Biomethane
Using the Maltin® System to capture the methane gas given off by the decomposition of organic waste, which would otherwise have escaped to become a greenhouse gas some 21 times more damaging than carbon dioxide, and using this gives the most environmentally friendly vehicle fuel in the world.
Other renewable fuels might be "less bad" for the environment when compared with fossil fuels, whereas using biogas is actually "doing good" for the environment.
Best really means best and biomethane produced from organic wastes is better for the environment than ANY OTHER fuel, including hydrogen, wind power, liquid biofuels such as biodiesel and bioethanol, wave and tidal power, etc.