No colour of H2 makes sense to decarbonise heating, and pretending otherwise risks delaying urgent action to slash emissions, write Richard Lowes and David Cebon in an article on the Recharge website.
‘Wrong side of history’ | Wake up to the hype around green hydrogen for heating
Governments around the world are developing strategies and suites of policies to support their climate change mitigating ‘net-zero’ ambitions. Of course, more recently, linked to the terrible Russian war against Ukraine, policymakers are also looking to limit exposure to fossil fuel imports and the risks they pose.
The current US administration has described hydrogen as a “game-changer” in the fight against climate change and the transition away from fossil fuels. The UK Prime Minister Boris Johnson believes it “has perhaps the greatest potential of all”, while Ireland’s Tánaiste (the deputy head of government) has called it “the holy grail” of energy policy.
Such proclamations are impacting the politics of energy. The European Commission is proposing to allow gas infrastructure owners to fund hydrogen-readiness work, and potentially using the energy bills of electricity consumers to pay for it. A new Energy Bill currently making its way through the UK Parliament could allow a ‘hydrogen levy’ on electricity sales. In normal times, such ‘cross-subsidisation’ would never be allowed. But the climate and energy price crises, mean we are no longer in normal times. The perceived need for speed means that rapid action is considered more important than due process.
And while climate change demands an emergency response, there is a risk that going too fast, without evidence-backed decisions, will actually undermine efforts to decarbonise.
To reach net zero, practically all fossil-fuel combustion needs to be replaced.
For buildings, heat pumps are a clear winning technology, extracting the majority of their heat output from outside air, ground or water. Even in cold temperatures, heat pumps can be powered using increasingly cost-effective, renewable electricity.
According to the most detailed and up-to-date global net-zero analyses from international management consultancy McKinsey and The International Energy Agency, heat pumps take up the lion’s share of building heating in their global net-zero predictions. The Intergovernmental Panel on Climate Change’s (IPCC) recent report explains that “scenarios assessed show a very modest role for hydrogen in buildings by 2050”. The IPCC also highlighted the importance of heat pumps.
The proponents of unchecked hydrogen use are on the wrong side of the evidence, and history. They ended up there because of money — or more specifically, sunk assets, which are now under threat as the world attempts to move away from fossil fuels and its associated infrastructure. The use of hydrogen made from natural gas with carbon capture and storage (CCS) could keep gas flowing through infrastructure that would otherwise be stranded, and maintain the need for oil and gas development and processing facilities through which hydrogen can be produced.
With gas currently providing the largest share of the world’s heating, as well as public policies being considered and designed to remove fossil fuel heating from buildings, it should come as no surprise that the gas industry has been overselling the idea of converting gas infrastructure to run on hydrogen.
Hydrogen is being promoted through a powerful international, political and media machine, associated with the incumbent fossil fuel industry, and it is lobbying governments around the world.
We have seen this lobbying first hand. And while research into and evidence of lobbying tends to be limited, there are plenty of publicly available examples, indicating the scale of the efforts. In a letter to the European Commissions, trade body Eurogas has said hydrogen “will play a key role” in the energy demand for the sectors of home-heating, transport and electricity generation.
In a rare intervention on political lobbying, an often taboo subject in the UK, The Times newspaper explained how both BP and Shell were lobbying the UK government to support hydrogen to be used for heating. The UK’s ‘All Party Parliamentary Group on Hydrogen’ , “a cross-party group of MPs and peers [member of the UK parliament’s upper house] that focuses on raising awareness of, and building support for large scale hydrogen projects” is funded directly by an industry group including Shell, Equinor, Cadent, Northern Gas Networks, SGN, Baxi, etc. These companies are all incumbents in the gas industry.
In the US, gas monopolies are promoting the conversion of their infrastructure to hydrogen and blending hydrogen into gas mix, while fighting government policies to reduce gas use alongside general efforts to undermine building electrification.
The scale of this lobbying is vast and has been mapped in detail across Europe where it has been described as “intense and concerted”. The lobby has seen some success in Europe, accused of hijacking European Covid recovery funds.
There are two potential impacts of such lobbying.
Firstly, there could be direct impacts on policy, with governments offering financial and regulatory support for investments in hydrogen, in spite of evidence suggesting this may be a poor use of funds. Indeed we are already seeing this.
But the second, more egregious outcome, would be that such efforts to promote hydrogen delay actual progress on climate change as policymakers are distracted from clearly better and cheaper options. Indeed, it has already been suggested that the oil sector knows the hydrogen solution for personal vehicles is flawed.
Pumping up the pressure
On the face of it, for countries such as the UK and the Netherlands, with well-developed and highly interconnected gas systems, it makes sense to consider the existing system and ask whether it be used in a zero-carbon world. The simplicity of ‘greening the gas’ or the idea of a ‘drop-in replacement’ is also an extremely effective lobbying and sales line.
