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What is Miscanthus?

Miscanthus is a tall perennial grass that has been evaluated in Europe during the past 5-10 years as a new bioenergy crop. It is sometimes confused with elephant grass (Pennisetum purpureum) and has been called both "elephant grass" and "E-grass". Most of the miscanthus cultivars proposed as a commercial crop in Europe are sterile hybrids (Miscanthus x giganteus) which originated in Japan. A number of ornamental varieties of miscanthus are also known to exist under various common names. Miscanthus can be harvested every year with a sugar cane harvester and can be grown in a cool climate like that of northern Europe. 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. miscanthus stand
Mature stand of Miscanthus x giganteus, approximately 3.5 m (11.5 ft) high, Forchheim, Baden-Württemberg, Germany, February 1995. Photo by Dr. I. Lewandowski, Institute for Crop Production and Grassland Research, University of Hohenheim, Germany.

How is Miscanthus grown?

Miscanthus is being grown experimentally in at least 10 European countries. The crop is established by planting pieces of the root called rhizomes, which are usually collected from "nursery fields" where miscanthus has already been established. The rhizomes can be broken up, collected and planted using existing agricultural equipment such as potato harvesters and planters. Irrigation in the first year and protection from frost improves the establishment rate. The crop is normally harvested from year 2 onwards, but yields continue to improve until they level off around the 5th or 6th year. miscanthus rhizome
Miscanthus rhizome propagation material ready for planting, about 10 cm (4 in) in length, June 1996, Vejle, Denmark. Photo by L.L. Wright, Oak Ridge National Laboratory.

What annual yields can be expected under U.S. conditions?

To date, there are no yield results from any trials in the U.S. Speculating from European data on small plots in agricultural experimental stations, the crop may attain as much as 25 t/ha (10 t/acre) dry weight by Fall. In Europe, it is usually considered desirable to harvest in early Spring, after nutrient recycling and drying has taken place. By then, the yield is reduced to about 15 t/ha (6 t/acre) dry weight. Over large areas, under typical agricultural practices, an average of about 8t/ha (3t/acre dry weight) may be expected at harvest-time. The European conditions for these trials range from latitude 50 N to 37 N (roughly from North Dakota to Kentucky, but note that the European climate tends to be warmer and more moderate at the same latitudes than the U.S.). Average annual temperatures and rainfall for the European trials range from 7.5 C to 17.5 C (45-63 F), and 500-1000 mm (20-40 inches), with irrigation at the warmer, more southern latitudes. Fertilizer needs appear to be relatively low, depending upon local soil fertility. miscanthus harvest
Miscanthus x giganteus harvested using a modified forage harvester mounted on a combine, Forchheim, Baden-Württemberg, Germany, February 1995. Photo by Dr. I. Lewandowski, Institute for Crop Production and Grassland Research, University of Hohenheim, Germany

Why is there so much interest in Miscanthus in Europe?

Miscanthus has

  • relatively high yields — 8-15 t/ha (3-6 t/acre) dry weight,
  • low moisture content (as little as 15-20% if harvested in late winter or spring),
  • annual harvests, providing a regular yearly income for the grower,
  • good energy balance and output/input ratio compared with some other biomass options, and
  • low mineral content, especially with late winter or spring harvest, which improves fuel quality.
miscanthus stand
Demonstration plot of Miscanthus x giganteus pictured just before harvest. The stand is approximately 2.5 m tall. Forchheim, Baden-Württemberg, Germany, February 1995. Photo by Dr. I. Lewandowski, Institute for Crop Production and Grassland Research, University of Hohenheim, Germany.

Are there any drawbacks?

There is little or no experience with this potential crop in the United States, so its performance under U.S. conditions is unknown. As with most of the new bioenergy crops, there seems to be a steep "learning curve". Costs are expected to drop and uncertainties to be reduced as first demonstration trials and then commercial plantings become more widespread. In particular, establishment costs appear to be fairly high at present (a wide range is reported from different European countries).
Miscanthus rhizomes have a low tolerance of frost. Care may be required in some locations to minimize frost damage, e.g. by growing a "cover-crop" over the winter, or by spreading a thick layer of straw in the fields.
Native species are often preferred in the U.S. However, sterile hybrids have been used for nearly all the European trials, making the escape of non-native plants unlikely.
miscanthus bales
Miscanthus straw being baled at a demonstration plot, Forchheim, Baden-Württemberg, Germany, February 1995. Photo by Dr. I. Lewandowski, Institute for Crop Production and Grassland Research, University of Hohenheim, Germany

For more information:

A short report, "Miscanthus: a Review of European Experience with a Novel Energy Crop", ORNL/TM-13732, is in preparation. Full text of the report in html and pdf format is available.
Dr. Iris Lewandowski, Institute for Crop Production and Grassland Research, University of Hohenheim (340), D 70599 Stuttgart, Germany, email: lewandow@Uni-Hohenheim.de
Dr. S. McCarthy/ Dr. M. Walsh, Hyperion Energy Systems Ltd., Main Street, Watergrasshill, Co. Cork, Ireland, +353 (21) 889461 (phone), +353 (21) 889465 (fax), email: energy@indigo.ie
European Energy Crops InterNetwork Web site: http://www.eeci.net/
Bioenergy Feedstock Development Program (BFDP), Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN, USA, (865) 576-8143 (fax), email: bfdp@ornl.gov