As U.S. energy policy turns to bioenergy, and second-generation biofuels in particular, to foster energy security and environmental benefits, consideration should be given to the implications of climate risk for the incipient bioenergy industry. As a case-in-point, we review evidence from the 2012 U.S. drought, underscoring the risk of extreme weather events to the agricultural sector in general, and the bioenergy supply chain in particular, including reductions in feedstock production and higher prices for agricultural commodities and biofuels. We also use a risk management framework developed by the Intergovernmental Panel on Climate Change to review current understanding regarding climate-related hazards, exposure, and vulnerability of the bioenergy supply chain with a particular emphasis on the growing importance of lignocellulosic feedstocks to future bioenergy development. A number of climate-related hazards are projected to become more severe in future decades, and future growth of bioenergy feedstocks is likely to occur disproportionately in regions preferentially exposed to such hazards. However, strategies and opportunities are available across the supply chain to enhance coping and adaptive capacity in response to this risk. In particular, the implications of climate change will be influenced by the expansion of cellulosic feedstocks, particularly perennial grasses and woody biomass. In addition, advancements in feedstock development, logistics, and extension provide opportunities to support the sustainable development of a robust U.S. bioenergy industry as part of a holistic energy and environmental policy. However, given the nascent state of the cellulosic biofuels industry, careful attention should be given to managing climate risk over both short- and long-time scales.

Lignin by-products from biorefineries has the potential to provide a low-cost alternative to petroleum-based precursors to manufacture carbon fiber, which can be combined with a binding matrix to produce a structural material with much greater specific strength and specific stiffness than conventional materials such as steel and aluminum. The market for carbon fiber is universally projected to grow exponentially to fill the needs of clean energy technologies such as wind turbines and to improve the fuel economies in vehicles through lightweighting. In addition to cellulosic biofuel production, lignin-based carbon fiber production coupled with biorefineries may provide $2,400 to $3,600 added value dry Mg-1 of biomass for vehicle applications. Compared to producing ethanol alone, the addition of lignin-derived carbon fiber could increase biorefinery gross revenue by 30% to 300%. Using lignin-derived carbon fiber in 15 million vehicles per year in the US could reduce fossil fuel consumption by 2-5 billion liters year(-1), reduce CO2 emissions by about 6.7 million Mg year(-1), and realize fuel savings through vehicle lightweighting of $700 to $ 1,600 per Mg biomass processed. The value of fuel savings from vehicle lightweighting becomes economical at carbon fiber price of $6.60 kg(-1) under current fuel prices, or $13.20 kg(-1) under fuel prices of about $1.16 l(-1).

This paper summarizes the results of an update to a resource assessment, published in 2005, commonly referred to as the Billion-Ton Study (BTS). The updated results are consistent with the 2005 BTS in terms of overall magnitude. The 2005 BTS projected between 860 and 1240 Tg of biomass available in the 2050 timeframe, while the Billion-Ton Update (BT2), for a price of 66 $ Mg-1, projected between 994 and 1483 Tg in 2030. For the BT2, forest residue biomass potential was determined to be less owing to tighter restrictions on forest residue supply including restrictions due to limited projected increase in traditional harvest for pulpwood and sawlogs. Crop residue potential was also determined to be less because of the consideration of soil carbon and not allowing residue removal from conventionally tilled corn acres. Energy crop potential was estimated to be much greater largely because of land availability and modeling of competition among various competing uses of the land. Generally, the scenario assumptions in the updated assessment are much more plausible to show a "billionton" resource, which would be sufficient to displace 30% or more of the country's present petroleum consumption and provide more than enough biomass to meet the 2022 requirements of the Renewable Fuel Standard. (C) 2014 Elsevier Ltd. All rights reserved.

Indicators are needed to assess both socioeconomic and environmental sustainability of bioenergy systems. Effective indicators can help to identify and quantify the sustainability attributes of bioenergy options. We identify 16 socioeconomic indicators that fall into the categories of social well-being, energy security, trade, profitability, resource conservation, and social acceptability. The suite of indicators is predicated on the existence of basic institutional frameworks to provide governance, legal, regulatory and enforcement services. Indicators were selected to be practical, sensitive to stresses, unambiguous, anticipatory, predictive, estimable with known variability, and sufficient when considered collectively. The utility of each indicator, methods for its measurement, and applications appropriate for the context of particular bioenergy systems are described along with future research needs. Together, this suite of indicators is hypothesized to reflect major socioeconomic effects of the full supply chain for bioenergy, including feedstock production and logistics, conversion to biofuels, biofuel logistics and biofuel end uses. Ten indicators are highlighted as a minimum set of practical measures of socioeconomic aspects of bioenergy sustainability. Coupled with locally prioritized environmental indicators, we propose that these socioeconomic indicators can provide a basis to quantify and evaluate sustainability of bioenergy systems across many regions in which they will be deployed.

