If the number of wood-burning fires in New Zealand homes was halved, the country would have to build six new power stations to provide the electric heating, a energy campaigner warns.
Local authorities in smog-prone cities like Christchurch, Timaru and Nelson are encouraging householders to get rid of their log-burners.
But Wellington energy analyst Molly Melhuish said policymakers appear not to notice this year's energy statistics reported an extra 5.6 petajoules per year of energy from household wood-burning.
After correcting for the efficiency of burning wood, this represented 10 per cent of the output of New Zealand's biggest hydro scheme on the Waitaki river.
"New Zealand's biggest and potentially cleanest renewable energy resource has slipped under the radar of policymakers," she said.
New national emission standards which took effect last September mean all wood-burners newly installed on properties of less than 2ha must emit no more than 1.5g of particulates per kg of fuel burned. And their fuel-to-heat efficiency must be 65 per cent or better.
Wood-burners installed before that date or used on properties larger than 2ha need not meet the new requirements.
Molly Melhuish said if New Zealand's wood burning were cut by half, an extra 265 megawatts would be needed to supply winter peak demand - equivalent to six new power stations the size of Mighty River's new 45MW peaking station. If every wood-burner was replaced by a heat pump, two new power stations would be needed.
Any ban on wood-burners would mean colder houses, she said.
Electrically heated houses were on average 2 degrees colder than those heated by wood-burners.
"Policymakers don't need to ban wood-burners. All they need to do is to ban smoky wood fires."