The parent company of the UK’s largest gas (and oil) boiler manufacturer, explained in its submission to a UK parliamentary inquiry into heating:
“Bosch believes that hydrogen gas, with a by-product simply of water, could be the closest silver bullet we have.”
In the same inquiry, one UK gas network owner explained that “a hydrogen-ready boiler solution supplied by a repurposed gas network – which is already built to meet peak heat demand in winter – offers the optimum route to decarbonise heat at the scale required with the lowest levels of disruption and most value for customers”.
In some respects, hydrogen does have some extremely valuable characteristics for clean energy systems. Firstly, it can be stored indefinitely (although the very small molecules make it prone to leaking out of most containers), which in a world of variable renewable energy is potentially attractive for long-term or transportable storage. Secondly, like fossil gas, it can be burned to produce heat or electricity; or used in fuel cells (producing heat and electricity at once). It can also be produced through the electrolysis of water, powered by increasingly cheap renewable electricity.
Yet just because you can do something, it doesn’t mean you should. And this is patently true for the idea of widespread hydrogen use. In the same way that champagne is reserved for special occasions, hydrogen is a premium product with specific value.
Even a cursory look at the basic technical details show hydrogen as a very expensive and environmentally unattractive solution for the heating and much of the transport sector.
Not a source of energy
A common misunderstanding is that hydrogen is itself a source of energy. It is not. It is solely a vector or energy carrier: a means of storing and transporting energy. Hydrogen gas does not exist in a state where it can be extracted from the environment in useful quantities, but it must be created, which is energy intensive and costly.
The reason why the fossil-fuel production industry is so keen on hydrogen is because nearly all hydrogen currently made globally (most of which is used in industry) is produced from fossil fuels, mostly gas, but some oil and coal.
Enter ‘blue hydrogen’, a term that refers to hydrogen produced from fossil gas with (some) greenhouse gas emissions captured in the production process and in theory stored so that they have no impact on the climate.
Blue hydrogen is controversial principally because of worries that it might be worse for the climate than simply burning methane. These concerns stem from the fact that the production of the gas used to make it could lead to increased fugitive methane emissions, a very potent greenhouse gas, and also because capturing and storing CO2 emissions is difficult, expensive and has not been successfully achieved at scale anywhere in the world.
A belief that the whole idea of hydrogen had been captured by the fossil-fuel industry led to Chris Jackson resigning as chairman of the UK’s Hydrogen and Fuel Cell Association, saying the group’s support for blue H2 “is at best an expensive distraction, and at worst a lock-in for continued fossil-fuel use that guarantees we will fail to meet our decarbonisation goals”.
With fossil gas prices skyrocketing to record highs, and the entire European continent aiming to rapidly reduce its exposure to Russian gas imports, blue hydrogen has rapidly gone out of fashion. Although you won’t hear that mentioned by many industrial hydrogen proponents.
Much of the hydrogen push has silently pivoted towards ‘green’ hydrogen, created from water using green electricity. While on the face of it, a move from fossil fuel-derived hydrogen to renewably produced hydrogen might appear to be a good thing, the reality is that burning green hydrogen at scale seems even less plausible than burning blue hydrogen. The energy content of green hydrogen comes from electricity and the production process involves significant energy efficiency losses.
The electricity could be used directly in 100% efficient electric heaters or even more efficient heat pumps which use electricity to extract heat from the environment. Heat pumps operate with an effective efficiency of over 300%, with each unit of electricity going in, resulting in three units of useful heat.
These conversion efficiencies are a basic element of energy economics, and are the nub of the green hydrogen debate.
Energy conversion basics
All energy conversion processes result in losses, meaning you get less useful energy out compared to the amount you put in. For example, a power station burning gas may be around 60% efficient with 40% of the energy lost as heat.
Fundamentally, the hydrogen pathway for heating (all the way from electricity generation to burning it in a boiler) has much greater energy losses than direct electric route. It therefore requires far more primary energy (about 6 times more) than using a heat pump to deliver the same amount of heat, leading to much higher costs.
The biggest energy loss associated with green hydrogen use is in the process of electrolysis, or splitting water molecules to produce the hydrogen in the first place.
A recent academic review put in-practice efficiencies at between 60% and 73% for electrolysis (i.e. one unit in and 0.6 to 0.73 units out), albeit with some scope for improvement; something the hydrogen industry (obviously) agrees with.
Blue hydrogen was, at least before the gas price explosion, potentially cost effective compared to widespread use of heat pumps in various independent pieces of analysis, albeit under less stretching greenhouse gas reduction targets.
