Understanding the environmental effects of alternative fuel production is critical to characterizing the sustainability of energy resources to inform policy and regulatory decisions. The magnitudes of these environmental effects vary according to the intensity and scale of fuel production along each step of the supply chain. We compare the spatial extent and temporal duration of ethanol and gasoline production processes and environmental effects based on a literature review and then synthesize the scale differences on space-time diagrams. Comprehensive assessment of any fuel-production system is a moving target, and our analysis shows that decisions regarding the selection of spatial and temporal boundaries of analysis have tremendous influences on the comparisons. Effects that strongly differentiate gasoline and ethanol-supply chains in terms of scale are associated with when and where energy resources are formed and how they are extracted. Although both gasoline and ethanol production may result in negative environmental effects, this study indicates that ethanol production traced through a supply chain may impact less area and result in more easily reversed effects of a shorter duration than gasoline production.
To date, feedstock resource assessments have evaluated cellulosic and algal feedstocks independently, without consideration of demands for, and resource allocation to, each other. We assess potential land competition between algal and terrestrial feedstocks in the United States, and evaluate a scenario in which 41.5 × 109 L yr−1 of second-generation biofuels are produced on pastureland, the most likely land base where both feedstock types may be deployed. Under this scenario, open-pond microalgae production is projected to use 1.2 × 106 ha of private pastureland, while terrestrial biomass feedstocks would use 14.0 × 106 ha of private pastureland. A spatial meta-analysis indicates that potential competition for land under this scenario would be concentrated in 110 counties, containing 1.0 and 1.7 × 106 ha of algal and terrestrial dedicated feedstock production, respectively. A land competition index applied to these 110 counties suggests that 38 to 59 counties could experience competition for upwards of 40% of a county's pastureland, representing 2%–5% of total pastureland in the U.S.; therefore suggesting little overall competition between algae production, terrestrial energy feedstocks and alternative uses for existing agricultural production such as livestock grazing.
We propose a causal analysis framework to increase understanding of land-use change (LUC) and the reliability of LUC models. This health-sciences-inspired framework can be applied to determine probable causes of LUC in the context of bioenergy. Calculations of net greenhouse gas (GHG) emissions for LUC associated with biofuel production are critical in determining whether a fuel qualifies as a biofuel or advanced biofuel category under regional (EU), national (US, UK), and state (California) regulations. Biofuel policymakers and scientists continue to discuss to what extent presumed indirect land-use change (ILUC) estimates should be included in GHG accounting for biofuel pathways. Current estimates of ILUC for bioenergy rely largely on economic simulation models that focus on causal pathways involving global commodity trade and use coarse land-cover data with simple land classification systems. This paper challenges the application of such models to estimate global areas of LUC in the absence of causal analysis. The proposed causal analysis framework begins with a definition of the change that has occurred and proceeds to a strength-of-evidence approach that includes plausibility of relationship, completeness of causal pathway, spatial co-occurrence, time order, analogous agents, simulation model results, and quantitative agent–response relationships. We discuss how LUC may be allocated among probable causes for policy purposes and how the application of the framework has the potential to increase the validity of LUC models and resolve controversies about ILUC, such as deforestation, and biofuels.
The ongoing debate about costs and benefits of wood‐pellet based bioenergy production in the southeastern United States (SE USA) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, ‘How is the production of wood pellets in the SE USA affecting forest systems and the ecosystem services they provide?’ To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE USA are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to nonforest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long‐term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.
Wood pellet exports from the Southeastern United States (SE US) to Europe have been increasing in response to European Union member state policies to displace coal with renewable biomass for electricity generation. An understanding of the interactions among SE US forest markets, forest management, and forest ecosystem services is required to quantify the effects of pellet production compared to what would be expected under a reference case or ‘counterfactual scenario’ without pellet production. Inconsistent methods to define and justify the counterfactual scenario result in conflicting estimates and large uncertainties about the impacts of pellet production on SE US forests. Guidelines to support more consistent and transparent counterfactual scenarios are proposed. The guidelines include identifying major influences on current SE US forest conditions, developing potential futures that clearly document underlying assumptions and associated uncertainties, identifying the most likely alternative feedstock fates, and estimating the effects of no pellet demand on future forest conditions. The guidelines can help modelers to more accurately reflect the past and current forest dynamics and to consider the implications for SE US forest landscapes of future scenarios with and without pellet production. WIREs Energy Environ 2017, 6:e259. doi: 10.1002/wene.259
Understanding the complex interactions among food security, bioenergy sustainability, and resource management requires a focus on specific contextual problems and opportunities. The United Nations’ 2030 Sustainable Development Goals place a high priority on food and energy security; bioenergy plays an important role in achieving both goals. Effective food security programs begin by clearly defining the problem and asking, ‘What can be done to assist people at high risk?’ Simplistic global analyses, headlines, and cartoons that blame biofuels for food insecurity may reflect good intentions but mislead the public and policymakers because they obscure the main drivers of local food insecurity and ignore opportunities for bioenergy to contribute to solutions. Applying sustainability guidelines to bioenergy will help achieve near‐ and long‐term goals to eradicate hunger. Priorities for achieving successful synergies between bioenergy and food security include the following: (1) clarifying communications with clear and consistent terms, (2) recognizing that food and bioenergy need not compete for land and, instead, should be integrated to improve resource management, (3) investing in technology, rural extension, and innovations to build capacity and infrastructure, (4) promoting stable prices that incentivize local production, (5) adopting flex crops that can provide food along with other products and services to society, and (6) engaging stakeholders to identify and assess specific opportunities for biofuels to improve food security. Systematic monitoring and analysis to support adaptive management and continual improvement are essential elements to build synergies and help society equitably meet growing demands for both food and energy.
