Organic chocolate manufacturer Green & Black’s is pioneering biochar, a new carbon-storage strategy

Dominic Lowe, managing director of chocolate maker Green & Black’s, is a concerned man. To combat global warming Lowe believes that we need not only to reduce the amount of carbon we release, but also to absorb carbon out of the air. For this reason, more companies need to start experimenting with ways to store the carbon they release, he says.

Handily for Lowe, the organic chocolate manufacturer’s founder, Craig Sams, thinks he’s found a way to store carbon in the soil in the form of charcoal, otherwise known as “biochar”. Sams’s latest venture, a company called Carbon Gold, is on a mission to turn organic waste into charcoal, and then to mix the charcoal with organic matter and minerals and sell it on as a soil conditioner and fertiliser.

Although biochar is known to have been used by native tribes to fertilise the tropical soils of the Amazon for farming, the concept of using biochar as a reliable fertiliser that is also a way to store carbon is relatively new to scientists. Simon Shackley, lead researcher at the UK Biochar Research Centre, admits that more work needs to be done to prove both claims.

The storage of charcoal in the soil needs to be closely monitored, he says. “Some of the charcoal may be blown off the soil,” Shackley points out. And while the biochar used by the Amazonians might have worked as a great fertiliser, it is by no means proven as an effective fertiliser in all soil types, he adds.

Despite biochar’s uncertainties, the UK government is still keen to find out how it could be put to use as a form of carbon storage. Shackley has just finished putting together a research paper for the government reviewing the current science on biochar, and is keen for companies to get involved in trialling charcoal as a form of fertiliser and carbon storage in their agricultural supply chains. So far, even UK retailers that are most vocal on climate change, such as Tesco, have yet to make any announcements on experimenting with biochar.

Green & Black’s seems to be a pioneer in the business world, then, when it comes to carbon storage. The company is working with Carbon Gold to see whether, with its financial help, biochar can take off as a self-produced organic fertiliser for its farmers in Belize.

Prunings to pyrolysis

Belizean farmers, currently supplying organic cocoa to Green & Black’s, are being asked by Carbon Gold to prune their cocoa trees hard and send the cuttings for pyrolysis (burning in the absence of oxygen) to make charcoal. Green & Black’s then pays Carbon Gold for the charcoal it has produced on the understanding that it is to be buried as carbon storage.

The model the two companies have created assumes that within one tonne of charcoal created, three tonnes of carbon has been stored. Green & Black’s pays above the average carbon-offset price to Carbon Gold, about £20 per tonne of carbon, which translates into £60 per tonne of charcoal. Of the £60 per tonne, the Belizean farmers will receive £50, Lowe explains.

Carbon Gold will try to recoup its costs by turning the charcoal into fertiliser and selling it on either to Belizean farmers or for sale in Europe as a garden fertiliser. Carbon Gold says it is confident of biochar’s soil conditioning and fertilising properties and intends to monitor the fertiliser as it is put to use by Belizean farmers on their cocoa trees in trials.

The experiment is still in its early days, having been set up in mid-2009, and so far less than 50 tonnes of charcoal have been created, but Green & Black’s and Carbon Gold intend to create 1,000 tonnes per year by 2011. This amount will cover about 30% of the company’s total carbon footprint, including that of its supply chain, according to Lowe.

Lowe is keen to promote biochar and seems certain it is a safe bet as a form of carbon storage. Carbon offsets, such as tree planting, are less convincing to him. “Some [companies] are planting trees, but I get suspicious about the tree-planting ones because I don’t see forests springing up, and there’s good science that they need to be in the right place,” he says.

The charcoal experiment also brings extra benefits to Green & Black’s. “The more you prune a cocoa tree, the more yield you get from it,” Lowe explains. Farmers tend not to prune as hard as they should, however, because of hard work involved, so Lowe is keen to introduce the incentive of selling cocoa prunings to create biochar. “A rise in yields is good for us. We want more high quality Belizan cocoa, and we’re locking up the carbon in biochar,” Lowe says.

Green & Black’s is willing to pay out extra for biochar carbon credits as it believes that its customers would expect the highest ethical standards from the company’s carbon offsets. “These trees would just rot and turn into CO2 if they weren’t turned into biochar,” Lowe says.

Global roll out

Lowe is keen that other companies should trial biochar production and he is willing to work with other cocoa producers to roll out projects worldwide. He is also in favour of growing trees especially to be turned into biochar, although he accepts that other environmental constraints, such as water scarcity, might render this difficult.

On the world stage, biochar is due to be discussed as a possible form of carbon storage at the climate talks in Copenhagen. However, the science behind biochar is yet to be reviewed by the official climate science body, the Intergovernmental Panel on Climate Change, which may stall talks on allowing biochar credits into carbon markets. Despite its promise, biochar may need to be trialled and proven by scientists on a wider scale before policy-makers can take it seriously.

Biochar’s claimed benefits

• Increases crop yields, sometimes substantially if the soil is in poor condition.
• Helps to prevent fertiliser run-off and leeching, allowing the use of less fertiliser and diminishing agricultural pollution to the surrounding environment.
• Retains moisture, helping plants through periods of drought.
• Replenishes exhausted or marginal soils with carbon and fosters the growth of soil microbes essential for nutrient absorption, particularly mycorrhizal fungi.