Hydrogen is the smallest, lightest and most abundant molecule in the universe. On Earth, it does not occur by itself naturally, but can be separated from water (H2O) or hydrocarbon compounds (fossil fuels) like gas, coal and petroleum to be used as an energy source. It’s already used for rocket fuel, but it is

now being pushed as a clean and safe alternative to oil and gas for heating and earthly modes of transport. Political support is mounting with almost $26bn of US taxpayer money available for hydrogen projects thanks to three recent laws – the Inflation Reduction Act, the Bipartisan Infrastructure Act and the Chips Act. Hydrogen is politically hot, but is it the climate solution that its cheerleaders are claiming?

Why all the hype about hydrogen?

The short answer is that the fossil fuel industry sees hydrogen as a way to keep on drilling and building new infrastructure. Friends of the Earth has tracked how the industry has successfully deployed its PR and lobbying machines over recent years to get policymakers thinking that hydrogen is a catch-all climate solution. Research by climate scientists (without fossil fuel links) has debunked industry claims that hydrogen should be a major player in our decarbonised future, though hydrogen extracted from water (using renewable energy sources) could – and should – play an important role in replacing the dirtiest hydrogen currently extracted from fossil fuels. It may also have a role in fuelling some transportation like long-haul flights and vintage cars, but the evidence is far from clear. However, with billions of climate action dollars up for grabs in the US alone, expect to see more lobbying, more industry-funded evidence and more hype.

What’s the difference between blue, grey, brown, pink and green hydrogen?

A green hydrogen production facility project in Africa at Namaqua Engineering in Vredendal with the University of the Western Cape, South Africa. Photograph: Esa Alexander/Reuters

Extracting hydrogen is energy intensive, so the source and how it’s done both matter. Currently, about 96% of the world’s hydrogen comes from coal (brown) and gas (grey), with the rest created from nuclear (pink) and renewable sources like hydro, wind and solar. Production of both grey and brown hydrogen release carbon dioxide (CO2) and unburnt fugitive methane into the atmosphere. This super-polluting hydrogen is what’s currently used as the chemical base for synthetic nitrogen fertilisers, plastics and steel among other industries.