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Terra preta, the "dark earths" of Amazonia that are inspiring modern researchers to turn to pyrolysis as a solution to a number of energy issues, were first documented in 1879 and have been studied scientifically since 1966, but their intersection with the bioenergy sector is much more recent.

The American Association for the Advancement of Science conference in January 2006 dedicated a session to terra preta. Later, in July 2006 at the World Congress of Soil Science, an interdisciplinary group of agri-char enthusiasts got so fired up that they banded together to form the International Agrichar Initiative. The group is holding its first conference this April in Australia.

"We need to get the engineers together with environmental scientists, with the economists and the policy analysts," says Johannes Lehmann, one of its organizers. Already the conference has over 50 attendees. "Get them together into one pot and stir heavily," he prescribes. "Then we can come up with a highly valuable alternative to waste management, to energy production and to land stewardship."

The meeting is partly sponsored by some of the companies that are pursuing pyrolysis as a business model. Already Dynamotive Energy Systems, a Canadian energy solutions provider, has a 100-ton-per-day plant up and running in West Lorne, Ontario. Dynamotive is also currently building a 200-tons-per-day facility 45 minutes west of Toronto. Their fast pyrolysis method produces 200 kilograms of char to every ton of bio-oil.

Best Energies, a Madison, Wis.-based biofuel company has a 12-ton-per-day pyrolysis unit working in Australia as a quarter-scale demo of the technology. "Think of maybe two semicontainers end to end and that's the size we're talking about," notes Cory Wendt, Best Energies' vice president of business development. His company began selling their 48- and 96-ton biomass-per-day pyrolysis units to the public on January 1, 2007. "In some countries carbon credits are a big driver and we offset a minimum of 9,000 carbon credits on an annual basis for the 48 ton-[per]-day units respectively," explains Wendt. They already have half a dozen clients in the pipeline and a binder full of other possible leads.

Eprida, which operates on a hybrid profit/not-for-profit basis in Athens, Ga., is working on a 12-ton-per-day unit, scaled to fit the needs of the farmer. "Our primary goal is to increase the quality of life for subsistence farmers, and in doing so we have the capability of reversing CO2 release and converting that whole cycle downwards," explains company president, Danny Day.

Day notes that financial incentives must be in place to reward farmers for sequestering carbon in order for the idea to work. It is a common concern for academics and businessmen alike. "Use of agri-char does not fall under existing subsidies with respect to renewable energy, because agri-char is not an energy use," Dynamotive's Desmond Radlein.

"An easy mechanism [for creating incentives for development of agri-char] would be through controlled subsidies where we actually say, 'What is this worth to us?'" Lehmann says. "That's where the policy comes in to be able to internalize some of these hitherto external benefits." Without those changes in place, all the back-of-the-envelope calculations, no matter how glowing, simply will not count.