By Brian Owens.
Green hydrogen? More like electrification with extra steps.
As humanity works to slash greenhouse gas emissions and stem the pace of planetary warming, scientists, governments, and industry leaders are looking for low-carbon alternatives to fuel the future. Alongside renewables such as solar and wind energy, hydrogen gas is bubbling to the forefront as a fuel of choice—especially for energy-intensive processes like forging steel.
However, the carbon footprint of hydrogen gas is not necessarily as tiny as proponents argue. According to new research led by Kiane de Kleijne, who studies the environmental impacts of new technologies at Eindhoven University of Technology in the Netherlands, hydrogen’s climate friendliness ultimately depends on many factors, not least of which are where and how the hydrogen is produced.
Today, most hydrogen gas is made from natural gas using a chemical process called steam reforming. This hydrogen—known as “grey hydrogen”—is highly polluting; for every kilogram of usable hydrogen gas produced, the process spits out emissions equivalent to 13.7 kilograms of carbon dioxide. A slightly better option is “blue hydrogen,” for which hydrogen gas production is coupled with a carbon capture and storage system. This can theoretically bring emissions down to around six kilograms of carbon dioxide per kilogram of hydrogen gas. However, carbon capture technology is expensive and largely unproven; it rarely reaches even modest levels of capture.
What’s really got experts’ attention is “green hydrogen,” which results when renewable energy—think solar or wind—is used to electrically split water into hydrogen and oxygen gases through a process known as electrolysis. The International Energy Agency, an intergovernmental organization, and many national governments claim that projects powered by green hydrogen produce no greenhouse gas emissions. This has spurred a flurry of subsidies from governments around the world designed to get the green hydrogen industry off the ground.
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