With some of the claims made about biomass power, you could be forgiven for thinking that we chop down entire forests and shovel everything into the furnace.
In fact, that perception is so rife that our most retweeted tweet on the @Biomass_UK_REA Twitter account is this graphic, which tried to put the record straight:
As the graphic explains, only a very small portion of a forest is harvested - roughly 2-4% of the standing stock. Here are the figures from 2000 to 2014 for the US Southern region (the biggest single region supplying UK biomass). It's taken from this study by forestry experts Forest2Market. What it clearly shows is that harvesting (in blue) has ranged from 2.9% to 3.7%, whilst the overall standing stock grew by roughly 10billion cubic feet over that time:
Most of that wood goes towards construction and furniture uses, which lock carbon away from the atmosphere in the form of buildings and chairs and tables.
Low-grade materials left over can go to a number of uses such as pulp and paper and also bioenergy.
But how much of it becomes bioenergy pellets for use in UK power stations? Here's another graph showing just removals (i.e. how much woody material was harvested each year) in 2000-2017. It shows that wood pellets accounted for just 2.7% of wood removals in the US Southern region:
So, if just 2-4% of the forest is harvested, and just 2.7% of that harvest ends up as pellets, how much of the forest in total is used for pellets? The figure, according to forestry experts Forest2Market is 0.09% (see p.19 of the report). You read that right: 0.09%, or less than a tenth of one percent. Net growth in the same forests each year is about seven times that amount.
The key to understanding this is appreciating the vast scale of the forests involved. The working forests of the Southern USA cover an area three times the entire landmass of the UK. Not only that, they also source from Canada and the EU to lower their impact on any one area.
When you appreciate the huge scale of forests out there (and remember, these forests are actually growing bigger/denser), 0.09% can add up. According to the UK's Committee on Climate Change, it could add up to 15% of the UK's primary energy supply whilst remaining a sustainable renewable source long into the future.