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A Review of Life-Cycle Based Tools Used to Assess the Environmental Sustainability of Biofuels in the United States
Citation:
Curran, M. A Review of Life-Cycle Based Tools Used to Assess the Environmental Sustainability of Biofuels in the United States. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R/12/709, 2013.
Impact/Purpose:
The growing realization by decision makers of the need to look broadly at the environmental impacts of engineered systems led to a proliferation of holistic approaches for assessing sustainability. To help clarify what the various approaches cover, the “Review of Life-Cycle Based Tools USed to Assess the Enviornmental Impacts of Biofuels in the United States” presents ten environmental assessment approaches that incorporate a life cycle perspective and describes what they can and cannot do.
Description:
There is no simple answer to the question “are materials from bio-based feedstocks environmentally preferable?” Bioenergy, as an alternative energy source, might be effective in reducing fossil fuel use and dependence, slowing or reducing global warming effects, and providing increased revenue for the farming community. But its production may also contribute to environmental harm, such as degraded soil and water quality. This brings into question how we define and measure its ‘sustainability.’ The issue of environmental sustainability related to bio-based materials is a complicated one. Achieving sustainability requires a re-thinking of our systems of production, consumption and waste management and an increased awareness of the need to avoid the shifting of problems, which often occurs with isolated measures. The environmental advantages should outnumber, or outweigh, the disadvantages to the environment and human health. The benefits of bioenergy have come under increasing scrutiny as researchers look closer at the global environmental impact of their production. For example, increased demand for corn could result in diverting corn supplies from making food and feed to making bioethanol which could in turn affect the production of competing crops, such as soybean, or the conversion of lands to use for corn production. The overall impacts of these types of shifts are not well understood. If used properly, bioenergy can help the U.S. meet its needs while maintaining ample supplies of food, animal feed, and clean water. To make this happen, well thought out national bioenergy policies that support the best options are needed for both the short and long-term future. Life Cycle Assessment (LCA) is a developing tool that can assist decision-makers in evaluating the comparative potential cradle-to-grave, multi-media environmental impacts of their actions in order to prevent unintended consequences. Some studies are called ‘life cycle analysis’ but focus on a particular issue or pollutant of concern, such as greenhouse gas (GhG) emissions, or the net energy gain or loss question. These focused studies fall short of a complete life cycle approach that helps us recognize how our choices influence each point of the life cycle so that we can balance potential trade-offs and avoid shifting problems from one medium to another and/or from one life cycle stage to another. This report explores how a systems thinking approach, such as LCA, can help decision-makers view the potential ‘cradle-to-grave’ environmental impacts of various types of biofuels and, thereby, choose the most favorable options that will keep us on the path toward sustainability. Ten tools that incorporate a life cycle perspective to evaluate biofuels were studied and compared: Carbon Management, Ecological Footprint, Exergy Analysis, Fuel Cycle Analysis, Greenhouse Gas Life Cycle Analysis, Life Cycle Assessment, Life Cycle Risk Assessment, Material Flow Analysis, Net Energy Balance, and Sustainability Indicators. Discussion on data and information needs is also provided.