NEW YORK: Hydrogen has the potential to become an important energy carrier in a future clean energy system, complementing electricity, but it will have to overcome formidable technical barriers first if it is to fulfil that role.
“Hydrogen has never enjoyed so much international and cross-sectoral interest, even in the face of impressive recent progress in other low-carbon energy technologies, such as batteries and renewables,” according to a recent report by the International Energy Agency (IEA).
Policymakers have taken an interest in hydrogen before — following the oil shocks of the 1970s, the climate concerns of the 1990s, and worries about peak oil in the 2000s — only for attention to fade again when oil prices fell and environmental policies switched to other more promising technologies.
But this time could be different, according to the IEA, because hydrogen may be an essential part of the tool kit needed to achieve the deep decarbonisation targets policymakers have set under climate agreements.
Plans to reduce net emissions near zero by mid-century, announced by some governments, have put the spotlight on sectors where electricity is not the preferred energy carrier and emissions are hard to abate.
Such sectors include aviation, shipping, iron and steel production, chemicals manufacturing, high-temperature industrial heat, long-distance road transportation and heat for buildings.
The planned double transition (shifting the delivered energy system to electricity, and decarbonising electricity generation) may not work in these areas.
Hydrogen may be a better energy carrier in at least some of these applications, according to the IEA (“The future of hydrogen: seizing today’s opportunities”, IEA, June 2019).
Hydrogen could have other benefits, including tackling air pollution and facilitating the clean energy transition while reducing disruption to workers and communities closely connected with fossil fuels.
Hydrogen systems could preserve a future role for at least some production, transportation and employment in the oil, gas and coal industries if they were paired with carbon capture, utilisation and storage technology.
Worldwide production of pure hydrogen is around 70 million tonnes per year, with another 45 million tonnes of hydrogen produced as part of a mixture of gases.
Pure hydrogen is mostly used in oil refining and the production of ammonia, mainly for fertilisers, while mixed gases are supplied for methanol and steel production. Pure hydrogen is not yet commonly used as a fuel.
Hydrogen can be produced directly from water by electrolysis, but nearly all the hydrogen currently in use is produced from steam methane reforming or coal gasification.
Electrolysis is the perfect pathway for turning excess electricity from solar, wind and other renewable sources into hydrogen with zero emissions.
By contrast, steam methane reforming and coal gasification are both energy-intensive processes that produce prodigious amounts of carbon dioxide (CO2). Pure hydrogen production currently accounts for 6 per cent of worldwide natural gas use and 2 per cent of worldwide coal use, the latter mostly in China.
Production accounts for around 830 million tonnes of CO2 emissions per year, equivalent to the combined emissions of Indonesia and the United Kingdom.
In a future clean energy system, hydrogen and electricity could be complementary energy carriers, since electricity can be readily transformed into hydrogen and back again. Hydrogen help solve problems of intermittent renewable electricity generation by providing a means of storing energy over time and transporting it over long distances. — Reuters