Multi-Fuel PEM Fuel Cell Power Plant for Vehicles 2009-01-1004

A multi-fuel PEM fuel cell power plant has demonstrated power production from both diesel and E85. The system combines a compact autothermal reformer (ATR) based fuel processor with an automotive fuel cell stack to convert liquid fuel into hydrogen and then electricity. While both the fuel processor and fuel cell have been developed over several years of collaboration with the automotive industry¹,²,³,⁴,⁵, this system is the first generation (Gen 1) demonstration of a lab-independent power plant with embedded controls, no external water input, an integrated heat rejection system, and automotive-style air, fuel, and water controls.

The Gen 1 prototype power plant has produced up to 10 kW_e net electrical output and demonstrated system efficiencies up to 31%. To achieve a tight schedule, the system utilized non-optimized off-the-shelf balance of plant (BOP) components including air compressors and water pumps that increased the parasitic power and reduced the efficiency. An optimized 10 kW_e system is projected to achieve over 34% net system efficiency and give a notable efficiency advantage over the small diesel ICEs typically used in truck Auxiliary Power Units (APUs). Furthermore, higher-power systems on the scale of 80 kW_e could achieve over 43% efficiency. These improvements would be enabled primarily via improved BOP, reduced pressure drop, more efficient DC/DC electronics, and higher hydrogen utilization.

Since the catalysts in the fuel processor and fuel cell are poisoned by sulfur, initial tests focused on fuels with sulfur less than 3 ppm-wt. Since these fuels are not widely available and would be a major limitation to consumers, a liquid-phase desulfurization technology was developed to allow operation on commercially available fuels. This desulfurizer enabled successful power plant tests on pump-grade Ultra Low Sulfur Diesel (ULSD) with 12 ppm-wt sulfur including 30 hours of automated power cycling.

A packaging study is also presented for the power plant in a heavy duty truck APU application.