The use of blue hydrogen within the energy sector should be restricted to applications where electrification is impractical and supplies of green hydrogen are not yet sufficient to meet demand, a senior figure at the Climate Change Committee (CCC) has stated.
David Joffe, head of carbon budgets at the CCC, said blue hydrogen should be seen as a transitional fuel while green hydrogen production is scaled up over the next few decades, eventually becoming a “supply of last resort” and ultimately being phased out completely.
Joffe was speaking to Utility Week following the release of the government’s hydrogen strategy earlier this week, which included a “twin track” approach to supply, covering both blue hydrogen produced by reforming methane and capturing emissions, and green hydrogen produced by electrolysing water using renewable energy.
He was also responding to a controversial US study published last week that claimed that burning blue hydrogen could actually have a greater impact on global warming than burning natural gas due to leakages during the production and transportation of the methane used to feed and fuel the reformation process.
Methane leakage
The headline figures from the study by researchers at Stanford University and Cornell University assumed a methane leakage rate of 3.5 per cent, primarily based on a prior study by one of the authors of natural gas production at fields in the US.
“There’s an issue here about whether you interpret that study as representing the situation in the US where most of the gas supply is from fracking and injected into distribution level grids that then leak a lot of gas as well,” Joffe told Utility Week.
“And I think 3.5 per cent might well be representative for the US, in that context, but we can’t draw conclusions that something based on natural gas cannot be compatible with tackling climate change anywhere in the world by just making assumptions that just happen to be specific to the US.”
He continued: “It’s certainly possible to produce fossil gas at scale and not put it through leaky pipes in a way that gives an overall methane leakage rate below 1 per cent. I’ve looked at a fair number of studies and it’s pretty clear to me that’s possible.”
Joffe said methane leakages from production in the UK and Norway – the main sources of natural gas supplies in Britain – are probably around this level, although he accepted that the figure is likely to be higher for imports of liquefied natural gas, firstly, because they may not be as well-regulated in the countries where it is produced, and secondly, because the liquefication, transportation and regasification of the fuel introduces more opportunities for leakage.
Gniewomir Flis, a project manager at the German think tank Agora Energiewende and formerly a consultant for Aurora Energy Research, agreed that the 3.5 per cent leakage rate used as the baseline assumption in the study is not representative of the situation in Europe: “The IEA estimates global emissions leakage at around 1.5 per cent so that’s already a lower number. That’s the number I would use as a global reference. But an average will hide large geographical variation.”
“In the US, the hunt for shale oil leads to many smaller wells, and sometimes to methane venting since it’s a by-product,” Flis added.
He said where the gas is extracted for its own sake from fewer, larger wells “there are fewer point sources for leakage, making the process easier to monitor”.
Flis said members of the Oil and Gas Climate Initiative have claimed to achieve methane leakage targets of just 0.2 per cent. He said this is “admittedly a lobbying group” so “I would take that with a grain of salt – the true leakage is almost certainly more – but it is an interesting reference point.”
Even if this 0.2 per cent rate is not actually being achieved at present, Flis said he can see no reason why it would not be possible: “Just last year, the Rocky Mountain Institute and SystemIQ launched an independent certification scheme. Their benchmark for best-in-class leakage rate is 0.05 per cent so it does seem like 0.2 per cent is not only achievable, but we can go beyond that.”
Joffe said regulations in the UK could be strengthened to ensure methane leakage and other emissions from natural gas production are as low as possible: “On domestic production, we think there is room to reduce the emissions intensity of North Sea fossil fuel production.
“There tends to be a greater focus on the oil aspect of that but oil and gas are both important, and we’ve set out ways in which the carbon intensity of those can be reduced in our sixth carbon budget advice report last year.”
He said this would raise costs and would therefore need to be matched by tougher regulations on imported gas to provide a level playing field: “Regardless of whether we’re doing blue hydrogen or not, any natural gas that we import should have as low a greenhouse gas footprint of production as possible and we should be putting in place policy to drive that down, whether that’s a carbon border adjustment-type approach of a tariff or whether that’s a standard for the footprint of greenhouse gases in terms of the fossil fuel production.”
Joffe also questioned the study’s use of 20-year timeframe as the baseline for calculating the impact of emissions on global warming. Methane is much more powerful warming agent than carbon dioxide but breaks down in the atmosphere over time.
“Certainly, the 20-year GWP would not be my preferred metric,” said Joffe. “The 100GWP is used across the world for comparisons on greenhouse gas emissions and that would be the default basis I would use.”
“CO2 is the real enemy in terms of climate change because it’s so long-lived. It’s basically forever in the atmosphere until you take it back out again with greenhouse gas removals.
“If you focus on methane at the expense of CO2 and therefore end up with more CO2 in the atmosphere, that’s going to have climate impacts not just for the rest of the 2040s but the 2050s, 2060s and through to 2100 and beyond, unless we take it back out again.”
Production
Joffe additionally challenged the study’s assumptions around the production of blue hydrogen.
The paper assumed as a baseline that blue hydrogen is produced using steam methane reformation – the way in which most hydrogen is currently produced – and that the carbon emissions from the process are captured at a rate of 85 per cent using electricity mainly generated using natural gas. It also assumed that the heat required for the steam reformation process is provided by burning natural gas, without capturing emissions from the flue gases.
