The interesting thing is the mixing of fuels of totally different structures with opposing qualities. eg. Hydrogen and CNG. They both suck compared to petrol or LPG but together they are showing great promise.
Storage is the issue unless mixed with another fuel successfully.
Im looking forward personally to bio-fuel from algae not grown in ponds or lakes but with cheap and ingenious vertical plastic bag factories. There are thousands of different types of algae and using bio-synthesis some are 50 per cent oil in stucture. 1 hectare of these farms can make 100000 litres compared to 30-100 litres for corn or soy. http://www.alternativeconsumer.com/2007/10/17/algae-the-next-great-biofuel-vertigro-energy/
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