Fact sheet: biosequestration

Fact sheet included in the Coalition's press release on its proposed Green Carbon Initiative.

What is it?

Biosequestration involves offsetting greenhouse gases by capturing and storing carbon in soil and plants. This includes restoring soil carbon through better land management; revegetation and reforestation; and biochar (converting biomass into charcoal, which can be fixed in soil).

Land Management

• According to the Garnaut Review, 70% of Australia is arid and semi-arid rangeland degraded by marginal grazing. Garnaut estimates approximately 50% of Australia’s 2006 CO2e emissions (approximately 576 million tonnes, or Mt) could be absorbed each year for the next 20-50 years by improved practices on Australian cropping and grazing lands, and by revegetation¹.
• According to scientist Dr Christine Jones an increase of 0.5% in soil carbon on 2% of Australia’s agricultural land would absorb a volume of CO2e exceeding Australia’s 2005 emissions².
• Steps to improve land management include changed practices for animal management and husbandry, select breeding, grazing techniques, fodder quality, and animal shelter. Improvements would enhance animal live-weight gains and abate greenhouse gases.

Revegetation

• CSIRO scientist Dr Phil Polglase estimates plantings to abate carbon emissions are profitable over 9.1M hectares of economically marginal low rainfall land at a carbon price of $20/tonne. Such plantings have potential to remove 143 Mt of CO2e each year – equal to approximately 25% of Australia’s 2006 emissions³.
• Forestry and revegetation are already partly recognized as carbon offsets under Kyoto.

Biochar

• Created by heating biomass in the absence of oxygen - a process called pyrolysis. Half the carbon is turned into biochar (charcoal) and fixed in soil. The other half is transformed into biofuels used to generate green energy.
• Advocates such as 2007 Australian of the Year Tim Flannery contend its widespread adoption could, over 20 years, remove the 200-250 Gt of carbon added to the atmosphere since 1850⁴.
• Resources firm Alumina estimates its existing pilot project⁵ can scale to offset 6 Mt of CO2e yearly. Alumina estimates total biochar potential of WA’s wheat belt at 25 Mt yearly, and total national potential at 100 Mt yearly – equal to approximately 17% of 2006 emissions.

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¹http://www.garnautreview.org.au/pdf/Garnaut_Chapter22.pdf
²http://www.soilcarboncredits.blogspot.com/
³http://www.afg.asn.au/resources/pdfs/AFG08/Session_3_B3_1.pdf
⁴http://beyondzeroemissions.org/2008/03/19/tim-flannery-australian-of-the-year-2007-talks-bio-char-why-we-need-to-move-into-the-renewable-age
⁵http://www.aluminalimited.com/index.php?s=about&ss=sustainability&p=risk_management#regulatoryRisk