(Reuters) – Governments and energy companies are placing large bets on clean hydrogen playing a leading role in efforts to lower greenhouse gas emissions, but its future uses and costs are highly uncertain.

“Without hydrogen by 2050 we cannot aim to be a net zero (carbon) economy,” Royal Dutch Shell CEO Ben van Beurden told the CERAWeek online conference this week. The universe’s most abundant element, hydrogen has been touted for decades as an alternative to fossil fuels, but attempts to commercialize it for use in vehicles and industry have largely failed. So far, commercial-scale production has been from natural gas or coal and it is a niche market used mainly in oil refining and heavy industry.

But so-called blue hydrogen, where carbon emissions from its production are not released into the atmosphere, and green hydrogen, which is made with renewable power, are attracting huge interest as a clean alternative to natural gas that can be used for heating homes, heavy industry and transportation. The European Union, Britain, Japan and South Korea, as well as leading oil and gas companies, such as Royal Dutch Shell, BP and Total, have set out plans to invest heavily in hydrogen.

In the Canadian province of Quebec, where hydropower is abundant, green hydrogen is going to be a reality, Canadian Natural Resources Minister Seamus O’Regan said. Canada last year unveiled a hydrogen strategy that could be worth $40 billion. But converting natural gas storage, pipelines, furnaces and boilers to hydrogen will be a costly and long process.

“Hydrogen will not be the solution to each and everything… it’s not the silver bullet that solves all problems,” Siemens Energy CEO Christian Bruch told the conference.