Post-harvest energy chipping feasibility in mature pine forests in the Coastal Plain of the US South

ABSTRACT

Research indicates that integrated systems, in which roundwood and energy chips are produced simultaneously, produce energy chips at the lowest cost. However, integrated systems may be feasible on a narrow range of sites. Post-harvest chipping, in which roundwood is harvested by one logging crew and energy chipping conducted independently by a second crew, may allow chips to be produced from more harvest sites. The goal of this study was to evaluate the feasibility of recovering logging residues and non-merchantable stems using post-harvest systems. Time-and-motion studies were conducted on both roundwood harvesting and post-harvest chipping on three harvest tracts on the Savannah River Site in the Coastal Plain of South Carolina. Hourly machine costs were estimated using the machine rate method. Harvesting costs per tonne were calculated using a modified Auburn Harvesting Analyzer. Energy chips were produced at an average estimated cost of $22.04 green t⁻¹ (USD, onboard truck) and $31.96 t⁻¹ delivered. Requiring the feller-buncher to fell and bunch non-merchantable stems reduced feller-buncher productivity by an average of 42% but did not reduce system productivity. This study suggests that post-harvest energy chipping can be a cost-effective alternative.

KEYWORDS:

• wood-energy
• bioenergy
• logging productivity
• logging cost

Acknowledgements

The author gratefully acknowledges the support of the USDA Forest Service-Savannah River, under Interagency Agreement 89303720SEM000037 with the US Department of Energy. The author thanks Beech Island Timber & Construction, Inc. and Tracy’s Logging, LLC for their cooperation during the study. Use of make and model names is for reader convenience and does not constitute an endorsement by the author, the University of Georgia, or the USDA Forest Service. This work was supported by the USDA National Institute of Food and Agriculture McIntire Stennis project 1018443.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Institute of Food and Agriculture [1018443]; USDA Forest Service [21-PA-11083600-363].