A team of biologists and engineers at Washington University in St. Louis have figured out how to make a carbon-neutral biofuel on the cheap using microbes.

Using just microbes, carbon dioxide, solar panel-generated electricity and light, the team was able to make an authentically carbon-neutral fuel alternative called n-butanol that can be used in blends with diesel or gasoline.

The fuel has a high energy content and a low tendency to vaporize or dissolve in water without combustion, unlike another common biofuel, ethanol. Ethanol is made out of corn, which has a surprisingly high environmental footprint, according to some researchers.

The project’s main researcher said the microbes’ potential uses are promising, but improvements are needed before the biofuel technique is rolled out for industrial use.