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Wood Power

Creating energy from wood is not new but a Massey University PhD student is investigating methods of extracting twice the electricity from the same amount of wood.

Petrol shortages during the First and Second World Wars forced New Zealanders to look at other fuels. Dual-fuel vehicles capable of running on both petrol and generator-gas were developed, with gas being produced on board from solid fuels such as wood, charcoal and coke. The concept was abandoned when petrol became available again.

Massey student Ric Sime is taking the process further by producing gas from wood at high pressure to fuel turbines, which in turn create electricity.

New Zealand is party to an international agreement to reduce net carbon dioxide production to pre-1990 levels. As a short term measure, the Government is encouraging the planting of forests to remove carbon dioxide from the atmosphere, says Sime, but in the long term, renewable energy solutions must be found. He says using wood for electricity production is one such renewable energy initiative.

His gas generator, when combined with gas-turbine technology, can meet the domestic electricity requirements of about 10,000 people.

"We're looking at old technology, but with an environmental theme, to efficiently utilise wood to make electricity."

Sime predicts pulp and paper companies will show a keen interest in his research because it opens up possibilities for their production systems. Wood-based fuels are already used on a large scale by New Zealand's forestry industry and some pulping mills use more wood energy than the entire electricity consumption of Wellington. Some wood is used to fuel steam turbines with efficiencies of less than 15%, whereas the new system has a conversion efficiency of about 40%.

Sime expects the higher efficiency obtainable with gas-turbines will result in the adoption of his technology by the forestry industry, though he says a commercial system is at least five years away.