Low Carbon Heat: Heat Pumps in London

September 2018

The Greater London Authority has commissioned a study into the implications of a widespread uptake of heat pumps in London's new developments, driven by the decarbonisation of the electricity grid.

Carbon content UK Grid electricity

You may not have time to read the full report published in September 2018 "Low Carbon Heat: Heat Pumps in London" which runs to 142 pages.

The principal conclusions are summarised here:

Air quality is also a key driver

A significant benefit of heat pumps over conventional boilers and gas-fired CHP is that there is no combustion involved (combustion of gas emits oxides of nitrogen). Beside the direct advantages (safety), technical advantages (e.g. no need for flues) this is very beneficial for cities like London with poor levels of air quality.

Alternative forms of low carbon heating

The Study also considers alternative forms of low carbon heating including direct electric heating, which has a significantly higher running cost; and the burning of hydrogen which emits no CO2 at the point of combustion.

However, upgrading the gas grid to contain very small hydrogen molecules would incur a huge national cost and upgrading all the boilers to burn hydrogen would also be a significant task. Production of hydrogen by steam methane reformation, which uses high levels of heat to crack methane into carbon and hydrogen, emits large volumes of CO2. This would require the development of economic Carbon Capture and Storage to achieve carbon neutrality.

Hydrogen can also be derived from electrolysis powered by renewable electricity, although the overall efficiency would be less than 70% before accounting for distribution losses, compared to an efficiency of well over 350% for a typical ground source heat pump.

It is clear from the Study that the only practical route to heating without CO2 emissions is to avoid combustion. The alternative is to use heat transfer: which means using heat pumps. There is no need to search for esoteric alternatives when tried-and-tested heat pumps are available now.


The full report published in September 2018 "Low Carbon Heat: Heat Pumps in London" runs to 142 pages.


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