Committed to H2
How Swedish scientists are working to fulfill the promise of achieving 100-percent hydrogen capability for gas turbines by 2030.
Jenny Larfeldt, professor and senior expert in combustion technology at Siemens Turbomachinery in Finspång, Sweden, has been researching the use of hydrogen as a fuel in gas turbines for over ten years. During this time, Siemens has successfully increased the percentage of hydrogen in the fuel mix. But the ultimate goal and the company’s commitment are to be able to run on 100 percent green hydrogen by 2030.
By Nils Lindstrand
“There are a lot of us here in Finspång who are determined to reach the goal of a totally renewable energy production using gas turbines,” says Jenny Larfeldt. But how do gas turbines and renewable energy fit together? She explains: Due to their flexibility and short ramp-up times, gas turbines have proven to be very effective in balancing volatile renewable energy production. These turbines could in the future be entirely fueled with hydrogen produced from water and surplus renewable electricity.
This so-called green hydrogen is basically one way of storing renewable energy, and by utilizing the existing gas grid it can, thus, solve the challenge of seasonal storage. “This is why gas turbines capable of running solely on hydrogen may just prove to be the missing link to establishing a truly green and sustainable energy sector,” argues Larfeldt.
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Engineering solutions to save the world
Jenny Larfeldt was always going to be an engineer. The question was which field to focus on. At the KTH Royal Institute of Technology in Stockholm, she began her studies at the mining department. She was intrigued by the area of energy, and at one time decided to take a course in advanced thermodynamics. “This immediately felt like home ground for me,” she recalls.
After graduating, Jenny Larfeldt decided to save the world. She moved to Gothenburg to work for Greenpeace. But she was not content to only highlight environmental problems, she wanted to solve them. PhD studies at the Chalmers University of Technology – she earned her PhD in 2000 with a thesis on wood-burning furnaces – offered her the right opportunity to forge a career in R&D.
“Then I got a chance to work with energy technology at a major industrial company, Siemens in Finspång. After a number of years as a research team manager, with a lot of administrative work, I can now fully apply myself as a senior expert, focusing on R&D.” Three years ago, Jenny Larfeldt also became an adjunct professor at Lund University.
Additive manufacturing breakthrough
In the last years, her quest for solutions has focused on the significant technological challenge of burning hydrogen gas. Not only is it a highly reactive fuel but its high flame speed threatens to suck the flame back, which may destroy the burner.
“We use dry low NOx burners, so, in order to protect the burner hardware, the speed of the fuel and air mixture upstream in the burner has to be higher than the flame speed of hydrogen,” explains Larfeldt. “The key to increasing the hydrogen ratio in the fuel mix lies in the burner design – we had to adjust the fuel injection accordingly. And our breakthrough came three years ago when we introduced additive manufacturing, or 3D printing, here at Siemens in Finspång.”
“This technology made it possible for us to adjust the design inside the burner without changing the exterior. In turn, it has also made it easier for us to retrofit existing turbines, and to dramatically speed up the development of burner design.”
Siemens’ pledge: 100% H2 combustion
In January 2019, Siemens signed a commitment, together with the members of the industry body EUTurbines, to gradually increase the H2 capability in gas turbines to at least 20 percent by 2020 and 100 percent by 2030.
As of today, Siemens gas turbines can already cover a wide range of H2. While aeroderivative units already fulfill the 2030 target today with their wet low emission (WLE) systems based on diffusion burner technology, they require water to abate NOx emissions. For dry low emission (DLE) systems, recent test results on the SGT-600 to SGT-800 burners demonstrated the ability to achieve 100 percent carbon- free combustion in the coming years. These recent advancements in burner technology have been made possible by additive manufacturing, which also ensures that the burner components remain compatible with previous models.
The goal is in sight: By 2030, Siemens gas turbines will be able – or can be retrofitted – to run fully on H2.
Lowering emissions on the path towards decarbonization
Using an ever increasing percentage of hydrogen as a fuel is indeed a major step to decarbonizing energy production, as its combustion process doesn’t emit greenhouse gases – it only produces energy and water.
While the path is set towards a future with 100 percent green hydrogen, the hydrogen gas currently used in gas turbines is a component of waste gas from industrial processes involving fossil fuels, so-called brown hydrogen, and the need to reduce harmful emissions remains.
“Siemens has an advantage in managing these challenges, because we already have a technology that works in lower temperatures than most alternatives,” says Larfeldt. This is why another aspect of her work focuses on limiting the temperature, which is the key to minimizing the undesirable production of nitrogen oxides, NOx.
Milestone testing in Berlin and Finspång
The effectiveness of the new burner prototypes is tested first one burner at a time and mapped at varying engine conditions. After proving the burners in single configuration, the next challenge is to test them under real conditions. Until January 2019, when the test center in Berlin received a hydrogen mixing station and several 3D-printed burner variants were tested, all of these tests had to be done in Finspång. In 2017, 30 burners were tested within the SGT-800 gas turbine with low amounts of hydrogen, and the following year the SGT-600 was tested with 18 burners. “It was a great feeling when we established that it was possible for us to run the gas turbine on hydrogen gas in realistic conditions. It was a massive effort from all of my colleagues in Finspång, and what a relief that it turned out to be a major success,” Larfeldt beams: “This is the fantastic Finspång team effort!”
However, with every test, there remains a further logistical challenge. “We need large quantities of hydrogen gas, but there is no large-scale production near Finspång,” explains Larfeldt. Seven containers with hydrogen in flasks at 250 bars pressure were sourced from all over Sweden. “We also got hydrogen in slightly larger flasks from Germany. Together this still only gives us enough hydrogen gas to do large-scale tests for less than one hour.”
In it for the long haul
As a finisher of the Swedish Iron Man competition, Jenny Larfeldt knows about persistence and overcoming setbacks. And she knows that it takes rigorous training and testing under realistic conditions to push oneself to the limits and achieve the level of endurance needed in order to cross the finishing line.
Similarly, the goal of 100 percent hydrogen combustion capability will be achieved step by step, test by test. “With hydrogen-fired gas turbines we can easily avoid the ‘valley of death’ where brilliant inventions die before they even scale to full potential,” says Larfeldt. “The same turbines can be used with different percentages of hydrogen in the fuel mix, with brown or green hydrogen. Existing gas turbines can be retrofitted to the latest standards. It’s an organic evolution.”
Some might have expected gas turbines to be a dying breed in the context of the future phase-out of carbon fuels. Actually, it’s quite the reverse, Larfeldt points out, while preparing for the next round of testing in Finspång: “They have a vital part to play in achieving zero-carbon energy production.”
Nils Lindstrand is a business and technology writer based in Stockholm, Sweden. His work has been published in a number of Swedish and international magazines.
Combined picture and video credits: Lasse Burrell; Siemens
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