High-efficiency ammonia-fueled hybrid power generation system combining ammonia decomposition, proton exchange membrane fuel cell and micro gas turbine: A thermodynamic model and performance optimization

As a carbon-free hydrogen (H2) carrier with the advantage of liquefaction storage and transportation, ammonia (NH3) is regarded as a competitive clean energy carrier for H2 production and power generation. This work designs a novel NH3-fueled hybrid power generation system, which combines ammonia decomposition reactor (ADR), proton exchange membrane fuel cell (PEMFC) and micro gas turbine (MGT) together with thermochemical recuperation for ADR. A system-level thermodynamic model has been developed to evaluate system performance with different optimization strategies. The model calculation reveals that the NH3 decomposition temperature drop from 500 °C to 350 °C can increase the energy efficiency from 33.5 % to 43.2 %, and two improved integration strategies have therefore been proposed. Mixing a part of NH3 with the exhaust gas from PEMFC anode to fuel MGT can reduce the NH3 decomposition demand and makes better use of waste heat from MGT. Integrating ADR with MGT combustor can lower the exhaust gas temperature and the efficiency loss when using high temperature NH3 decomposition catalyst. Both strategies can improve the system energy efficiency, to about 40 % and 44 % when NH3 decomposition temperature is 500 °C and 350 °C, respectively, and demonstrate better flexibility in adapting to changes in NH3 decomposition temperature.