There is, however, not one independent study that suggests green hydrogen is cost effective compared to the widespread use of heat pumps. The high cost of hydrogen compared to alternatives becomes quite obvious once you understand how the energy efficiency of green hydrogen and compares to electrification.
The graphic above spells this out. The first route (shown on the left) shows transmission of the electricity to a consumer where it powers a heat pump. As heat pumps use electricity to heat a building from the environment that results in around three (or more) units of heat for every unit of electricity consumed, they have an effective 300% efficiency (known as the “coefficient of performance” or COP, which is in this case three). While some losses occur in the transportation of electricity, the overall effect is that 100 units of electricity results in about 270 units of heat reaching the consumer. This is an amazing energy uplift when you consider the value of clean electricity and that over two thirds of the useful heat is coming from an inexhaustible renewable source.
The second route (centre) uses a simple electric space heater, powered by green electricity. There are small losses in electricity transportation, but most of the 90 kWh of electricity reaching the heater is converted into useful heat, yielding about 86 kWh.
The third route on the right shows the generation of green hydrogen which is burnt in a boiler for heating. Significant losses occur in the conversion of electricity to hydrogen. But further losses occur as energy is used to store the hydrogen and transport it to buildings and also when the hydrogen is burnt in boilers. 100 units in at the start of the process leads to 46 out in this pathway. Comparing the left hand and right hand routes, the heat pump route delivers about six times more heat than a green hydrogen boiler for the same amount of electricity generation.
This six times difference is the stark reality of using hydrogen for heating compared to heat pumps.
If providing the equivalent amount of heat by the green hydrogen route requires up to six times as much primary energy, it would be necessary to build up to six times as many offshore wind turbines or nuclear power stations, all with their own environmental and resource impacts. Clearly this electricity capacity would take much longer to build, cost more and would delay decarbonisation. Hence comments from the UK’s Climate Change Committee CEO warning that switching all heating to hydrogen would be “impractical”, particularly when climate change demands rapid and immediate action.
Perhaps it is not quite that simple
Now, you might be thinking, OK that’s great in theory, but you don’t always have renewable electricity being generated when you need your heat pump running and so you will not be able to get that efficiency all of the time.
This is certainly true for some of the time. However, as pointed out by the late Sir David Mackay – the British physicist, mathematician, Regius Professor of Engineering and Chief Scientific Advisor to the UK Department of Energy and Climate Change – even running a heat pump solely on electricity generated by gas power stations would still use less gas and therefore have lower emissions than using a gas boiler. That’s because, even though your gas power station may be only 50% efficient, your heat pump is 300% efficient and that makes the overall process more efficient than burning gas in a boiler.
It’s also important to bear in mind that heat pumps perform less well when it is colder with a performance of possibly 150% (a coefficient of performance of 1.5). But even in that case, the heat pump would still generate three times more heat per unit of electricity than green hydrogen. Using a heat pump will therefore always be more efficient and require less primary energy than burning green hydrogen for the same amount of heat.
The impracticality of hydrogen is not just limited to expanding the electricity sector to infeasible levels. The UK gas grid is currently not suitable for transporting hydrogen and an investment of £22 bn ($26bn) would be needed to make it so according to analysis for the UK government; that’s similar to the total current value of the UK gas grid. There is also no getting away from the fact that hydrogen would require geographically based conversions, turning off whole areas of gas at a time and then refilling and reconnecting them, potentially leaving whole areas without heat or hot water for days.
Need for speed
Clearly the climate is changing and atmospheric greenhouse gas concentrations continue to increase. Slow progress thus far means that the world needs to decarbonise as quickly as possible. Any delay to decarbonising heating or transport, such large chunks of current emissions, could be disastrous. We obviously also need to wean ourselves off increasingly expensive fossil fuels.
Taking the hydrogen-for-heating route would not just cost much more but would take longer to achieve, requiring so much more primary energy. This idea is unlikely to ever get beyond limited trials.
A more likely scenario is that more time is wasted considering the idea of burning hydrogen for heat and more is spent funding companies to research it because politicians do not want to take the required difficult decisions. The lobbying will continue and while governments are slowly beginning to understand the limits and costs of hydrogen, lobbying is moving towards local authority policymakers where future decisions will need to be made.
Amidst the hype, citizens are become increasingly confused about future heating technologies. All of this leads to climate delay and continued exposure to fossil fuels.
But when decision-makers are faced with the real-world cost implications of hydrogen for heat, the role of electrification and energy efficiency will eventually be realised. Yet this may be too late.
Decarbonising heat will be hard enough. And when speed is everything, there is no time for the hydrogen distraction.
About the authors
David Cebon is professor of mechanical engineering at the University of Cambridge, and an executive at the Centre for Sustainable Road Freight
Dr Richard Lowes is a senior associate at the Regulatory Assistance Project and research fellow in the University of Exeter’s Energy Policy Group