A big advantage for miscanthus production in the U.S. is that it does well in cooler climates, which removes much of the competitive advantage for the Southeast. Like other bioenergy crops, the harvested stems of miscanthus may be used as fuel for production of heat and electric power, or for conversion to other useful products such as ethanol.

Switchgrass

There is more documented research on switchgrass for biofuels than any other of the grass crops commonly mentioned for alternative energy. While some contend yields can reach 15-18 tons per acre, Lee says those type yields are extremely difficult to attain in the Southeast.

Switchgrass can be used in standard bales, pellets and other forms for use in hydroelectricity production. It does respond to nitrogen and does have some tolerance for drought. It doesn’t grow as well on lighter, sandier soils in the Southeast. Like miscanthus, switchgrass may be better suited for profitable growth in areas other than the Southeast.

Energy cane

Ben Legendre, LSU AgCenter sugarcane specialist, says research into what’s called energy cane — sugarcane that produces large amounts of plant matter with high sugar content — began in the early 1970s following the oil embargo. But after the embargo ended and gasoline prices retreated, interest waned.

Legendre said sugarcane varieties aimed at energy production are not appropriate for sugar production. He said researchers are looking for varieties that produce high yields of plant material — called biomass — and have capabilities for use in energy production.

In the Southeast, energy cane can regularly produce 20-25 tons per acre. It is planted by cane and has a larger stem than either switchgrass or miscanthus.

Carlos Riva, CEO of Verenium, whose company is actively involved in developing energy cane production in the Southeast, says, “Energy cane” is currently being grown at university test plots in the South, to see how well it produces (and how it fares in hurricanes).

Verenium has leased 20,000 acres to begin growing the crop on a large scale. Every acre of energy cane should yield 1,800-2,000 gallons annually (compared with 800 gallons for conventionally produced ethanol from sugar cane in countries like Brazil).

Napier grass

Sometimes called elephant grass or Uganda grass, Napier grass is well suited to production in the Southeast. Georgia researchers have been able to produce 20-25 tons per acre, using only 100 pounds of N per acre and no P or K.                                    

It is native to the tropical grasslands of Africa. Napier grass is a tall perennial plant, growing to a height of 12-15 feet. It can’t tolerate cold weather and would have to be harvested prior to first frost, if used as a biomass crop in the Southeast.

rroberson@farmpress.com