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MHI to develop fuel cell triple combined cycle power generation system; expected to deliver power generation exceeding 70% (LHV) in larger applications

Mitsubishi Heavy Industries, Ltd. (MHI) will begin developing basic technologies for a triple combined cycle power generation system integrating solid oxide fuel cells (SOFC) and a gas turbine combined cycle (GTCC) power generation system.

Conceptual drawing of the triple combined cycle power generation system configuration. Source: MHI. Click to enlarge.

With the support of the New Energy and Industrial Technology Development Organization (NEDO), the company will launch a two-year study this year as part of a project entitled “Development of Systems and Basic Technologies for Solid Oxide Fuel Cells (SOFC).” NEDO previously received and accepted a proposal from MHI.

In a triple combined cycle power generation system, an SOFC power generation system is placed before the GTCC system. By generating power at three stages—the fuel cell, gas turbine, and steam turbine—the resulting fuel cell combined cycle (FCCC) system achieves outstanding efficiency in generating power from natural gas. The FCCC system is expected to achieve the world’s highest power generation efficiency exceeding 70% (LHV) for several hundred MW class power generation and over 60% (LHV) efficiency for several tens of MW class power generation.

As part of the study, MHI will develop the basic technologies needed to combine SOFC and gas turbine power generation systems. For the SOFC system, the company will test the system’s characteristic features and durability under high pressure of up to 3.0 MPaG (Megapascal [gauge]). Issues to be considered for the gas turbine system include conversion of gas turbines and combustor development. MHI also plans to demonstrate a power generation simulation involving SOFC and a gas turbine system working in conjunction.

MHI sees FCCC triple combined cycle power generation as a revolutionary technology that will result in 10% to 20% improvements in power generation efficiency over existing natural gas-fired power generation systems. The company plans to pursue development based on the results of the basic technologies study, with the ultimate goal of commercializing the technology.



Looks like utilities are desperate for new, more efficient central power systems. But the capital costs of FCCC systems will give potential buyers pause. And the SOFC component looks to play a small role in the above description.

But the program is called “Development of Systems and Basic Technologies for Solid Oxide Fuel Cells (SOFC).” So perhaps the gas/steam turbine part is just a diversion.


Adding a fuel-cell topping cycle to a CCGT is one of the obvious improvements.  Japan, which imports nearly all of its fuel, has an obvious need for it.  MHI is an obvious candidate to develop this technology.

For carbon capture, the FC tail gas (essentially nitrogen-free) could be scrubbed of CO2 before passing it to the combustor.  This would require either a new hot-gas scrubbing system (not amines) or cooling and reheating, which means some efficiency loss.  But even if you went down to 60% efficiency, capturing 80% or so of the carbon would make other schemes look pretty sad.

Note that this would also work with cleaned syngas from coal.

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