Design andOptimization of an Innovative SolidOxide Fuel Cell–Gas Turbine Hybrid Cycle for Small Scale DistributedGeneration

The supply of energy services plays a major role in human society but also induces major environmental problems. Common efforts have to be focus on the development of new power conversion systems with reduced environmental impact and higher efficiencies to preserve the resources. Distributed power generation and cogeneration represent an attractive way for a more advantageous and sustainable fossil or biofuels energy conversion. According to the International Energy Agency [1], the building sector accounts for more than 30% of the world total energy consumption. Consequently distributed generation and cogeneration systems have received increasing consideration in the last years. However, the available technologies for small-scale applications, at the building level, are often significantly less efficient than the large-scale systems typical of centralized power production. Those mainly consist of internal combustion and Stirling engines affected by high maintenance costs, detrimental emissions, vibrations, and noise. The introduction of micro gas turbines, in the range of 30–100 kWel, have reduced the last two problems, but are characterized by a low efficiency and are not yet available in the smaller power range typical of single or multi-family houses. Molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC) are considered as the most promising technologies to alleviate all the above-mentioned problems. Both MCFC and SOFC operate at high temperature (higher than 600 C) admitting the direct conversion of unreformed fuel such as natural gas or biogas and offering the possibility of cogeneration and poly-generation. Among these two options, SOFCs are the favorite candidates for distributed generation or cogeneration in buildings since they have a higher power density, a higher operating temperature (up to 1,000 C) and potentially a higher reliability at small scale than MCFC. Furthermore, SOFCs have a range of capacity covering all Abstract