Does burning wood for home heating cause GHG emissions? If so, what is the impact? [Alan Journet]
Since wood is biomass, and thus a carbon-based resource, burning it does, indeed, release greenhouse gases – notably carbon dioxide. However, there are extenuating circumstances. The basic question is how does burning wood compare to other source of home heating?
The most efficient way to generate heat is to minimize the number of energy transformations that occur on the way to the end-use. This is because, as the second law of thermodynamics dictates, each energy transformation results in some loss of energy (as heat). Burning wood has the advantage that this is direct and has the minimum of such transformations. Once catch will be the emissions resulting from its harvest, processing, and transport to your fireplace. Electrical heating seems clean, but this will depend on the source of the electricity. Generating electricity results in several transformations: energy resource à turbine –à transmission à domestic heater. If the source of the electricity is solar panels or wind, this may be minimized, but if the source is coal, oil, or natural gas, emissions will be considerable. Natural (fracked) gas heating looks good superficially as this is a direct fuel à heat conversion. The problem is in the fracking and transmission of the natural gas to us. Here substantial fugitive emissions of methane make the natural gas potentially worse that electricity from a coal-fired power plants.
However, in addition to the GHG emissions, we have to consider other emissions from burning wood, namely the particulates (soot) and other potentially toxic volatile organic compounds. Thus, burning wood in a fireplace in an air quality maintenance area could impose other (human health) problems.
Bottom line: it’s probably difficult to calculate and has to be a judgment call that each of us with the potential to burn wood have to make.
Other considerations: An open fire place (the old conventional kind) is probably not a good idea since this turns out to be a net loser of heat from the home (it goes up the chimney) whereas one of the new wood stoves (Vermont Castings, for example) can be a positive. It’s also worth considering how air-tight is the home. If it’s really air-tight, the heat will be retained and wood burning minimized. But if the home leaks like a sieve, much excess wood will have to be burned to compensate. So, an energy audit might be worthwhile as a first step to address leakage before resorting to the wood stove.
Another aspect of wood burning is the question of scale. If we are just using dead / downed firewood, we are not compromising the ability of the tree to continue sequestering carbon. But if our firewood comes from harvested living trees, besides burning and releasing the carbon dioxide, we have also interrupted that tree’s ongoing sequestration potential. And we’d want to be careful that our using firewood isn’t stimulating a forest harvest industry – further reducing ongoing carbon storage.
Also, recall: there’s no such thing as a benign energy source. What we have to be doing is constantly evaluating our energy sources for their GHG emissions and other environmental impacts.