Dec 24, 2021
Hydrogen: the Silver Bullet or Smoking Gun to the Decarbonisation of Heating Our Homes?
One of the biggest challenges we face in a zero carbon transition is moving away from the fossil fuels that most homes still rely on for heating.
One of the biggest challenges we face in a zero carbon transition is moving away from the fossil fuels that most homes still rely on for heating.
Understanding the colours of Hydrogen
There’s currently a fair amount of promotion of ‘hydrogen-ready’ boilers, which seems to be led by the fossil fuel industry. At the moment only ‘grey hydrogen’ is being produced, from the steam reformation of natural gas. So it’s still a fossil fuel and leads to higher carbon emissions than gas.
The main industry proposal is for ‘blue hydrogen’, made by the same process but adding in a not yet invented way of capturing and storing the emitted carbon. There are questions about how this will be achieved.
Green hydrogen is the only variety produced in a climate-neutral manner.
‘Green hydrogen’ is made from the electrolysis of water using electricity from renewable sources. In a Zero Carbon Britain model, excess electricity would be allocated to make green hydrogen and other synthetic fuels. These are important for certain purposes — such as manufacturing, larger vehicles and planes, and running ‘peaker plants’ at times of high grid demand.
In an effort to understand and convey the areas in which Hydrogen can be of value, Michael Liebreich (Chairman and CEO of Liebreich Associates and host of The Cleaning Up podcast) has created, iterated and shared his take on a Hydrogen Ladder — a merit order for the various cases of clean hydrogen.
As a firm advocate of decarbonising our planet as quickly and cost-effectively as possible, Michael is strongly against using clean hydrogen in certain sectors where there are cheaper and more efficient electric solutions, such as cars and domestic heating.
Using hydrogen to heat homes raises questions, given how valuable it is for those other uses and the difficulty of making it. A heat pump can use 1 unit of electricity to give 3 or 4 units of heat. Whereas via hydrogen, 1 unit of electricity might give only 0.6 units of heat (if hydrogen generation is 70% efficient and the boiler 90% efficient).
Overall, the heat pump would then be 5 or 6 times as efficient as hydrogen at delivering heat from renewable electricity. In theory it could all be zero carbon, but if hydrogen is more than an occasional top up option it will demand far more electricity generation (and so several times as many wind and solar farms).
The diagram below (taken from the highly informative paper on hydrogen published by LETI) contrasts the limited efficiency of converting natural gas to hydrogen (futuristic ‘Blue Hydrogen’) and distributing it through the gas grid (at 58%), with using green electricity to heat homes via air source heat pumps (at 270%)
Our priority must be on reducing energy demand/ increasing energy efficiency whilst ‘turning off the taps’ on our carbon emissions through the use of fossil fuels.
The current proposals for hydrogen heating our homes do have a silvery look. We know that heat pumps will work and will reduce carbon emissions, but a ‘hydrogen-ready’ boiler might never actually reduce carbon emissions.
