Sustainable Biomass Energy: Greater Focus without a Consensus, Yet. By Gary Radloff Director of Midwest Energy Policy Analysis Wisconsin Bioenergy Initiative Among the challenges with next-generation energy is whether biomass feedstocks will be grown sustainably on the rural landscape. The United States, and specifically the Midwest, has an abundant but finite amount of land and biomass feedstocks to develop the emerging bioeconomy. While the amount of research and commentary about sustainable production of biomass to energy grows, there remains an agreement on the critical trade offs necessary for success. A great deal of hope is being pinned on changing a U.S. and global energy system that is still dominated by high carbon fuels of coal and gasoline to more renewable energy sources. Biomass to energy is just one part of that renewable energy source mix, but for Wisconsin it could be a significant part of an alternative energy strategy. We have learned that first generation biomass feedstocks of corn and soybeans do impact soils, water quantity and quality and wildlife habitat. More research and an increase in policy papers on the topic of sustainable biofuels are starting to help bring the many related issues into a clearer focus. The first challenge is simply trying to define sustainability. Generally, sustainability is the term to describe the ability to meet current needs in a manner that does not jeopardize the capacity of future generations to meet their needs.1 The Ecological Society of America has concluded that sustainable production of biofuels must not negatively affect energy flow, nutrient cycles, and ecosystem services, and these factors must be considered in biofuel production systems.2 “In agricultural ecosystems, several factors have been used to determine sustainability, including the net primary productivity of the plants grown there, the nitrogen content of those plants, soil fertility, and insect abundance. Researchers often have included species diversity, nutrient loss, soil loss, and economics in the list of factors for consideration”.3 The standard sustainability “three-legged stool” definition includes environmental, economic and social criteria to be addressed. This article will review some of the current literature on sustainable bioenergy. Energy end uses of conversion to liquid fuels and combined heat and power will be considered somewhat interchangeably. The focus will be primarily agricultural biomass feedstock sources. (Editorial note: A pending future article will look at some recent issues with woody biomass to energy.) Solely within the agriculture system, there are tensions over competing uses that require careful research and robust dialogue about next steps.
Renewable Energy Production Today, biomass to energy makes up more than half of the total U.S. renewable energy generation. About 20 percent of the renewable energy used was biomass consumed for industrial applications, principally the papermaking sector, by facilities producing solely heat and steam. The U.S electric power sector renewable energy total is tiny, with only three percent from renewable sources compared to 48 percent coal, 21 percent natural gas and 20 percent nuclear. Burning wood for heat has been around since the early days of human history and Wisconsin residents and businesses still use it for heat. 1 Our Common Future (1987) and Mitchell, et. al. (2010) 2 Ecological Society of America. (2008) 3
Our Common Future (1987) and Mitchell, et. al. (2010)
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Public policy is incrementally driving the United States toward greater renewable energy use; biomass for renewable fuels is likely to lead the pack. The Energy Security and Independence Act (EISA) mandates 36 billion gallons of renewable fuel by 2022. The only commercial-scale renewable fuel today is corn to ethanol through fermentation. Today about 12 billion gallons of ethanol are produced, but that is projected to grow only to 15 billion gallons annually under EISA. There are limits to even meeting the current federal law (EISA) with a goal of 36 billion gallons of renewable fuels by 2022. It would take an estimated 514 million tons of dry biomass to meet the EISA fuel mandate.6 For a comparison, about 104 tons of corn is used today for first generation ethanol. Can the current landscape handle the biomass feedstock supply demand for the federal mandates of the future? Further, if the utility sector continues to look to biomass for sources of heat and power production from the land must continue to be even greater. Currently, the public policy for renewable power is a hodge-podge of state Renewable Portfolio Standards (RPS) mandating varying levels. In Wisconsin the utilities have been mandated to use ten percent renewable energy by 2010 and new legislation wants to push the 25 percent by 2025. Wind power is the most likely source to meet the demand from the utility sector, although multiple biomass to energy projects are advancing in Wisconsin including the Bayfront Power Plant in Ashland, portions of the Charter Street Plant in Madison, E.J. Stoneman Power Plant in Cassville and a Public Service Commission (PSC) permit is being considered for a We Energies/Domtar partnership at Rothchild, among others. As