Hydrogen transport by tube trailers needs ‘strict leakage mitigation’

The Green Alliance report, Hydrogen’s role in a clean power economy, warns that one of hydrogen’s main risks is leakage, “due to its small molecules”. Hydrogen is a short-lived climate pollutant because it slows the removal of atmospheric methane, a potent greenhouse gas. The report said leakage rates above 19% could result in a 20-year climate impact “higher than from burning natural gas”.

While such levels are not typical and leakage is expected to fall as hydrogen technologies mature, it cautioned that certain transport and processing stages “are more vulnerable to leaks which could add up to significant overall emissions”.

The report highlighted particular concern around transporting compressed or liquefied hydrogen in tankers — described as a secondary transport method. The long-term objective is a hydrogen pipeline network, which typically has leak rates of around 1%. However, tube trailers require less infrastructure and are likely to play an interim role in early markets. Liquefied hydrogen, the report said, “is especially prone to leaks (around 10-20%) and so should only be used when necessary”.

The Green Alliance’s leakage estimates draw on a 2024 paper, Hydrogen emissions from a hydrogen economy and their potential global warming impact, published by the European Commission’s Joint Research Centre and authored by Alessandro Arrigoni and Laura Bravo Diaz.

That paper described the filling and transport of compressed hydrogen via tube trailers as “a mature technology with low losses”, with losses below 1% of delivered hydrogen, mainly from purging trailer hoses and leakage from fittings and valves. By contrast, the delivery chain for liquefied hydrogen is less developed and currently more prone to leakage. It cited estimates from Air Liquide suggesting around 10% of hydrogen could be lost during liquefaction and through boil-off during transfers.

Overall, Air Liquide estimated that the current compressed hydrogen supply chain loses about 4.2% of hydrogen delivered to gas stations, while losses in the liquefied hydrogen supply chain can reach up to 20% at liquid hydrogen stations. The company projects lower losses by 2030, with around 2 per cent losses at hydrogen refuelling stations and a further 2 per cent during dispensing.

The Green Alliance report also noted that a hydrogen economy would require geological storage in the UK. Some options, such as salt caverns, are already under development, while others — including depleted gas reservoirs — require further testing.