MHI Achieves 3,000-Hour Operation, Unprecedented in Japan,
Of SOFC-MGT Combined-Cycle Power Generation System

MHI began developing the SOFC-MGT combined-cycle power generation system in 2004 at MHI's Nagasaki Shipyard and Machinery Works under consignment by the New Energy and Industrial Technology Development Organization (NEDO). In 2007 the system marked a maximum power generation capacity of 229 kW, unprecedented in a system of this kind at that time, and confirmed 52.1% power generation efficiency (LHV: lower heating value, power output terminal), also the highest level in this class. The company has now achieved the 3,000-hour milestone.

Based on this success, MHI will pursue further reliability enhancement and system downsizing. The company is also working toward a business/industrial-use hybrid system* combining SOFCs and an MGT in joint development with Toyota Motor Corporation. MHI further plans to develop a system for use by power generation companies.

SOFCs are ceramic-based fuel cells that operate at a high temperature above 900 degrees Celsius (1,650 degrees Fahrenheit) and produce electricity directly by chemical reaction between the hydrogen and carbon oxide removed from city gas and oxygen in the air. The SOFC-MGT combined-cycle power generation system utilizes the unreacted portion of city gas exhausted from the SOFC module and hot air likewise discharged from the SOFC module. The gas and air from the SOFC module are used to drive an MGT to generate electricity. This two-stage power generation system is able to achieve significantly higher power generation efficiency than conventional fossil-fuel power generation systems, and will thus contribute to the realization of a very high-efficiency power generation system.

MHI has been vigorously pursuing various power generation methods to reduce CO2 emissions, including high-efficiency thermal power generation systems, nuclear power systems, and renewable energies such as wind power and photovoltaic cells, and sees the SOFC technology as a promising effective way. As higher power generation efficiency is expected by combining SOFCs with other power generation systems – ranging from small-scale (under one MW) to large (several hundreds of MW) – MHI views the development of large-scale combined cycle power generation systems using SOFCs as a key challenge and powerful trump card. As to business/industrial-use hybrid power generation system combining SOFCs and an MGT for under one MW, MHI has been conducting joint development with Toyota Motor Corporation since 2008. Toyota has an affiliate company, Toyota Turbine Systems Inc., which sells MGTs.

* A hybrid system capable not only of power generation but also of thermal supply such as hot water and steam.