next generation renewable energy fuels begin to emerge, the feedstock mix is expected to change. Cellulosic biofuels are receiving intensive research through U.S. Department of Energy (DOE) funding. The Great Lakes Bioenergy Research Center (GLBRC) centered in Madison, includes a team of researchers trying to break the cellulosic ethanol bottleneck through a cross-disciplinary set of work that includes sustainability as a specific evaluation track. Different cellulosic feedstocks such as woody biomass are expected to have the lowest early-stage costs followed by straw and high-yield grasses. In some regions such as Iowa and Nebraska, corn stover and cobs might be more dominant. A recent report from the National Academy of Science’s workshop on the sustainability of biofuels estimates this will take to at least 2030 before large scale cellulosic fuel production is in place although a handful of demonstration projects are now opening.7 The longer time line for commercialization of cellulosic biofuels allows for science to catch up as well on sustainable land management practices for biomass feedstock growth and harvesting. “By promoting best management practices and developing plants for biofuels in the most environmentally efficient way as well as in optimal geographic locations, the development of these energy sources can be as sustainable as possible from the very start of production.”8 Yet, others take a somewhat more skeptical view of this transition noting that policy and planning must align in addition to scientific research. “Greater knowledge is needed regarding the long-term environmental impacts of largescale production and use, specifically, as to whether the environmental attributes are indeed a net positive.”9 Getting policy, planning and research to align also takes a vision for sustainable biomass energy and two authors writing for the National Wildlife Federation have started well down that path.
One Vision of Sustainable Biomass Energy A critical evaluation of the lessons learned from first generation biofuels provides the foundation for the vision spelled out by authors Loni Kemp and Julie Sibbing in their paper, “Growing a Green Energy Future: A Primer and Vision for Sustainable Biomass Energy.” 6 Estimate from Randy Jackson and the Great Lakes Bioenergy Research Center (2010) 7 National Research Council p. 14 (2010) 8 Mitchell, et. al p. 7 (2010) 9
Baker Institute and Rice University Forum p. 12 (2010)
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The first generation biofuel of corn-to-ethanol from fermentation has created a great deal of criticism from some in the environmental policy networks. The concerns with particular agriculture lands include:
• Too much soil erosion • Too much pesticide and fertilizer runoff • Too much fossil high-carbon energy used for inputs and tractors • Too little soil organic matter retained in soils • Too little habitat for wildlife and beneficial insects • Too much of an incentive for farmers in other countries to clear their forest (leading to massive releases of carbon that exacerbates global warming) to make up for the deficit of commodities created by the diversion of crops from food and animal feed.
In short, (under current conditions and management practices), the natural ecosystem cannot continue to regenerate and grow such crops into the future without serious environmental degradation and massive fossil fuel injections—not a good scenario for a sustainable source of renewable energy.”10 Kemp and Sibbing are very clear that sustainable biomass must help address global warming. This takes on the issue of whether the policy goals of greater energy security and reducing greenhouse gas emissions can be taken on simultaneously. Using life cycle analysis the first generation biofuel of corn-to-ethanol does not fare well, especially when a factor for indirect land use is added to the equation. Indirect land use is when farmers, in say the Midwest states, expand corn production for ethanol or soybean production for biodiesel, then farmers in other countries may clear carbon-rich land like the rainforests to make up for the global reduction caused by feedstock going into energy uses. The science on indirect land use is still in dispute in many circles and has created a schism between former allies in agriculture and environmental communities promoting renewable energy solutions from the land. The authors say that policy incentives should only promote bioenergy that has a life cycle greenhouse gas balance significantly better that fossil fuels.11
The Challenge of Sustainability At least six critical dimensions of sustainability must be considered for biofuels implications for land use and biodiversity, according to the authors of one of the studies done for the Ecological Society of America. Virginia Dale, Keith L. Kline, John Wiens and Joseph Fargione in their report, “Biofuels Implications for Land Use and Biodiversity” list the dimensions:
• Feedstock Type: (For example switchgrass, corn stover, manure, hybrid poplar or willow, etc.) • Feedstock Location: (For example near the biorefinery, along riparian ways such as buffer strip, adjacent to the forest, cold or wet lands, etc.) • Feedstock Extent: (For example in 20 percent of a watershed or 5 percent of a watershed, patchy or blocky area, etc.) • Environmental Attributes: (For example ecosystem benefits or damages in areas of erosion, soil carbon, water quality, runoff and wildlife, etc.) • Original (land) Conditions: (For example native forest, pasture, agriculture fields, Conservation Reserve Program land, etc.) • Feedstock Management: (For example use of no-tillage, single cut, skidder tires, fertilizer, cover crops, etc.)12
10 Kemp, Loni and Sibbing, Julie M. p. 2 (2010) 11 Kemp, Loni and Sibbing, Julie M. p. 2 (2010) 12
Dale, et al, page 7 (2010)
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These authors suggest that a landscape approach is needed for evaluating the above dimensions for sustainable biomass to energy management. These broader land use factors also start to capture the social, economic and ecological costs and benefits of the system. “This landscape approach needs to consider many factors, including the type and location of plant species to be grown for biofuel feedstock, farming and harvesting systems involved in their production, transportation to refineries, the type and location of the production facilities, and transportation of the fuel to market.”13 It is worth noting that many of these factors go into life cycle analysis (LCA) and the policy dimensions of that calculation can determine the winners and losers in biofuel production. A further elaboration of these dimensions follows. The U.S. government funded research points to switchgrass as a leading biomass feedstock for energy use.
Switchgrass as a Biomass Feedstock Type Which biomass feedstock is chosen can be a significant factor in minimizing land use change and life cycle greenhouse gas emissions. For example, a next-generation biofuel may come from the feedstock switchgrass. When considering the question of sustainability and biofuels, the Ecological Society of America has concluded that sustainable production of biofuels must not negatively affect energy flow, nutrient cycles, and ecosystems services.14 A very thorough looks at biofuels and sustainability comes from four recent papers commissioned by the ecological society of America. Research on switchgrass has been going on at the University of Nebraska since the 1930s. This perennial grass can produce a deep-rooted system that sequesters carbon and provides a better buffer from other crop runoff. The United States Department of Agriculture (USDA), Natural Resources Conservation Service (NRCS) has used switchgrass in conservation plantings and buffer strips. Switchgrass provides food and cover benefits for wildlife, along with big bluestem, little bluestem and Indiangrass for habitat benefits. It is known as one of the big four-prairie grass in conservation circles.15 The United States Department of Energy (DOE) has identified switchgrass as a model perennial herbaceous cellulosic biomass to energy feedstock.16 University research also shows switchgrass has very good potential to provide a high-energy value and low greenhouse gas emission value.
• An energy model using estimated agricultural inputs and simulated yields predicted switchgrass produced 700% more output than input energy.17 • Validation of these modeled results with actual inputs from switchgrass grown on 10 farms at the field scale in Nebraska, South Dakota, and North Dakota produced 540% more renewable energy (net energy value NEV) than non-renewable energy consumed over a five year period and had a (petroleum energy ration PER) of 13.1.18 • Average GHG emissions from switchgrass-based ethanol were 94% lower than estimated GHG emissions for gasoline.19
Opponents of switchgrass monocultures contend that diverse mixtures of native plants are ecologically more beneficial and should be considered for biomass production. Research on bird habitat generally finds diverse grasslands are preferred over monocultures. “Although managed switchgrass monocultures produce 1.5 to 4 times more biomass than native tallgrass prairies, minimal research has been conducted that directly compares the ecological benefits of monocultures and mixtures…In an evaluation of 34 grasslands sites in northeastern US, CRP grasslands with the greatest number of plant species had the lowest potential ethanol yield, whereas sites with a small 13
Dale, et. al p. 1 (2010) Ecological Society of America (2008) 15 Mitchell, Rob, et. al. p. 2 (2010) 16 Dale, et. al. (2010) 17 Farrell, et. al (2010) 14
18
19
Schmer, et. al (2008) Schmer, et. al (2008)
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number of grass species had the greatest potential ethanol yield. The low diversity CRP sites could produce more than 600 gallons of ethanol per acre while maintaining the ecological benefits of the CRP sites.”20 The overall goal for biomass energy crop systems is that they be managed sustainably so that they do not degrade habitat, deplete carbon stocks, damage biodiversity or need high inputs of chemicals with high amounts of nitrogen and phosphorus. Other potentially sustainable feedstocks could come from waste materials, algae, and planting winter cover crops for biomass on existing cropland. To avoid competition with agriculture lands now growing food, an increasing amount of focus is being placed on the opportunity of using marginal lands for energy crops.
