Ag Sense: Canola ideal biodiesel crop

By Sangu Angadi: Ag Sense

The biodiesel industry is rapidly growing in the United States. Energy security, fuel quality, and environmental and economic benefits are driving this growth. Biodiesel can be produced in this country with existing technology, thus reducing reliance on foreign oil. With a higher cetane rating, lubricity and oxygen content, biodiesel offers better fuel quality when compared with fossil fuel-derived diesel. It is also a cleaner burning fuel with lower sulfur or greenhouse gas emissions.

The biodiesel production process involves simple esterification of long-chain fatty acids derived from plant and animal sources. Comparing energy input and output relations of fossil fuel, biodiesel and ethanol suggests that the net energy output is highest with biodiesel.

Although a number of different feedstocks for biodiesel production have been used, a crop that is well adapted to the local conditions is the best choice. In eastern New Mexico, water is the most limiting and driving factor for crop adaptation. Therefore, a crop producing more biodiesel per unit of water use is preferred. Comparing soybean and canola, canola produces 33 percent more biodiesel per acre because it has greater than 20 percent higher oil content. The oil content of canola and sunflower is comparable, and the suitability of one over the other depends on how well they adapt to eastern New Mexico.

Canola is the third most important oilseed crop of the world. Canola is the improved version of rapeseed with improved oil quality resulting from reduced saturated fatty acid and improved meal quality attributed to lowered glucosinolate content in the meal. Canola has the lowest saturated fat content among all edible oilseeds. Therefore, canola oil is highly recommended by the Heart and Stroke Foundation for human consumption.

One of the disadvantages of biodiesel is a cold combustion problem. Although, unsaturation of the oil reduces the cold combustion problem, the increased degree of unsaturation (from mono- to polyunsaturated fatty acid) reduces the stability of the oil.

For example, soybean oil is high in polyunsaturated fatty acid and is therefore susceptible to auto-oxidation. Canola has a higher content of monounsaturated fatty acid and lower amounts of di- and tri-unsaturated fatty acid content. Therefore, it balances cold combustion and stability very well. In addition, high oleic canola varieties have been developed with 85 percent oleic acid, which are well suited for biodiesel production.

Both spring and winter canola are grown in the United States and Canada. Although winter canola is preferred in the southern High Plains because of its higher yield potential and tolerance to mild winters, spring canola can also fit in the rotation.

Canola has a tap root system similar to sunflowers, but depth and water extraction ability are lower than sunflowers. If water is available at depth (3 to 5 feet), canola can use that water to stabilize yield under water stress. The most critical stage for yield formation is the flowering period. Heat stress or drought stress at this stage can severely affect yield. From agronomic studies in Colorado, it appears that canola is slightly more efficient in using water for biodiesel production compared to sunflowers.

Canola is a good rotational crop in a cereal-based rotation system. Quite often, a wheat yield increase to the tune of 25 percent has been reported when a wheat planting follows a canola crop.

Sangu Angadi is a crop physiologist at New Mexico State University Agricultural Science Center at Clovis. He can be reached at 985-2292, ext. 125, or andagis@nmsu.edu.