Researchers from Ghent University have estimated how plants can be converted into gasoline very quickly as it takes millions of years for the natural process for its conversion. The grass is broken down quickly by pre-treating it and then Clostridium bacteria similar to that found in your gut is added to produce Decane. Decane is one of the main components of Gasoline and jet fuel. Decane is a polluting fuel. Hence, commercial jets require it for at least the next few decades, so, researchers believe that their process is more economical to make it commercially executable.
For building their system and make it work, scientists initially treated the grass with a compound it had broken it, making it easier for bacteria to digest. The family of Clostridium bacteria is responsible for making up good bacteria in our gut rather than the bacteria that kills you. Fermentation is done for producing lactic acid and its derivatives in beer and further treatment yielded caproic acids. With further processing, that was converted into decane, a primary ingredient of gasoline and jet fuel.
Decane and other similar products are not clean fuels because they produce CO2 when burned. Even though they are not clean they have a much higher energy density as compared to lithium batteries. As such, be the main fuel used in aviation for the foreseeable future, as jet planes need to be relatively light to get above. As of now, this process can only produce a few drops of biofuel but researchers are saying that the process is already relatively efficient and we work more on it, it could possibly be made commercially feasible. Unlike corn, grass grows pretty much anywhere, so the ability to convert it into fuel cheaply would be a huge step.