and result in fewer greenhouse gas emissions compared with centralized power plants while avoiding transmission losses throughout the grid.
Protonic Ceramic Fuel Cell
During their REBELS project, the CFCC developed a PCFC with a mixed proton and oxygen ion conducting electrolyte that allows the fuel cell to operate at lower temperatures (~500-650°C). PCFCs are different from traditional solid oxide fuel cells, which utilize oxygen-conducting electrolytes and often require higher temperatures (700-800+ °C) to operate optimally. The composition of the PCFC was optimized throughout the project and a gadolinia-doped ceria (GDC) interlayer was added, ultimately resulting in a fuel flexible, durable, scalable cell. A key feature of this fuel cell is its ability to avoid coking – formation of carbon deposits that clog active sites and can cause catastrophic failure – when operating on a variety of carbonaceous fuels. The PCFC shows an especially high-power density when operating directly on hydrogen, ammonia, and methanol fuel at 600 °C, though it can successfully operate on many other fuels.
The CFCC partnered with FuelCell Energy to tackle both the development of larger-format PCFCs and a low-cost manufacturing process. FuelCell Energy successfully employed their ceramic manufacturing expertise to scale-up the PCFC from a button cell (~1 cm2) to an 81 cm2 cell while still maintaining its power density. Over 100 PCFC cells were manufacturing during this project. FuelCell Energy also brought their decades of manufacturing know-how to bear in designing a manufacturing process that maximized yield and minimized cost and complexity, bringing this technology closer to becoming a commercially viable option for DG applications.
The CFCC has received follow-on small business technology transfer (STTR) funding from the Army Research Office to develop propane-powered tubular PCFCs, and to develop and test a bundle of these cells. The Army STTR program encourages high-tech small businesses in the U.S. to partner with research institutions to yield innovative solutions. Thus far, this project has yielded 2 patents, 1 provisional patent, and additional invention disclosures in process, as well as 30+ publications, and 50+ conference papers and presentations. Since it was awarded in 2014, this project also spurred the growth of interest and funding for PCFC research and development.