An important aspect of Energy Strategy 2050 is an increasingly decentralised energy supply. Potential energy suppliers include stationary fuel cells, especially high-temperature fuel cells, which operate at temperatures of up to 900 degrees Celsius. In terms of efficiency, these small-scale power plants are unbeatable: a fuel cell can simultaneously supply a household with electricity and heat and at the same time harness 95 % of the energy in the fuel. In contrast, the current energy supply for households, which is fed by mains electricity and fossil energy sources, achieves an overall efficiency of just 60 %.
Thanks to their high efficiency, high-temperature fuel cells also emit less CO2 than the energy suppliers commonly used today. CO2 emissions can be reduced even further if CO2-neutral gas from renewable sources such as biomass is used as fuel.
Until now, however, fuel cells have not been able to establish themselves as an energy source. One problem is their relatively short service life, which makes the devices more expensive. Furthermore, high-temperature fuel cells are sensitive to sulphur compounds such as those found in biogas. Such impurities are therefore first removed from the gas – which is a costly process.
The Achilles’ heel of the high-temperature fuel cell is the catalyst that splits the fuel molecules and thus releases hydrogen for the energy-generating reaction. Conventional catalysts do not tolerate repeated switching on and off very well because the catalytically active component nickel clumps and loses its function over time. The high operating temperature also has a similar damaging effect over time.