As exciting as these changes are, for many can now generate their own power from rooftop panels, there’s still no such thing as a free lunch. The wind doesn’t always blow, and the sun doesn’t always shine — yet customers always want their lights to turn on at the flick of a switch. As a result, power producers will continue to depend on reliable ways to quickly generate large amounts of electricity to replace the drop in solar electrons that happens when the sun sets and to serve as a cheaper and cleaner alternative to old-school fossil fuels like coal.
One solution has been natural gas. And GE’s HA turbine – the world’s largest and most efficient gas turbine – continues to lead the market. These powerful machines weigh as much as a fully loaded Boeing 747. They combine decades of know-how from previous gas turbine generations — GE designed the first gas turbine for power generation in 1949 — with technology that GE engineers developed for jet engines. (Turbines and jet engines are quite similar; both use a rotating compressor, a combustor and a turbine to generate electricity or thrust.) For example, the HA uses so-called variable vanes to channel pressurized air through their cores — technology that GE engineers originally developed for supersonic jet engines.
GE deployed the first HA turbine at a power plant in northern France in 2016. A few months later, the site was certified as the most efficient combined-cycle power station in the world. When hooked up to a steam turbine, the setup reached a record-breaking 62.22 percent efficiency, allowing the plant to generate 605 megawatts — enough to supply the equivalent power needed for more than 680,000 French homes.
It can go from zero to full throttle in less than half an hour, enabling the plant operator, EDF Energy, to quickly respond to changing demand, as well as supply from intermittent sources such as wind and the sun. Earlier this year, a plant in Japan with an HA turbine inside clocked in at 63.08 percent efficiency, marking a second world-record.
A world record is more than just bragging rights. “It can save power producers a lot of money,” says John Lammas, Chief Technology Officer for GE Power’s Gas Power Systems business. “We calculated that a 1,000-megawatt power plant using a pair of HA turbines could save $50 million on fuel over 10 years by raising efficiency by 1 percent.”
Since the HA’s launch in 2016, GE has received orders for more than 80 turbines from customers in the U.S., Europe and Asia; 30 of them are already generating electricity. As of August 2018, they have accumulated more than 175,000 fired hours of operation. GE Power CEO Russell Stokes called the turbine “the world’s most reliable, lowest-cost-of-electricity gas turbine and one of the industry’s most successful new products to date.”
Still, it’s not all roses. Earlier this summer, for example, an HA turbine at a power plant encountered an oxidation issue that affects the lifespan of a single blade component. The same issue is expected to impact other HA units, and GE’s field service engineers have proactively started working with customers to resolve the issue. “Obviously, this was a frustrating development for us, as well as for our customers,” Stokes wrote in a recent LinkedIn post addressing the issue. “But we have identified a fix and we’ve been working proactively with HA operators to address impacted turbines. The minor adjustments that we need to make do not make the HA any less of a record setting turbine – they are meeting – and in many cases exceeding – their performance goals at every customer site today.”
Stokes acknowledged that “teething problems inevitably and almost necessarily occur,” and that GE crews are working closely with customers to quickly solve them. “Every new product introduction includes a period after its launch where experts fine-tune and adjust the technology,” he said. “This is normal.”
GE Power tests its turbines and their latest upgrades at a unique test bed next to its state of the art manufacturing facility in Greenville, South Carolina. The test stand, which is disconnected from the power system to prevent wreaking havoc on the local grid, comes equipped with its own gas plant and 4,500 sensors monitoring the complex machine as engineers run it through a litany of stressful conditions, such as operating the turbine at 110 percent of its rated speed, mimicking a power surge in Mexico or extreme heat in Saudi Arabia. The HA turbine was tested at ambient temperatures ranging from minus 37 degrees Celsius to 85 degrees Celsius — far beyond what it would encounter in service.
Besides working closely with customers and learning from their experience, GE engineers are busy testing ideas to make the machine even better. One involves a 3D-printed fuel nozzle that efficiently mixes natural gas with air and injects it into the combustion chamber. GE Aviation is already printing fuel nozzles for its latest jet engines like the LEAP and the GE9X, but this would be the first application in the power generation sector. GE Power has already used 3D printing, also known as additive manufacturing, to produce and ship more than 9,000 turbine parts. That number will quickly grow. “Additive opens the design space to areas that we have yet to explore,” says Guy DeLeonardo, Application Engineering Leader for GE Power’s Gas Power Systems business. “Engineers don’t have to follow the rules, just their imaginations.”
Lammas, who spent 20 years working for GE Aviation, said his team was already testing technologies that can bring gas power plant efficiency to 65 percent. Besides 3D printing, they are also testing components made from a space-age material called ceramic matrix composites (CMCs). This material, which GE spent 30 years developing, allows the turbine to work at temperatures as high as 2,400 degrees Fahrenheit — where most metal alloys grow soft. As a result, engineers design efficient turbines that don’t need as much cooling air and generate more power while burning less fuel.
“Both CMCs and 3D printed parts will allow us to increase the firing temperature of our turbines,” Lammas says. “We also keep improving the aerodynamics and looking at higher pressures and temperatures in the heat recovery part of the generator in the steam turbine to capture more of the gas turbine’s exhaust energy. Finally, we are using some of the world’s most powerful supercomputers to model the heat flows inside the turbine and operate it in unsteady conditions. This will really allow us to take the next machine to the greater limits.”