Energy crops may come from a variety of sources in the future. Examples of such crops include switchgrass, hybrid poplar, energy cane, giant reed, giant miscanthus, and napier grass. Since 1975, the Department of Energy has been conducting feedstock selection experiments. In the 1990's under budgetary constraints, DOE decided to focus their efforts on switchgrass. For the purposes of this study, switchgrass is selected as a model crop representing all the various alternative dedicated energy crops. Switchgrass is a perennial native grass that has a large native range. Switchgrass can be grown from Colorado to the East Coast of the U.S. and from the Gulf Coast into Canada. Switchgrass yields in some areas can exceed 10 tons per acre and does not require large amounts of inputs. It should be noted that other crops such as hybrid poplar, energy cane, giant reed, giant miscanthus, Napier Grass, and willows could provide higher yields at a lower cost in some areas of the country.
To evaluate the potential of dedicated energy crops to provide feedstocks to the bioproduct market, potential geographic range, yields, and enterprise budgets of switchgrass are incorporated within POLYSYS. For the purpose of this analysis, the geographic ranges where production can occur are limited to areas where switchgrass can be produced with high productivity under rain-fed moisture conditions. Geographic regions and yields are based chiefly on those contained in the Oak Ridge Energy Crop County Level Database (Graham, et al, 1996). The production of switchgrass included in this analysis is assumed suitable on 368 million of the total 430.2 million acres included in POLYSYS. Switchgrass yields, by ASD, range from an annual rate of 2 to 6.75 dry tons per acre (dt/ac) depending on location. Switchgrass is not a crop option in western arid regions.
In this application, switchgrass is not available in the first two years of simulation. Currently, in the United States, switchgrass is not produced as a dedicated energy feedstock, although it is grown on some CRP acres and on hay acres as a forage crop. The lack of large-scale commercial production plus the lack of switchgrass seed necessitates a lag time before switchgrass can become a feedstock for ethanol or other bioproduct production. A minimum of two years to begin large scale switchgrass production is assumed.
Switchgrass expected prices are a function of one year lagged market prices. Once planted, the expected yields for switchgrass remain fixed for the life of the production rotation. Also, once acres are planted into switchgrass, they remain in switchgrass through the end of the simulation.
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