Cornell University researchers claim to have developed a way of making bio-diesel continuously, without the need to fill and empty batch reactors.
Making biodiesel involves a reaction called transesterification in which the triglycerides and free fatty acids in oils from plants such as corn or linseed react with methanol to form methyl esters of 16-18 carbon atoms in length.
Purified methyl esters can then be used in place of diesel fuel.
However, transesterification is a slow process and currently the only way to speed it up is to cook chemicals in batch reactors at high temperatures and pressures.
But having to produce fuel in batches also limits the rate at which biodiesel can be made.
Now, Christian Fleisher and his colleagues have developed a process to produce the transesterification reaction as the necessary chemicals mix and flow through a pipe.
According to New Scientist, the result is a system - known as a "plug flow" reactor - in which plant oil and methanol is added continuously at one end, while biodiesel flows out of the other.
Fleisher says it is possible to achieve this speed increase by using a catalyst, such as sodium hydroxide. So, instead of taking hours, the transesterification reaction takes place in under three minutes.
Fleisher has now set up a company called Biodiesel Technologies to commercialise the idea.