Researchers at the University of Technology in Twente have developed a new technique which enables the large-scale production of bio-fuel without adverse effects on food supplies. An oil can be extracted from agricultural and forestry waste products and processed in existing refineries into fuel for cars and aircraft.

Farmers in developing countries like Brazil have turned en masse to growing crops like sugar cane for bio-diesel. In theory, this is better for the environment and a good alternative to increasingly expensive fossil fuels.

Listen to the interview with Sascha Kersten:

Waste products
Unfortunately there are major disadvantages with this kind of bio-fuel. Production often takes place on agricultural ground which was previously used for food crops. Either that or swathes of rainforest are felled for the purpose. The bio-fuel developed in Twente does not have these drawbacks. Only waste products are used.

Sascha Kersten of the University of Twente:
"We want to base it purely on waste products. Straw and sawdust, for example, or the chaff from corn. We don't interfere directly with the food chain."

Billions of years
The scientists have imitated the process by which fossil fuels are produced under conditions of enormous heat and pressure within the Earth's crust. The natural process takes billions of years.

"We're giving nature a helping hand. There is a whole range of processes in nature which over billions of years convert biomass into gas, petroleum and coal. In our process we can take the same biomass and convert it into an oil which resembles petroleum - in just a few seconds."

The researchers heat sawdust, wood shavings and plant remnants in a reactor to around 500 degrees Celsius in an oxygen-free environment. This process, known as pyrolysis, produces an oily fluid. The heat is generated by the partial incineration of the biomass.

Wood shavings
The bio-oil produced can be used 'as is' as a fuel for power stations, but the scientists have further developed the technique so that excess oxygen can be removed from the oil by adding hydrogen under high pressure. This makes it suitable for processing in existing refineries.

One limiting factor is the high cost of hydrogen, but the researchers hope to be able radically to reduce the use of hydrogen in the short term. They expect the fuel produced by this process to be available at filling stations within five years. In ten years time 20 percent of the fuel for cars and aircraft could be generated from brushwood and wood shavings.