Hydrogen ICE – lower emissions than BEVs?
H2 ICE engine: Cummins
The government says that air quality emissions from hydrogen Internal Combustion Engines are not acceptable – but they actually have lower overall pollution than current BEVs.
A lot of companies are getting interested in hydrogen combustion, especially, for trucks, given that the main “zero emission” alternative for a 44-tonne truck is a 1-Megawatt battery pack, which is heavy, extremely expensive and responsible for large amounts of pollution at the manufacturing stage.
In contrast, green hydrogen is intrinsically carbon-free, and converting an internal combustion engine to run on hydrogen is relatively straightforward (as shown by Toyota with cars and Cummins with trucks). Until hydrogen fuel cells come down in price, which the industry hopes will happen in the early 2030s, hydrogen combustion is easily the lowest cost way of eliminating CO2 from HGVs.
However, the government will not allow any development grants to be given for hydrogen combustion cars or trucks, and is taking next to no interest in the fuel, on the grounds that it is not zero emission. Hydrogen combustion emits no carbon and no particulates, but it does emit NOx, or oxides of Nitrogen – albeit in far lower quantities than a diesel engine (McKinsey found that, when used with current exhaust after-treatment systems, hydrogen ICE emits “no significant NOx”). However, it’s not zero emission, runs the government’s argument.
That is true, but it spectacularly misses the point. BEVs are nowhere near zero emission – car manufacturers are careful to call them zero tailpipe emission. Battery manufacturing causes significant amounts of pollution, in terms of CO2, particulates, NOx – basically every pollutant emitted by a petrol engine. According to a study by engineering consultants, Ricardo, a 2020 BEV was responsible for just over 50% as much NOx as an equivalent ICE car, mostly thanks to the energy-intensive extraction of critical minerals, plus even more energy-intensive battery manufacturing.
According to Polestar, which is an EV manufacturer, manufacturing a Volvo XC 40 with a petrol engine saves eight tonnes of CO2 compared to a Polestar 2 with an 82 kWh battery pack. The BEV then emits no further CO2, so the break-even point, where cumulative emissions of a BEV are the same as an ICE, is 65,000km (40,000 miles), assuming the average EU grid electricity mix.
In contrast, a current BEV will never break even against a hydrogen ICE in terms of CO2 or particulates. It would also struggle to break even in terms of NOx.
The government has fallen into the classic trap of determining means rather than ends. They have decided batteries are good and combustion is bad. The goal they should be aiming for is to reduce lifecycle CO2 emissions as quickly as possible.
Ironically, their own experts agree. The government’s Air Quality Expert Group said in 2023 that, “Using hydrogen as a combustion fuel can create NOx, but emissions are not inevitable and likely can be abated successfully.” They went on to say that, in a commercial diesel engine running on hydrogen with standard SCR after-treatment, “tailpipe NOx emissions [were] close to zero (0.02 g/kWh)”.
Hydrogen ICE offer the lowest emissions for both greenhouse gases and air-quality pollutants – at least until the battery supply chain is decarbonised or fuel cells come down in price. Either of those developments is probably 10 years away.
If the government’s goal is to promote BEVs regardless of CO2 emissions, then the current policy is fine. If its goal is to reduce CO2, it needs to encourage hydrogen ICE – and the sooner it does that, the faster it will reduce CO2.