GLASGOW - A Scottish gas distribution firm plans to offer hydrogen produced with renewable energy to hundreds of homes for domestic heating, in a trial that could lead to a major roll-out of the cleaner fuel across Britain, slashing carbon emissions.

The trial by SGN is part of surging global interest in hydrogen as an alternative clean energy source, as pressure grows to shift away from polluting fossil fuels, whose emissions are heating up the planet.

Singapore is among nations, including Britain, Australia, Japan, Germany and the United States, that are exploring the use of hydrogen. Some nations already have hydrogen strategies focusing on production and use in power generation, heating and industry. Hydrogen is already being trialled in Germany to make low-emissions steel.

SGN's H100 Fife hydrogen project aims to supply the gas to about 300 homes initially and, based on the outcome of the trial, quickly scale this up to include more homes and businesses.

Eventually, the aim is to roll out hydrogen widely across the network to replace natural gas.

The firm is one of four national gas distributors in Britain.

While hydrogen produced using renewable energy is still more expensive than natural gas, costs are coming down as the technology using wind, solar or hydro power becomes cheaper.

The trial aims to offer a climate-friendly solution that is familiar to customers, said project director Craig McCafferty during a briefing in Glasgow on Thursday (Nov 4). The idea is to make it easy for customers to opt in and ensure no added costs for them. It would be merely swopping one gas for another.

The trial, which will run from 2023 to 2027, will cost £28 million (S$51.3 million) and is partly funded by the Scottish government.

If it is a success, the trial could eventually lead to a sizeable drop in emissions for Britain if hydrogen use is expanded in coming years.

About 24 million British homes use natural gas, and domestic heating is responsible for about a third of the nation's carbon dioxide (CO2) emissions. Around 85 per cent of homes use gas-fired central heating.

A switch to hydrogen, which produces no CO2 when burned, could help Britain meet its climate targets.

The project production site will be built in Levenmouth in Fife, north of Edinburgh. The electricity generated by a large wind turbine will power an electrolyser, which splits water into hydrogen and oxygen. The hydrogen is stored in pressurised tanks and then piped to the homes.

SGN will lay new plastic gas pipes. The firm wants to maintain the existing gas pipelines so that customers who opt out can simply switch back to using natural gas.

But using hydrogen does present some challenges.

Dr Sarah Kimpton from DNV, a global assurance and risk management firm, who is advising the project on safety aspects, explained that hydrogen cannot be used with some types of steel pipes because it makes them brittle.

This means that deploying hydrogen throughout a national gas network will require replacing some parts of the system. That process is already under way in Britain as part of a national rejuvenation programme, she said. Nationally, there is a large roll-out of polyethylene gas pipes.

Another challenge is that pure hydrogen cannot be used with existing natural gas home boilers for heating or cookers, or in existing gas-fired power stations, she told The Straits Times. This is because hydrogen burns hotter than natural gas. It is also more flammable.

The SGN project will give trial customers new gas appliances at no charge, Mr McCafferty said.

Burning hydrogen also produces nitrogen dioxide, which is a greenhouse gas, so it is not a 100 per cent green solution. But overall, he added, the climate impact of using hydrogen is less than using natural gas.

What is key, though, is sourcing the hydrogen from green energy, and not by using natural gas as a feedstock, the main way of producing hydrogen currently.

"There is a lot of research and evidence out there to demonstrate that we can do this safely," Mr McCafferty said.