Australia is to get its first commercial biochar plant, The Age has reported. Due to be built in Melbourne over the next 12 to 18 months, the plant will turn green waste into electricity, with soil-enhancing biochar being produced as a side-product.
Biochar, a type of charcoal with a sponge-like structure, is produced by heating organic matter using a method called pyrolisis – a high-temperature, low-oxygen technique. The organic matter (wood, green waste etc) is basically smouldered rather than burned.
The result is a substance that dug into soils can have some great benefits. Biochar’s ability to sequester carbon means it could be an important weapon in the fight against climate change. It also has the potential to help food growers be more productive.
It certainly did the business in the Amazon, where indigenous people traditionally used biochar to create wonderfully rich, deep black soils (Terra preta) near their settlements.
The resultant soil horizons rich in organic matter were up to two metres deep, compared with 10cm-20cm in surrounding soils, says Cornell University, with stored carbon an “order of magnitude higher than in adjacent soils”.
For reasons not clear, the organic matter in these black soils is very persistent, with high levels maintained for hundreds of years after soils are abandoned.
Whether biochar will live up to the hype isn’t yet clear, but it is certainly shows potential.
The Melbourne plant will hopefully get it out there on a bigger scale. It plans to sell biochar for a few hundred dollars a tonne – similar to the price of premium potting mix.
Photo: ALBERT BATES
By: Simon Webster
First published: September 2011