Hydrogen's not for Heating
Dave Toke's green energy blog - Sunday, 22 March 2020
A facade to delay transition to a clean energy economy
The natural gas industry is now campaigning to save its business by extolling the alleged virtues of converting gas to supply heating by 'blue' hydrogen. This blue hydrogen production would be done using natural gas to produce the hydrogen whilst capturing and storing the 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.
Using hydrogen to heat buildings is four times less efficient than using heat pumps
Blue hydrogen is not a substitute for energy from renewable energy. Even if the hydrogen were 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 than using heat pumps (using renewable electricity) to supply heating in buildings.
First, carbon capture, in the blue hydrogen production process, is unlikely to be close enough to 100% because carbon extraction processes become more and more expensive the higher the proportion of carbon is captured (over 85%).
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 waste 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% efficient. That is bad enough since using renewable electricity to supply heating would not involve these losses.
However, things get a 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 transfer the same heat compared to burning 'green' (renewable) hydrogen. We're going to need a lot of offshore windfarms and solar farms already, so burning renewable hydrogen when you could be using heat pumps supplied by renewable energy is a big, big waste of renewable energy.
Focus on electrifying heating
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 should be ruled out as a means of heating buildings
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 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.