Gas turbines are getting an upgrade. Turbine makers want to make them more compatible with hydrogen fuel, which is being touted as cleaner than natural gas. A combined cycle power plant located in Bugok, South Korea. Image: Siemens Energy.
With half the emissions of coal, a lower price tag and almost none of the particulates, natural gas is easy to love.
It is still the fossil fuel of choice for many countries in Asia. Some, like Brunei and Singapore, are powered almost exclusively by it. Touted as a clean-enough “transition” fuel, natural gas – a mix of methane and other vapours produced from age-old biomass underground – has become a popular choice, and its use has been increasing at the expense of oil and coal.
In the United States, over 100 power plants switched from coal to natural gas between 2011 and 2019. The same trend is expected in Asia in the coming years.
But the case for fossil fuel reliance in the long run is getting harder. Zero-carbon energy sources like solar and wind are becoming increasingly viable as costs drop. The US Energy Information Administration predicts that electricity generated from natural gas will hit a peak around 2030 globally, with current policies.
The International Energy Agency (IEA) estimates that natural gas power generation needs to fall by some 90 per cent by 2040, for the world to hit net-zero emissions by mid-century. Much will depend on whether the Asia-Pacific region, already one of the largest natural gas users globally, can wean itself off the fuel in the coming years. As it stands, demand from the region may double by 2050.
Responding to such pressures, major gas turbine manufacturers are making continuous technological advancements to be hydrogen-compatible. The lightest gas on Earth combusts similarly to natural gas, producing waste heat which further rotates generators (much like in traditional combined cycle plants), with one key difference – it does not emit carbon dioxide in the process. This caveat offers a lifeline for existing investments in natural gas plants.
“The ability to substitute natural gas with hydrogen over time means investments in gas power plants today will have remarkable asset resilience for investors,” said Andreas Pistauer, head of generation at Siemens Energy Asia Pacific. Making the case for retaining natural gas plants with a hydrogen swop, he details how “[this] eradicates the need to undertake huge amounts of resources to construct entirely new facilities.”
Most hydrogen produced today requires the use of fossil fuels, such as coal and natural gas, generating emissions in the process. But there has been increasing interest in cleaner methods of hydrogen production. For example, ‘blue hydrogen’ and ‘green hydrogen’ as cleaner methods of production, are expected to feature widely in a net-zero world. In the production of blue hydrogen, carbon emissions are captured and stored, while green hydrogen production is powered through the use of renewables such as solar.
The ability to substitute natural gas with hydrogen over time means investments in gas power plants today will have remarkable asset resilience for investors. Siemens Energy has 20 turbine models that can take on hydrogen fuel in its mix, and has been deploying such technology for industrial use since the 1960s.
Explaining how this mode of hybridisation supports the shift to low-carbon fuels, Pistauer is optimistic that such turbines will reap carbon savings in the short-to-medium term while also affording time for groundwork and infrastructure to be set in place for the smooth integration of hydrogen facilities in the long run.
Still, development is set to be a slow burn for now. Green hydrogen is currently selling at US$3 to US$7.50 per kilogramme, several times higher than natural gas. Its cost is expected to drop in the coming years with better technology and economies of scale, but fast growth is expected only after 2035.
Burning hydrogen to generate electricity may also raise eyebrows, as electricity is needed to create hydrogen fuel from water in the first place. But Pistauer said there is a use case for hydrogen in providing back-up power for intermittent sources of energy like the wind and sun.
The ability of gas power plants to provide flexible load is key when complementing, or even enabling the rapid growth of renewable, but fluctuating, capacity. While efficient, more importantly this flexibility is critical to enable large renewable capacity in the grid. The gas can also be stored for months, allowing excess solar energy generated in summer to be used in dark winters.