GE's New Flexible Gas Turbine: All the Power, None of the Waste

Conventional natural gas turbines suffer from a hefty performance tradeoff: they can either burn fewer BTUs per hour, or they can rapidly adjust their output to meet changing energy demands. The new FlexEfficiency gas turbine from GE, however, promises to do both while making renewable energy even cheaper.

When energy production turbines were first widely implemented in the 1980s, they were designed with overall efficiency in mind, not adaptive performance. They were built to run constantly at a steady speed with a static energy output. Ramping the output up and down or shutting down turbines entirely to meet energy demands generally wasn't even a consideration. In fact, cold-starting many of these turbines put tremendous stress on internal parts as the entire rig heated up to its normal operating temperature, shortening operational lifespans and making them generally unsuitable for the rigors of renewable energy's intermittent production.

The new FlexEfficiency turbine (or F-Series for short) by General Electric, however, has been redesigned from the ground up specifically for the challenges posed by the green energy industry. Built in Greenville, SC, the F-series is available in both 50 Hz varieties for Europe, Asia, and Africa as well as 60 Hz for the US, Japan, and the Middle East.

It boasts a solid 61-percent efficiency rating when used in a combined cycle operation. It achieves this level of efficiency through a combination of improved materials such as nickel-based superalloys and single-crystal materials along the hot areas, intricate cooling gas channels and better, computer controlled physics-based models of the combustion process which allows for tighter tolerances, better seals, and unprecedented control over temperatures within the turbines themselves. And when paired with a concentrated solar array, such as the forthcoming Ivanpah Solar Power Facility in California, the turbines can reach 70-percent efficiency.

As such, the F-series can drop its power output from 750 MW to 100 MW, then ramp back to 750 MW again in just 13 minute—that's a ramp-rate of 50MW a minute, roughly twice the speed as current systems. Conventional turbines could only drop their output by about 200 MW before shutting down completely, and took much longer do to so. Even from a cold start, the F-series initiates nearly twice as fast as previous turbines, starting up in just under half an hour thanks to technologies GE borrowed from its jet engine division.

These improvements save significant amounts of money and resources. Power plants can expect to save between $2.6 and 3.5 million each year by adopting the F-series, said Eric Gebhardt, GE Energy's vice president of thermal engineering. What's more, that same plant would use approximately 6.4 million cubic meters fewer of natural gas—about 4,000 European homes-worth—and spew out 12,700 fewer metric tons of CO2 and 10 fewer tons of NOx, like taking 6,000 cars off the Autobahn every year. [Technology Review - IEEE - GE Flexibility - GE - Ecomagination - GE Energy 1, 2 - Image: GE]