Marginal Land as a Feedstock Location Various studies are trying to measure how much marginal land is available in the United States, and similar work is being done to determine the amount of marginal land in Wisconsin. One estimate states that in the US there could be between 51 and 67 million hectares of marginal land that could produce as much as 321 million tons of biomass. The 2007 US Census of Agriculture identifies some 30 million acres of land that includes idle lands, land in cover crops for soil improvements and fallow rotations. Again, biomass crops could also be targeted in a more careful land use planning strategy on farms as rotations strips or buffers with cropland.21 A five-year study conducted on marginal land that qualified for CRP in Nebraska demonstrated that the potential ethanol yield of switchgrass was equal to or greater than the potential ethanol yield of no-till corn (Varvel et. al. 2008).22 Work on identification of marginal lands in Wisconsin is still under development, but preliminary research puts the estimate at six million acres of marginal land. The preliminary study identified “open land” that is not currently in agriculture, but was capable of producing crops. A second phase of work is trying to refine the margin of area is the broad first-phase of analysis. This work selected potential feedstocks of switchgrass, hybrid willow or corn stover for a unit of analysis. The GIS mapping and work done by Steve Ventura at the University of Wisconsin-Madison defines marginal land as generally the most environmentally sensitive parts of our landscape – steep topography with fragile soils or low and wet. In its current state (fallow, CRP, etc.), these lands provide ecosystem services such as wildlife habitat, flood protection, and groundwater infiltration. Conversion to cropland, even low intensity systems such as permanent grass culture, involves tillage, nutrient application, and land cover homogenization that may have negative environmental consequences. Conversely, conversion of steep or wet land currently in food crop production to less intensive bioenergy crops may generate more ecosystem services.”23
Feedstock Extent Developing sustainable biomass energy practices on the land will take work at both the farm and landscape scales. First, individual landowners make a wide range of decisions every day about how to manage their agriculture or forest lands, particularly when for commercial use. Getting best practices land use management from the farmer and forester are critical. In Wisconsin, the Wisconsin Department of Natural Resources (DNR), Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP), and the University of Wisconsin faculty and researchers are collaborating to develop sustainable nonwoody biomass guidelines. The work is to be completed in late 2010 or early 2011. 20
Mitchell, Rob, et. al. p. 4 (2010) and Adler, et. al (2009) Dale, et. al. (2010) 22 Dale, et. al (2010) 23 Ventura, et. al. (2010) 21
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The Wisconsin Forestry Council already has advisory woody biomass harvesting guidelines. Getting agriculture landowners to add an energy crop or switch from a row crop to energy crop will first take the right economic market signals and there may be a need for policies to incentivize practices that catalyze eco-system services enhancement. One policy incentive will be discussed later in this paper. The authors of the paper, “Biofuels: Implications for Land Use and Biodiversity” have made a strong case for looking at the landscape scale for sustainable development. “The sustainable development of renewable fuel alternatives can offer many benefits but will demand a comprehensive understanding of how our land-use choices affect the ecological systems around us.”24 One point is that different biomass feedstock choices may vary by region. For example, southern United States regions may have advantages for biomass feedstocks such as miscanthus, pine, sorghum and northern regions may have advantages for hybrid poplar willows. Both regions have advantages for switchgrass. “Decisions on how crops are grown and managed will determine their effects on carbon sequestration, native plant diversity, competition with food crops, greenhouse gas emissions, water quantity, and water and air quality.”25
Environmental Attributes The old axiom in health care patient treatment starts with “do no harm,” and the same should be true for treatment of the landscape for biomass to energy development. A more positive focus should be what environmental attributes can be improved under biomass to energy development. More research is needed in this area, but existing knowledge about agriculture and forest management can be built upon. First stage biofuels of corn to ethanol raised concerns about water quantity use and despite improvements in re-use of water in the production process concerns remain. “Much is known about water quantity issues required for crop growth at the local farm scale, and there is broad consensus that, given future issues with water quality and quantity, dedicated bioenergy crops should be grown where irrigation is not required, generally east of the 100th meridian”26 (which divides North Dakota, South Dakota, Nebraska, Kansas roughly in half and splits portions of Oklahoma and Texas).
