Uncovering the mystery of the wood chip

Gina Castell investigates mysterious disappearances, talking to Ian Shield about research uncovering the mystery of the wood chip

‘Streamlining the Supply Chain’ project is focused on how a crop grows and how you maximise that crop. The energy crops are grown from scratch, but the project also deals with material straight out the forest. However, things got a bit complicated when a certain discovery was made.
It was discovered that a lot of crop yield suddenly disappeared through the rest of the supply chain. A supply chain maps out each stage, step-by-step, in getting a biomass material. A supply chain is how you harvest, store, prepare and deliver the material. Whilst streamlining looks at the losses at each of those stages.
If we know what the losses are, by measuring them, we can try to minimise them. We need to educate people, to spread knowledge saying ‘don’t do this! Be careful! You’re spoiling the life-cycle!’ Spoiling here refers to higher energy costs and harmful greenhouse gas emissions.
Material taken from the forest is low value but decent quality. They’re the ones that didn’t make it into the mainstream, the left overs like branches, brash and round wood. Some mixed woodland too, like conifers and broadleaf.
The biggest losses happen in storage. Wood material for energy is never going to be fresh, like fresh vegetables plucked out of the field. Because the wood is low value, people don’t put as much care into storing them. A lot of the wood is chipped, so these huge heaps of wood chips are left outdoors to dry out. They are dried-out by microorganisms in nature, carrying out microbial activity. Because of this drying, the wood chip loses weight and energy. Energy is lost as carbon dioxide and, the far more dangerous, methane.
Around 20% of the weight is lost. 20% sounds horrendous. However, although it’s not ideal, the practice is still sustainable. The main message is to not deliberately squash the wood chip heaps, as more methane could be released, the more powerful greenhouse gas. Instead, load it with a long reach (those dinosaur looking cranes) so the only squashing is from its own weight. Although work has been done across North America and Northern Europe, things could be quite different in tropical wet conditions, with potentially higher losses.
So remember, using chips is ok.
Just don’t deliberately squash them. It’s a climate killer.
Words by Gina Castellheim

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