Understanding what it takes to move from a corn-based liquid fuels industry to one that is cellulosic-based requires a complex transition over time. This transition implies, among other things, a shift from annual cropping systems considered under United States Department of Agriculture (USDA) policy as commodity crops, to perennial lignocellulosic crops that are herbaceous and wood-based. Because of changes in land use as well as biomass and other crop supplies, land-based environmental amenities such as water quality, soil health and tilth, air quality, and animal and avian species populations and their diversity change also. Environmental effects are measured as magnitudes (how much they are impacted), and direction of the impact (either positive or negative). By developing a series of quantitative and qualitative metrics, the larger issue of defining relative sustainability may be addressed, and this can be done at a finer detail of regional (scale) and environmental amenity-specific impacts. Although much literature exists about research relevant to specific environmental variables, there is no published, documented, nor research literature on direct application of environmental over-compliance with regards a 'biorefinery.' Our three goals were to (1) understand and quantify bioenergy sustainability and some key environmental effects in a generic set of examples; (2) explain the effort and means to define and quantify specific qualitative environmental measures, and to determine a way to understand changes in these measures over time and what their implications might be; and (3) use these outcomes to evaluate potential sites in any geographic area. This would permit assessment of candidate locations, combined with an understanding of co-production of fuels, chemicals, and electric power, to interpret sustainability measures and the relationship between environmental sustainability and economic sustainability. The process of determining environmental sustainability effects as a result of providing renewable energy is complex. We have only included in this report environmental effects as a result of producing biomass for the biorefinery, and the area represented by the footprint of the biorefinery itself. In doing this, we have defined critical environmental variables (water, soil, air, and flora and fauna) and discussed some measurable indicators used to quantify effects such as nitrate content, soil organic matter, air particulates, and avian species diversity, respectively. We also point out the need to perform specific sustainability risk assessments, and the need to continually evaluate the life cycle inventory with an accompanying life-cycle assessment. Only in this dynamic framework can environmental sustainability be determined, evaluated and assessed, and contrasted with economic sustainability goals of a firm or an industry.

The increasing demand for bioenergy crops presents our society with the opportunity to design more sustainable landscapes. We have created a Biomass Location for Optimal Sustainability Model (BLOSM) to test the hypothesis that landscape design of cellulosic bioenergy crop plantings may simultaneously improve water quality (i.e. decrease concentrations of sediment, total phosphorus, and total nitrogen) and increase profits for farmer-producers while achieving a feedstock-production goal. BLOSM was run using six scenarios to identify switchgrass (Panicum virgatum) planting locations that might supply a commercial-scale biorefinery planned for the Lower Little Tennessee (LLT) watershed. Each scenario sought to achieve different sustainability goals: improving water quality through reduced nitrogen, phosphorus, or sediment concentrations; maximizing profit; a balance of these conditions; or a balance of these conditions with the additional constraint of converting no more than 25% of agricultural land. Scenario results were compared to a baseline case of no land-use conversion. BLOSM results indicate that a combined economic and environmental optimization approach can achieve multiple objectives simultaneously when a small proportion (1.3%) of the LLT watershed is planted with perennial switchgrass. The multimetric optimization approach described here can be used as a research tool to consider bioenergy plantings for other feedstocks, sustainability criteria, and regions. Published in 2012 by John Wiley & Sons, Ltd

Background: This study evaluates the global economic effects of the current US RFS2, and the potential contribution from advanced biofuels. Results & discussion: Our simulation results suggest that these mandates lead to an increase of 0.21% in the global gross domestic product in 2022, including an increase of 0.8% in the USA and 0.02% in the rest of the world, relative to our baseline no-RFS scenario. The incremental contributions to gross domestic product from advanced biofuels in 2022 are estimated at 0.41 and 0.04% in the USA and the rest of the world, respectively. Conclusion: Although production costs of advanced biofuels are higher than for conventional biofuels in our model, their economic benefits result from reductions in oil use and their smaller impacts on food markets compared with conventional biofuels. Thus, the US advanced biofuels targets are expected to have positive net economic benefits.

