Hydrogen-capable natural gas turbines gain traction in power sector

Several US power utilities are moving in the hydrogen direction as they experiment with hydrogen blending in natural gas turbines and announce goals of replacing gas with 100% hydrogen by midcentury.

One of the latest hydrogen commitments from the power sector came earlier this year when Duke Energy announced a $4 billion investment in hydrogen-enabled natural gas generation as the utility winds down its coal assets. During the company's latest quarterly earnings call, CFO Steve Young said "we believe our natural gas units are well-positioned to take advantage of hydrogen technology as it evolves."

Duke's announcement builds on hydrogen's momentum in the power sector. In 2020, the Long Ridge Energy Terminal in Ohio announced plants to transition a 485-MW gas-fired power plant to run on General Electric's new hydrogen-capable turbine, which is able to burn a gas stream blended with 15%-20% hydrogen. And on the Gulf Coast, Entergy Texas is also developing the Orange County Advanced Power Station, a 1,215-MW power facility along the Texas-Louisiana border that will be capable of using 30% hydrogen by 2026 using turbines that Mitsubishi Power developed.

Experimentation with hydrogen blending in turbines is happening elsewhere around the country as well, including in Siemens Energy's Intermountain Power Project in Utah and Mitsubishi's proposed $1 billion facility slated to produce green hydrogen for gas-fired turbines in Montana.

"Hydrogen does a lot of things that we really need done," said Alex Kizer, senior vice president of research and analysis at Energy Futures Initiative. "We need clean, flexible, load-following resources for the grid, and these are things that gas generally does today, where you can call on it at any time. Many people are thinking that that's maybe something hydrogen can do, too."

The move toward hydrogen in the power sector is also attractive to investors, Kizer said, because hydrogen allows utilities to start small. In contrast with other clean technologies with high upfront capital spending investments, like advanced nuclear plants, utilities can leverage existing facilities to begin blending hydrogen at low levels in the near term, then ramp up to higher levels over time.

A Duke Energy pilot project, for instance, has an initial goal of co-firing hydrogen in gas plants at a 30% rate by 2024 and a midterm goal of 100% hydrogen by 2030.

"I think investors really like that it can do that smoothing of the transition – I think that's very compelling," Kizer said. "There's scalability in your financial commitment."

Generating electrons from hydrogen

There are unique challenges to blending hydrogen in gas streams at all points along the value chain. Within turbines, gas and hydrogen respond differently to combustion. Hydrogen ignites faster than gas, which brings the flame closer to the nozzle through which the gas stream comes.

"Because hydrogen combusts so much faster, you have to design the nozzles differently so that they keep the flame further away and don't melt themselves," said Joshua Rhodes, a research associate at the University of Texas Energy Institute. "If you were to try to run high blends of hydrogen in an older vintage facility, you would essentially get what they call blowback, and it would melt itself from the inside."

Yet there are some older vintage turbines capable of burning gas streams with low levels of hydrogen, and there are a variety of factors that determine blending capability — turbine age, the speed of turbine rotation, and, among others, the size of the hydrogen vs gas molecules.

"These are tuned instruments, and you really got to understand how this different product will impact your expensive assets," Kizer said.

Raising blending levels up to the 30% range and beyond typically requires a whole new category of technologies, and a variety of companies have brought a range of hydrogen-capable turbines to market in recent years.

General Electric, for instance, has its 7Ha models that are capable of blending up to 50%. And the gas technology company INNIO claims its converted gas turbine can run on a variable fuel mix with up to 100% hydrogen.

But the full impacts of incorporating hydrogen into the gas system remain to be seen. Policy support to usher hydrogen into the power sector will be critical, Kizer said, but it's not yet clear what policy mix will be necessary or how it could impact consumer-level prices.

"It's vitally important that we figure this out, and I think utilities are spending time experimenting right now," Kizer said. "There [are] unique challenges to actually generate electrons from hydrogen."