European thinktank Transport & Environment (T&E) is calling for the UK to use the majority of its green hydrogen in aviation by 2030, arguing hydrogen will be essential for decarbonising aviation and should not be wasted on questionable use cases such as road transport and heat.

The UK government has set a target for 10% of jet fuel to be sustainable aviation fuel (SAF) by 2030 and has consulted on details of the mandate, including at what level to set a power-to-liquid (PTL) subtarget. PTL fuels such as e-kerosene are made from green hydrogen and captured carbon.

T&E is calling for a PTL subtarget of 5.5% of total aviation fuel by 2030. This would require 3.74GW of green hydrogen production capacity, powered by 37.4TWh of renewable power, or around 9.4GW of offshore wind generation capacity, it said. 

It would mean more than two-thirds of the UK’s 5GW green hydrogen target for 2030 would be dedicated to SAF, or more than one-third of its 10GW low-carbon target including blue hydrogen.

The UK government has set a target of 10% sustainable aviation fuel by 2030

The UK has the world’s third-highest aviation emissions behind the US and China, T&E added. The sector emitted 38.5m t CO₂ in 2019.

Other high emitting sectors—such as power, passenger cars, domestic heating, heavy goods vehicles and most industries—can be best decarbonised directly with clean electricity, it said. T&E expects heat to be decarbonised by a mass rollout of heat pumps—as is already happening in other countries.

T&E even goes so far to suggest banning hydrogen in surface transport. “There are over 1m EVs [electric vehicles] on the road in the UK now, yet we still have talk of hydrogen cars,” said its UK policy manager, Matt Finch. “When you analyse truck movements, the vast majority could be electrified today. There are very few use cases we do not think EVs will be capable of within time.”  

Considering the level of investment in battery technology, further technological breakthroughs are inevitable, Finch said. “So let us not try to set up a hydrogen road network of any description. Hydrogen itself is a scarce resource. Whatever goes into road cannot go to better uses like aviation and the hydrogen market.”

Other sectors that would be suitable for hydrogen are far smaller than aviation, T&E said. In 2019, total emissions from UK steel and iron production were 9.4m t. Cement production emitted 4.4m t and glass production just 0.4m t. Grey hydrogen demand is also relatively low in the UK and should shrink in the future as oil use declines, Finch said. “Aviation is the biggest problem that can be solved with hydrogen, so let us attack this first.” 

There are few alternatives for decarbonising aviation. It remains to be seen if electric planes can hit the “sweet spot” in aviation of 1,500km range and 200–300 person capacity. But even if they do, synthetic fuels will still be needed for long-haul flights, Finch added. Second-generation biofuels will also play a role in SAF, but there is a limit to their availability—T&E estimates they will be able to meet only around 20% of aviation demand.

T&E’s proposed PTL target is far higher than the government’s assumed maximum of 2.7%. However, the government's figure is based on a study it commissioned where any carbon used in making PTL would have to come from direct air capture (DAC). This is “a massive limitation,” Finch said. “DAC is far and away the most expensive CO₂source, at maybe €450/t [$501/t], while some other sources are a tenner.”

If the government wants to use the mandate to kickstart the DAC industry, it could always introduce 2.7% of e-kerosene made with DAC as a “sub, sub-mandate”, T&E said.

Support for a sub-mandate is far from unanimous. Trade group the UK Petroleum Industry Association argued there should be no sub-mandate at all, cautioning it is too early to try to “pick winners”.

“PTL technology is still in development and needs to be proven at scale… any trajectory including a PTL subtarget needs to be deliverable and not reliant on ‘silver-bullet’ technology.”  It also expressed concern over “enormous” clean energy requirements for PTL.

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Author: Killian Staines