Zero-carbon hydrogen has been injected into a UK gas network for the first time in a groundbreaking trial that could help to reduce carbon dioxide emissions.

The 20% hydrogen and natural gas blend is being used to heat 100 homes and 30 faculty buildings at Keele University in Staffordshire. Unlike natural gas, when hydrogen is burned it produces heat and water as opposed to carbon dioxide.

“Heat hasn’t been particularly decarbonised to date and it’s a very big challenge,” said Lorna Millington, the future networks manager at Cadent, the gas distribution network that led the £7m HyDeploy project. “The aim was to turn the theoretical evidence into something real and tangible that the consumers within the Keele network are now getting to experience every day.”

Heating homes and businesses accounts for half of the UK’s energy consumption and a third of its carbon dioxide emissions. Rolling the 20% hydrogen blend out across the country could save about 6m tonnes of carbon dioxide emissions a year, the equivalent of taking 2.5m cars off the road.

The hydrogen is captured using an electrolyser, which runs electricity through water to split it back into hydrogen and oxygen. This can then be injected into existing modern gas networks, with no need for customers to change appliances or pipework.

The Health and Safety Executive granted the project exemption in 2018 from the current 0.1% limit on hydrogen in the UK gas network after an extensive examination of evidence to ensure it would be safe. Keele University was identified as an ideal location, because it owns and operates a private gas network that can be isolated from the main network.

Two years of preparation involved gas safety checks on all buildings in the trial, laboratory tests on gas appliances and research on the effect of hydrogen on materials found in the gas network.

All appliances sold after 1996 must be able to sustain 23% hydrogen under current regulations. “The materials we use in our network are actually more than capable of dealing with the levels of hydrogen that we were looking at,” said Millington.

The trial will run until July and if successful a pilot will be rolled out in the north-east to deliver the 20% hydrogen blend to 670 domestic and commercial properties in Winlaton, Gateshead.

Mark Horsley, the chief executive officer at Northern Gas Networks, said: “We’re really excited about the opportunity. There is a strong groundswell for decarbonisation, and I think opportunities for each individual home to contribute to that is quite powerful.”

The pilot, the first of its kind in the UK, would start in December and run for 10 months. Customers have already been notified about the upcoming change. “Early indications are that it’s going to be very positively received,” said Horsley.

The project is part of global exploration into the potentials of a “hydrogen economy”, in which the gas could also be used to generate electricity and produce heat with benefits for transport, heavy industry and domestic energy use.

The energy needed to produce hydrogen from water can be provided by solar, hydro or wind power to produce “green hydrogen”, but there are challenges in doing so at scale.

It still may be some time before the technology can be rolled out nationally, but “the 20% is a massive step forward for us as an industry and for the UK in achieving that net zero goal”, Horsley said.