This post is by David Cebon, professor of mechanical engineering at Cambridge University.
There has been a lot of talk about hydrogen in the past year or two. Advocates for a ‘hydrogen economy’ make claims about how ‘green hydrogen’ (made by electrolysing pure water with renewable electricity) will power future energy systems. The idea is that green hydrogen will be generated at times of day when renewable electricity is cheap (ie when supply is high and demand is low). The hydrogen gas will be stored in underground salt caverns until needed and then either converted back into electricity and injected into the electricity grid or piped around the country to heat buildings and fuel lorries.
A promise to solve the big carbon problems
The promise is that, with one silver bullet, this imaginative scheme solves three big decarbonisation problems: electricity storage, heating buildings and powering heavy transport systems.
Some of these advocates recognise that generating and storing green hydrogen at the necessary scale is an immense task that will take many decades to achieve. Consequently, they propose to use ‘blue hydrogen’ as a stop gap. This is made from natural gas by a Steam Methane Reforming (SMR) process, then the resulting CO2 by-product is captured and stored in depleted oil wells (otherwise known as CCS).
Alternatively, an ‘electron economy’ uses electric heat pumps to heat buildings, battery-powered or catenary-powered electric lorries and various possible technologies with high electricity storage efficiency.
The hydrogen economy vs the electron economy
Over the past year I have researched and written technical blogs on these subjects: on powering lorries, heating buildings and electricity storage, and one bringing together the arguments. Here are my main conclusions:
- Energy conversion processes required by the green hydrogen economy (electrolysis, compression, storage and fuel cells) are very inefficient: wasting energy as low grade heat. A huge amount of new renewable electricity capacity would be needed to compensate for the wasted energy.
- The proposed green hydrogen economy is unlikely to be realisable in the UK because of sheer amount of renewable electricity required, the low Technology Readiness Level (TRL) of large scale electrolysis and the undeveloped technology for storing hydrogen in salt caverns. An ‘electron economy’ has a significantly higher likelihood of success, in a much shorter timeframe.
- For heavy goods vehicles, direct electrification, via batteries and ‘electric roads’, are options with a higher TRL, lower energy consumption, lower carbon emissions and lower costs than hydrogen-powered fuel cell vehicles.
- Heat pumps are a much better option for heating buildings than hydrogen boilers. Heat pumps are readily available now and have much lower energy consumption, carbon emissions and fuel costs.
- For electricity storage, green hydrogen is unlikely to be competitive with more efficient alternatives such as cryogenic (liquid air) storage and compressed air storage. Both offer almost equivalent storage capabilities at much lower ‘levelised cost of storage’, and higher TRL.
- Shifting the energy for lorries and heating buildings to blue hydrogen would result in the UK importing and burning an additional 260 TWh of natural gas per year. This would increase natural gas imports by 50 per cent and increase overall gas consumption by nearly 30 per cent. It would be detrimental to the country’s balance of trade and energy security.
- The push for hydrogen is likely to delay the international decarbonisation project and undermine efforts to keep the global average temperature less than 1.5 oC or even 2.0 oC above pre-industrial levels.
So why is there suddenly so much hype about hydrogen?
A lifeline for fossil fuel companies
Peer reviewed research shows there is currently a concerted effort by an international ‘discourse coalition’, “primarily of gas industry incumbents, [who are] under threat from the decarbonisation of heating” and that “the green gas storyline is being oversold by incumbents.” In other words, the international fossil fuel industry, which is under existential threat from electrification, is promoting hydrogen as a solution: to create confusion among politicians and the public and delay its own demise. According to Pierre-Etienne Franc, founding member and secretary of the Hydrogen Council who leads hydrogen projects at Air Liquide: “Ultimately, blue hydrogen is an easier way for an oil company to pivot to clean energy than going full-on renewable… It’s a way to avoid having stranded assets from the current fossil fuel-based system”.
Undoubtedly, the main players in the hydrogen lobby understand they cannot deliver on their promises. They know green hydrogen is a deeply flawed concept. Consequently, they are pursuing a ‘bait and switch’ strategy in which they promise a green hydrogen future but then fall back to an interim blue hydrogen position which will consume a large amount of additional natural gas.
They also know that blue hydrogen will take decades of development to deploy at sufficient scale, during which time they can sell much cheaper ‘grey’ hydrogen(made by the SMR process but with CO2 released into the atmosphere) instead. They ignore the fact that grey hydrogen will make CO2 emissions considerably worse than the status quo (ie just burning natural gas).
This delay will give the fossil fuel industry a (temporary) reprieve. They also know that they won’t be able to deliver the promised net zero future because the CCS process will always leak at least ten per cent of the CO2 into the atmosphere and the oil and gas supply chain will continue to generate fugitive methane emissions, equivalent to the carbon footprint of Europe.
The hydrogen economy will not be viable long term
It is probable that the hydrogen economy project will fail in the end. Hydrogen solutions are far too expensive to compete with electric solutions, because hydrogen processes are fundamentally inefficient and waste a lot of valuable energy. Just as the free market has rejected hydrogen powered cars because of their excessive energy costs, so too the market will conclude that hydrogen powered lorries, hydrogen powered heating and green hydrogen electricity storage are all too expensive to compete with energy efficient electrical alternatives.
Unfortunately, this will take years to play out. In the meantime, encouraged by the hydrogen hype, the government will continue to subsidise hydrogen projects and technology development and the hydrogen lobby will continue to obfuscate its fundamental lack of competitiveness.
The tragic consequence is that confusion and delay will threaten to derail efforts to decarbonise the nation and the world in time to prevent the worst effects of global warming. This should be of major concern to the environmental movement.
Electrification is the route to fast decarbonisation
If the UK government is serious about decarbonisation, it should pursue a strategy of electrifying everything possible, as soon as possible. That includes all land transport and heating of buildings, with a commensurate large scale increase in sustainable electricity generation. There should also be a strong emphasis on energy efficiency throughout the economy, including insulating buildings and improving the energy efficiency of lorries. Hydrogen should only be used for the applications that cannot be electrified. These include some industrial processes, possibly aviation and the manufacture of ammonia, which is used for fertiliser production and is being proposed as a liquid fuel for shipping.
