People get obsessed with hydrogen, and I can see why. It is the lightest and most abundant element in the universe. It’s colourless, and odourless. In its liquid form it carries three times as much potential energy as petrol. But burn it and all you leave behind is water.
Hydrogen is a miraculous molecule. And yet we’re moving away from using it in many of the scenarios in which it has been proposed. In February 2025, the UK government’s Climate Change Committee said “…we see no role for hydrogen in buildings heating and only a very niche, if any, role in surface transport.”
If the government follows the advice of the committee, it will not support schemes that use hydrogen for domestic heating or powering cars.
This didn’t surprise people watching the space closely. Because in spite of all its miraculous properties, physics is largely against the idea of using hydrogen in heating or transport. And a panel including many eminent scientists was never going to miss that.
This doesn’t mean that there won’t be a big hydrogen economy in the future. It just ratifies what role hydrogen should play. A role that is shaped by finance as much as physics. By demand, by competition, by regulation – just like any other economy.
Here comes the science bit
Hydrogen can’t just be plucked out of the air. You have to extract it. There’s some underground. But mostly today it comes from two sources. You can make it from methane gas using a process called steam reforming. This so-called ‘grey hydrogen’ accounts for about 99% of all hydrogen we make today1. And for every tonne you make, the process emits at least 10 tonnes of carbon2. You can capture that carbon to make so-called blue hydrogen, but hardly anyone does.
The most common alternative is to make hydrogen from water, through a process called electrolysis – not quite the same as the process your beautician uses to remove hair, but similar in principle. It releases a fraction of the carbon emissions. So why don’t we make more hydrogen this way?
Once you do the analysis, hydrogen looks a little less miraculous. But that doesn’t mean it isn’t useful. And it certainly doesn’t mean we shouldn’t be investing in a green hydrogen economy.
The economics bit
Electrolysis requires electricity, and that electricity has to come from renewables if it’s going to be low carbon ‘green hydrogen’. Electricity right now is expensive, and that makes green hydrogen expensive. Some 2.5 times as expensive a grey hydrogen, to be precise, according to the European Hydrogen Observatory (based on 2022/23 energy prices in the UK)3.
Simply put, power is pricey. And electrolysis is a lossy process. Today, it’s about 80% efficient with the most advanced processes, i.e. one fifth of the energy you put in is lost. And that’s not the only place you make losses.
