Biodiesel blends shown effective as alternative fuels in irrigation pumps

Oct. 26, 2011
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Donald Johnson, Professor, Agricultural and Extension Education

By Fred Miller, University of Arkansas Division of Agriculture Communications

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FAYETTEVILLE, Ark. — Research by University of Arkansas Division of Agriculture scientists has shown that a biodiesel blend can make a suitable alternative fuel for agricultural lift pumps.

Don Johnson, professor of agricultural and extension education, said Arkansas has more than 41,000 irrigation pumps for about 4.5 million acres of irrigated cropland. The state ranks fourth in the nation in irrigated crop acreage and fourth in the number of irrigation lift pumps. The increasing demand for energy has focused attention on developing renewable, alternative fuels for these and other transportation and industrial uses.

Research has shown that biodiesel blends, in which biodiesel fuel from vegetable oils and animal fats is mixed in varying percentages with petroleum-based diesel fuel known as D2, can significantly reduce diesel engine exhaust emissions, including hydrocarbons, carbon monoxide and particulates, Johnson said. Some research has indicated higher emissions of nitrous oxide (NOX) pollutants from engines running on biodiesel, he said.

Johnson worked with biological and agricultural engineer Subodh Kulkarni, former graduate student Jason Davis and Damon Kennon, testing supervisor for Engines Inc., to compare the NOX emissions, fuel efficiency and performance of B20 (20 percent), B50 (50 percent) and B100 (100 percent) blends of biodiesel with conventional D2 diesel fuel.

The Arkansas Soybean Promotion Board and Future Fuel Chemical Co. of Batesville helped support the research and the tests were conducted on a John Deere PowerTech 4.5‐L model 4045HF280 engine provided by Engines, Inc. of Jonesboro. Johnson said this power unit was selected for the tests because it is typical of irrigation pump engines used in the Arkansas Delta region.

At the rated engine speed of 2,400 rpm and the typical pumping speed of 1,800 rpm, there was no significant difference between B20 biodiesel and D2 diesel fuel for NOX emissions, power or performance, Johnson said. At 1,800 rpm there was a 3.4 percent increase in fuel consumption for B20, but no other differences between it and D2 diesel.

B50 and B100 biodiesel showed significant losses in performance and fuel efficiency in the tests, Johnson said.

“What we learned,” Johnson said, “is that B20 biodiesel is a suitable replacement for D2 diesel fuel in irrigation lift pumps for those farmers who want to lower polluting exhaust emissions.”

Johnson said the determining factors for farmers might be the cost of biodiesel and the small loss of fuel efficiency at typical operating speeds. “It’ll come down to an economic decision,” he said.