Sustainability of Bioenergy from Forestry - ACS Publications

Chapter 6

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Sustainability of Bioenergy from Forestry Marcia Patton-Mallory* U.S. Forest Service, 2150 Centre Ave., Building A, Fort Collins, Colorado 80526 *E-mail: [email protected]

Modern forestry practices in the U.S. have developed around a set of sustainability concepts, practices and principles that can help inform the broader discussion around bioenergy. New concepts such as greenhouse gas emission profile are being included in proposed sustainability criteria for broader bioenergy feedstock production.

Introduction Modern forestry practices in the U.S. have developed around a set of sustainability concepts, practices and principles that can help inform the broader discussion around bioenergy. In fact, the systems that have developed for forestry can be considered a model system for assuring sustainability in new bioenergy plantations and land use systems. This paper discussed how sustainability factors are woven into modern forestry practices, and the new concepts in proposed sustainability criteria for broader bioenergy feedstock production. For the purpose of this paper, the term bioenergy is used to include heat, power and biofuels. Biomass is one of the few renewable energy sources that will be used to produce all three types of energy, and potentially result in significant competition for limited resources in some parts of the country. Since biomass used for energy can grow on lands that are also valuable for food production, efficiency in biomass production and conversion need to be a fundamental consideration. In recent years there also has been increased interest in understanding full life-cycle implication of producing bioenergy, both in terms of net energy and net greenhouse gas (GHG) emissions. Recently developed sustainability criteria are starting to address this topic, in addition to the traditional set of water, biodiversity, and other considerations. Not subject to U.S. Copyright. Published 2012 by American Chemical Society In Perspectives on Biofuels: Potential Benefits and Possible Pitfalls; Taylor, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


Forestry as a Model System for Sustainability Although all woody biomass originally comes from trees, it enters the feedstock supply chain from various places. Woody biomass feedstock can come from forest residues (tree tops, limbs and trimmed logs) generated when harvesting sawlogs and pulpwood; during forest thinning to improve growth of remaining forest stands or to reduce fire hazard; from lumber trimmings during construction and other municipal clean wood waste streams; from forest product mill residues; and from purpose-grown wood energy crops. It is rare that a forest biomass product is produced alone. Usually, it is co-produced with a higher value product that remains in service for a long time (such as lumber in houses or furniture). Also, woody biomass is produced from managed forested ecosystems that also provide a number of co-benefits, including clean water, wildlife habitat, carbon sequestration, recreation, in addition to forest products. These same forests are also systems that are cycling carbon as part of the natural biosphere, often called the biogenic carbon cycle. When this is in balance, no new CO2 is added to the atmosphere because forests are sequestering at a rate that is greater than or equal to what is being release through natural process and uses, such as bioenergy. Forest products also are used in place of more energy intensive materials, such as concrete and steel. This adds complexities to the discussion of sustainability because where you draw the boundaries, time frame, and trade-offs are not always obvious. When forest biomass is not used for energy or other purposes, there is not a simple alternative scenario. For example, future probability of insects, decay, storm damage, and fire are partially dependent on future climates. These all occur as part of the natural disturbance processes in forests. These alternative fate considerations are often ignored in life-cycle analysis because they are difficult to predict with any certainty for a specific location and time. However, they need to be part of considering sustainability in its broadest terms.

Public vs Private Forests In the eastern United States only nine percent of the forested landscape is managed as public land, and in the west 58 percent is public land. The public lands can be managed by federal, state or local governments and have their own set of rules and regulations that reflect principles of sustainability. For private forest lands, forest landowners in some states have Forest Practices Acts or Best Management Practices that are required. Some states have also developed Biomass Harvesting Guidelines. Over the past 20 years, a number of systems to certify sustainable forestry have developed. Larger private forest land owners and some states have adopted these voluntary certification systems (e.g. Sustainable Forestry Initiative, Forest Stewardship Council) or participate in the American Tree Farm Program. The certification is identified with products that are made from wood grown in these forests. It is a way to let consumers know that the product comes from lands where sustainable forest practices are assured using a third party monitoring system. 102 In Perspectives on Biofuels: Potential Benefits and Possible Pitfalls; Taylor, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

On federal lands, a broad range of environmental laws govern sustainability of forest management. These include compliance with laws such as the Endangered Species Act, Clean Water Act, National Forest Management Act, and National Environmental Policy Act.


