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UK researchers aim to prove farm climate cure
Stuart McDill, Reuters
A modern take on the age-old farming technique of plowing charred plants into the soil could help tackle climate change and even food security, according to researchers in Scotland.
Their study is looking at biochar, a charcoal like substance produced from heating farm or food waste, which when plowed into the soil can store the greenhouse gas carbon dioxide and may help retain nutrients and water.
The process of making biochar also produces low-carbon energy, including heat and an energy-rich gas which can be burned to produce electricity.
“The farmer can use his agricultural residues to produce clean energy. He is off-setting the fossil fuel usage that he would ordinarily have,” said Jason Cook, a PhD student at Edinburgh University…
(6 Oct 2009)
His dark materials: The man behind Green & Black’s chocolate wants to save the planet – with charcoal
Rhiannon Harries, The Independent
Booking my ticket to Hastings to visit Craig Sams, I notice a link on the train operator’s website that allows me to check the carbon footprint of my trip. It’s a fitting start to a journey to meet one of the foremost pioneers of the green movement – not least because the latest endeavour of the man who brought the macrobiotic diet to Britain and made organic chocolate one of the most fashionable foodstuffs of the past decade is an ambitious global carbon-capturing initiative that may hold part of the answer to climate change.
Sams, now 65, decamped to the Sussex town from west London full-time with his journalist wife Josephine Fairley, 52, eight years ago, as they were slowly disentangling themselves from Green & Black’s, the enormously successful organic, Fair Trade chocolate brand they founded together in 1991. In the time that Sams and Fairley owned the company, they managed to change the taste of a nation, convincing consumers weaned on insipid milk chocolate that the bittersweet delights of their rich, cocoa-heavy offering were a more sophisticated, not to mention ethical and healthy, choice.
Set up in partnership with the former music promoter and Sams’ fellow eco-entrepreneur Dan Morrell, Carbon Gold is a company with a bold plan to get farmers around the world transforming their agricultural waste – which would otherwise be burned or left to rot, releasing carbon dioxide into the atmosphere – into a type of charcoal known as “biochar”. Produced by heating plant matter in the absence of oxygen, biochar is essentially a stable form of raw carbon, which can be used to fertilise soil.
Simply as a low-cost, organic means of regenerating degraded farmland, it represents an exciting development. But it is its potential as a means of sequestering carbon, reducing carbon-dioxide emissions and slowing climate change that could have the greatest impact on the future of the planet…
(27 Sept 2009)
The Biochar debate
Dave Elliot, environmentalresearchweb
Converting biomass into charcoal type char which can be used to improve soil fertility, while also trapping carbon dioxide, certainly has major attractions. Some energy is generated too. But a key issue is whether, in net climate terms, the loss of (some) biomass for direct conversion to energy is balanced by the gain from CO2 entrapment and extra CO2 absorption by more fertile soils- especially if the combustion route also used geo-sequestration i.e. CCS?
A parametric study of bio-sequestration by Malcolm Fowles at the Open University, suggested that from a global warming perspective we should displace coal with biomass if the latter’s conversion efficiency is much over 30%. Otherwise we should sequester carbon from biomass rather than generate energy.
However, this was only a preliminary study and he felt that a more comprehensive analysis might shift the balance more towards bio- sequestration. He did not include carbon savings from hydrogen and other pyrolysis products, or crucially from reduced soil emissions- that’s hard to assess after all. And costs were not included in his model, although qualitatively and intuitively he felt bio-sequestration should be cheaper than geo-sequestration by CO2 capture and storage. (Fowles, M. (2007), “Black carbon sequestration as an alternative to bio-energy’, Biomass and Bioenergy 31: 426-432, doi:10.1016/j.biombioe.2007.01.012)
Clearly though there are lot of unknowns- for example as to the permanence of bio-sequestration – how long will the carbon stay trapped in the soil? Some say thousand of years, based on historical examples of charcoal use. But then that was in traditional ‘no til’ agricultural contexts: farming methods would now have to change if we wanted to avoid releasing the stored carbon…
(3 Oct 2009)
Survey of the literature that avoids the current hype. -KS
