The growth of renewable power means that the owners of the world’s gas turbines have to accept some Darwinian logic: Adapt or die. The challenge is particularly acute in the U.K., where electricity production from wind, solar and hydropower installations is booming. The total installed capacity of the country’s renewables sector now exceeds that of fossil-fuel-fired generation, or power plants that burn coal, gas and oil.
Any increase in renewable energy production is good news in the battle to reduce carbon emissions, but it also diminishes the traditional role of gas-fired facilities in baseload power generation — the stable, near-constant supply of the bulk of a grid’s electricity demand. That’s why the U.K.’s gas-fired plants are reinventing themselves to work flexible, part-time shifts; they continually join and drop off the grid according to the level of renewable power production, which itself relies on the fickle elements. “It’s a completely new environment,” says Amit Kulkarni, general manager of F-class turbines at GE. “Instead of being on all day, a gas power plant could be switched on and off on a daily basis.”
It’s not an easy task. The constant switching makes it harder for gas-to-power producers to predict their wholesale electricity revenues, and it also puts more mechanical strain on a plant’s hardware, not least its massive turbines. It means that efficiency, flexibility and reliability — rather than just availability — have become the name of the game for power plant operators seeking to upgrade and revitalize their gas turbines. “Our customers have switched their focus to their operating costs,” Kulkarni says. This means a power producer may be watching the power market on an hourly — rather than daily or weekly — basis. “Less conventional revenue streams matter more and more.”
One operator doing exactly that is Uniper, an international energy company, and the fifth-largest power generator by installed capacity in the U.K. Included in its portfolio is a 400-megawatt gas-fired power plant in Enfield, North London, which has racked up nearly 20 years of operation.
An improvement to the site’s turbine, which is set to be completed next year, will breathe new life into Enfield. “This upgrade could give Enfield at least another 15 years of service,” Kulkarni says. It also will improve Enfield’s competitive position compared with other gas generation plants in the U.K. GE says that increasing the efficiency of baseload power generation — that’s when the power plant runs at full power — by just 2 percent could result in as much as $4 million in annual fuel savings. A 1 percent boost in part-load generation — a situation when the plant doesn’t operate at maximum output — could yield $1 million in savings per year.
Enfield’s existing GT26 turbine was originally manufactured by French company Alstom, which was acquired by GE in 2015. The rejuvenated version, called GT26 HE — the HE stands for high efficiency — will feature a blend of materials science, combustion, cooling and aerodynamics technology originally developed for a fleet of GE gas turbines.
The GT26 HE also will receive a boost from 3D printing. GE’s printers will build components such as the turbine’s lances, which inject fuel into the roaring superheated air in the second combustion chamber. But there’s a twist — literally. The special L-shaped design of the 3D-printed lance, which is around the size of a human arm, means the component can inject gas perpendicularly to the hot airflows of the turbine. “It’s just not possible” to achieve the same results with traditional metal components cast in a foundry, Kulkarni says. “Switching to a 3D-printed design unlocked the opportunity to optimize fuel-air mixing.
The new design also will help smooth out hot spots in the flame and lower the nitrogen oxide (NOx) emissions from the burning of natural gas, which are tightly controlled by the U.K. government and its Environment Agency.
The Enfield plant is the launch site for GE’s GT26 HE upgrade, but there is big potential for further deals. There are nearly 100 GT26 turbines operating around the world that can generate around 36 gigawatts, which is roughly equivalent to powering the entire grid of Egypt or Argentina.
Such upgrades will help gas-fired plants to better support the changing energy mix. Although growth in wind and solar generation shows no sign of slowing, there will always be times when the sun doesn’t shine and the wind doesn’t blow. In the end, necessity will be the mother of reinvention for the world’s gas-fired turbines.
Top image: The GT26 HE turbine will breathe new life into Enfield. Image credit: GE Power.