biofuel

Peer-reviewed letter written in response to a March 11, 2015, letter to US EPA Administrator Gina McCarthy (http://bit.ly/1HsSaWf), in which the Ecological Society of America objected to EPA’s proposal that sustainably harvested woody biomass could reduce carbon emissions. Citing a November 2014 EPA memorandum (known as the McCabe memo; http://1.usa.gov/1zMeZf2), the Ecological Society letter argued that the EPA’s stance would undermine federal efforts to “deter rapid deforestation, lower carbon emissions, and mitigate the effects of global climate change”.

For analyzing sustainability of algal biofuels, we identify 16 environmental indicators that fall into six categories: soil quality, water quality and quantity, air quality, greenhouse gas emissions, biodiversity, and productivity. Indicators are selected to be practical, widely applicable, predictable in response, anticipatory of future changes, independent of scale, and responsive to management. Major differences between algae and terrestrial plant feedstocks, as well as their supply chains for biofuel, are highlighted, for they influence the choice of appropriate sustainability indicators. Algae strain selection characteristics do not generally affect which indicators are selected. The use of water instead of soil as the growth medium for algae determines the higher priority of water- over soil-related indicators. The proposed set of environmental indicators provides an initial checklist for measures of algal biofuel sustainability but may need to be modified for particular contexts depending on data availability, goals of stakeholders, and financial constraints. Use of these indicators entails defining sustainability goals and targets in relation to stakeholder values in a particular context and can lead to improved management practices.

A global energy crop productivity model that provides geospatially explicit quantitative details on biomass
potential and factors affecting sustainability would be useful, but does not exist now. This study describes a
modeling platform capable of meeting many challenges associated with global-scale agro-ecosystem modeling.
We designed an analytical framework for bioenergy crops consisting of six major components: (i) standardized
natural resources datasets, (ii) global field-trial data and crop management practices, (iii) simulation units and
management scenarios, (iv) model calibration and validation, (v) high-performance computing (HPC) simulation,
and (vi) simulation output processing and analysis. The HPC-Environmental Policy Integrated Climate
(HPC-EPIC) model simulated a perennial bioenergy crop, switchgrass (Panicum virgatum L.), estimating feedstock
production potentials and effects across the globe. This modeling platform can assess soil C sequestration,
net greenhouse gas (GHG) emissions, nonpoint source pollution (e.g., nutrient and pesticide loss), and energy
exchange with the atmosphere. It can be expanded to include additional bioenergy crops (e.g., miscanthus,
energy cane, and agave) and food crops under different management scenarios. The platform and switchgrass
field-trial dataset are available to support global analysis of biomass feedstock production potential and corresponding
metrics of sustainability.

The US Congress passed the Renewable Fuels Standard (RFS) seven years ago. Since then, biofuels have gone from darling to scapegoat for many environmentalists, policy makers, and the general public. The reasons for this shift are complex and include concerns about environmental degradation, uncertainties about impact on food security, new access to fossil fuels, and overly optimistic timetables. As a result, many people have written off biofuels. However, numerous studies indicate that biofuels, if managed sustainably, can help solve pressing environmental, social and economic problems (Figure 1). The scientific and policy communities should take a closer look by reviewing the key assumptions underlying opposition to biofuels and carefully consider the probable alternatives. Liquid fuels based on fossil raw materials are likely to come at increasing environmental cost. Sustainable futures require energy conservation, increased efficiency, and alternatives to fossil fuels, including biofuels.

As with all land transformation activities, effects on biodiversity and ecosystem services of producing feedstocks for biofuels are highly variable and context specific.  Advances toward more sustainable biofuel production benefit from a system's perspective, recognizing spatial heterogeneity and scale, landscape-design principles, and addressing the influences of context such as the particular products and their distribution, policy background, stakeholder values, location, temporal influences, and baseline conditions.  Deploying biofuels in a manner to reduce effects on biodiversity and associated ecosystem services can only be done with planning, monitoring, and appropriate goverance.   The effects of biofuels can be avoided or reduced by conservation of priority biodiversity areas, recognizing the context specific effects of biofuels, and adopting location-specific management of production systems.  Developing those management strategies takes time and effort.

Potential global biodiversity impacts from near-term gasoline production are compared to biofuel, a renewable liquid transportation fuel expected to substitute for gasoline in the near term (i.e., from now until c. 2030).  Petroleum exploration activities are projected to extend across more than 5.8 billion ha of land and ocean worldwide (of which 3.1 bllion is on land), much of which is in remote, fragile terrestrial ecosystems or off-shore oil fields that would remain relatively undisturbed if not for interest in fossil fuel production.  Future biomass production for biofuels is projected to fall within 2.0 billion ha of land, most of which is located in areas already impacted by human activities.  A comparison of likely fuel-source areas to the geospatial distribution of species reveals that both energy sources overlap with areas with high species richness and large numbers of threatened species.  At the global scale, future petroleum production areas intersect more than double the area and a higher total number of threatened species than future biofuel production.  Energy options should be developed to optimize provisioning of ecosystems services while minimizing negative effects, which requires information about potential impacts on critical resources.  Energy conservation and identifying and effectively protecting habitats with high-concervation value are critical first steps toward protecting biodiversity under any fuel production scenario.

We present a system dynamics global LUC model intended to examine LUC attributed to biofuel production. The model has major global land system stocks and flows and can be exercised under different food and biofuel demand assumptions. This model provides insights into the drivers and dynamic interactions of LUC, population, dietary choices, and biofuel policy rather than a precise number generator.

The Alternative Fuels Data Center (AFDC) provides information, data, and tools to help fleets and other transportation decision makers find ways to reduce petroleum consumption through the use of alternative and renewable fuels, advanced vehicles, and other fuel-saving measures.

The estimation of greenhouse gas (GHG) emissions from a change in land-use and management resulting from growing biofuel feedstocks has undergone extensive – and often contentious – scientific and policy debate. Emergent renewable fuel policies require life cycle GHG emission accounting that includes biofuel-induced global land-use change (LUC) GHG emissions. However, the science of LUC generally, and biofuels-induced LUC specifically, is nascent and underpinned with great uncertainty. We critically review modeling approaches employed to estimate biofuel-induced LUC and identify major challenges, important research gaps, and limitations of LUC studies for transportation fuels. We found LUC modeling philosophies and model structures and features (e.g. dynamic vs. static model) significantly differ among studies. Variations in estimated GHG emissions from biofuel-induced LUC are also driven by differences in scenarios assessed, varying assumptions, inconsistent definitions (e.g. LUC), subjective selection of reference scenarios against which (marginal) LUC is quantified, and disparities in data availability and quality. The lack of thorough sensitivity and uncertainty analysis hinders the evaluation of plausible ranges of estimates of GHG emissions from LUC. The relatively limited fuel coverage in the literature precludes a complete set of direct comparisons across alternative and conventional fuels sought by regulatory bodies and researchers.

Improved modeling approaches, consistent definitions and classifications, availability of high-resolution data on LUC over time, development of standardized reference and future scenarios, incorporation of non-economic drivers of LUC, and more rigorous treatment of uncertainty can help improve LUC estimates in effectively achieving policy goals.

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)