Skip to content

The BTU Busters

Waseca, Minn. — When a solid-fuel stove manufacturer wanted to compare the heat energy values of renewable fuels, he couldn’t find a chart to look them up. So AURI scientists Jack Johnson and Al Doering decided to create one.

“We believed there was a need,” Johnson says. “There’s been an explosion of companies looking for renewable fuels. Wood has been the classic used for years, but now with more pressure on that, and higher prices, many ag products have become competitively priced.” (See Ag Innovation News, July 2002)

Stove manufacturers, mining operations, utilities and other fuel buyers can use the AURI Fuels Initiative’s chart to compare Btus (British thermal units), ash and sulfur for 25 ag-based fuels, from alfalfa to wheat. “This information hasn’t been available anyplace in the country in any one spot, so this is really cutting edge,” Johnson says.

Heat of the matter

Values testing was done at three labs — Minnesota Valley Testing in Bismarck, N.D., Twin Port Labs in Superior, Wis., and AURI’s lab in Marshall, Minn. As numbers started coming in, significant differences were revealed, Johnson says. The Btu value for high-oil corn, for example, is about four percent higher than shell corn. Dried distillers grain, a byproduct of ethanol plants, also has a relatively high Btu value.

“One of the best looking biomasses right now is dried distillers grain,” Johnson says. Due to the growth of ethanol plants in the Midwest, distillers grain is receiving a lot of focus from companies utilizing renewable fuels, Doering adds.

Values were calculated for products with moisture and then recalculated on a dry-matter basis. Moisture lowers Btu value because energy must be used to dry the fuel before burning. A dry-matter comparison helps fuel buyers compare products, Doering says.

The chart does not include cost per Btu, the researchers say, because those costs vary based on market prices, volume purchased and transportation. Johnson says he will work with individual clients to help determine costs.

Cost-effective fuel

The tested products came from a geographically small area in southern Minnesota, Doering emphasizes, so actual ag fuel performance could vary. Cost effectiveness of any fuel, he says, varies due to moisture, seasonal changes, transportation and the form in which the fuel is burned. Johnson says the figures should be used to “compare relative combustion specifications.”

“Many of (the ag fuels) are more economical to burn than wood, oil and natural gas,” Johnson says. While coal is still cheaper, most renewables “burn much cleaner” and are blended in to meet emission standards.

Steel plants and utilities are some of the potential renewable fuels users; home use includes pellet and corn stoves.

The fuel chart is available from AURI’s Waseca office and is posted on AURI’s Web site: