Polysys

POLYSYS is an U.S. agricultural sector policy simulation model that includes national demand, regional supply, livestock, and aggregate income modules (De La Torre Ugarte, et al, 1998). POLYSYS is anchored to published baseline projections for the agricultural sector and simulates deviations from the baseline. In this study, a 2006 10-year United States Department of Agriculture (USDA) baseline for all crop prices, yields, and supplies (except hay) is used. This baseline, which runs through the year 2015, was extended to 2030 using the assumptions presented in Appendix B. All dollar values presented in the results on the agricultural sector impacts are in nominal dollars through 2015 and in 2015 dollars thereafter.

The POLYSYS model includes the eight major crops (corn, grain sorghum, oats, barley, wheat, soybeans, cotton, and rice), as well as dedicated energy crops and hay (alfalfa and other hay included). Corn and wheat residue costs and returns are added to the corresponding crop returns if profitable. POLYSYS is structured as a system of interdependent modules of crop supply, livestock supply, crop demand, livestock demand and agricultural income. The supply modules are solved first, then crop and livestock demand are solved simultaneously, followed by the agricultural income module. This project includes a bioproducts module which fills exogenous

Table 1. Summary of Conversion Technologies and Cost Information Sources.

Conversion Technology

Facility Size-Output

Facility Size-Feedstock Use

Cost Information Source

Ethan3ol from Shelled Corn (Dry Mill)

48 MM Gal/

year

17,105,455 bushels

McAloon, A., F. Taylor, W. Yee, K. Ibsen, and R. Wooley. 2000. "Determining the Cost of Producing Ethanol from Corn Starch and Lignocellulosic Feedstocks". National Renewable Energy Laboratory (NREL/TP-580-28893). Joint study sponsored by USDA and DOE; e-mail correspondence from Dr. Vernon R. Eidman

Ethanol from

Cellulosic

Residues

(Stover,

Switchgrass,

Rice Straw, and

Wheat Straw)

69.3 MM Gal/year

Stover 772,333 dry tons

Switchgrass 984,375 dry tons

Rice Straw 670,573 dry tons Wheat Straw 1,061,538 dry tons

Aden, A., M. Ruth, K. Ibsen, J. Jechura, K. Neeves, J. Sheehan, B. Wallance, L. Montague, A. Slayton, and J. Lukas. 2002. "Lignocellulosic Biomass to Ethanol Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover". National Renewable Energy Laboratory & Harris Group (NREL/TP-510-32438).

Ethanol from Food Residues

69.3 MM Gal/year

984,375 dry tons

Aden, A., M. Ruth, K. Ibsen, J. Jechura, K. Neeves, J. Sheehan, B. Wallance, L. Montague, A. Slayton, and J. Lukas. 2002. "Lignocellulosic Biomass to Ethanol Design and Economics Utilizing Co-Current Dilute Acid Prehydrolysis and Enzymatic Hydrolysis for Corn Stover". National Renewable Energy Laboratory & Harris Group (NREL/TP-510-32438).

Ethanol from Wood Residues

32.4 MM Gal/year

500,036 dry tons

BBI International. 2002. "State of Maine Ethanol Pre-Feasibility Study". Prepared for Finance Authority of Maine.

Biodiesel from Soybeans

13.0 MM Gal/year

9,000,000 bushels

English, B., K. Jensen, and J. Menard in cooperation with Frazier, Barnes & Associates, Llc. 2002. "Economic Feasibility of Producing Biodiesel in Tennessee".

Biodiesel from Yellow Grease

10.00 MM Gal/year

80,000,000 pounds

Fortenberry, T. 2005. "Biodiesel Feasibility Study: An Evaluation of Biodiesel Feasibility in Wisconsin". University of Wisconsin-Madison, Department of Agricultural & Applied Economics. Staff Paper No. 481.

demands from the feedstock sources. The bioproducts module captures the dynamics of corn grain and cellulosic feedstocks competing to fill ethanol demand by using a searching by iteration method to find the optimal allocation of feedstocks to satisfy these demands.

There are 938 million acres within the United States that are either owned or in the hands of agricultural producers. The 2002 Census of Agriculture has determined that 430.2 million acres can be classified as cropland, while 395 million acres is classified as pastureland or rangeland (Figure 7). Of this total cropland, POLYSYS has 307 million acres available for the 8 major crops and for hay. Additionally, cropland pasture can come into production if the loss of regional pasture can be made up with additional hay production. This analysis does not include the possibility of planting and harvesting dedicated energy crops in acreage enrolled in the Conservation Reserve Program (CRP), nor does it include land currently classed as pasture/rangeland. The objective of the model is to fill projected energy demands from corn grain, soybeans, dedicated energy crops, crop residue and wood residue supplies and estimate the effects upon production, prices, acreage, government payments and net returns of all model crops and livestock.

Private Land Base 934.2 Million Acres

Total Cropland 430.2 Million Acres

□ Pasture/range

□ POLYSYS Planted Cropland

□ Cropland Pasture

□ POLYSYS Planted Cropland

□ Cropland Pasture

Source: USDA, National Agricultural Statistical Service, 2004

Figure 7. Land Use by Major Use Category, 2002.

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