Biofuels Watch, a British lobby group, worries that a craze for the stuff could see virgin land tilled specifically to grow crops such as switchgrass, whose only purpose was to be pyrolised and buried.

ECONOMIST: Biochar could enrich soils and cut greenhouse gases as well

After finding a plot of virgin prairie grass on his father's land, Mr Block began to build.

ECONOMIST: Building houses

Branson is something of a venture capitalist, plucking his favorite ideas from hundreds of solicitations that land in Virgin's London offices every week.

FORBES: Red Baron