68% of fuel cell electrical efficiency measured at LENI

© 2011 LENI/EPFL

Ceramic fuel cells convert the chemical energy of injected fuel into electricity with unprecedented efficiency, at small power scale. Micro-cogenerators (electricity + heat) of 1-2 kWe, based on this technology, are under development and in demonstration.

The Industrial Energy Systems Laboratory (LENI) performs R&D on ceramic fuel cells since over 10 years in collaboration with industrial partners. Thin planar ceramic and metal components, stacked in series and fed with fuel (hydrogen, natural gas, biogas,…) and air, convert the fuel chemical energy directly into electricity and coproduced heat. In the laboratory, LENI has measured gross electrical efficiencies of 65-68% (based on methane lower heating value) on 6-cell clusters (see Figure) fed with steam-methane mixture. The fuel cell stack as such, produced and supplied by their industry partner SOFCpower (Italy)/HTceramix (Yverdon), has a volume of 200 ml and a footprint of 100 cm2 and delivers ca. 100 W. Its design was developed at LENI. In application as a product, 10 such compact clusters (60 cells) stacked in series deliver 1 kWe to cover the base load of single homes, with negligible acoustic and polluting emissions. In today’s energy context focused foremost on savings and rational use, fuel cells converting 2/3 of gas energy (natural gas, biogas, maybe woodgas) have a role to play in decentralised supply. Sustaining its research effort, LENI and its partners estimate that gross efficiencies >70% are soon within reach, to target kW-products with net electrical efficiency well above 50% (including the auxiliaries). By comparison, a natural gas combined cycle power plant achieves up to 58% electrical efficiency, but at large scale only (400 MWe, centralised), without heat cogeneration. Besides, gas transport and distribution towards customers is associated with less losses (<1%) than electrical transmission from central power plants (ca. 7%).