A review of studies looking at heating homes with hydrogen has found that high cost and poor energy efficiency means the gas isn’t a viable solution, despite many governments pushing ahead with the idea
27 September 2022
Hydrogen, often touted as a green alternative to heating buildings with natural gas or other fossils fuels, is unlikely to play a significant role in decarbonising homes, a review of international studies has found.
That is bad news for governments, including the UK, that are hoping to use hydrogen as a simple substitute for existing gas boilers. “I think hydrogen is ultimately the silver bullet,” Jacob Rees-Mogg, the UK’s newly-appointed energy minister told the House of Commons on 23 September. “We create it from renewable sources… we use it as an effective battery and it can then, with some adjustments, be piped through to people’s houses to heat them during the winter.”
The review by Jan Rosenow at the Regulatory Assistance Project, a non-governmental organisation, looked at 32 studies from the UK, European Union, California and São Paulo in Brazil. Overall, they show that hydrogen is “less economic, less efficient, more resource intensive and associated with larger environmental impacts”, writes Rosenow.
Cost and energy efficiency are two main problems, says Rosenow. Today, more than 95 per cent of hydrogen is produced using natural gas or coal. Carbon capture and storage technology could help reduce emissions from this production, but policymakers largely agree that green hydrogen, made via electrolysis with renewable electricity, is the better solution.
But if you are going to use renewable electricity to heat your home, you might as well power a heat pump instead, as this is cheaper and more efficient. “It takes about five times more electricity to heat a home with hydrogen than with an efficient heat pump,” says Rosenow. Hydrogen-dominated heating would cost UK consumers 73 per cent more than systems relying on district heating and heat pumps, according to a recent study.
Further, “significant uncertainties” exist over the viability of converting countries’ existing gas networks to hydrogen, and hydrogen infrastructure is more extensive than that needed for heat pumps, increasing environmental impacts, writes Rosenow.
“It is difficult to think of any circumstances in the decarbonised future when it would make sense to use hydrogen for heating,” says David Cebon at the University of Cambridge. When the ambient temperature drops below -20°C, air source heat pumps become less efficient, but even in such cold conditions, “heat pumps still deliver heat with lower carbon emissions than hydrogen boilers”, says Cebon.
Countries like the US and Australia, which are also toying with the idea of using hydrogen to decarbonise heating systems, have “huge” renewable electricity potential, says Cebon, which they should use “in the most efficient way possible, via heat pumps”. If they have excess electricity, it will be more profitable to sell it directly via interconnectors “than to waste energy converting the electricity into hydrogen”, he adds.
Hydrogen could play a limited role in certain circumstances — Rosenow estimates it could provide “about 1-2 per cent of total [domestic] heating demand”. And, for example, green hydrogen power plants will be required to decarbonise other sectors, such as heavy industry processes, and for the seasonal storage of electricity.
With that in mind, countries like the UK should continue existing trials to better understand “important details around the technical challenges of heating with hydrogen”, says Rosenow. Just don’t expect a silver bullet.
Journal reference: Joule, DOI: 10.1016/j.joule.2022.08.015
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