Carbon Gold Ltd.

Sometime around 2000 B.C., the Amazon people discovered a trick for improving crop yields. They found that plowing the charred remains of burned food scraps, manure, and other organic waste into carbon-poor soil made plants grow better. What they didn't know was that they had also discovered a method of carbon sequestration that could benefit a future civilization: ours.

When allowed to decompose naturally, wood chips, yard clippings, cornstalks, and other types of organic matter give off about 90 percent of their carbon in the form of methane and carbon dioxide. But cooking them at high heat under low-oxygen conditions forms what's known as
biochar, which retains as much as 50 percent of the organic material's original carbon. Some scientists who study biochar, including those at the Department of Energy's Pacific Northwest National Laboratory, argue that we could theoretically dial back global warming by turning plant waste into biochar and mixing it into soil.

The British company Carbon Gold is among the first to try to cash in on biochar's promise. Though neither the United Kingdom nor the United States has implemented policies that would promote biochar, as of February, Australian political leaders were debating plans to make biochar a centerpiece of the country's carbon-cutting effort.