TODAY THE FACTORIES THAT MAKE GASOLINE, diesel and jet fuel are huge clusters of steel pipes and tanks that consume prodigious amounts of energy, release toxic fumes, and run on an exhaustible resource, petroleum. But tomorrow they might be microscopic, and they might run on the garbage hydrocarbons that are all around us—the paper of this magazine, scrap lumber from a construction project, or the leaves you raked off your lawn last month.
The trick is to transform the hydrogen- and carbon-based molecules inside these everyday items into a liquid at room temperature, thus making them suitable for use in internal-combustion engines. The most promising efforts involve genetically modifying single-celled organisms to do this conversion work for us. Many of these organisms already build hydrocarbons out of raw materials found in the environment, though not in a way that makes the product available for human use. For example, algae are very good at turning carbon dioxide into fatty acids that can be refined into fuel, but getting the algae out of the water and the fatty acids out of the algae requires so much effort that the process is mostly used for pricey products, such as cosmetics.