Forest Biomass: Renewable, Low Carbon, and Limited

Forest biomass, such as logging slash and low-value trees, offers great promise as a source of renewable energy. Thriving markets for these materials will add value to working forests and provide an important tool for addressing a number of conservation objectives, including hazardous fuels reduction, habitat management, and restoration of degraded woodlands. In 2005, as part of the “billion ton study”, the U.S. Department of Energy and U.S. Department of Agriculture concluded that America’s forests had the potential to produce 368 million dry tons of woody biomass on an annual basis. This number is not universally accepted, and USDA and DOE are revisiting the assessment, but estimating this resource is a difficult task. Available forest acreage is limited by a number of non-market factors, such as environmental regulations, conservation efforts, non-timber forest values, and landowner behavior. Beyond this, economic factors will dictate where biomass is available and in what quantities.

As national policy and global markets increase demand for woody biomass, prices for these materials are likely to rise. High prices will benefit forest landowners and improve the bottom line for sustainable forest management, but they will also increase costs for existing users of biomass. Some are concerned that increased demand will bring energy producers into competition with the forest products industry for pulpwood and residues, or drive wood harvesting to unsustainable levels. On the other hand, the forest products industry is able to pay higher prices for wood fiber than most energy producers can afford, because of the high value of timber, pulp/paper, and other wood products relative to the value of energy. Consequently, the availability of low-cost biomass will limit where and to what extent bioenergy is seen as cost-effective. This is particularly true as the cost of others renewables (such as wind, solar, geothermal, and water technologies) continues to decline.

On June 11, the Environmental and Energy Study Institute (EESI) held a briefing about the role that forest biomass can play in contributing to renewable energy supplies in the United States. Bioenergy has been a central, and often controversial, element in the debate surrounding the climate and energy legislation currently moving through the Congress. Much of this controversy has focused on the real or perceived impacts of using biomass and land resources for energy. This briefing focused on the size of the forest biomass resource in the United States, as well as its position within a larger context of national and global wood fiber markets. Understanding these issues is necessary to assess the impacts of policy decisions on forest productivity, biodiversity, forest landowners, and the forest products industry, and to appreciate the role that forest biomass can realistically play in meeting national objectives.

• Estimating biomass supply is a complex exercise, and depends upon a number of assumptions regarding the size of the physical resource, harvesting constraints, logistical costs, landowner behavior, and economics.
• USDA and DOE, in their “Billion Ton Study”, estimated that 368 million oven dry tons (odt) of woody biomass could be made available on an annual basis. Supply curve analysis suggests that 50 million odt of the total could be obtained at a price of $44/odt. Of this, 45 million odt would come from private forest lands alone. Combined with agricultural residues and dedicated energy crops, this amount would be sufficient to meet the 16 billion gallons of cellulosic biofuels mandated by the national Renewable Fuels Standard (RFS).
• Forest residues will likely be an important source of woody biomass for energy production, but quantities are limited and there is considerable uncertainty about how to collect them in a cost-effective manner. As demand for biomass increases (such as under a combined national Renewable Electricity Standard (RES) and the national RFS), pulpwood will likely make up a significant amount of the overall demand. Pulpwood is generally more expensive than residues, but the infrastructure is already in place to harvest and move this commodity. Under these circumstances, localized competition between energy facilities and the forest products industry for wood fiber is likely to occur.
• A Union of Concerned Scientists (UCS) analysis estimates that a national RES mandating 25 percent renewable energy by 2025 would increase demand for forest residues by 62 million odt, mostly as a replacement for coal in co-firing applications at existing plants.
• The current definition of timberland qualifying as “renewable biomass” under the Energy Independence and Security Act of 2007 excludes biomass from public lands and some non-plantation private forests, reducing the available supply of woody biomass.
• Landowner decisions will likely reduce available woody biomass supplies even further. Whereas nearly 100 percent of farmers are focused on revenue, many owners of private forestlands do not react to price signals, instead owning forests for recreation, aesthetics, biodiversity conservation, and other non-timber objectives. Many other private owners do have the tools or the knowledge requisite for participation in forest product markets.
• Creating a new market for woody biomass in the energy sector will provide companies an incentive to manage forests sustainably in order to guarantee future supply, a trend likely to lead to investments in forest regeneration. Opening new markets for sustainable forestry will be especially important as other markets, notably in paper, face the prospect of a long-term decline.
• The United States had the same number of acres of forested land in 2007 as it did in 1907, demonstrating that it is possible to maintain a thriving forest products industry without losing forest acreage. The nation currently has 40 million acres of marginal croplands that could be used to expand forest cover (and woody biomass supply) even further.