GE Unleashing a Hydrogen Gas Power Future

But as questions about the long-term use of natural gas—a fossil fuel—in a carbon-free energy ecosystem emerge, the company is building on years of experience exploring how GE gas turbine technology could run on hydrogen fuels, as Dr. Jeffrey Goldmeer, director of Gas Turbine Combustion & Fuels Solutions for GE Power—and GE’s topmost hydrogen expert—told POWER in an interview this month [..].

POWER: How did you become involved in hydrogen?

Goldmeer: I’ve been in my current role as the fuel-flex leader for the gas turbine business for 12 years. I came to GE Power out of GE Global Research Center, where I worked in combustion for six years, and for the last three years at the R&D center, I actually managed the combustion team there. My background is in combustion and fuels, my PhD is in combustion. So I’ve been doing combustion and/or fuels in one way or another for my entire career [..].

We have [several GE gas turbine modes, including] 6Bs, 7Es, 6Fs, 7Fs that are working in this space with fuels that have hydrogen today, whether it’s an [integrated gasification combined cycle (IGCC)] plant or a refinery. We actually have a 6B that’s running in Asia on a fuel that somewhere between 70% and 95% hydrogen—it varies. We’ve installed over 70 to 75 gas turbines burning low-Btu fuels that contain hydrogen, and those turbines combined have over 4 to 4.5 million operating hours. There are other fuel categories that mimic, from a heating value perspective, hydrogen and natural gas blends, and if I throw those turbines in then we have something like 6 million operating hours. And so part of our experience comes from actually having been doing this for decades.

Our first gas turbine working in an IGCC project, if I recall correctly, it was the late 1980s. So, we’ve been doing this for 30 years. Part of this is continuing to take lessons from the industrial sector for these fuels and applying them to this large-scale utility side. So we continue to learn about what it means to be working with fuels that have hydrogen. And a lot of these lessons are things around the plant. How do you modify a natural gas plant to run with fuels that have hydrogen?

We have to think about [balance of plant], safety systems, accessories, all these things. It’s not just the gas turbine. We have to think about the entire gas turbine combined cycle—the whole plant, anything that the fuel touches, any auxiliary systems that could potentially be impacted. But that’s also combustion technology. And so we’ve been doing development of combustion technology for, for fuel flexibility as a whole, again, for decades. It’s not just hydrogen. We focus on a whole realm of fuel flexibility, whether it be heavy liquids and crude oils for the Middle East, whether it’s naphtha and condensates—the whole gamut.

But when it comes to hydrogen, specifically, we can roll the clock back about 15 years, 16 years or so. Going back to that time period, the U.S. Department of Energy was thinking that coal was going to become a dominant supplier of fuel for the U.S. It was, at the time, but it would become more so with gas prices going up. And so they created what was known as the High Hydrogen Turbine Program. GE applied for and received funding for that program to develop gas turbine technology, specifically combustion technology, to increase the efficiency of the gas turbine when operating on a high-hydrogen fuel. The thought process behind that was that if IGCC was going to become the dominant provider of power in the future, displacing gas plants, that carbon capture might be something that we need to deal with. But obviously adding up post-combustion carbon capture system onto a power plant decreases the efficiency of the plant. So the DOE was trying to understand how could you increase the efficiency of the plant, and therefore a huge driver would be the efficiency of the gas turbine. So that’s how it evolved. In retrospect, it’s really funny to see how 15 years ago we thought coal would be the dominant fossil fuel, and here we are today where coal is in a very different place than it was 15 years ago.

So the team was looking at architectures that dealt with those characteristics of hydrogen. We took that from the combustion lab at the R&D center—I actually was the manager at the time we were doing single-nozzle testing—took that to our facility in Greenville, South Carolina, where we eventually tested a full combustion chamber. The combustion technology had a lot of advantages [..]

Now as customers are saying to us, ‘Hey, we’re interested in utility-scale power generation, we’re thinking about HA class turbines, but we are worried about what happens in a potential future where we have to run with hydrogen.’ And the great thing is because that combustion system had its genesis in this DOE high-hydrogen program, it carries some of that capability with it. In the laboratory, we’ve already demonstrated that combustion system [can] run up to 50% hydrogen blended with natural gas.

Let’s start fundamentally with the differences between hydrogen and natural gas. Physically, hydrogen is a smaller molecule, so we have to worry about hydrogen leaks where normal fittings and seals at certain levels, where we wouldn’t leak with natural gas. Hydrogen is much more flammable than natural gas or methane. Methane’s lower flammability limit is about 7% by volume and goes up to 20%. Hydrogen starts at about 4% on the lower flammability [scale] and goes up to about 75%. So, hydrogen is much more flammable. If you have a leak of hydrogen, it becomes more dangerous. Hydrogen flames are harder to see with the naked eye than a flame with a traditional hydrocarbon. And so immediately, when we begin to think about the implications of running hydrogen on a gas turbine, before we even talk about combustion challenges, we need to think about fundamental safety issues [..]

You can’t use a standard fuel nozzle because you can’t pass all that hydrogen through it three times the flow. So you have to modify fuel nozzles in order to be able to flow that much. From a combustive perspective, hydrogen is incredibly reactive. One metric around reactivity of a fuel is the flame speed. You know, how fast that flame wants to propagate into the unburned fuel. And that’s always something that from a combustion design perspective you’re aware of so that you can maintain a margin to flame-holding and flashback issues. Hydrogen has got a flame speed that, depending on the study you look at, is about an order of magnitude faster than methane. So that hydrogen flame will want to propagate upstream into the unburned fuel much faster. So you have to have a combustion system that is explicitly configured to deal with that issue. That’s why, to burn 60, 70, 80, to 100% hydrogen in a combustion system is a real challenge. How do you deal with the fact that the flame wants to go someplace that, as a design engineer, you don’t want the flame to be?

But that being said, when you can master all of those challenges, hydrogen is a clean-burning fuel—it doesn’t carry any carbon with it—so that’s a positive [..]

GE has some fantastic know-how around combustion engines using hydrogen.

[1] https://www.powermag.com/the-power-interview-ge-unleashing-a-hydrogen-gas-power-future/