Mitsubishi Hitachi Power Systems has commenced demonstration testing of a 250 kW pressurised hybrid power generation system integrating a solid oxide fuel cell (SOFC) stack and a micro gas turbine (MGT). The aim is to achieve a commercial launch during 2017.
Under a programme supported by Japan’s New Energy and Industrial Technology Development Organisation (NEDO), a national R&D agency, a system intended for both business and industrial use has been installed at the Senju Techno Station of Tokyo Gas Co. It is intended that ultimately there will be four of these demonstration sites. The SOFC-MGT system is to be technically evaluated as a cogeneration system that generates power and also makes effective use of waste heat.
SOFCs are ceramic fuel cells that operate at high temperature – 900°C (1650°F). In a pressurised hybrid system, power is generated directly by the chemical reaction between oxygen in the air and hydrogen and carbon monoxide extracted from reformed city gas. Residual fuel is then used to drive an MGT. This two-stage system achieves significantly higher power generation efficiency.
Air pressurised in the MGT’s compressor is supplied to the SOFCs for use in generating power, and the high-temperature exhaust is fed to the MGT. The heat and pressure, together with the residual fuel, are used to generate power. The pressurised SOFCs produce a substantially increased voltage, leading to enhanced power generation efficiency.
The demonstration system delivers a generation efficiency of 55%. It is a follow- up to the prototype (Model 15) system that has been undergoing demonstration testing at Kyushu University since spring 2015. Three more demonstration sites are to be added, in a factory of Toyota Motor Corporation, which is jointly developing the hybrid system; in a plant belonging to NGK Spark Plug Co, with which MHPS is forming a tie-up for mass-producing the cell stacks; and a facility of Taisei Corporation. At the various venues, demonstration testing will focus on the hybrid system’s operating efficiency, operability and durability in diverse environments, and on the techniques required to achieve reduced costs and achieving mass production as a run-up to commercial marketing.
