A probabilistic estimate of the frequency of mowing and baling days available in Oklahoma USA for the harvest of switchgrass for use in biorefineries

Abstract

Determining the time available for required harvest operations is an essential prerequisite to optimizing lignocellulosic biomass (LCB) harvest costs. Estimating the number of days expected to be available for mowing and baling is difficult because agricultural field work is heavily weather dependent. Harvest costs are expected to constitute a large component of the cost to deliver LCB to a biorefinery. Harvest costs depend in part on the investment required in harvest machines, and this investment depends on the number of field workdays during the harvest window. Therefore, a reasonably precise estimate of the number of harvest days is necessary to determine the investment in harvest machines required to support a LCB biorefinery. The objective of this study was to determine the number of suitable field workdays in which switchgrass (Panicum virgatum) can be mowed and the number of days that mowed material can be baled. Empirical distributions of the days available for mowing and for baling switchgrass were determined for nine counties in the USA state of Oklahoma. Distributions were determined for each month and for two potential harvest seasons (short, October-December and extended, July-February). Beginning harvest in July and extending harvest through February would require only 37% as many baling machines as would be required for a short (October-December) harvest season. This potential reduction in harvest machine investment is consistent across location. An extended harvest season could reduce the investment required in harvest machines and the costs to deliver feedstock. (C) 2009 Elsevier Ltd. All rights reserved.