Status and market opportunities of solid oxide fuel cells based cogeneration systems

The most sustainable technology for conversion of natural gas into electricity and heat in the low to medium power levels, is a Solid Oxide Fuel Cell (SOFC) based Combined Heat and Power (CHP) unit. Electrical efficiencies of up to 60 % and total efficiencies of more than 90 % down to electrical powers of only 1 kW, makes these systems attractive for applications in varying power classes. The range between 10 and 50 kWel is especially promising for competition with conventional CHP units and the electrical grid. Different system layouts options exist to meet the technical requirements of specific applications as well as the cost targets for a early market entry. Main distinguishing features are the method of processing natural gas into a hydrogen-rich reformate (i.e. partial oxidation vs. steam reforming) and the cell stack technology used. As a result, electrical efficiencies, system complexity, and costs vary. Applied to cogeneration, the overall efficiency has the ma in impact on the profitability of the CHP unit, provided there is existence of a sufficient heat demand. Electrical efficiencies are dominated by power to heat ratios or the utilization factor, this means the number of operation hours needs to be increased. The calculation of CHP cost saving potentials is impeded strongly by application dependent parameters like profiles of heat and electricity demand as well as local gas and electricity prices. For Germany, payback periods can be calculated since typical load profiles of single and multi-family homes are available. Here, the choice of SOFC system layout depends on the economic viability of electricity feed-in to the grid. If funding is available, high electrical efficiencies are clearly favored. This is also valid for applications where only domestic hot water heating is required. Small base load power generators are profitable provided that the system cost targets can be met. Larger SOFC system in a power range of >100 kWel face a strong compe