If the name Pongamia pinnata doesn’t ring a bell in terms of biofuel crops, it soon will. Also known as pongam tree, karum tree and poonga-oil tree, the fast growing, drought hardy evergreen boasts delicious-looking lavender flowers that develop into a lush display of pods bursting with oil-soaked seeds. Are you excited yet? Pongam is native to India but it can thrive in hot, dry climates elsewhere, and the biofuel company TerViva is planning to grow about a million acres of pongam trees for biofuel in the U.S., Texas and Canada over the next ten years.
Before we get into the biofuel stuff, it’s worth noting that pongam trees are the Ginsu knives of treedom. They have a million and one uses, as cataloged by researchers at Purdue University, ranging from folk medicines, soap, tanning agents and antiseptics to poultry feed, livestock fodder, insect repellent, soil enhancer, dyes, and lubricants. But wait, there’s more. In folk cultures the seeds are used to poison the tips of fish spears. Also the bark can be used to make string and rope, and the wood has a high energy content as a fuel.
But What About the Biofuel?
Oh right, the biofuel. Pongam seed oil has been used as a substitute for kerosene, and TerViva has developed an “elite” strain that produces oil that shares the basic properties of other biofuel feedstocks. As a biofuel crop, pongam trees fit into the preferred mold of a non-food crop that requires little in the way of irrigation and pest control, so it can be grown on marginal lands. They also have a bonus advantage. Pongam trees are leguminous, which means they fix atmospheric nitrogen and do not require fertilizers.
What Now, Pongam?
Logan Hawkes of Southwest Farm Press reports that TerViva has introduced groves of pongam trees in Texas on a pilot basis, to determine how well the trees grow in that climate. Hawkes also notes that the seeds can be harvested and prepared with conventional equipment already in use for nut trees, peanuts and other crops. After the oil is removed, the leftover seed cake can be used as fertilizer or blended with soybean for animal feed.
Growing Trees for Biofuel
While up-and-coming biofuel crops like camelina have great promise (just ask the Air Force!), trees are also edging their way into the picture. The main advantage is that standing groves of biofuel trees can double as wildlife habitats and managed forests, without having to plow up the entire soil surface at harvest time. Trees can also serve in bioremediation projects. For example, poplar is another fast-growing biofuel tree that has been used to absorb soil contaminants (again, ask the Air Force!).
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