The early 21st Century has seen the sort of time-warp that Dr Who himself would be proud of, as more and more homes have gone back to burning wood – hundreds of years after it was largely abandoned, firstly in favour of coal and then subsequently, oil, gas and electricity.
The lure of this natural, renewable and carbon neutral fuel is easy to understand, but like every other form of energy we harness to help us live our lives, it has an effect on the environment – though in some ways that you might not expect.
One area that has produced some concern is the particulate emissions coming from wood burning stoves. Obviously in built up areas this might conceivably become a problem, but even so, a typical wood burner emits only around 30 per cent of a conventional open fire – so they’re unlikely to cause much of a problem under normal circumstances, despite their growing popularity.
Although some places have been designated “smoke control areas” by the local authority under the provisions of the Clean Air Act (1993), a number of manufacturers have designed wood burning stoves which are classified as “exempt” for use here too.
Making sure that you only burn fully dried logs – or commercially available pellet or chip fuels – should help avoid creating too much in the way of smoke or particles. Even if you don’t live in a smoke control area, it’s probably a good way to help reduce the chance of friction with your neighbours!
Wood has a fairly low energy density – that’s the measure of how much you need to burn to gain a given amount of heat. Tonne-for-tonne, it has about a third the energy density of natural gas, 40 per cent that of oil and 60 per cent of coal. Clearly, on this basis, the transport element of wood’s environmental impact looks quite high; it may be a carbon neutral fuel itself – but think of all that diesel needed to get it to your door. Ordering half the number of sacks of coal would provide the same warmth, and cut the transport emissions considerably.
However, wood burning households tend either to be in rural areas, near to where the raw material is grown or close to commercial suppliers – both of which tend to reduce the distances involved. Since transport costs are a major part of the wood fuel economics, in many ways this is a self governing factor; after all, who would opt for wood, if the price of delivery is too high?
Efficiency has a big influence on the environmental impact of using any kind of energy – and wood is no exception. The good news here is that the latest generation of wood burning stoves offer unprecedented levels of efficiency compared with the alternatives. Today’s stoves can routinely achieve 80%or more, while conventional open fires offer 25% at best – dropping to around 5% at worst.
Habitat and Biodiversity
One very positive aspect of the upsurge in wood burning has been its effect on biodiversity and habitat. With a growing commercial value in forestry products, managing woods has itself received a welcome shot in the arm at a time when, in many parts of the country, natural woodland habitats and the species that depend on them have been suffering from years of gradual decline.
Wood is, clearly, one of the most sustainable of all fuels; growing trees in Britain is scarcely hard. In choosing and using it to heat our homes we pick as near perfectly carbon neutral a source of energy as it’s possible to find, while at the same time helping to ensure the long-term future of forests and the animals and plants that thrive in them. As impacts go, that surely has to be a pretty good outcome!
Everything we do has environmental implications, and that is as true of wood burning as it is for anything else. Utilising any energy source – however essentially renewable it may be – inevitably has some kind of an impact, even if the overall environmental cost/benefit balance ultimately ends up being a positive one.
All in all, given its growing popularity, although wood burning might seem a decidedly backward-step, it looks like its time has come!