The study did explore a situation in which the flue gases from heating are captured, but at a lower rate of 65 per cent, and again assumed the capture process is powered using gas-generated electricity.
The paper acknowledged that renewable electricity could be used to provide the heat required for steam methane reformation and to power carbon capture but did provide not emissions estimates for these scenarios.
“It’s pretty clear that electricity’s relatively easy to decarbonise and a lot of the sources of zero-carbon electricity are now cost-competitive with fossil electricity so it’s not clear to me why you would include a significant carbon intensity of electricity within that process,” said Joffe.
More importantly, Joffe said the study did not consider the alternative production processes, in particular, autothermal reformation.
Autothermal reformation combines steam methane reformation with the partial combustion of methane to provide heat for the reaction (hence the name). Although this means the heat cannot be provided using renewable electricity, the emissions from combustion are released together with those from reformation of the methane and there is no need to capture emissions from separate flue gases.
These combined emissions can also be captured at a higher rate. A paper commissioned by the Department for Business, Energy and Industrial Strategy and released alongside its hydrogen strategy on Tuesday (17 August) estimated the figure at 95 per cent, compared to 85 per cent for steam methane reformation.
“Steam methane reforming is the dominant way of producing hydrogen from methane globally but it’s not designed for integration with carbon capture and once you think carbon capture is important you would instantly switch auto thermal reforming, simply because it produces a pretty pure stream of CO2 directly out of the process,” said Joffe.
With this possibility in mind, Joffe said the CCC has estimated the reduction in full lifecycle greenhouse gases from burning blue hydrogen when compared to burning natural gas at 60 to 85 per cent – a much greater saving than that suggested by the US study.
“There’s certainly no case that they’ve analysed that says this is blue hydrogen done well,” he remarked.
Joffe said this reduction could “conceivably” reach 90 per cent if the highest carbon capture rates claimed by proponents of autothermal reformation are achieved: “We have reasonable confidence, because we have no reason to believe otherwise, that the technology performance will deliver something pretty high, but that needs to be proven”.
The role of blue hydrogen
Even if the top end of the CCC’s estimated range can be achieved, Joffe nevertheless urged restraint in the use of blue hydrogen: “You don’t want to be using much of a technology option that’s only giving you up to an 85 per cent emissions reduction if the overall aim is to achieve net zero, which means 100 per cent reduction.”
He said greater reductions should be sought through electrification, energy efficiency or the use of green hydrogen wherever possible.
As well as keeping emissions lower, Joffe said minimising the use of blue hydrogen would also limit reliance on carbon capture and storage, which will also be needed for other purposes, and on imports of natural gas. He said extensive use of blue hydrogen would be “pretty undesirable from a strategic perspective.”
“We do regard home heating as one of those areas where there are other solutions,” he added. “I’ve got a heat pump. It works very well. I think that can definitely be a mass solution.
“Can it work for every home? Maybe not. But I think we can get pretty close to the majority of homes having heat pumps, and some that might not have a full heat pump solution, might have what we call a hybrid heat pump, which is a heat pump doing most of the work and then hydrogen boiler kicks in and just does last 20 per cent, particularly on cold days or when the wind’s not blowing to power the heat pumps.
“Heat pumps have to be the priority. They have to be the main way of decarbonising homes. And yes, at the margins there can be a role for hydrogen boilers, but it is at the margins, and it’s not the main solution. Otherwise, you just need way too much hydrogen.”
At the same time, Joffe said for applications where electrification is not feasible and supplies of green hydrogen are insufficient to demand “you’ve got have something – a 75 per cent, 85 per cent emissions reduction – rather than zero by leaving the fossil gas there.
“That’s the point for us; that there is an opportunity to do something that gets rid of the unabated gas and it might not be 100 per cent emissions reduction but up to 85 per cent is significantly better than zero.”
He continued: “It is important to think as well about, not just about the energy balances as in the annual average, but in some years the wind won’t blow as much as in others or there might be outages of some kinds of plants or whatever; if everything we’ve got is zero carbon but we haven’t built the resilience then what happens when a bit doesn’t work?
“Do we then have to burn fossil fuels to make sure the lights stay on? Do we build extra zero carbon just in case? Or do we have something that’s pretty low carbon, not completely zero carbon, but it’s there on tap just in case we need it?”
Joffe said the CCC expects blue hydrogen production to peak in the late 2030s and then begin falling from then on: “We think that if you’ve already built the blue hydrogen infrastructure but it’s utilisation is falling over time – it’s fallen into a backup role as a supply of last resort – that’s a useful role, whether it’s used for power generation in a cold winter when we need to power all of the heat pumps, whether it’s used as hydrogen for industry, whether we’re relying on some imported hydrogen and the imports don’t turn up.
“There’s worlds in which having that extra contingency might be helpful.”
But he concluded: “Obviously at some point it becomes stops being sensible to do any fossil fuels at all, even with CCS; you just switch to entirely clean solutions but we think that’s unlikely by 2050, though not impossible.”