Clean destruction of waste ammonia with consummate production of electrical power within a solid oxide fuel cell system

Abstract

The response of a solid oxide fuel cell towards waste ammonia has been studied using a small tubular solid oxide fuel cell system, since ammonia is present in certain biogas in large quantities as a breakdown product of biological waste. SOFCs are not only tolerant to ammonia, but can actually utilise the ammonia present in biogas to produce electrical power, at the same time acting as an environmental clean-up device breaking down the ammonia pollutant to nitrogen and water. Ammonia is catalytically decomposed over the nickel cermet anode to N₂ and H₂, and the H₂ is then electrochemically oxidised to water. Direct electrochemical oxidation of the ammonia does not occur, and no undesirable nitrogen oxides are formed.