Hydrogen is also highly explosive and more leaky than natural gas – making its transportation difficult and expensive.
“Engineers can solve some of these problems, and at the end of the day we do lots of inefficient things already – an internal combustion engine in a car is only 20pc efficient,” says Liebreich.
“But the physics of hydrogen has cost implications right the way throughout the chain. It hits you in the production, it hits you in the transportation, it hits you in the storage and then it also hits you in the usage of hydrogen because it is bulky and dangerous.”
At the moment, the case for subsidising green hydrogen in many countries rests on a hope that costs can eventually be driven down to $1 (77p) per kilogram.
This is the goal of subsidies of up to $3 per kilogram lavished on energy companies by Joe Biden’s Inflation Reduction Act in the US.
But because of its physical limitations, there is no certainty prices will ever reach this ultimate goal, Liebreich has argued, with developers needing to spread their costs out over 10 to 15 years. And even if it comes down to $2 per kilogram, that still leaves huge unaddressed costs when scaled up to tens of millions of tons.
In the UK, the Government announced £2bn worth of subsidies for 11 projects last year with a total capacity of 125 megawatts and an average strike price of £241 per megawatt hour.
Hinkley Point C, the 3.3Gw nuclear power plant being built in Somerset, received a strike price of £92.50 per megawatt hour.
“People say there’s an experience curve,” Liebreich says. “That argument absolutely applies to the electrolysers, which will probably get very cheap … but [the majority of the cost comes from] the electricity and compressors, and pumps, and tanks, and heat exchangers, and substations – all that basic engineering.”
For these reasons, many energy experts have long argued hydrogen is therefore better suited to niche processes that cannot easily be decarbonised in heavy industry.
As a starting point, this should include the 700,000 tons of hydrogen the UK already uses in processes such as oil refining and the production of petrochemicals such as fertilisers. Liebreich is scathing of projects to produce tiny quantities of hydrogen to power schemes such as “green” buses.
“Why is anybody putting money into hydrogen buses in Aberdeen?” he adds. “It’s absurd.”
In the longer run, when cheap power from renewable sources such as wind and solar is available – and at negative prices on a regular basis – there are hopes that hydrogen could be produced in larger quantities and then even used as a backup for the power grid.
A report by the Royal Society – which relied on historical analysis of weather patterns – called for the gas to be stored in vast salt caverns, so it can be burned when output from renewables is not sufficient to keep the lights on during the dimmest, low-wind weeks of winter.