As world leaders wrangle over climate change targets in Glasgow, one technology that could help make them a reality is attracting a lot of buzz.

Hydrogen – long used in rocket fuel – is being touted as a revolutionary low-carbon energy source. It already powers some UK buses and French trains, and its advocates say it could also be harnessed on a mass scale in cars, aircraft, as well as in people’s homes.

Construction equipment maker JCB has just signed a multi-billion-pound deal to import and supply hydrogen produced using renewable energy. And Morgan Stanley has predicted that if governments honour their carbon-cutting commitments (a big if) then sales of hydrogen could total $600bn by 2050, up from $150bn today.

What is hydrogen? And will it live up to the hype?