Sunday, 22 March 2020

Why using hydrogen to supply heating would be a terrible choice

The natural gas industry is now campaigning to save its business by extolling the alleged virtues of converting gas heating to supply by 'blue' hydrogen. This blue hydrogen production would be done using natural gas to produce the hydrogen whilst capturing and storing carbon dioxide produced in the process. But this is a facade that will delay transition to a sustainable clean energy economy and waste renewable energy into the bargain.

Blue hydrogen is not a substitute for energy from renewable energy. Even if the hydrogen was sourced from renewable energy (and not much of it will be) the result would be a grandiose waste of renewable energy. This is because using hydrogen from renewable energy to heat buildings is around four times less energy efficient compared to using heat pumps (using renewable electricity) to supply heating in buildings. 

The gas industry's plan is to start off with blue hydrogen, after which at an unspecified period this would be replaced by green hydrogen generated from renewable energy like wind or solar. There are three big reasons why hydrogen in general is a bad choice for our heating networks. 

First, carbon capture, in the blue hydrogen production process, is unlikely to be close enough to 100 per cent because carbon extraction processes become more and more expensive the higher the proportion of carbon is captured (over 85 per cent). 

In practice, of course, the carbon capture will probably not even be 85% as the gas industry seeks to produce hydrogen at a low commercial costs and tries to absorb the many infrastructural costs of changing the system to hydrogen. These are rather greater than the gas industry is letting on at the moment since hydrogen will need to be distributed differently compared to natural gas at present. 

Second, such a programme will provide support for a continued fossil fuel industry (including unabated methane leakage from extraction activities). The industry will include the possibility (read near-certainty) of production that is not subject to carbon capture and storage. There is then the issue of monitoring and accountability over the extent to which the carbon is stored in a sustainable fashion. These are likely to be lacking.

The reality is that 'blue hydrogen' in the UK will be used to develop new natural gas fields that will only be economic if they carry on supplying large quantities of unabated natural gas to other parts of the world. 

A third reason why 'blue hydrogen' is bad is that using 'blue' hydrogen, in as much as it succeeds in paving the way for supply of renewable hydrogen, will lock in a huge wastage of renewable energy compared to using this renewable energy much more efficiently. 

On the one hand the electrolysis process by which renewable energy is converted to hydrogen is only 80 per cent efficient. That is bad enough since using renewable electricity to supply heating would not involve these losses. However things get a lot lot worse when you realise that the best way of suppling heating in efficiency terms is through electrically powered heat pumps. These use the renewable energy input some 3-4 times more efficiently to produce the same heat compared to heating by 'green' (renewable) hydrogen.  We're going to need a lot of of offshore windfarms and solar farms already, so using renewable hydrogen when you could be using heat pumps supplied by renewable energy is a big, big waste of renewable energy.

We ought to focus on electrifying the heating system, not locking it in to hydrogen. New build properties can be built to maximise energy efficiency and using heat pumps to supply what should be a much-reduced need for heating services. Existing buildings can be heated with district heating supplied by large scale heat pumps, or at worst converted to electricity-only heating, or preferably fitted with heat pumps.

Hydrogen has its purposes, but heating buildings is not a good purpose. So all those green anti-nuclear activists who have for many years been thinking that hydrogen is a good way of using renewable electricity for heating should think again. Far from helping towards a renewable energy economy they may actually be inadvertently promoting demands for nuclear power since they will be increasing the need for non-fossil fuels to supply all the hydrogen needed for the heating sector. Green energy involves energy efficiency as well as green energy supply, and blue and even green hydrogen should be ruled out as a means of heating buildings.


  1. ‘Starting from end-use, we need heat, power and vehicle fuel. Some want this energy be mostly provided by electricity - from solar pv, wind and, some say, nuclear.  Trouble is you can't store electricity easily or for long times.  The rival view is that gas is better - it's easy to store and transmit with lower losses and already delivers 4  times more energy (as heat) than electricity in the UK.  Indeed, unless massively expanded, the power grid could never deliver as much (for heat as well as for EV charging).  
    Yes, we have to get away from fossil gas and ‘blue gas’ is not the way ahead (CCS is a costly dead end, only saving limited amounts of CO2) but green gas (P2G green hydrogen and /or biomethane) can be a flexible option- for balancing, heating and for vehicles, assuming we have a very large renewable capacity, providing excess at times for P2G conversion and then storage. Some of the excess can also be stored as heat for district heating nets.
    Yes, heat pumps can sometimes deliver 3-4 times more energy out than with direct use of power, but not always. And at best that may only just help compensate for the big (maybe 4x) expansion of grid power needed if we want to use heat pumps for heating.  I’m happy to see home heat pumps used in off gas grid areas, and big heat pumps being used with some surplus green power for district heating /heat stores. Some directly domestically delivered heat from renewables is possible (solar heat maybe PVH), but I can’t see us being able to feed enough green power via the power grid to run home heat pumps and also for charging EVs on a wide scale. And I don’t relish an electro-nuclear future fill in, with Small Modular Reactors feeding District Heating networks. While green electrification is fine up to a point, there are limits to the ‘wire’ option: we also need green gas & green heat delivered by pipe’.

  2. I really think you've totally missed the point here and got things precisely the wrong way around. It's the power to gas route that uses much much more electricity than using heat pumps to supply heating. Where do you think we get the hydrogen from? It's geneated from a lot of electricity which, if used to power the heat pumps would produce a lot more heating, for each kWh of primary renewable energy input. All the models say that by the way - (it seems obvious to me anyway) - see work done for the Committee on Climate Change. We can build a few more electricity connections a lot more easily than we can build twice as many windfarms surely! Sorry to say this, but your strategy makes a bigger case for adding more nuclear power stations than anelectricity to heat via heat pumps strategy.

  3. ‘The conversion efficiency of power to gas is now much higher than I think you assume, with PEM cells at 80% or more, whereas I think you have an idealised view of heat pump efficiency. That can fall a lot in winter and they can only be effective if buildings are well insulated. All adding to the very high cost. Even if they do use power more efficiently, meeting all our peak heating needs with them in real time would require a huge expansion of the power grid. By contrast P2G conversion of the input power and gas delivery would allow peak heating to be supplied from gas stores - or from heat stores/District Heating’.

  4. I think we are both right - that's why the government has decided on a compromise hybrid approach