A New Zealand company which says it has patented world-first industrial technology to microwave forest waste is planning to offer charcoal to farmers and horticulturists who want to boost the quality of their soils.
The technology can capture significant amounts of carbon dioxide from the atmosphere and hold it for 10,000 years by putting the charcoal into topsoils, and at the same time improve plant growth.
The company, Carbonscape, has begun initial batch scale production of the "biochar" at its Marlborough plant.
Forestry Minister Jim Anderton officially opened the plant today and said the technology "appears to be a huge breakthrough in charcoal development".
A Carbonscape spokesman, Nick Gerritsen, said simply burning biomass, such as wood waste, was generally considered carbon neutral because it's assumed that the carbon released to the atmosphere will be re-absorbed in trees that eventually grow to replace the original forest.
But putting the biochar into the soil is considered carbon-negative because it actually reduces atmospheric carbon.
Using woodwaste to trap the carbon as charcoal was likely to be a far more accessible technology than some other approaches to geo-sequestration, such as pumping liquid carbon dioxide deep underground into disused oil and gas reservoirs.
And in addition, it will allow farmers to tap methods which have been used for thousands of years in tropical rainforests, such as in the Amazon basin, to improve soil structure and plant productivity.
Buried in the topsoil, the charcoal can improve soil fertility, cut soil emissions of greenhouse gases such as methane and nitrous oxide, reduce nitrate and phosphate leaching, increase nitrogen fixation and help soil organisms to extract more carbon from the atmosphere, Mr Gerritsen said.
"The potential for carbon credits from forestry and agriculture worldwide is huge," he said. In New Zealand, biochar could help solve the problem of the 13 million tonnes of radiata pine waste dumped every year, and in the USA, it could help the State of Iowa make use of 22 million tonnes of corn husk waste each year.
Carbonscape was set up by Mr Gerritsen a technology start-up advisor, renewable energy developer Vicki Buck, Professor Chris Turney of Exeter University, businessman Hamish Macfarlane and investor Tim Langley.
Some of the same executives are involved in a Marlborough company, Aquaflow Bionomic Corporation, producing biodiesel from algae harvested from sewage ponds.
Initial production of biochar from the big Marlborough microwave oven is expected to go to a research project at Lincoln University, where soil scientists and agronomists will assess its effect in soil.
At the same time, the company will be investigating the potential to recover valuable oils and other chemicals from the gas driven off the charring wood, and to burn some of the "syngas" to generate electricity needed to power the microwave.
Livestock farmers have effectively been given a holiday by the Government on paying for their animals' methane emissions - which account for about 49 per cent of New Zealand's total greenhouse gas emissions.
The biochar technology could offer farmers and other rural sector groups, such as foresters with pre-1990 forests, a new way to offset their "carbon debt".
The Government said in this year's budget that it is investing $10 million in research and development, and commercialisation, of bioenergy and energy efficiency opportunities, including biochar.
It has already funded two professorships at Massey University involving different aspects of the research and development of charcoal technology.