Wood chips

Scientists have long been able to derive oils from wood, but until now they have been unable to effectively process it so that it could be used in conventional engines.

Now, researchers at the University of Georgia have developed a new chemical process, which they are working to patent, that inexpensively treats the oil so that it can be used in unmodified diesel engines or blended with biodiesel and petroleum diesel.

In the process, wood chips and pellets – roughly a quarter inch in diameter and six-tenths of an inch long – are heated in the absence of oxygen at a high temperature, a process known as pyrolysis. Up to a third of the dry weight of the wood becomes charcoal, while the rest becomes a gas. Most of this gas is condensed into a liquid bio-oil and chemically treated. When the process is complete, about 34 percent of the bio-oil (or 15 to 17 percent of the dry weight of the wood) can be used to power engines.

The researchers are currently working to improve the process to derive even more oil from the wood.

Tom Adams, director of the University Faculty of Engineering outreach service, said that test plots have been set up to explore whether the charcoal that is produced when the fuel is made can also be used as a fertiliser.

Although the new biofuel has performed well, Adams said further tests are needed to assess its long-term impact on engines, its emissions characteristics and the best way to transport and store it.

'It’s going to take a while before this fuel is widely available,' Adams said. 'We’ve just started on developing a new technology that has a lot of promise.'

The research was funded by the US Department of Energy, the Georgia Traditional Industries Pulp and Paper Research Program and the State of Georgia.