FROM STRAW TO FUEL

ENERGY: Up to 10% of pricey petrol could soon be replaced with inexpensive and environmentally friendly ethanol sourced from straw. The Royal Veterinary and Agricultural University in Copenha-gen has invented a method which makes the conversion process up to 4 times faster and cheaper than current generation technology. Now bioethanol can become competitive.

“We lack the last part of technology development, but we are certain to get there”, says Professor Claus Felby at the Royal Veterinary and Agricultural University in Copen-hagen. Together with senior engineer Jan Larsen at Elsam Engineering A/S, he has filed for a patent on a process which can convert straw into valuable fuel.

1 ton per hour
The new concept, which could see a large proportion of expensive petrol being replaced with inexpensive and environmentally friendly ethanol, may revolutionise the development of sustainable fuel. In the last two years, the process has been tested in a pilot project at Fynsværket, a combined heat and power plant at Funen, with a capacity of one ton per hour.

“We have the technology, and we know that it works, says Claus Felby. We can convert straw into ethanol in a very simple, rapid and low-energy process. We can run 3-4 times as much biomass through the system and use 3-4 times less energy than previously. The next obvious step would be to build a factory so that the potential could be exploited fully. We are collaborating with Elsam because the power supply plant at Fynsværket is already based on the combustion of straw and waste. So it is obvious to connect our production plant to a power station which has the heat, steam and electricity required to convert the straw into ethanol”.

There is nothing new in using ethanol as replacement for petrol. It is already used today in countries such as Brazil, USA and Sweden, where maize and grain are frequently used as feedstock. In the US there are even plans to stipulate that petrol contains 30% ethanol by 2025. What is new about the Danish invention is that the process has for the first time made it technically and financially feasible to use residual products such as straw and organic household waste as feedstock for ethanol production.

Yeast added
The straw itself is liquidized by means of enzymes and a special mixing technique.

Then ordinary yeast is added to the mix. The result is ethanol which can literally be poured directly into the petrol tank without further processing. Claus Felby says that today 10% of petrol can be replaced with ethanol made from straw without any problems. And in 5-10 years he expects that it will be possible to replace about 40% of petrol with the new type of fuel. If the technology is seriously taken up, it will be possible to replace Denmark’s entire current consumption of petrol with biofuel generated from 16% of Denmark’s agricultural land area.

The reason why production of ethanol based on straw has not advanced further than the pilot project is because there is simply no Danish market, Claus Felby says. “We have the technology and it is even 100% CO₂ neutral, but we are lacking support from relevant legislation to continue”, he says. “Today all cars in Denmark can run on a petrol mixture with 10% ethanol, and that quantity could be produced on a small proportion of Denmark’s agricultural land area.”