Original (land) Conditions One area where there may be growing consensus is that prime agriculture lands that provide food should not be the primary target area for energy crops. The discussion around food versus fuel with first generation corn-to-ethanol technology drew attention to the land use competition issue. Today, it is expect corn-to-ethanol production, now at about 12 billion gallons, likely reaches peak production at 15 billion gallons. How much land in the U.S. and Wisconsin should be dedicated to food and fiber from traditional agriculture will still draw a debate, but most advocates of next-generation biofuels agree that marginal lands should be targeted. But, the original condition of these marginal lands will be an issue when converting them to growing energy crops. The soils will not have been worked for a time and these lands are typically more steeply sloped. The definition of “marginal” could vary greatly, particularly by region. “Depending on the time and place, marginal land may also refer to idle, underutilized, barren, inaccessible, degraded, excess or abandoned lands, lands occupied by politically or economically marginalized populations, or land with characteristics that make a particular use unsustainable or inappropriate,” note the authors of the report Biofuels: Implications for Land Use and Biodiversity.”27
24
Dale, et. al. p. 1 (2010) Dale, et. al. p. 2 (2010) 26 Mitchell, et. al. p. 5 (2010) 25 27
Dale, et. al. p. 5 (2010)
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Feedstock Management Ultimately, feedstock management practices will be a key to success in achieving sustainability. Reducing fertilizer and utilizing no-till can be critical to carbon sequestration and limiting greenhouse gas emissions, for example. These will be steps to improving overall environmental quality when added with strategic cropping practices such as planting buffer strips, increasing the use of perennial crops strips along swales and conventional crops fields. This can all be a part of a systems approach to landscape scale land use planning for energy crop development.
A Policy Option for Wisconsin Wisconsin can enhance its environmental protection and increase economic opportunity for rural landowners through public policy to encourage renewable energy crops. The key to success is a strong standard for sustainable management, a clear goal to enhance eco-system services at a landscape scale and support to the landowner for crop establishment. An important component of this policy would be targeting lands that now have row crops planted on highly erodible lands (HEL) for next generation energy crops. A similar targeting of areas already coming out the Federal Conservation Reserve Program (CRP) could be considered for this program. Likewise, the state could use research already done under the Wisconsin Buffer Initiative to target lands that could better protect state waterways from chemical runoff. A combination of careful research and selection of targeted lands and well-defined growing and harvesting guidelines for the energy crops might include a designation for a certified biomass crop area. Producers and landowners adopting the guidelines and growing biomass crops in the designated areas could receive eligible payments. Program developers should use a systems approach to assess the energy crop establishment carbon sequestration implications, the potential impacts on the downstream eco-systems, and current soil and water quality of the area. The program designer’s focus on eco-system services – including those that are biodiversity—based, could provide information to local soil and water conservation staff necessary for the development and implementation of land-management approaches that meet multiple needs. Additonally, they should consult with UW experts and others to look at the impacts of energy crops at different spatial scales – from farm and forest landscapes to watersheds and foodsheds – and assess the best land use strategies to meet sustainability goals. These steps would be used to determine and map the priority lands targeted for programmatic implementation. A stakeholder advisory group could be utilized including private land trusts, organizations working on wetland and prairie restorations, and conservation and environmental protection advocates to make sure lands for energy crops complement other statewide efforts to protect sensitive lands at the watershed scale. This might include looking at the state Land Legacy maps, Forest Legacy maps, Stewardship Program designated lands, Working Lands Enterprise Areas, and Working Lands Purchase of Agriculture Easements (PACE) program areas to complement state efforts on enhanced eco-system services while establishing energy crops. A fee structure could be established for training and education and certification of the biomass crop areas. A similar exercise should occur to work with other existing state and federal policy efforts. At the state level this might include the Fuel for Schools program and at the federal level the Biomass Crop Assistance Program (BCAP). The state Energy Crop Reserve Program should make it a priority that encourage crops grown under this systems-based landscape approach will include buffer strips, transitional lands or strips between existing row crops and waterways, land near a grassland restoration area, and crops and land that can maximize sequestration of atmospheric carbon dioxide.
