the fuel cell installation is operated at temperatures between 80 ° c . and 300 ° c . and ensures that the efficiency is optimized , since the waste heat from the fuel cell stack is utilized at least in some other way . for the purpose , there is provided an evaporator upstream of the fuel cell stack . at least one line is connected to the fuel cell stack for rendering available a heat content from at least a part of the fuel cell stack to be utilized in one or more further units of the installation .