Utilization of ammonia as energy carrier

Abstract

This article explains possible energy conversion technology such as fuel cells and direct combustion by utilizing ammonia as an energy carrier. For supply of ammonia to fuel cells, catalytic activities for pre-decomposition on metal supported catalysts were investigated. Power generation characteristics of two types of fuel cells, i.e. solid oxide and anion exchange membrane fuel cells (SOFCs and AEMFCs) were evaluated by supplying ammonia to fuel electrodes. Direct supply of ammonia was possible for the power generation of SOFCs due to their high operation temperatures, whereas the allowable level of residual ammonia should be clarified for AEMFC to avoid poisoning of the electrode. As for direct combustion of ammonia, reduction of NOx emission, enhancement of combustion intensity as well as that of radiation heat transfer are the issues for utilizing ammonia as a fuel which has a significant advantage of no CO₂ emission. Some schemes to solve the issues are also discussed.