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The Eco-Worrier on Keeping Warm

(Photo: Air Source Heat Pump)

The complex challenge of keeping ourselves warm while minimising both our consumption of resources and our production of pollution was brought home to me recently when a friend who lives in a fairly remote spot told me that he had decided to ‘go green’ and get rid of his oil-fired boiler and Rayburn cooker and switch entirely to electricity from his renewables-only provider.

The next time we met he had hit an unexpected problem; the company he had contacted with a view to removing the old plumbing and installing electric radiators, a new electric hob and cooker and an immersion-heater for hot water had calculated that if he had everything switched on at once it would exceed the capacity of the power-supply to his house. A very expensive upgrade was going to be required if he wanted to proceed. Perhaps it was time for a rethink.

There is certainly a great deal of urgency in decarbonising domestic heating, which is our largest single source of CO2 emissions. At present 85% of such heat comes from natural gas, 6% from oil, 3% from electric storage heating and 2% from the direct electric heating that had tempted my friend. It is difficult to calculate precisely the amount of heat contributed by wood-burning stoves and biomass boilers but on a UK-wide scale it appears to be relatively small.

In July 2020 both the Confederation of British Industry (CBI) and the Committee on Climate Change (CCC) advised the UK government to take some dramatic action, namely to ban the sale of new oil-fired boilers by 2023 and those burning gas by 2025. The CBI saw the switch to new forms of heating providing 150,000 new jobs and a means of reviving the battered economy as it recovers from Covid-19. There will no doubt be a great deal of pressure on the UK government to enact such eye-catching measures as it prepares to host the global climate conference in Glasgow next year. I cannot help feeling that the annual winter-fuel payment currently given to all pensioners - rich and poor alike - may well be sacrificed to support the necessary investments.

There are other sources of heat which, in view of their reliance on burning fossil fuels, are going to rapidly disappear. The solid fuel stove and boiler and the moveable bottled gas and kerosene heater will surely follow the coal fire of the 19th and early 20th century into history within a decade.

There are flammable alternatives to fossil fuels. Biomass is the oldest but it has received some bad publicity. The huge power station at Drax in Yorkshire has gradually been converting from coal to biomass but questions have been raised as to how ‘green’ some sources of its fuel actually are; for example there are stories of woodchip from Siberia coming by train to Rotterdam, being shipped to Teesport, then carted by rail or down the A1 to Drax. Similar tales surround domestic wood-pellet boilers, whose fuel can travel from as far afield as Louisiana and West Africa.

Wood-stoves have been criticised because they emit CO2 and particulates but in rural areas - and if logs come from local woodlands where new trees replace old - the emissions are no different, albeit rather faster, than if the trees had been left to die and rot as part of the natural carbon cycle.

One possible fuel of the future is hydrogen. When burned, either in a boiler or an internal combustion engine, the only emission is water-vapour. The problem is that the hydrogen has to be manufactured, but clearly not from the traditional source of fossil fuels. The great hope here, as it is in the entire energy sector, is for a massive surplus of renewable energy from wind, solar, hydro or geothermal sources which will be used in off-peak hours to manufacture hydrogen from water through the process of electrolysis. $hundreds of billions are being invested in the hydrogen economy with the aim of powering everything from heavy trucks, tractors, industry, ships - and even aircraft - as well as fuelling domestic boilers. The massive challenges involved are not limited to producing all that ‘surplus’ renewable energy; hydrogen is a highly volatile and flammable gas which can find the smallest leak and it is also very corrosive, requiring the replacement of the entire gas distribution network with new materials if it is to replace natural gas.

The remaining possible heat-sources are all based directly on electricity. In its simplest form is the basic ‘element’, which heats up as the electricity is passed through. The resulting warmth is transmitted to the surrounding room through the simple 1/2/3 bar reflector, a convector, radiator or by a fan-heater blowing air over the hot element. The problems with heat from electricity, which was originally derived by burning fossil fuel in a power station or generator, are its inefficiency and resulting cost. Instead of converting coal, oil or gas into electricity - the most refined and adaptable form of energy - transmitting it through the national grid with unavoidable losses and then turning it back to heat is far less efficient and costlier than burning the fuel where the heat is needed.

Electric storage heaters became extremely popular fifty years ago and were seen as a good way to make use of the surplus electricity from nuclear power stations, which at the time were seen as the future of electricity generation. Unlike gas, for example, nuclear power is difficult to regulate to match demand so selling the overnight surplus at a very low ‘white meter’ price for night-storage heaters was an attractive option. It works well for offices, other workplaces and for the elderly and housebound, but the disadvantage for most families is that although breakfast-time is very cosy, by the time they get home from work and from school the heat has largely dissipated and some other form of heat is needed for chilly evenings.

Since the disasters at Three Mile Island, Chernobyl and Fukushima have scared the world away from nuclear power, interest in their associated heat-storage systems has also waned. However, all is not necessarily lost for storing ‘off-peak’ heat. With recent advances in insulation materials and storage media such as liquid/solid salts, such systems, alongside batteries like the Tesla ‘Powerwall’ and those of parked electric cars, could be important methods of storing and utilising excess peak-power from renewable energy sources.

A much more efficient means of utilising electricity is the heat pump. This does not generate heat by burning anything but extracts the ambient heat contained a metre or so under the ground through a network of buried pipes - hence ‘ground source’, or alternatively absorbs the heat from the outside air by a fan blowing it through a heat exchanger or ‘air source’. The process works in the opposite way to a car radiator or the grid on the back of a fridge. They of course are both intended to disperse excess heat - from the engine and from the cooled food respectively - rather than the heat-pump’s purpose of gathering natural heat from air at any temperature above freezing. The great benefit of this technology is that instead of energy-sapping heat-generation, it simply drives two small motors, one blowing the air or pumping the water which is absorbing the ambient heat and the other powering the compressor, again like that in your fridge, to circulate the refrigerant. As a result this technology typically produces four units of heat for each unit of electricity that it consumes. The main ‘downsides’ are the initial cost, for which the government offers subsidies, and the fact that a heat pump typically heats the water to just 50C which, while an adequate temperature for bath-water and underfloor heating, usually requires larger radiators than with the higher water temperature provided by a conventional boiler. The friend I mentioned earlier is currently looking at heat pumps.

Of course much the ‘greenest’ way to stay cosy is to wrap up well, both indoors and out and not to heat rooms when you aren’t using them. Bedrooms, for example, have been shown to provide much more natural sleep when cool than when they are hot. Instead of wasting energy on heating the room, invest in a warm duvet and look on the dark Covid-Winter nights stretching ahead as opportunities for a good, long, low-energy and rejuvenating natural sleep.

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