Dimensions of Sustainabilty When people talk about sustainability, it is important to ask them what they mean. The three dimensions of sustainability: economic, environmental and social considerations are important. These are briefly outlined below, with aspects that relate to biofuels. •

Economic – – – –

•

Environmental – –

–

•

Direct and indirect land use effects Soil health, water quantity and quality, air quality, biodiversity and habitat, GHG emissions, genetically modified organisms and invasive species Ecosystem services- co-production on a landscape

Social – – – –

•

New linkages in markets – energy – food - wood products Direct effects (supply, demand, cost and price) Regional and international trade Jobs in rural areas

Regional, national, and international “New Energy Economy”- renewable and advanced technology Labor rights, land rights and participation Energy security and food security

Cultural and spiritual values

Also, there are major differences in the biomass feedstocks, whether they are also food and feed sources, and if they are redirecting material from other disposal options. The challenge with applying sustainability principles is developing the value proposition for bioenergy that has formal sustainability certification. In the forestry sector, the certification of forest products has been more of a market access issue, and not necessarily a willingness of people to pay more for certified products. 103 In Perspectives on Biofuels: Potential Benefits and Possible Pitfalls; Taylor, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

Challenges to Sustainability Sustainability issues need to be addressed in the production of bioenergy as well as in the conversion processes. The dimensions of sustainability are detailed by Dale and Kline (1):


•

Production – – – – – –

•

Feedstock Type Feedstock Management Feedstock Location Feedstock Extent on Landscape Environmental Attributes Original Conditions of Land

Conversion – – – – – –

Transport of Feedstock Net Energy Water Use GHG Emissions Location of Biorefinery Transport to Markets

The Council on Sustainable Biomass Production (2) has recently released a set of sustainability criteria that could be used for voluntary certification of all non-food biomass feedstocks. The components of their criteria include: Climate Change, Biological Diversity and Productivity, Water Quality and Quantity, Soil Quality, Socio-Economic Well-being, and Integrated Resource Management Planning. Recent laws such as the Energy Security and Independence Act of 2007 set goals for biofuels production and have attempted to address sustainability criteria indirectly by narrow definitions of what qualifies as “renewable biomass” including broad exclusions of biomass from certain types of forests. While these may be well intended, the result is that broad categories of biomass that are currently a disposal problem will not qualify if used to produced biofuels. The debate about how to assure sustainability of biofuels produced from all sources will likely continue.

104 In Perspectives on Biofuels: Potential Benefits and Possible Pitfalls; Taylor, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.


Competition with Existing Products and Between Bioenergy Uses The ability to increase bioenergy production from all sources of biomass requires a direct consideration of how compatible these new uses are with production of existing products. For example, scientists are exploring ways to produce biofuels as part of the process of making paper from wood. Producing heat and power from mill residues has been a long term practice at forest products industries, and is a major part of our domestic renewable energy portfolio. The collection and utilization of logging residues that historically were left in the forest represents a large and currently under-utilized source of biomass. In agricultural systems, using corn cobs and stover can be added to the system that produces biofuels from corn, either as thermal process energy or as separate cellulosic biofuels process. Our models of supply and demand for bioenergy feedstocks need to be more directly linked to price of fossil fuels they replace (such as petroleum) so that we can better understand how different incentives and market forces interact.

Summary Producing biofuels that “make sense” and meet sustainability concerns can take many forms. In general it makes sense when bioenergy uses material that otherwise would have negative environmental consequences, is produced on marginal lands with minimal inputs, has production scaled to match local feedstock availability, is compatible with maintaining working landscapes, and that has favorable net energy and net greenhouse gas profiles.

References 1. 2.

Dale, V.; Kline, K. Defining Bioenergy Sustainability; Presentation at Biomass 2009, Fueling our Future, March 17, 2009. Council on Sustainable Biomass Production. Draft Provisional Standard for Sustainable Production of Agricultural Biomass; April 14, 2010.

105 In Perspectives on Biofuels: Potential Benefits and Possible Pitfalls; Taylor, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2012.

Sustainability of Bioenergy from Forestry - ACS Publications

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