Only very clean and very low carbon renewable energy technologies should be subsidised in homes which are on the UK gas grid, under the Renewable Heat Incentive.

1/ In most UK homes, the carbon saving from heat pumps is only 9% (vs solar thermal at 10-20%.) Heat pumps may be no better than condensing gas boilers. Why should they be subsidised at all? To appease industry lobbyists?

The Energy Saving Trust heat pump study reports that average heat pumps have only a 9% carbon benefit over an average gas boiler in terms of operation.

Only 9%! See page 19 which says “a heat pump installed in 2010 produces 9% less carbon dioxide than an average gas boiler” This difference is barely significant and puts heat pumps in the same environmental performance category as gas boilers, and probably on a par with condensing gas boilers. (I am surprised that the EST report does not state this fact.)

On top of this the heavier and raw-material-intensive heat pumps will contain more embodied energy and carbon (locked up in their components and manufacture process) so that they may actually end up performing worse than condensing boilers, based on a more balanced, total life cycle assessment.

It seems that, environmentally, upgrading to a better than average gas boiler would be as good as fitting a heat pump. Clearly on-gas-grid locations are not suitable for heat pump subsidy.

A solar thermal system typically displaces 10-20% of the fuel which a gas boiler burns, which in turn displaces a similar amount of carbon. (Why is this, about of 30% of a home’s use of gas for heating is for heating water, and of this between one third and two thirds can be displaced by solar). So it might make sense if government were to promote solar thermal far more than it currently plans to do so under the RHI. Paying more total subsidy for a heat pump which saves a lower percentage of carbon than a solar water heating system can do makes no sense at all.

The EST report adds that heat pumps save on average 28% carbon compared an average oil boiler and that the potential for carbon savings will increase in future under the UK Government’s plan to decarbonise the electricity grid. So one can probably conclude:

1/ today heat pumps may merit state subsidy where high carbon fuels such as oil, coal and electricity are being displaced
2/ solar thermal may merit a higher total annual subsidy than heat pumps and that it can roll out in all homes, whether on the gas grid or off it.

2/ The wood fuels / urban air quality issue. This is a no-brainer (hopefully not a wheeze).

3000 people die each year because of air pollution. Most of this air pollution happens in urban situations.

London’s air quality problem is so bad that it may even hit the Olympics. It seems that our complaints about the Beijing Olympics are coming home to roost. It would be madness for Government promote, via subsidy, more wood burning in cities, all of which are on the gas grid. The consequences would be lethal.

Much better to burn wood in thinly populated areas which are also closer to where it is produced – and where dilution can be at least part of a “solution” to its air pollution.

I do hope this is useful. There is a risk that some self-serving parts of the renewables industry will sink further into the PR trap of putting highly questionable industry interests ahead those of the taxpayer, the consumer the environment (and indeed of plain old evidence). Last year we witnessed   the REAL Code serving the industry rather than the consumer by failing to look closely and promptly at our notifications of false performance claims in the renewable energy industry. Please, not again!