If you’re following conversations about climate, net zero or decarbonisation, it’s hard to miss the hype around hydrogen. Fossil fuel companies and gas grid operators have been lobbying politicians on the subject for years. The government’s hydrogen champion, Jane Toogood, recently published her report, which takes an unsurprisingly optimistic view of the opportunities offered by hydrogen.
Its proponents say we can solve the climate problem with clean, low carbon hydrogen which could replace all the natural gas we use, through a safe and easy switchover. In their view, we’ll heat our homes with it, cook with it, even fuel our cars with it. This imagined widespread hydrogen future bolsters the lobbyists’ business model. But the future mustn’t look like this. Leaked hydrogen has a global warming effect which could undo much of its expected climate benefits.
That isn’t to say we shouldn’t ever use it. Clean hydrogen will be a solution to certain decarbonisation challenges, where alternatives are scarce or have potentially worse environmental impacts. This includes some industrial processes, as an ingredient in many bulk chemicals, to provide dispatchable power generation, and perhaps for aviation and shipping fuels. Burning clean hydrogen produces no carbon emissions, although it can lead to local air pollution.
Any hydrogen used should ideally be what’s known as ‘green hydrogen’, produced by renewable electricity. In the short term, there’s a valid case for ‘blue’ hydrogen. This is hydrogen extracted from natural gas with any carbon emissions captured and stored, though methane leaks upstream must also be addressed. Hydrogen produced in these ways and used in industrial clusters is very likely to be needed as an effective way to bring down emissions.
Hydrogen still has a climate risk
But pumping hydrogen into our homes and cars should not be an option on the table. Energy efficiency measures and heat pumps are far safer and more economical options to decarbonise heat in buildings. And hydrogen has a dirty side. If it leaks or is vented unburnt from production facilities, pipelines, storage facilities or end uses, it enters the atmosphere. There, it interacts with other gases and acts indirectly as a powerful greenhouse gas, contributing to global warming. Over 100 years, hydrogen’s impact is estimated to be twelve times stronger than carbon dioxide.
Unfortunately, leakage risk is high. Hydrogen is a tiny molecule that’s very difficult to contain. Leaks are hard to detect and, if it leaks a lot, the climate impact would be significant. A recent study, published in Nature, looked at the potential impact of the widespread adoption of blue hydrogen. It showed that, if system wide methane leaks continue at around two per cent and high hydrogen leakage occurs, over half of the climate benefits of switching to a hydrogen economy could be lost. How and where we use hydrogen matters. Pumping it through the millions of pipes in our existing gas network is likely to result in high levels of leakage.
There’s also been a lot of talk about the idea of mixing clean hydrogen into our existing gas grid, perhaps blending up to 20 per cent by volume (the rest being natural gas). Both E3G and the Regulatory Assistance Project have raised the alarm about this, upsetting a few hydrogen lobbyists and drawing the attention of the Climate Change Committee. We’ve analysed how the costs and benefits of this proposed blending are affected by the risk of leakage. We found that blending could result in only a four per cent reduction in greenhouse gas emissions, at best, and this would be at significant cost.
Part of the motivation for considering blending is to create a reliable and consistent use for hydrogen to encourage its overall production to scale up. This may be a valid reason, but it will introduce additional costs which the government wants to charge to already high consumer energy bills. And the climate benefits will be minimal, especially if leakage rates are high.
We already know that methane, another powerful greenhouse gas, seeps out from the gas network more than official records show, and hydrogen is known to be even more leaky than methane. Clean hydrogen for everything might sound like the holy grail of climate solutions but, in the accelerating climate emergency, we can’t afford to take wrong turns and waste money and effort on something that could be a big step backwards. Dieselgate taught us that, to great environmental and financial cost. We need to find a better way of linking hydrogen producers with the best and most impactful end uses. Blending it into the gas network isn’t one of them.