Wits University researchers have found a way to produce biofuel from plants such as maize and sugar cane that could slash production costs.
They’ve developed a technology that cuts the energy requirements of bio-ethanol production by as much as 40%. Interest from the private sector could result in its commercialisation.
Bio-ethanol is the world’s most common biofuel. Its use has been slowed by fears that the energy needed to make it may be greater than the energy content of the fuel.
Research headed by Neil Stacey has shown that it is not necessary to purify ethanol fully before blending it with petrol.
The purification of ethanol has traditionally been water-intensive, making it unpopular in a dry country like SA. A big portion of the cost of bio-ethanol production is tied up in the distillation process that separates ethanol from the water that makes up most of the fermentation product.
This ethanol is seldom used as a fuel on its own; it is blended with petrol. Stacey argues that since the ethanol is used in a petrol blend it doesn’t have to be purified first. The water could just as easily be eliminated from the mixture after the blending with petrol.
The Wits team’s findings were published recently in the science journal Energy & Fuels. Stacey’s co-authors were Aristoklis Hadjitheodorou, an engineer from Shell, and Prof David Glasser.
The research has far-reaching implications. It means bio-ethanol production could offer energy savings of as much as 2megajoules (MJ)/l of ethanol produced. This advancement has the potential to save more than 40bnKWh of energy a year.
Recent legislation has mandated a 2% ethanol blend for all petrol in SA. This will require 200Ml of ethanol each year, so this new approach has the potential to save SA more than 100mKWh/year.
The team is in talks with Tongaat Hulett about commercialising the technology to meet the demand created in SA by new legislation. But "getting the big oil companies to buy into biofuels is difficult enough even without trying something unconventional," says Stacey.
"Discarding the assumption that you have to start with full purification opens up so many possibilities. We’re saving 2MJ/l with a process that’s really just a rough draft [of the final procedure]," he says.