UK Edition
Green heat: could hydrogen solve the climate challenge of Britain's reliance on gas?
Deep in a glen in Dumfries and Galloway, five miles up a single-track road from the nearest town, sits an abandoned farmhouse.
The surrounding hills are home to more sheep than people, the mobile phone signal is patchy, and when snow blankets the valley in winter it is barely accessible except by 4x4.
It is, perhaps, an unlikely location for pioneering research into Britain’s energy future.
Yet in early 2014, a team of scientists and engineers began conducting tests here that they believe could help solve one of the biggest policy challenges facing the country.
Backed by £400,000 of government funding, and £200,000 from companies including SSE, they spent months repeating an experiment some 120 times.
First, they would shut the farmhouse windows and lock its doors. Then, retreating to a cabin 200ft away behind a wall of sandbags, they would pump one of five types of gas into the property to simulate a leak.
Using air samples piped back to their makeshift lab from 15 different parts of the house, they would measure how the gas had distributed – and calculate how likely it would be to explode.
Then they would open the farmhouse doors and windows to let the gas disperse, tweak a few variables and get ready to do it all over again.
Their aim? To test just how dangerous it might be to run Britain’s gas network using not natural gas but hydrogen.
Today, natural gas – composed primarily of methane – is used to heat more than 80pc of homes in the UK. When it burns, it releases carbon dioxide, a greenhouse gas that causes global warming.
If Britain is to meet its targets under the Climate Change Act, which requires it to slash greenhouse gas emissions to 20pc of their 1990 levels by 2050, it has to find a different way of heating its homes.
As yet, there is no firm plan for how to do so.
The Committee on Climate Change (CCC), the Government’s official adviser, warned last month that emissions savings so far have been almost exclusively in the power sector and that “policies are not in place to broaden the sources of emission reduction”.
Decarbonising heat is, as Alan Whitehead MP, former shadow energy minister, put it recently, the “elephant in the room”. Most prescriptions so far have involved "the electrification of the heating system": replacing gas boilers with either direct electric heating, or heat pumps.
Powered by electricity, heat pumps circulate fluid through pipes either buried beneath the ground or a machine resembling a big air conditioning unit on the outside of a building, drawing in heat from the environment.
“As far as customers are concerned, that does mean, among other things, ripping out all their boilers, ripping out the mains, and replacing those with heat pumps,” Whitehead told the Utility Week Energy Summit. “I would predict that pretty much every customer would regard that transition with some horror.”
Iain Conn, chief executive of British Gas owner Centrica, was equally forthright: “We pay 5p/kwh for gas, and 15p/kwh for electricity – so this whole idea of electrifying everything is mad, especially when we have got natural gas plumbed into all of the homes.
"And if you electrify everything, what are you going to generate the electricity from? For quite a while I’m afraid it’s going to be more natural gas-fired power stations.”
An alternative solution, both men suggested, is not to change the heating system, but to change the gas.
“Rather than ripping everything out,” Whitehead proposed, “we look at: can we supply, for example, green gas, or different forms of gas supply into the system? Leaving it substantially as it is but actually changing the carbonisation mix of what goes into it – and giving the customer a much better deal.”
Several 'green’ gas options have been mooted; 'biomethane', derived from crops or waste, is already being fed into the UK gas grid at a small scale – but this still produces carbon dioxide when burnt.
The greenest gas option, advocates argue, is pure hydrogen. Unlike methane, hydrogen burns cleanly, producing just water and heat.
Thanks in no small part to the Hindenburg disaster, it also has a reputation for being dangerously flammable.
Hence the farmhouse in Scotland.
“Gas leaks are rare, but do occur from time to time from sources as diverse as a defective gas appliance to DIY accidents,” says Mark Crowther, technical director at Kiwa Gastec, who devised the testing.
“The project was designed to prove whether accidental leaks from a pure hydrogen, or hydrogen and natural gas mixture supply, would have more or less risk attached than a leak from a natural gas supply.”
The outcome was, he insists, reassuring. Because hydrogen is much lighter than natural gas, the testing showed it was actually less likely to accumulate in dangerous amounts.
