We live on a finite planet, resources are limited, most stuff is running out etc. The good news is that there are resources that rely on the sun in one way or another, that are getting constantly renewed, i.e. renewables. These are solar, wind, hydro and biomass (or woodfuel). But biomass is not quite a 'renewable' as we've assumed even without the issue of using arable land to feed power stations instead of people.
As we all know the two 'big' renewables, wind and sun, have some intermittency issues for which woodfuel would appear to offer a solution, insomuch as it can be called upon on demand. The largest coal burning power station in the UK, Drax, is the largest biomass burning facility, and there are many thousands of biomass heating systems in schools, swimming pools, offices and homes. The UK is now importing over 5 million tonnes of 'eco fuel' a year (1) (mainly from the US) and is the largest importer of wood pellets in the world. (2) This is a very environmentally damaging way of reducing our CO2 emissions, is at the tax payer’s expense, and will probably increase as zero emission electric cars continue to gain popularity and the requirement to charge them at night will increase the need for 'on-demand' base load generation.
So, might growing the UK based supply chain of woodfuel offer a solution to this problem? UK tree cover is low by European standards; (3) much of the planting since the First World War has been of commercial conifers, mostly planted on land that is good for little else except extensive sheep farming. An energy crop on our doorstep, not competing for food production, what’s not to like? Oh and things get better because the rate of conifer planting increased (thanks to it tax advantages) in the 60's and 70's, and there are now millions of trees that are now ready for harvest.
So far so good. But if we dig a little deeper things get more complicated. As I've mentioned these trees were planted on poor land and poor land in the UK means wet. So species that were planted were chosen because they do well in wet conditions, a little too well. With plenty of water, mild winters and little management (there were no tax breaks for that) UK plantations don't produce a high percentage of high quality sawlogs - the timber is not dense enough, there are too many irregular sized logs and few commercially 'in demand' species. This all means that UK grown timber commands poor prices on international sawlog markets.
You could argue that leaves all the more for burning, so still, so far so good. Yet building an industry on a continued supply of wood that is good for nothing other than burning will soon cause real problems for the UK fuelwood supply chain. About 20 years ago, when the first of the post war UK plantings were harvested, the industry realised that the market for low quality softwood wasn't strong. This, combined with reductions in the tax breaks given for tree planting, meant that (re)planting rates dropped significantly throughout the 1980's. With 30-40 year harvesting cycles the supply of UK grown timber will start to shrink from about 2020. The good news is that planting rates have picked up this century. So maybe with staggered harvesting some sensible imports and dare I say some very careful use of non-conventional fossil fuel sources this 10 or 15 year supply gap can be bridged? Well no. As a result of the quality issues faced by the industry real efforts were made to increase the yields of valuable sawlogs produced by UK forestry. This is very much a good thing, leading to increases in the percentage of land planted with high environmental value native broadleaves (being paid for in part by the higher returns on the conifers). Also the practise of planting on blanket bogs with the associated methane releases has been stopped. Policy has moved away from “never mind the quality look at the hectares”.
Of course the downside of this improvement in saw log yield is that although the tonnage of UK produced timber might recover, the quantities of cheap low grade wood suitable for burning won't. Meaning that to even maintain the current levels of woodfuel use we'll need to import evermore woodfuel which apart from making no environmental sense, will, as global demand continues to rise, be expensive. So, while we continue to replace fossil fuel boilers with woodfuel ones the question has to be asked which will become too expensive to burn first, wood or oil? Or will subsidies mean the UK will start to chip quality sawlogs for use as woodfuel, a result that will make little environmental or economic sense.