Transport fuel from grass or lucerne

Press, 11 February 1981, Page 25

Transport fuel from grass or lucerne

PA Auckland The production of a transport fuel from grass or lucerne could reduce the New Zealand overseas petrol bill by half and pave the way for vast foreign exchange savings. The assertion has been made by four scientists at the Ruakura Agricultural Research Centre in a paper to be presented this week at the annual conference of the New Zealand Institution of Engineers in Auckland.

The process, they argue, could have a double benefit for' New Zealand. On one hand, the level of overseas exchange earnings could soar through the export. of an animal feed ingredient, protein concentrate, that is extacted from the crops, and on the other, substantial savings in the amount of petrol imported might be achieved through the production of fuel from the residual biomass material. They believe that a 6 per cent penetration of the big European market for the concentrate — in 1978, 19 million tonnes of

oilseed was imported there — would support a leaf protein industry large enough to supply 50 per cent of New Zealand’s present petrol requirements. I he four men, Messts R. M. McDonald, J. E. Swan. P E. Donnelly, and R. A. Mills, say their proposal has advantages over more po r -uiai systems based on wood or beet where po'ential exports must be sacrificed to produce fuel. “A point in favour of protein extraction systems, is that the land continues to earn overseas funds ar the -.ame time as producing fuel,” the paper says. “A protein concentrate selling price of $3OO a tonne would give gross export earnings of $660 a hectare. This is about the same as the gross expert value of products from sheep that might otherwise have been grazed on the same hectare.” The scientists have calculated that the fuel produced from the pressed forage would allow additional foreign exchange savings of $4OO to $5OO a hectare, assuming replacement of petrol at t'he 1979 ex-refinery price of 20c a litre.

They list several routes available for the conversion of the biomass to transport fuels — hydrolysis followed by fermentation to ethanol; gasification to methane, hydrogen, or methanol; and anaerobic digestion to methane. Green forage crops, particularly grass and lucerne, may prove to be as equally attractive as a source of fuel as the use of beet, grain or wood, they say. “Between 18 and 30 per cent of the dry weight of these crops is protein and about half of this can be mechanically extracted and processed to a protein concentrate for use as an animal feed ingredient.' “The fibrous fraction remaining can be converted to transport fuels. “The protein extraction process has been commercially proved although further development of pulping and pressing techniques is necessary for application to fuel production.” - '. . The paper says that hi-. cerne protein concentrate is already being sold in Europe and the United States and that there is potential to export 190,600 tonnes a year to Japan.