General Electric recently unveiled its FlexEfficiency technology, which delivers both flexibility and efficiency to power plants. The technology responds to and mitigates the variability of wind and solar power by rapidly ramping up and down a jet engine that burns natural gas. The GE turbine can vary its output twice as fast as any other gas plant. RMI’s electricity practice welcomed the news as one of a number of ways forward for adding renewables to the electric grid.
“This [technology] could absolutely help advance renewables on the grid,” says Lena Hansen, who leads RMI’s Next Generation Utility (NGU) initiative. “Since we can’t control the wind and sun, we need other flexible resources that we can control to compensate for their variable power output and maintain the balance [of supply and demand].”
RMI’s NGU initiative aims to transition the U.S. electricity sector away from fossil fuels to efficiency and renewables by 2050, driving toward a system that is affordable, clean, resilient and reliable. Reliability is key to integrating more renewable energy onto the grid: Utilities must generate and supply electricity the instant it is used; if the balance is off, the grid goes down and blackouts result. To maintain that balance, systems need flexibility.
Hansen says there are a number of ways to add flexibility to the grid and integrate renewables, including diversifying them by location, diversifying them by type, and forecasting their output. One strategy focuses on the demand side—making the load more flexible. (This means consumers contribute to energy balancing—for example, using intelligent building controls to pre-cool a building earlier in the day, rather than running air conditioners during expensive afternoon peak periods.) Another strategy is to store energy. Another is GE’s solution: use natural gas plants that can compensate for the variability of supply.
The technology is a result of GE’s $500 million R&D investment. “The industry is a very competitive space, and we really need to continue to invest in order to maintain our technology leadership,” says Jim Donohue, marketing manager for heavy-duty gas turbines at GE Power & Water. “Several years ago, when we started to embark on this, we saw that the existing infrastructure was going to have some difficulty with [anticipated increases in renewable deployment] and we would need to have a very flexible power plant like the FlexEfficiency50 to be complementary to the renewables we have seen and expect to continue to see.”
GE will initially deploy the technology in China, a country that is installing more wind turbines than any other in the world, and Turkey, where GE will work with the Turkish company MetCap to develop the world’s first integrated renewables combined cycle plant. GE is working with other partners around the world to bring FlexEfficiency technology to its utility customers.
The technology won’t come to the U.S. for a few years. That’s because North America generates electricity at 60 hertz, while much of the world, including China and Turkey, operates on the 50-hertz system; the different frequencies require machines that spin at different speeds. “From a business standpoint, it makes more sense to bring it into the 50 hertz market first,” says Donohue. “We absolutely see a need for flexible generation in the U.S. We will be migrating the technology from the 50 hertz over to the 60 hertz in the next couple of years.”
A May 2011 International Energy Agency report, “Harnessing Variable Renewables: A Guide to the Balancing Challenge,” concludes that large shares of renewable energy are feasible, despite its variability, as long as power systems and markets are configured to optimize their flexible resources.
Hansen says the IEA is right on. “There is no technical reason why we can’t integrate a lot of variable renewables,” she says. “It’s possible. It just requires a different way of doing business. It requires shifting markets to be faster, more cooperation, larger balancing areas—those types of shifts in the way we run our markets and the way we deal with these resources and the way we use the other resources we have.”
U.S. utilities will demand the technology only if it is cost-competitive. Donohue says the price of the FlexEfficiency50 plant is consistent with current technology, at the same dollar-per-kilowatt price point. “The real benefit to a customer, then, is twofold,” says Donohue. At the same price point, the biggest cost of a plant is fuel. The consumer benefits because less fuel is burned to generate the same amount of electricity. And, he explains, “Because of the flexibility in the plant, there are also ancillary services and revenues that you get from system operators for having very quick start times, the ability to ramp up very quickly.”
Although RMI supports the development of this new technology, Hansen emphasizes that there are many other ways to integrate renewables, and flexible supply-side power plants are not the only solution to transforming the electricity system. “This is really helpful, but we shouldn’t hang our hat on it,” Hansen says. “We should also focus on other solutions, like demand-response, institutional changes, having markets that operate publicly and having bigger areas that we balance power over. We don’t want to send the message that the only way to accelerate renewables is to build a lot of new gas plants. It’s hitting on the right issues, and we should think about it as a portfolio of strategies to integrate renewables.”