Las Vegas entrepreneur Rosalie Bingham chats to David McKee

Rosalie Bingham is a woman on a mission. The Las Vegas entrepreneur has seen a problem — casino waste — and wants to turn it into an opportunity: clean power. The engine for this transformation would be something she calls “the Green Machine.” Technically, what it is in an anaerobic-digestion system. The concept of anaerobic digestion is hardly new. It is defined as “a collection of processes by which microorganisms break down biodegradable material in the absence of oxygen.” The Assyrians of tenth century B.C. used biogas to warm up their bathwater. The first “green machine” was built by British colonials in Bombay, in 1859. Perhaps distrusting the safety of the machine, they built it on the grounds of a leper colony.