A green future for gas turbines?
Siemens Energy is confident that hydrogen will ensure a green future for its gas turbine technology – the question is whether there will be enough green fuel to go around.
Is there a future for the faithful gas turbine in an energy market that is increasingly turning away from gas for heat and electricity production – as much for economic reasons as climate concerns?
“It’s a big debate, and it’s also a matter of perspective and a matter of timeline,” muses Karim Amin, a member of Siemens Energy’s executive board and vice president of its generation business. However, he is sure that there is.
This may not be surprising given Siemens Energy’s significant share of the turbine market, but in the medium term it is clear that the technology is not going anywhere.
Citing IHS Markit data, Amin said capacity forecasts have moved upwards over the past two years, with average annual additions over the next decade expected to increase from 44GW/year in 2020 to 57GW/year in 2021. Forecasts in early 2022 now suggest this. will rise north of 60GW/year.
“There’s a lot of pressure to move away from gas and push more towards renewables, which is true, but at least in the middle of the future, the thread is that we’re adding more gas,” he continued.
Nevertheless, the German-headquartered energy giant wants to future-proof its offering by building gas turbines that can burn increasingly larger mixtures of hydrogen with natural gas.
Round the mixture
To support this move, Siemens has added facilities at its manufacturing facility in Finspång, Sweden, creating what is called Zero Emission Hydrogen Turbine Center (ZEHTC) and was visited by Energy Voice as part of a press delegation in early September.
When new turbines are tested before being shipped to customers, the excess selenium is combined with outgoing solar panels and used to produce hydrogen in an electrolyser. That hydrogen is then stored and can later be used as fuel for further gas turbine testing.
The addition of batteries also creates a local microgrid for the plant, and a grid connection means it can even export electricity, if and when needed. Although it remains small scale, the integration of different production and storage methods reflects the wider energy system of the future.
In many ways, qualifying units to accept green fuels is a sustainable approach to dealing with the huge volume of facilities that will remain in operation during the decades-long energy transition.
“There are tens of thousands of gas turbines out there in the world. Not all of them will just die and disappear when we go through an energy transition,” says Hans Holmström, CEO of the company’s Swedish operations.
“Many of them will be converted step by step, burning more and more non-fossil fuels.”
That qualification is already underway, with the vast majority of the group’s heavy-duty gas turbines capable of “co-firing” with mixtures of up to 30% hydrogen.
Many other units for industrial applications can already accept higher blends of up to 75%, while an SGT-A35 model with a wet low emission (WLE) system can burn 100% hydrogen.
More than 55 units around the world have been tested for these high hydrogen mixtures and have accumulated millions of hours of operation since the 1960s, the company says.
The result is a reduction in CO2 emissions of anywhere from 11% to 100%, depending on the mix (although the carbon impact of the hydrogen production itself must also be factored into the calculations).
By 2030, it is intended to reach 100% hydrogen on the heavy dry low emission (DLE) systems, while future developments would see some units accept other fuels such as cracked ammonia, biodiesel and green methanol.
‘How much do you have?’
The market seems interested in the possibilities, Amin suggested, but was quick to stress that the viability of hydrogen commitment is less about technical capacity and more about ensuring sufficient supply.
“When you participate in discussions and so on, you always have the question: how much hydrogen can your gas unit burn?” he said. “I have a simple answer and say: How much do you have?”
“You give me what you have, we burn it! But how much do you have?”
This again plays into the importance of integrated energy networks, he continued, adding that the discussion usually raises many more follow-up questions around how to transport hydrogen from production sites to production facilities, the costs involved and how much energy customers are willing to pay for their power and/or products as a result.
“It’s not really a question of how much you can burn, it’s really how much you can create the infrastructure around it at the scale that we need and at [right] affordable level,” he explained.
Efficiency is also an issue. Why bother keeping gas-fired equipment at all in a net-zero system, if the long-term goal is to reach 100% renewable energy?
Aside from its deliverability, Amin said the utility and scale of gas-fired rotating equipment in the electricity market means hydrogen is a viable bridging solution for dealing with intermittent renewable power – not to mention the additional efficiency gains with other applications such as combined heat and power (CHP).
“If we just fast forward, let’s say X number of years from now; if the grid investment is done, if the interconnection works, if the inertia is there, then you don’t need to have gas-fired rotating equipment,” he said.
“But until you get there, how do you use this bridge in a way that has the least impact on the environment? [In this case] you lose efficiency… but on the other hand you reduce CO2 – and the question is, is the cost of CO2 more important than the efficiency you lose, or vice versa?”
It’s a question that governments and power producers all over the world are facing. But hydrogen or no hydrogen, the gas turbine seems unlikely to disappear from our energy system anytime soon.
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