An outlook for sustainable forest bioenergy production in the Lake States
Introduction
Agriculture feedstocks producing about 176 million dry tonnes annually in the United States are a critical source of biomass for energy production but are insufficient to meet growing demand (Perlack et al., 2005). Forest-derived biomass when combined with agriculture residues has the potential to significantly increase supply by diversifying feedstock procurement. Matching the volume of forest biomass sustainably available from more than 21 million hectares (52 million acres) of public and private forestland in the Lake States region of Minnesota, Wisconsin, and Michigan (Butler, 2008) is the focus of this analysis.
The Lake States region represents an area of the United States uniquely characterized by a significant mix of agriculture and forest production. The bioenergy industry is rapidly evolving and currently includes a number of electricity and thermal heating facilities, corn-based ethanol processing plants, and prospects for next generation biofuels such as cellulosic ethanol production (Dovetail, 2007). State policy has also evolved significantly to influence investments in bioenergy production capacity (Aguilar, In press).
Despite the potential for growth, little is known of the collective physical, economic, and environmental availability of forest biomass in the region or the cumulative effects of increased demand, both for energy and non-energy uses. We therefore characterize available biomass in Minnesota, Wisconsin, and Michigan and implications for sustainability in the context of an emerging bioeconomy, which broadly includes thermal heating, electricity, transportation fuels, and related bioproducts from forest residues (Duchesne and Wetzel, 2003). Assessment of forest biomass availability, the economics of removal, existing and projected demand, and corresponding policy incentives may provide a useful framework for other regions of the country. The propensity for third-party forest certification and adoption of biomass harvest guidelines are also highlighted to illustrate the use of environmental safeguards in unison with bioenergy development.
Section snippets
Lake States regional distinctions
The primary forest products industry in the Lake States is comprised of three main sectors: pulp and paper, engineered wood products, and lumber. Combined, about 4000 primary and secondary wood manufacturing companies produce about USD $40 billion of product shipments each year, and as of 2005 total direct employment exceeded 200,000 jobs. In Wisconsin, approximately 96,000 individuals are employed in primary forest manufacturing making it Wisconsin's largest manufacturing workforce. An
Forest biomass supply
Forest biomass supply was calculated by aggregating the volume available from integrated harvest operations, other forest removals like land clearing and cultural operations, and unused mill residue. Supply estimates were made for each county in Minnesota, Wisconsin and Michigan and focus most on the largest and least expensive source of biomass – integrated harvesting operations – where sawlogs are utilized in traditional timber and pulpwood markets and the residuals for bioenergy and related
Source and growing stock
The ability to meet growing demand for bioenergy production will rely in part on recovering new sources of biomass. Harvest residues, or the tops and branches of trees and trees too small for other markets, are the largest unused source in the Lake States. They are also the least expensive to collect when integrated with commercial timber harvesting operations where the roundwood, or sawlog portion of the tree, are removed for higher-valued markets and the biomass is removed subsequent to
Costs and opportunities
The supply of biomass is highly price-sensitive up to the point where roadside prices become competitive for pulpwood. Currently, only the lowest-value material is typically used in thermal or energy applications to be competitive with natural gas or coal fuel sources. The roadside price paid for biomass is also determined by its proximity to processing facilities and the extent of competing uses. Increased demand created by incentives for renewable energy could create increased competition and
Implications for a Lakes States bioeconomy
There are high expectations for a Lake States bioeconomy. Prospects exist for increased employment and economic benefits but they hinge financially on the ability to procure, transport, and utilize forest biomass in conjunction with agricultural residues. There is also potential for enhanced forest productivity through commercial thinning, which could increase the volume of biomass available for thermal heating, electricity, and biofuels production; all of which offers opportunities for reduced
Conclusion
The outlook for thermal heating, electricity, and biofuels production in the Lake States holds promise, but questions remain. When looking to the future with a focus on sustainability, the most significant need is accurate assessments of biomass availability. Statewide estimates, including the ones in this study, provide useful information but do not fully reflect local constraints and resource demands. The economics of harvesting and transportation, the value of different feedstocks,
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