Cycle analysis of micro gas turbine-molten carbonate fuel cell hybrid system

A hybrid system based on a micro gas turbine (μGT) and a high temperature fuel cell, i.e., molten carbonate fuel cell (MCFC) or solid oxide fuel cell (SOFC), is expected to achieve a much higher efficiency than conventional distributed power generation systems. In this paper, a cycle analysis method and performance evaluation of a μGT-MCFC hybrid system, of which power output is 30 kW, are investigated to clarify its feasibility. A general design strategy is obtained that decreasing fuel input to a combustor and a higher MCFC operating temperature lead to higher power generation efficiency. A higher recuperator temperature effectiveness and steam-carbon ratio moderate requirements for the material strength of a turbine. It is also confirmed that a μGT-MCFC is much feasible to a μGT-SOFC in terms of its moderate heat-resistance of turbine and recuperator materials. In addition, employing a combustor for complete oxidation of MCFC effluents without additional fuel input, i.e., a catalytic combustor, the power generation efficiency of a μGT-MCFC is achieved to over 60% (LHV).