Indicators are needed to assess environmental sustainability of bioenergy systems. Effective indicators will help in the quantification of benefits and costs of bioenergy options and resource uses. We identify 19 measurable indicators for soil quality, water quality and quantity, greenhouse gases, biodiversity, air quality, and productivity, building on existing knowledge and on national and international programs that are seeking ways to assess sustainable bioenergy. Together, this suite of indicators is hypothesized to reflect major environmental effects of diverse feedstocks, management practices, and post-production processes. The importance of each indicator is identified. Future research relating to this indicator suite is discussed, including field testing, target establishment, and application to particular bioenergy systems. Coupled with such efforts, we envision that this indicator suite can serve as a basis for the practical evaluation of environmental sustainability in a variety of bioenergy systems.

The report, Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply (generally referred to as the Billion-Ton Study or 2005 BTS), was an estimate of 'potential' biomass based on numerous assumptions about current and future inventory, production capacity, availability, and technology. The analysis was made to determine if conterminous U.S. agriculture and forestry resources had the capability to produce at least one billion dry tons of sustainable biomass annually to displace 30% or more of the nation's present petroleum consumption. An effort was made to use conservative estimates to assure confidence in having sufficient supply to reach the goal. The potential biomass was projected to be reasonably available around mid-century when large-scale biorefineries are likely to exist. The study emphasized primary sources of forest- and agriculture-derived biomass, such as logging residues, fuel treatment thinnings, crop residues, and perennially grown grasses and trees. These primary sources have the greatest potential to supply large, reliable, and sustainable quantities of biomass. While the primary sources were emphasized, estimates of secondary residue and tertiary waste resources of biomass were also provided. The original Billion-Ton Resource Assessment, published in 2005, was divided into two parts-forest-derived resources and agriculture-derived resources. The forest resources included residues produced during the harvesting of merchantable timber, forest residues, and small-diameter trees that could become available through initiatives to reduce fire hazards and improve forest health; forest residues from land conversion; fuelwood extracted from forests; residues generated at primary forest product processing mills; and urban wood wastes, municipal solid wastes (MSW), and construction and demolition (C&D) debris. For these forest resources, only residues, wastes, and small-diameter trees were considered. The 2005 BTS did not attempt to include any wood that would normally be used for higher-valued products (e.g., pulpwood) that could potentially shift to bioenergy applications. This would have required a separate economic analysis, which was not part of the 2005 BTS. The agriculture resources in the 2005 BTS included grains used for biofuels production; crop residues derived primarily from corn, wheat, and small grains; and animal manures and other residues. The cropland resource analysis also included estimates of perennial energy crops (e.g., herbaceous grasses, such as switchgrass, woody crops like hybrid poplar, as well as willow grown under short rotations and more intensive management than conventional plantation forests). Woody crops were included under cropland resources because it was assumed that they would be grown on a combination of cropland and pasture rather than forestland. In the 2005 BTS, current resource availability was estimated at 278 million dry tons annually from forestlands and slightly more than 194 million dry tons annually from croplands. These annual quantities increase to about 370 million dry tons from forestlands and to nearly 1 billion dry tons from croplands under scenario conditions of high-yield growth and large-scale plantings of perennial grasses and woody tree crops. This high-yield scenario reflects a mid-century timescale ({approx}2040-2050). Under conditions of lower-yield growth, estimated resource potential was projected to be about 320 and 580 million dry tons for forest and cropland biomass, respectively. As noted earlier, the 2005 BTS emphasized the primary resources (agricultural and forestry residues and energy crops) because they represent nearly 80% of the long-term resource potential. Since publication of the BTS in April 2005, there have been some rather dramatic changes in energy markets. In fact, just prior to the actual publication of the BTS, world oil prices started to increase as a result of a burgeoning worldwide demand and concerns about long-term supplies. By the end of the summer, oil prices topped $70 per barrel (bbl) and catastrophic hurricanes in the Gulf Coast shut down a significant fraction of U.S. refinery capacity. The following year, oil approached $80 per bbl due to supply concerns, as well as continued political tensions in the Middle East. The Energy Independence and Security Act of 2007 (EISA) was enacted in December of that year. By the end of December 2007, oil prices surpassed $100 per bbl for the first time, and by mid-summer 2008, prices approached $150 per bbl because of supply concerns, speculation, and weakness of the U.S. dollar. As fast as they skyrocketed, oil prices fell, and by the end of 2008, oil prices dropped below $50 per bbl, falling even more a month later due to the global economic recession. In 2009 and 2010, oil prices began to increase again as a result of a weak U.S. dollar and the rebounding of world economies.

