How Did Prometheus Beat Google at Making Gasoline?

Prometheus is not the first startup to take on the problem, but they seem to be the first to to make fuel-from-air cost effective.

They take water and carbon, and using a chemical reaction convert this mixture to alcohol. Then, and this is their secret sauce, instead of using a traditional thermal process which requires a lot of energy, Prometheus is converting this alcohol at room temperature, using electricity and a carbon nanotube membrane, yielding fuel at a much cheaper cost.

Note: This technical explanation to why Prometheus is able to do what Google has not comes from the Prometheus CEO's recent post on Hacker News