Development Progress of a 70% Efficient Hybrid SOFC-I.C. Engine Hybrid System for Stationary Applications up to 1 MW

Abstract

Flexible and dispatchable, high-efficiency power generation supplied with carbon-neutral renewable fuels is needed to help enable defossilization of the electric grid. Pressurized, hybrid SOFC systems fueled with hydrogen, biogas, or renewable natural gas can generate clean power at ultra-high efficiency. This presentation presents an update on the development progress of a full-scale, hybrid system that targets low cost (<1000 $/kW) and ultra-high efficiency (70%-LHV) distributed power generation for applications up to 1 MW. The system features mature, metal-supported SOFC technology and the system design, control, hardware integration, and demonstration activities are funded by the U.S. DOE ARPA-E INTEGRATE Program. Some of the more novel aspects of the system include the intermediate operating cell temperature (600°C) and internal reforming capabilities which enable excellent thermal management and effectively reduce air preheater duty by >60% over more conventional SOFC systems operating near 800°C. Pressurization of the system decreases area specific resistance (ASR) and increases stack power density, thereby lowering capital cost. The use of a gasified diesel engine converts the residual chemical exergy in the anode tail-gas from the SOFC to drive auxiliaries and produce net additional power. Furthermore, the syngas engine enables a simple engine after-treatment for achieving ultra-low engine emissions (NOx, CO, PM, UHC). Updates on critical hardware advancements around pressurized multi-stack, 30 kW fuel cell modules, low-speed high efficiency rotating equipment, and ultra-high efficiency power electronics are provided. Results from experimental testing, system design and layout, and demonstration test facility capabilities are presented and discussed. The presentation concludes with a techno-economic outlook for such power generation systems in various stationary applications, as well as comparison with competing distributed generation technologies, such as solar PV-battery systems, microturbines, stationary engines, and non-hybridized SOFC technologies. Figure 1