Moving forward with new heat technologies

He also discusses the importance of a UK nationwide programme of significant energy efficiency improvements to housing stock; without which technologies such as domestic heat pumps will underperform.

Key considerations

Dr Robert Sansom, independent consultant and member of the IET’s Energy Policy Panel.

Ruling hydrogen out would be unwise

Frequently, the focus seems to be on two hydrogen production methods, i.e. natural gas reforming or electrolysis.

There are other choices for hydrogen production. For example, from biomass gasification. 

This is important because, to achieve net-zero, the UK must have a strategy for greenhouse gas removals.

Possibly, in future, we might be able to decarbonise without the need for removals but that is not the case at present.

The key technology here is biomass with carbon capture and storage (or BECCS).

The Climate Change Committee’s (CCC’s) sixth carbon budget report has 250TWh of energy bioenergy and waste by 2050 in its Balanced Net Zero Pathway, most of which is indigenous. In addition, there is scope for imported hydrogen, produced using solar PV.

These options warrant further investigation before a decision can be made. Ruling them out at this stage would be unwise. 

The cost of wind power has dropped considerably and there is optimism that the cost and efficiency of electrolysers will also improve in the near future, to be on par with, or possibly better than, gas reforming for hydrogen production.

There are additional challenges with importing hydrogen, such as losses, but again worth testing further.

Significant obstacles to adopting heat pumps

The argument for air source heat pumps can be very persuasive, the conversion efficiency is much higher than from hydrogen. 

However, the main obstacles come from the changes required to the UK’s housing stock, electricity network upgrades and the provision of hot water. 

Without significant energy efficiency improvements to most of the UK’s housing stock, domestic heat pumps will underperform. 

Heat pumps will also increase electricity demand significantly, which is likely to require the street circuit network to be upgraded. 

A typical heat pump is likely to be between 5kWth to 10kWth and incapable of supplying hot water on demand, so some form of hot water storage will be required.

Retrofitting hot water storage will be expensive and unlikely to be welcomed by householders if it involves loss of storage space. 

In addition, the amount of hot water storage required will need to take account of the longer water heating times, particularly if the pump is also used for heating – potentially necessitating more storage. 

Alternatives for heating water directly such as immersion heaters and electric showers operate at much lower efficiency and higher cost.

Next steps

We still don’t know enough about these alternative heating technologies, so we should certainly not rule any of them out at this stage. 

Our focus should be to find out more about how they can work, particularly in terms of cost, performance, implementation logistics, and consumer needs. This can only be done by trialling them at scale.

This is not an excuse for procrastination. We should get going on a nationwide programme of housing insulation improvements.

We can start this immediately with a targeted housing insulation improvement of 30 per cent, roughly equivalent to increasing the average rating to EPC C across the UK. 

For heat pumps, this is essential, particularly for older buildings, but it is also necessary for hydrogen, as it will reduce the volume required if it is adopted for heating.

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