2. Efficiency of FC and combined cycles
2.1. Operating temperature and fuel cell efficiency
Most FCs use H2. One exception is the direct-methanol FC
reported by Toshiba [6]. The primary fuel—mostly natural gas or
biogas, undergoes an endothermic conversion consisting of
reforming and shift reactions to generate the required H2. Hightemperature
FCs (HTFCs) allow heat integration between the fuel
conversion and the power generation processes. In contrast, lowtemperature
FCs (LTFCs) do not, and additional fuel is burnt to
supply the heat for the main fuel conversion [7], resulting in
electrical efficiencies around 35% for LTFC against 41% for HTFC.
Similar estimates result from MCFC integration [5] (see Table 1).