Biochar, a material used by Amazonian Indians to enhance soil fertility centuries ago, may help slow global warming. Mass production of biochar could capture carbon that otherwise would wind up in the atmosphere as carbon dioxide, the main greenhouse gas leading to global warming.

The heat drives off gases that can be collected and burned to produce energy. It leaves behind charcoal rich in carbon. Amazonian Indians mixed a combination of charcoal and organic matter into the soil to improve fertility, a fact that got the scientists interested in studying biochar's modern potential.

The study involved a "life-cycle analysis" of biochar production, a comprehensive cradle-to-grave look at its potential in fighting global climate change and all the possible consequences of using the material, said a Cornell release.

It concludes that several biochar production systems have the potential for being an economically viable way of sequestering carbon - permanently storing it - while producing renewable energy and enhancing soil fertility.