When the biodegradable wastes and sewage undergo anaerobic sludge digestion, that means in the absence of free gaseous oxygen from the atmosphere, the micro organism access the oxygen from the organic matter of the wastes itself, so in this process a lot of methane gas is generated and this methane gas can be used in several useful ways. I am glad that this vehicle is powered with such gases coming out of human wastes.

Thank you...steem on that hunt.