As opposed to ethanol.

The key to the breakthrough is a process developed by both Dumesic and Cortright called aqueous phase reforming. In passing a watery slurry of plant-derived sugar and carbohydrates over a series of catalysts-materials that speed up reactions without sacrificing themselves in the process-carbon-rich organic molecules split apart into component elements that recombine to form many of the chemicals that are extracted from non-renewable petroleum.

According to Dumesic, a key feature of the approach is that between the sugar or starch starter materials and the hydrocarbon end products, the chemicals go through an intermediate stage as an organic liquid composed of functional compounds.

"The intermediate compounds retain 95 percent of the energy of the biomass but only about 40 percent of the mass, and can be upgraded into different types of transportation fuels, such as gasoline, jet and diesel fuels," said Dumesic. "Importantly, the formation of this functional intermediate oil does not require the need for an external source of hydrogen," he added, since hydrogen comes from the slurry itself.

As part of a suite of second generation biofuel alternatives, green gasoline approaches like aqueous phase reforming are generating interest across the academic and industrial communities because they yield a product that is compatible with existing infrastructure, closer than many other alternatives in their net energy yield, and most importantly, can be crafted from plants grown in marginal soils, like switchgrass, or from agricultural waste.

While several years of further development will be needed to refine the process and scale it for production, the promise of gasoline and other petrochemicals from renewable plants has led to broad industrial interest.

The process is more like current petroleum refining than a yeasty brewing system that produces ethanol, and the output is superior. It's still the wrong way to get liquid fuel since it requires food as an input, but it is less wrong than ethanol systems.