An energising breakthrough that could help lower carbon dioxide emissions

This is not a miracle solution, but it could make a big contribution

The history of renewable energy is strewn with miraculous technologies that seemed to promise limitless, cheap, low-carbon power, but which turned out to be limited, expensive and to have unforeseen drawbacks.

We have been through nuclear power, which is expensive with long-term safety problems; windmills, which are more expensive and intrude on the land or sea-scape; and solar power, which is more expensive still. We have been promised tidal power, but the Severn Barrage needed huge capital spending and would have had a dramatic effect on local habitats. Wave power has not worked at reasonable cost.

Other technologies might work in theory but have yet to be demonstrated in practice. Cold fusion is a kind of nuclear power that has not yet been invented. Carbon capture and storage, to decarbonise the burning of coal, oil and gas, has not yet been proven on a commercial scale. Geothermal energy, drawing heat from deep underground, turns out to be a daunting engineering challenge in places other than Iceland, where hot water rises to the surface naturally.

So some scepticism is required about the heat pump system about which, as we report today, Ed Davey, the Energy and Climate Change Secretary, is so excited. It seems too good to be true that this technology can take the latent heat from Thames river water and concentrate it to produce domestic hot water at 45C for 140 homes. But this time, the “futurephoria”, even if it should be prudently restrained, does seem justified.

This is not a miracle solution to the problem of climate change, but it is an important breakthrough that could make a big contribution to lower carbon dioxide emissions. The technology requires a small amount of electricity for the pumps, but even if that electricity comes from fossil-fuel sources the overall carbon output of the system is significantly lower than gas water heating, for taps and central heating, and the cost is 20 per cent lower.

This technology may lack space-age glamour. As with better insulation and combined heat and power schemes, it is small scale, local and decentralised. It is not exactly low-tech: the physics involved is sophisticated. But it is simple and contains few moving parts. Best of all, in the jargon of the day, it is scaleable: it could be extended to millions of homes across the country – anywhere near rivers, lakes or reservoirs. Presumably there is a limit to the amount of latent energy that can be extracted from such sources. It is unlikely, for example, that it could be used to generate electricity, but it could substitute for a large proportion of gas water heating nationally.

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