No one would accuse Craig Venter of harboring humble ambitions. In 2000 he decoded the human genome faster than anyone else—and he did it more cheaply than a well-funded government team. More recently he's set a new goal for himself: to replace the petrochemical industry. In a Maryland lab, he's manipulating chromosomes in the hopes of creating an energy bug—a bacterium that will ingest CO2, sunlight and water, and spew out liquid fuel that can be pumped into American SUVs. NEWSWEEK's Fareed Zakaria spoke to Venter about the brave new world of biologically based fuels. Excerpts: