Hydrogen Economy

At least twice in the past 50 years—in the 1970s, after the oil crisis,and in the 1990s, when climate change started to acquire political salience—there has been excited talk of replacing hydrocarbons with hydrogen.

It didn't happen.

There were several reasons for this.

For a start, ripping up and replacing the world's fossil-fuel infrastructure is a huge job.

And even were that an easy thing to accomplish, hydrogen itself has drawbacks.

Though better than batteries, it stores less energy in a given volume than fossil fuels can manage.

More important, it is not a primary fuel.

You have to make it from something else. This can be done by a chemical reaction called steam reforming but, besides steam, the other ingredient of that process is a hydrocarbon of some sort, which rather defeats the object of the exercise.

Or it can be done by the electrolysis of water.

This has appropriate green credentials as long as the electricity is either from renewable sources or a nuclear-power plant.

But the laws of thermodynamics mean that the energy content of the hydrogen which comes out of the process is less than the electricity that went in.

This inbuilt inefficiency raises the question "why not simply power the enduse electrically, rather than using hydrogen as an intermediary?"

To counter these arguments those who believe that things hydrogen-related really are different this time around can point to two things in their favour.

Several of the relevant technologies, notably electrolytic equipment, are now at a stage where it is possible to believe they might soon become cheap enough to do the job.

And the idea that economies need to be decarbonised fully in order to curb climate change is gathering speed.

Until 2019, for instance, Britain had planned to cut carbon emissions by 80% from their levels in 1990 by 2050.

It then, however, upped the ante to become the first big economic power to commit itself to a 100% cut.

This has implications for hydrogen.

Electrification using renewable sources such as wind and solar power would probably have got the country to 80% observes David Joffe, a member of the Committee on Climate Change (CCC),an organisation that advises Britain's government on how to bring the transformation about.

But full decarbonisation, he says, is a much bigger task, and one for which hydrogen may prove necessary.