When engineer Sanford Moss built GE’s first gas turbine more than a century ago, things didn’t go exactly as the company planned. The machine used too much fuel and produced too little power. Moss put the design on the shelf until the outbreak of World War I, when the National Advisory Committee for Aeronautics, NASA’s predecessor, realized it could use the device to supercharge aircraft engines and gain superiority in the air. The new application also thrust GE into a new business: aviation.
Moss’ innovation spirit — and gas turbines — live on at GE Power, the company’s unit building and servicing equipment for the gas power generation industry. Some 116 years after his breakthrough, engineers there are using the latest research and technologies to build a super-efficient gas turbine that could push the efficiency of a combined-cycle power plant above 64%.
How much is that? Just a decade ago cracking 60% efficiency was considered a feat akin to breaking the sound barrier or running a four-minute mile. But things started changing in 2014, GE launched its line of ultra-efficient HA gas turbines — the H stands for high-efficiency, A stands for air-cooled — and the record-keepers had to get busy.
GE developed two models of the machine — the 7HA for markets like the U.S. at 60 hertz, and 9HA for grids in Europe and elsewhere using 50 hertz. In 2016, the first power plant with a 9HA turbine in France scored a Guinness World Record by clocking in at 62.22% net efficiency. Two years later, a 7HA turbine in Japan hit 63.08% gross efficiency.
The latest evolution of the technology, 7HA.03 in GE nomenclature, is aiming even higher. GE just said the first two units are going to Florida Power & Light Company’s Dania Beach Energy Center near Fort Lauderdale. The highly efficient machine, which also can generate 430 megawatts will allow FPL to squeeze .4% more power from every cubic foot of natural gas relative to GE’s prior 7HA.02 product, potentially saving the utility close to $1 million a year on it gas bill. (Combined with a steam turbine harnessing the exhaust energy off the HA, a power plant can pump out as much as 1,282 megawatts, the equivalent electricity needed to power approximately 1 million U.S. homes.) In Asia where gas prices are significantly higher, the potential savings could be near $4 million, compared to the previous 7HA.02 model.
GE said in a press release the new power plant will “produce considerable economic benefits to FPL customers, including more than $300 million in net savings for FPL customers over the life of the plant, as well as significant reductions in air emissions by replacing older generating technologies.”
There are other benefits. The gas turbine can ramp up to full power in just 10 minutes, allowing operators to pick up slack when the wind stops blowing or the sun stops shining and renewable generation drops off.
How does the machine do all of that? For starters, the turbine is building on GE’s experience of using a titanium blade that allows it to pass additional airflow to generate more power. The engineers also brought the fuel mixing system from GE’s largest gas turbine — the 9HA — over to the 7HA to obtain better performance, lower emissions and increase its fuel flexibility, so it could also run on a mix of alternative fuels including hydrogen.
Flexibility is also the new name of the game. The new mixing systems allow the 7HA.03 to gradually dial back to just 30% of its full load while still remaining in compliance with emission regulations. Think of the gas turbine operating like the accelerator in your car. In certain situations like an increased speed limit or driving up a hill, pressing the accelerator creates the additional power and work needed to move your car; but other situations like coasting down a hill or idling at a stoplight require you to take your foot off the accelerator to prevent wasting fuel or worse. This idea is known as turndown and GE's 7HA.03 takes it to new limits. This flexibility is especially important in markets with a high percentage of intermittent renewables on the grid. On the flip side, when wind dies (or demand surges), the turbine can jump in quickly to help, adding more than 75 megawatts of power a minute, a 25% jump over the previous model.
The 7HA.03 wasn’t the only news for the HA technology. GE also announced that it received its 100th order for the turbine this week. Today, there are 40 HA units in commercial operation globally supplying 18 gigawatts of power, the equivalent electricity needed to power more than 13.5 million U.S. homes. GE’s fleet of HA gas turbines has surpassed more than 415,000 operating hours and secured 100 unit orders from 40 customers in 18 countries.