While hydrogen is also odourless, raising further safety fears, this could be addressed by artificially adding odour, as is done to natural gas.
“Overall it would appear hydrogen is of about the same risk as mains gas,” says Crowther. “Because of this, and its zero carbon footprint, in the grand scheme of things, its widespread use will almost certainly be safer for the future of mankind.”
Countering the fear of explosions is, however, far from the only challenge.
Natural gas is a naturally occurring fossil fuel; and while North Sea supplies may be dwindling, pipelines and liquefied natural gas (LNG) ships bring plentiful supplies from elsewhere, while fracking could yet uncover new domestic gas reserves.
If hydrogen is to be used instead, Britain needs to find a very large supply.
The easiest source, according to a major feasibility study by Northern Gas Networks (NGN) released today, would be to extract it from the naturally-occuring methane - a compound of hydrogen and carbon - using 'steam methane reformer’ plants.
Carbon dioxide produced in the process would be captured and pumped out for storage in disused gas fields in the North Sea.
NGN’s 'H21’ project proposes making Leeds the first city in the world to convert to run on pure hydrogen.
The key selling point of the plan is that the existing gas networks could then be used to transport the hydrogen to homes and businesses, whose central heating systems could remain largely intact.
The catch? Every gas boiler, cooker and fire would need to be replaced or upgraded, at an estimated cost of £3,000 per household.
Though disruptive, the study suggests it would be no more so than the original conversion in the 1960s and 70s of appliances from town gas (itself 50pc hydrogen) to natural gas.
All in, it estimates the plan to convert Leeds could cost £2bn, with ongoing running costs of £139m a year, on top of the cost of the natural gas.
And that’s just the beginning. “You would never just convert one city,” says Dan Sadler, who ran the H21 study for NGN and is currently seconded to the energy department. “You would only ever start if you were incrementally going to convert the whole UK.”
Leeds, he suggests, could feasibly be converted by 2026-29. In his vision, a network of 16 more cities and towns spanning from Aberdeen to Cardiff would follow, culminating with London in 2050. The potential price tag? £50bn, with running costs at £2.8bn a year.
Sadler proposes that the financial pain be eased by paying for the upgrades, like current network charges, through regulated bill levies. No household would face an upfront charge for new appliances - though bills could still rise by a peak of about £170 a year by 2050.
The sums are huge, but, as Sadler points out, a single new nuclear power station costs £18bn.
“Whatever we do it’s going to cost a lot of money. The alternative is we get 90pc of people in cities who use gas for their heating to convert to electric, and we then have to rebuild all the electrical infrastructure.”
Eventully, he adds, new 'green’ sources of hydrogen could be developed, using surplus renewable power to create it through electrolysis. Hydrogen could one day be shipped in as LNG is today, Sadler suggests. “I know this sounds a bit heroic, but you’ve got to think big.”
Of course, companies like NGN, whose business model is built around gas networks, and Centrica, Britain’s biggest household gas supplier, have a vested interest in the continued use of gas.
Professor Jim Skea, a member of the Committee on Climate Change, sounds a note of caution. “I don’t think we have found in our analysis that using hydrogen networks for residential heating is necessarily the most cost effective way to do things,” he says.
The CCC’s scenarios for hitting the UK’s carbon targets currently envisage a continued push for heat pumps, as well as district heating schemes, where heat produced from a power station or factory is used to heat water for nearby homes.
However, Prof Skea acknowledges major challenges around the public acceptability of heat pumps, as well as coping with the added electricity demand.
He predicts a “patchwork of solutions” may emerge and says the CCC is open-minded.
“We are not technology-prescriptive; we have scenarios but they are not blueprints for the future. If other people can come up with ideas about achieving the same outcome in a more technically, more economically efficient way, we are very much interested in the evidence.”
Sadler is convinced his hydrogen plan should be part of the solution.
“Whether we can decarbonise heat is a huge question mark in terms of policy. No one has ever come up with a real, practical way to do it,” he says. “I know this is a practical way to do it.
"The challenge is whether we can get the political will. It’s such a big idea - but the Climate Change Act is such a big challenge. Big challenges need big ideas.”