Researchers Develop Enhanced Bio-oil for Diesel Fuel Extender or Substitute
18 May 2007
A team of University of Georgia (UGA) researchers has developed an enhanced pyrolysis-derived bio-oil from pine wood chips. The new and still-unnamed fuel can be blended with biodiesel and petroleum diesel to power conventional engines.
Although it has long been possible to produce bio-oils via pyrolysis, the resulting product was too difficult or too expensive to process to enable its use in conventional engines. The new process, which the researchers are patenting, inexpensively treats the bio-oil so that it can be used in unmodified diesel engines or blended with biodiesel and petroleum diesel.
The exciting thing about our method is that it is very easy to do. We expect to reduce the price of producing fuels from biomass dramatically with this technique.—Tom Adams, director of the UGA Faculty of Engineering outreach service
The process pyrolizes wood chips and pellets to create charcoal (up to 1/3 of the dry weight of the wood) and a gas. Condensation of the gas produces liquids composed of two phases: an oily bottom phase and an aqueous phase. The removal of most of the water present in the aqueous phase results in the formation of a second oily phase the researchers call “polar oil.”
The oily bottom phases were more soluble in biodiesel than the polar oils. Monolignols, furans, sugars, extractive-derived compounds, and a relatively small fraction of oligomers were the main bio-oil compounds soluble in biodiesel. Water and low-molecular-weight compounds responsible for many of the undesirable fuel properties of bio-oils were poorly dissolved in biodiesel.
At the end, about 34% of the bio-oil (or 15 to 17% 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.
The researchers have also set up test plots in Tifton, Ga., to explore whether the charcoal that is produced when the fuel is made can be used as a fertilizer. Adams said that if the economics work for the charcoal fertilizer, the biofuel would actually be carbon negative.
Although the new biofuel has performed well, according to Adams, further tests are needed to assess its long-term impact on engines, its emissions characteristics and the best way to transport and store it.
“Production and Fuel Properties of Pine Chip Bio-oil/Biodiesel Blends”; Manuel Garcia-Perez, Thomas T. Adams, John W. Goodrum, Daniel P. Geller, and K. C. Das; Energy Fuels, ASAP Article 10.1021/ef060533e S0887-0624(06)00533-0
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