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Conclusion As more research comes out on the potential for greater eco-system benefits from strategic use of energy crops, the likelihood of policy consensus may occur. Without this rigorous documentation from research, a healthy skepticism will remain. The authors of these papers have helped to frame the discussion going forward and that is an important step. Clearly delineating the policy trade-offs, such as energy security, rural economic growth, greenhouse gas reduction or neutrality, along with potential eco-system benefits from sustainable practices must be measured and quantified to the extent possible. It is also clear that this issue goes beyond how best to use the biomass, but rather how to preserve the soil, air and water quality. It is worth remembering that sustainability has never been an issue for legacy energy from high greenhouse gas emitting coal and gasoline. Still, it is critical to raise the bar for next generation. Next generation energy must have a land ethic that views the land and biomass not as producing a commodity, but rather the land and the biomass it produces as a community asset now and forever.
Sources and Articles Reviewed Dale, Virginia H., Kline, Keith L., Wiens, John and Fargione, Joseph. 2010. Biofuels: Implications for Land Use and Biodiversity. Ecological Society of America. Energy Information Administration. 2008. Web Site: www.eia.doe.gov. Accessed June 2010. Garcia, C.H. and Ventura, S.J. 2008. Marginal Land for Energy Crop Production in Wisconsin. Report to Wisconsin Department of Agriculture, Trade and Consumer Protection. Land Information and Computer Graphics Facility, University of Wisconsin-Madison. Portions of the findings published in the Status of Wisconsin Agriculture. 2009. Department of Agricultural and Applied Economics. College of Agricultural and Life Sciences. Kemp, Loni and Sibbing, Julie M. 2010. Growing a Green Energy Future: a Primer and Vision for Sustainable Biomass Energy. National Wildlife Federation. Koshel, Patricia and McAllister, Kathleen, Rapporteurs. 2010. Expanding Biofuel Production and The Transition to Advanced Biofuels. Lessons for Sustainability from the Upper Midwest. Summary of a Workshop. National Research Council of the National Academies. Proceedings of the National Academy of Sciences. Mitchell, Rob, Wallace, Linda, Wilhelm, Wallace, Varvel, Gary and Wienhold, Brian. 2010. Grasslands, Rangelands, and Agricultural Systems. Ecological Society of America. Robertson, G. Phillip, Hamilton, Stephen K., Del Grosso, Stephen J., and Parton, William J. 2010. Growing Plants for Fuel: Predicting Effects on Water, Soil, and the Atmosphere. Ecological Society of American. Schmer, M.R., Vogel, K.P., Mitchell, R.B., Follet, R.F., and Perrin, R.K. 2008. Net Energy of Cellulosic Ethanol from Switchgrass. Proceedings of the National Academy of Sciences 105: 464-469. Varvel, G.E., Vogel K.P., Mitchell, R.B., Follet, R.F., and Kimble, J.M. 2008. Comparison of Corn and Switchgrass on Marginal Soils for Bioenergy. Biomass and Bioenergy. 32: 18-21.
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