Using waste wood from the logging industry for energy generation – is it a good idea?

The idea of using energy from wood waste is being pushed on the EECA’s Business website (EECA stands for Energy Efficiency and Conservation Authority – they’re a government organisation).

The claim is that using waste wood from the logging industry is a cheap way to get energy and has low emissions (because any CO₂ released by burning wood is recaptured when the next crop of trees grow).

There’s an interesting video here on a school using waste wood: www.eecabusiness.govt.nz/node/18653

And the EECA 'wood energy knowledge centre' is here: www.eecabusiness.govt.nz/renewable-energy/wood-energy-knowledge-centre/types-of-wood-energy/wood-residue

Any thoughts on this? Is it a good idea?

The claim of low emissions does sound a bit like accountancy ‘magic’ (“oh sure, we burn it and release CO₂ but we’ll capture it later – therefore it counts as ‘low’ emissions”). But then does this kind of wood waste just rot on the forest floor and release CO₂ anyway?

Some key facts

• Most of New Zealand’s wood residue comes from our 1.7 million hectares of pine plantations.
• On log landings (skid sites) in forests, tree-length material is cut into logs. Off-cuts from the base, tip and mid-sections of trees become waste material (averaging 4-6% of the wood volume) and branch material is also leftover.
• When large trees are felled in the forest, they frequently break when they hit the ground. This breakage typically occurs at around two-thirds to three-quarters of the tree height. Often these broken sections are small and of low value so they are not moved to log landings and are instead left to rot away. However, this leftover tree material has the potential to be used as fuel.
• When logs are processed into lumber in sawmills, wood residue is left over in the form of planer shavings, sawdust and ‘slabwood’. This residue can also be used as fuel.