vital soil nutrients like nitrogen, phosphorus, and potassium. Biomass suppliers will incorporate the costs of soil damage and nutrient loss from biomass collection into the minimum price they are willing to accept. Nutrient replacement cost (CNR) varies by feedstock and harvest technique. After adjusting for 2007 costs, estimates for nutrient replacement costs range from $5 to $21 per ton. Based on the model’s baseline oil price ($111 per barrel) and research estimates, nutrient replacement was assumed to have a mean (likeliest) value of $14.20 ($15.20) per ton for stover, $16.20 ($17.20) per ton for switchgrass, $9 per ton for Miscanthus, and $6.20 per ton for wheat straw.1 Alfalfa was assumed to have a 2-year stand with the first-year nutrient costs incorporated into the establishment costs discussed below and a cost of $65 per acre for second-year nutrient application. Given the yield assumptions for second-year alfalfa, this corresponds to approximately $16.25 per ton. Nutrient replacement was assumed unnecessary for woody biomass. The cost of nutrient replacement depends on the natural gas price and is therefore dependent on energy costs. EIA projected natural gas to oil price factor for 2022 was used to scale fertilizer costs at varying oil price levels. At the high oil price ($191 per barrel), nutrient replacement costs increase by about $1.35 per ton. At the low oil price ($52 per barrel), nutrient replacement costs decrease by about $1.00 per ton.
Harvest and Maintenance Costs (CHM) and Stumpage Fees (SF)
Harvest and maintenance cost (CHM) estimates for cellulosic material have varied based on harvest technique and feedstock. Noncustom harvest research estimates range from $14 to $84 per ton for corn stover (McAloon et al., 2000; Aden et al., 2002; Sokhansanj and Turhollow, 2002; Suzuki, 2006; Edwards, 2007; Hess et al., 2007; Perlack, 2007; Brechbill and Tyner, 2008a; Khanna, 2008; Huang et al., 2009), $16 to $58 per ton for switchgrass (Tiffany et al., 2006; Khanna and Dhungana, 2007; Kumar and Sokhansanj, 2007; Brechbill and Tyner, 2008a; Duffy, 2008; Khanna, 2008; Khanna et al., 2008; Perrin et al., 2008; Huang et al., 2009), and $19 to $54 per ton for Miscanthus (Khanna and Dhungana, 2007; Khanna, 2008; Khanna et al., 2008), after adjusting for 2007 costs.2 Estimates for nonspecific biomass range between $15 and $38 per ton (Mapemba et al., 2007, 2008). Woody biomass collection costs up to roadside range between $17 and $50 per ton (USFS, 2003, 2005; BRDI, 2008; Jenkins et al., 2009; Sohngen et al., 2010). Spelter and Toth (2009) find total delivered costs (including transportation) around $58, $66, $75, and $86 per dry ton3 for woody residue in the Northeast, South, North, and West regions, respectively.4
Using the timber harvesting cost simulator outlined in Fight et al. (2006), Sohngen et al. (2010) found harvest costs up to roadside about $25 per dry ton, with a high cost scenario of $34 per dry ton. Based on an oil price of $111 per barrel, the model assumed harvest and maintenance costs have mean (likeliest) values of $44.20 ($47.20), $37.20 ($39.20), $46.20 ($49.20), $33.20 ($34.20), and $27.20 for stover, switchgrass, Miscanthus, wheat straw, and
1 For parameters with an assumed skewed distribution in Monte Carlo analysis, the “likeliest” value denotes the value with the highest probability density.
2 Harvest and maintenance costs were updated using USDA-NASS agricultural fuel, machinery, and labor prices from 1999-2007 (USDA-NASS, 2007a,b).
3 Based on a conversion rate of 0.59 dry tons per green tons.
4 Northeast includes Pennsylvania, New Jersey, New York, Connecticut, Massachusetts, Rhode Island, Vermont, New Hampshire, and Maine. South refers to Delaware, Maryland, West Virginia, Virginia, North Carolina, South Carolina, Kentucky, Tennessee, Florida, Georgia, Alabama, Mississippi, Louisiana, Arksansas, Texas, and Oklahoma. States in the North region are Minnesota, Wisconsin, Michigan, Iowa, Missouri, Illinois, Indiana, and Ohio. West includes South Dakota, Wyoming, Colorado, New Mexico, Arizona, Utah, Montana, Idaho, Washington, Oregon, Nevada, and California.