If a tree falls in the wood and it is used to generate energy, is it good for the environment? Forestry is big business, but how sustainable are the use of these resources for providing us with heat? The answer is, it’s complicated, and like everything in the misty world of sustainability there are different ways to tackle this question and different answers as well. So, in this blog we are going to try and debunk the myths and clarify the argument for and against using biomass as an energy source.
SETTING THE SCENE
We use biomass to produce heat, which means burning wood which comes from trees that have been planted for the purpose of harvesting. Commercial forestry plays a significant part in the Scottish economy and has also become synonymous with the Scottish landscape. What we are not doing is chopping down native broadleaf woods in and around the distillery to make whisky. On average we burn 260 x 3m logs a week (about 16 trees) which are chipped and transported 2 miles to the distillery. Trees take in CO2 as they grow, they store carbon (as wood), and expel oxygen. When be burn the wood, this carbon reacts with oxygen in the air and is released from our boiler in the form of CO2 again. In Scotland, thankfully there are laws which means that replanting of trees is required after felling an area of land – this means we replant all the trees which are felled for our energy.
THE BENEFITS OF BIOMASS
Currently under government and European guidelines, the CO2 that’s released when you use wood as biomass is classified as carbon neutral, because trees absorb CO2 when they grow, and that ‘emission’ is accounted for when the tree is felled (not when the tree is burned). It’s important for the forestry sector to account for these emissions at source, so that it can keep a balance between trees that are growing and being harvested. So, when the Drimnin estate (where we source our trees from) replant and grow the trees that are felled, this virtuous biogenic cycle is maintained, reusing the power of atmospheric carbon over and over.
THE PROBLEMS WITH THIS
Firstly, there are other greenhouse gases that are released when we run the tractor to chip the wood, and then others when we burn the chip too – some of these don’t get re-absorbed through the biogenic cycle. This means that using biomass always creates some added emissions.
Secondly, we have an increasingly narrow window to stop adding to atmospheric CO2 concentrations – Scotland is aiming to hit net zero carbon emissions in 35 years, whereas IPCC (Intergovernmental Panel on Climate Change) have highlighted the coming decade as the timeframe for meaningful action to reduce our emissions. It will take a tree 10 years to start making a dent on absorbing CO2 and then the amount that it can absorb every year increases significantly – until it is mature and then it’s felled. Being able to maintain this planting/harvesting cycle in a timely fashion is very important when thinking about carbon balances.
Thirdly, in certain types of biomass there’s additional processing and transport emissions associated with biomass which could be huge. We are lucky to have access to local timber to provide us with our biomass energy, but there is increasing criticism around the use biomass for energy production, which is in part being driven by the fact that the process is classified as ‘carbon neutral’ and there are calls for its renewable energy status to be removed on the grounds that it is not sustainable. As we have mentioned sustainability is all about context, and in the case of some power generation, the odds do not stack up. There are examples of biomass power stations the UK, and in North America, where this sustainability area becomes very grey because they are powered using wood pellets.
To make pellets, you must haul the wood chips to a processing plant, where the wood is dried, turned into dust and then reformed into pellets, all of which requires fuel, and then it needs to be shipped to its final destination, which could be a transatlantic journey!
What this does is increase the amount of carbon released into the atmosphere for every unit of energy you get out of the wood. This study conducted in 2009 suggests that the creation and hauling of wood pellets from North America results in a carbon footprint that is 3 x higher than UK sourced wood chips. This means to reabsorb the carbon that has been released you would need to plant 3 times more trees than you are using.
There is an argument that says that a strong biomass sector which is replacing fossil fuels will drive wide spread foresting projects because the price of timber will go up ‘the forest that pays is the forest that stays’ (as the forest consultant once told me) – but it could also mean that in countries where there is little regulation or where extraction is happening illegally, people use the high price of timber to capitalise on tree felling, and are not under any obligation to replant.
SO WHERE DOES THAT LEAVE US?
Ultimately the planet doesn’t care whether the carbon that we released today has come from a tree or not, the point is that we have too much carbon in the atmosphere and to reduce that we need to make sure that we are sequestering more carbon than we are releasing, every year.
So, for biomass to wipe its carbon face every year there needs to be more trees planted and maturing than are being burned. We can’t be responsible for how all forests are manged, but we are lucky that on the Drimnin estate we can demonstrate that balance within the context of a full cycle of the tree.
What really will be the game changer here, is how soon technology for Biogenic Emission carbon capture and Storage (BECCS) is developed and rolled out across the industry for biomass power. This effectively would capture all the CO2, from our boiler, liquify that gas, and make it possible for it to be stored permanently, either in the earth’s bedrock, or cement, or in the ocean, so that every tree that is grown for biomass is instantly a carbon credit which makes meeting the urgent carbon goals A LOT easier.