Landscape implications of bioenergy feedstock choices are significant and depend on land-use practices and their environmental impacts. Although land-use changes and carbon emissions associated with bioenergy feedstock production are dynamic and complicated, lignocellulosic feedstocks may offer opportunities that enhance sustainability when compared to other transportation fuel alternatives. For bioenergy sustainability, major drivers and concerns revolve around energy security, food production, land productivity, soil carbon and erosion, greenhouse gas emissions, biodiversity, air quality, and water quantity and quality. The many implications of bioenergy feedstock choices require several indicators at multiple scales to provide a more complete accounting of effects. Ultimately, the long-term sustainability of bioenergy feedstock resources (as well as food supplies) throughout the world depends on land-use practices and landscape dynamics. Land-management decisions often invoke trade-offs among potential environmental effects and social and economic factors as well as future opportunities for resource use. The hypothesis being addressed in this paper is that sustainability of bioenergy feedstock production can be achieved via appropriately designed crop residue and perennial lignocellulosic systems. We find that decision makers need scientific advancements and adequate data that both provide quantitative and qualitative measures of the effects of bioenergy feedstock choices at different spatial and temporal scales and allow fair comparisons among available options for renewable liquid fuels.

As part of a project to investigate sustainable forest management practices for producing wood chips on the Oak Ridge Reservation (ORR) for the ORNL steam plant, the BioBaler was tested in various Oak Ridge locations in August of 2011. The purpose of these tests and the subsequent economic analysis was to determine the potential of this novel woody biomass harvesting method for collection of small-diameter, low value woody biomass. Results suggest that opportunities may exist for economical harvest of low-value and liability or negative-cost biomass. (e.g., invasives). This could provide the ORR and area land managers with a tool to produce feedstock while improving forest health, controlling problem vegetation, and generating local employment.

Sorghum has great potential as an annual energy crop. While primarily grown for its grain, sorghum can also be grown for animal feed and sugar. Sorghum is morphologically diverse, with grain sorghum being of relatively short stature and grown for grain, while forage and sweet sorghums are tall and grown primarily for their biomass. Under water-limited conditions sorghum is reliably more productive than corn. While a relatively minor crop in the United States (about 2% of planted cropland), sorghum is important in Africa and parts of Asia. While sorghum is a relatively efficient user of water, it biomass potential is limited by available moisture. The following exhaustive literature review of sorghum production practices was developed by researchers at Oak Ridge National Laboratory to document the current state of knowledge regarding sorghum production and, based on this, suggest areas of research needed to develop sorghum as a commercial bioenergy feedstock. This work began as part of the China Biofuels Project sponsored by the DOE Energy Efficiency and Renewable Energy Program to communicate technical information regarding bioenergy feedstocks to government and industry partners in China, but will be utilized in a variety of programs in which evaluation of sorghum for bioenergy ismore » needed. This report can also be used as a basis for data (yield, water use, etc.) for US and international bioenergy feedstock supply modeling efforts.« less

Numerous studies have evaluated air quality and greenhouse gas mitigation benefits of biomass energy systems, but the potential environmental impacts associated with large-scale changes in land-use patterns needed to produce energy crops have not been quantified. This paper presents a framework to assess the potential soil, water, and biodiversity impacts that may result from the large-scale production of dedicated energy crops. The framework incorporates producer economic decision models with environmental models to assess changes in land use patterns and to quantify the consequent environmental impacts. Economic and policy issues that will affect decisions to produce energy crops are discussed. The framework is used to evaluate erosion and chemical runoff in two Tennessee regions. The analysis shows that production of dedicated energy crops in place of conventional crops will significantly reduce erosion and chemical runoff.

Scale-up projects are an important step toward demonstration and commercialization of woody biomass because simply planting extensive acreage of hybrid poplar will not develop markets. Project objectives are to document the cost to plant and establish, and effort needed to monitor and maintain woody biomass on agricultural land. Conversion technologies and alternative end-uses are examined in a larger framework in order to afford researchers and industrial partners information necessary to develop supply and demand on a local or regional scale. Likely to be determined are risk factors of crop failure and differences between establishment of research plots and agricultural scale field work. Production economics are only one consideration in understanding demonstration and scale-up. Others are environmental, marketing, industrial, and agricultural in nature. Markets for energy crops are only beginning to develop. Although information collected as a result of planting up to 5000 acres of hybrid poplar in central Minnesota will not necessarily be transferable to other areas of the country, a national perspective will come from development of regional markets for woody and herbaceous crops. Several feedstocks, with alternative markets in different regions will eventually comprise the entire picture of biofuels feedstock market development. Current projects offer opportunities to learn about the complexity and requirements that will move biomass from research and development to actual market development. These markets may include energy and other end-uses such as fiber.