After a false start at the Heritage plant in the USA, GE has found a site for the first commercial application of its 7H gas turbine technology, the 60 Hz version of its H System. It will be powering a new 800 MW combined cycle project being planned by Hydro-Québec, one of North America’s largest producers with 38 000 MW of installed capacity. GE has recently completed validation testing and the commercial launch of its 9H, the 50-hertz version of the H System, at Baglan Bay in south Wales.

The Suroit facility, to be built at Beauharnois, southwest of Montreal, will be based on two GE 107H combined-cycle systems. It is expected to enter commercial service in mid-2007. GE say that one of the H system’s selling points was its high efficiency, in line with Canada’s and Québec’s commitment to the Kyoto Protocol. Today’s most efficient combined-cycle plants have hit a plateau at around the 57-58% efficiency mark; the H system, claims GE, represents a step change by offering a system that is capable of 60% while also providing a platform for continued evolutionary improvements in combined-cycle efficiency.

Developed under the US Department of Energy’s Advanced Turbine System programme, the H System features a new kind of closed-loop steam cooling system that allows the higher firing temperatures required for increased efficiency. In addition to the steam cooling system, GE engineers designed the H turbine’s first-stage buckets and nozzles with single-crystal components to withstand higher temperatures over a long service life.

Much of the H design, however, is based on well established turbine technology. The compressors were based on the designs for the CF6-80C2 aircraft engine and its aeroderivative LM6000 gas turbine. A dry low NOx combustion system, which mixes fuel and air prior to ignition to reduce emissions, has been proven in millions of hours of operation on other GE gas turbines around the world.

Components for the Suroit project will be covered by a GE-Toshiba agreement. GE has H system integration and performance responsibility, and will manufacture the gas turbines and supply the integrated control systems for the power train. Toshiba will manufacture the compressors under licence, along with Toshiba-designed generators and steam turbines.