Miscanthus Grass
Miscanthus is a genus of about 15 species of perennial grasses native to subtropical and tropical regions of Africa and Southern
Asia, with one species (M. sinensis) extending north into temperate Eastern Asia.
The most widely known and studied varieties are:
• Miscanthus floridulus
• Miscanthus giganteus
• Miscanthus sacchariflorus (Amur silver grass)
• Miscanthus sinensis
• Miscanthus tinctorius
• Miscanthus transmorrisonensis
The species that has attracted most of the attention in relation to cellulosic ethanol production is Miscanthus giganteus. This is the sterile hybrid between M. sinensis and M. sacchariflorus. Miscanthus giganteus has been trialed as a biofuel in Europe since the early 1980s. Miscanthus is a perennial C-4 rhizomatous grass and stems emerge from the rhizome annually through March and April. In the first year of growth stems reach up to 1-2 meters in height by late August. The cooler temperatures in autumn trigger senescence and translocation of nutrients to belowground parts of the plant. By February only dry leafless canes remain; the fallen leaf material recycles nutrients and returns organic matter to the soil providing a mulch layer which helps to suppress weeds in spring. In the first year of growth the yield is limited and the stems often remain uncut. Annual harvesting takes place from the second year, during which time the crop can be expected to reach a maximum height of 3-3.5 meters. The crop has a useful life of 15-20 years. Its annual yield can reach up to around 20 tonnes per acre. It is sometimes called "elephant grass," and thus confused with the African grass Pennisetum purpureum, also called "elephant grass."
The rapid growth, low mineral content, and high biomass yield of Miscanthus make it a favorite choice as a biofuel. Miscanthus can be used as feedstock for ethanol production, often outperforming corn and other alternatives in terms of biomass cost and gallons of ethanol produced. Additionally, after harvest, it can be burned to produce heat and steam for power turbines. In addition to the amount of CO2 emissions from burning the crop, any fossil fuels that might have been used in planting, fertilizing, harvesting, and processing the crop, as well as in transporting the biofuel to the point of use, must also be considered when evaluating its carbon load. When mixed in a 50-50% mixture with coal, Miscanthus biomass can be used directly as a fuel in some current coal-burning power plants without modifications. Miscanthus can also be used for a range of non-energy end uses such as game cover, animal bedding, and cat litter or biocomposites.