Published in Bioenergy and Land Use Change (pp. 141–153). John Wiley & Sons, Inc.
While many data sets are increasingly available to describe land cover characteristics, these data require careful analysis and supplemental research before conclusions can be drawn about the scope, magnitude, and drivers of change. Land cover data, typically derived from remote sensing, are frequently analyzed to estimate land use change (LUC) that may be attributable to policies such as the U.S. Renewable Fuel Standard, which encourages bioenergy. However, land cover classifications such as grassland do not clearly differentiate among multiple land uses (pasture, fodder, crop, yard, wildlife corridor, decorative cover, and erosion control strip), many of which may occur on a single parcel simultaneously. A land cover class in one data set rarely corresponds exactly to the same land cover class in another data set. Further, persistent improvements in remote‐sensing systems result in changes in spatial and temporal resolutions that lead to changes in classification methodology, which limit the ability to use those data sets to accurately measure changes occurring on the ground. Most LUC estimates are derived by comparing land cover across a few points in time and using aggregate land cover classes such as “forest,” “cropland” or “urban.” Analyses that cover short time spans or rely on just a few points in time are likely to generate spurious results if dynamic interacting classes such as U.S. cropland and grassland are considered. We review land cover dynamics in the Western Corn Belt (WCB) region, which comprises the U.S. states of Iowa, Minnesota, Nebraska, North Dakota, and South Dakota, to illustrate how the selection and manipulation of data can result in estimates of change associated with the cropland‐grassland transition that vary by over 100%.
Bio-oil derived via fast pyrolysis is being developed as a renewable fuel option for petroleum distillates. The compatibility of neat bio-oil with 18 plastic types was evaluated using neat diesel fuel as the baseline. The plastic materials included polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyoxymethylene (POM), POM copolymer, high density polyethylene (HDPE), polybutylene terephthalate (PBT), polypropylene (PP), polyethylene terephthalate glycol (PETG), polythiourea (PTU), four nylon grades, and four thermosetting resins. Specimens of each material were immersed in the test fuels for a period of 16 weeks to achieve full saturation. Except for PP and HDPE, the plastic materials underwent higher volume expansion in bio-oil than in the baseline diesel (which was negligible in most cases). This volume increase corresponds to the higher polarity of the bio-oil. PPS, PET, and PTFE were unaffected by bio-oil exposure, but modest swelling (between 2 and 5%) occurred for the two acetals (POM and POM copolymer), Nylon-12, PBT, PETG, and the four resin grades. More moderate swelling (8–15%) was noted for Nylon-6, Nylon-6/6, and Nylon-11, and excessive swell (>40%) occurred for PTU. The nonpolar nature of PP and HDPE matches that of diesel, leading to higher solubility (swell) in this fuel type. The relatively low volume expansion following exposure indicates that many of the existing infrastructure plastics (excluding PTU) should be suitable for use with bio-oil.
Water consumption and water quality continue to be key factors affecting environmental sustainability in biofuel production. This review covers the findings from biofuel water analyses published over the past 2 years to underscore the progress made, and to highlight advancements in understanding the interactions among increased production and water demand, water resource availability, and potential changes in water quality. We focus on two key areas: water footprint assessment and watershed modeling. Results revealed that miscanthus-, switchgrass-, and forest wood-based biofuels all have promising blue and grey water footprints. Alternative water resources have been explored for algae production, and challenges remain. A most noticeable improvement in the analysis of life-cycle water consumption is the adoption of geospatial analysis and watershed modeling to generate a spatially explicit water footprint at a finer scale (e.g., multi-state region, state, and county scales) to address the impacts of land use change and climate on the water footprint in a landscape with a mixed biofuel feedstock.
The U.S. biomass resource can be used several ways that provide domestic, renewable energy to users. Understanding the capacity of the biomass resource, its potential in energy markets, and the most economic utilization of biomass is important in policy development and project selection. This study analyzed the potential for biomass within markets and the competition between them. The study found that biomass has the potential to compete well in the jet fuel and gasoline markets, penetration of biomass in markets is likely to be limited by the size of the resource, and that biomass is most cost effectively used for fuels instead of power in mature markets unless carbon capture and sequestration is available and the cost of carbon is around $80/metric ton CO2e.
Biomass Utilization Issues
Biomass is a limited resource with many competing uses. Its allocation for fuel, power, and products depends upon characteristics of each of these markets, their interactions, and policies affecting these markets. In order to better understand competition for biomass among markets and the potential for biofuel as a market-scale alternative to petroleum-based fuels, the Transportation Energy Futures (TEF) study created a unique modeling tool to analyze the impact of these multiple demand areas.
There are compelling reasons for use of biomass in each of these three markets:
• Fuel: Biomass is the primary renewable resource that can be used to generate liquid fuels for today’s vehicles and infrastructure.
• Power: Technology is currently available to enable co-firing with coal, reducing the carbon intensity of baseload electricity and providing one of the few renewable dispatchable options.
• Products: Mixtures of chemicals with carbon-hydrogen-oxygen bonds such as those found in biomass are too valuable to burn.
Federal policy and activities have supported both biofuels and biopower. Relevant policies include the renewable fuels standard, the renewables portfolio standard, the clean energy standard, and many state and regional greenhouse gas (GHG) policies. Goals for biofuel policies include reduction in petroleum and, especially, petroleum imports to increase energy security. Other goals for biofuel policies focus on environmental and economic concerns, GHG emissions reduction, and diversification of agricultural products. Goals for biopower policies include displacement of coal for environmental concerns and GHG reduction. In the past two decades, the U.S. Department of Energy’s research and development (R&D)