Abstract
There is no doubt that we have to find alternative fuels, to replace the derivatives from crude oil such as gasoline and diesel. There is also no doubt that the internal combustion engine will be the main propulsion technology for road transport for a long time.
At the same time the alternative fuels should decrease the noxious emissions (NOx, particles) and decrease the net greenhouse gas emissions (CO2). Such alternative fuels can be methyl or ethyl esters (biodiesels), alcohols from biomass (methanol, ethanol, ...), vegetable oils, animal fats, etc., or even hydrogen.
The authors do not consider natural gas (and also not LPG), as an alternative fuel since millions of cars, trucks, three wheelers are operating in countries as Argentina, India, ... This proves that a gaseous fuel is not excluded for road transport (natural gas). The authors at the Ghent University, Transport Technology research group, have a lot of experience with some of these fuels. Hydrogen engines are running on the test rigs with a higher power output than a gasoline engine and an efficiency better than a diesel engine. Tests are done on a 6 cylinder truck engine with biodiesels, pure vegetable oils and animal fats. Experience is gained from medium speed stationary engines running on animal fats and the residue of a fatty acid distillation. Recently research was started on methanol.
Without going into detail and without considering all possible alternative fuels, this paper will summarize some of the pro‟s and contra‟s. Also the question is posed if bio oils can be a fuel for road transport, taking into account their physical and chemical properties, and the long term engine durability.
Keywords: alternative fuels, hydrogen, methanol, bio-oils, engine performances