Switchgrass is a native prairie grass of "the tall grass prairie", in contrast to the short grass of the "high plains". Known for its hardiness and rapid growth, this perennial grows during the warm months to heights of 2–6 feet. Switchgrass can be grown in most parts of the United States, including swamplands, plains, streams, and along the shores & interstate highways. It is self-seeding (no tractor for sowing, only for mowing), resistant to many diseases and pests, & can produce high yields with low applications of fertilizer and other chemicals. It is also tolerant to poor soils, flooding, & drought; improves soil quality and prevents erosion due its type of root system.

Switchgrass is an approved cover crop for land protected under the federal Conservation Reserve Program (CRP). CRP is a government program that pays producers a fee for not growing crops on land on which crops recently grew. This program reduces soil erosion, enhances water quality, and increases wildlife habitat. CRP land serves as a habitat for upland game, such as pheasants and ducks, and a number of insects. Switchgrass for biofuel production has been considered for use on Conservation Reserve Program (CRP) land, which could increase ecological sustainability and lower the cost of the CRP program. However, CRP rules would have to be modified to allow this economic use of the CRP land.

Miscanthus x giganteus is another viable feedstock for cellulosic ethanol production. This species of grass is native to Asia and is the sterile triploid hybrid of miscanthus sinensis and miscanthus sacchariflorus. It can grow up to 12 feet (3.7 m) tall with little water or fertilizer input. Miscanthus is similar to switchgrass with respect to cold and drought tolerance and water use efficiency. Miscanthus is commercially grown in the European Union as a combustible energy source.

Corn cobs and leaves, wood chips and paper pulp are also feedstocks for cellulosic ethanol.

 

The Advantages of Cellulosic Feedstocks

Cellulosic feedstocks have many advantages over using corn to produce ethanol. Because cellulosic crops are not used for food, there is inherently less price volatility. And because a wide variety of crops can be used, they can be grown in a wide variety of geographic locations--even on marginal lands--and can, therefore, be more abundant. Plus, with certain crops, more ethanol can be produced per acre than can be made with corn.

With so many advantages, it seems only natural that we have dedicated energy crops, rather than using food crops for ethanol production.

Here are some numbers to think about.

Right now, corn yields, on average, about 160 bushels per acre, with industry predictions climbing all the way up to 300. And we get about three gallons of ethanol per bushel. That means for every acre of corn harvested, about 900 gallons of ethanol can be made.

Add in four tons of stover (converted cellulosically) per acre, with which you can produce 100 gallons per ton, and we're looking at additional ethanol production of 400 gallons per acre--for a grand total of 1,300 gallons per acre. And that's using two different feedstocks, with two different harvest times, two different costs and two different conversion processes.

Now consider a dedicated biomass energy crop like switchgrass, miscanthus or sorghum. These crops can be harvested, at the present time, at a rate of 20 tons per acre, with ethanol production of 100 gallons per ton, for a total of 2,000 gallons per acre. You can see why energy crops and the cellulosic process will be huge successes.

And that's with the current numbers. Imagine how big this would be if crop yields and gallons per acre were increased and cost were continually driven down. That's exactly where this industry is heading.