[cRiPpLe_rOoStEr]

Ethanol may seem kinda easier to develop, and also easier to adapt a vehicle to use it, but biomethane/bio-CNG also has its advantages in spite of the tank placement issue and a slight decrease in the payload of a vehicle. While ethanol relies mainly in edible produce (be it sugarcane, sugarbeets, sweet sorghum, corn, wheat, rice, whatever has some high sugar content) as its feedstocks, biomethane can be sourced not just from agricultural produce and residues but also recovered from wastewater treatment plants, landfills, or even biodigesters used to process animal residues in farms and meat-processing plants.

Basically all the same technology developed around fossil Natural Gas/CNG can be easily turned to biomethane/bio-CNG, and when we remember that even some 3rd-world countries use CNG it seems kinda weird that it's not so widely developed in America. In Bolivia, nowadays 80% of the public transport fleet (buses and taxis) run on CNG, and in Venezuela since 2009 at least 50% of all the brand-new vehicles must be capable to run on CNG in order to save gasoline and diesel for export. So, why not turning to bio-CNG instead of extracting shale gas (which has a high environmental impact) or giving dollars away to some random corrupt dictator in a 3rd-world country?