Ecosystem service analysis and cost-benefit analysis provide methods to examine tradeoffs among sustainability goals and an integrative perspective of sustainability.

Any given tool or framework for assessing sustainability for a given fuel does not determine whether the fuel contributes to improving sustainability of the transportation sector. In fact, the report Toward Sustainable Agricultural Systems in the 21st Century (NRC, 2010) suggests that sustainability is not a particular end state, but a trajectory toward achieving a set of environmental, economic, and social goals. In the context of this report, the question is whether substituting a portion of petroleum-based fuels with algal biofuels could move the transportation sector along a trajectory toward greater sustainability with respect to each of the four goals: contributing to energy security, maintaining and enhancing the natural resource base and environmental quality, producing fuels that are economically viable, and enhancing the quality of life for society as a whole. The environmental, economic, and social effects of algal biofuel production and use have to be compared with those of petroleumbased fuels and other fuel alternatives to determine whether algal biofuels contribute to improving sustainability.

Given the four aspects of sustainability and the multiple goals within each aspect, a participatory approach is necessary to develop a collective vision of the importance of various sustainability objectives relative to each other. Stakeholders would be involved from the beginning of a sustainability assessment. Such an approach that involves different stakeholders would help ensure that tradeoffs among sustainability goals would be acceptable to the various parties.

6.4 OPPORTUNITIES FOR ALGAL BIOFUELS TO IMPROVE SUSTAINABILITY

Algal biofuels have the potential to contribute to improving the sustainability of the transportation sector, but innovations and research and development (R&D) are needed to realize their full potential. Preliminary assessments in the literature suggest that several resource use and environmental challenges likely would have to be overcome for algal biofuel production to be scaled up in a sustainable way. Suitable locations for algal biofuels could be limited by the number and area of sites that are close to a source of CO2, fresh water, brackish water, wastewater, or combination thereof. Innovations and R&D in various aspects of the supply chain will help realize much of the potential for algal biofuels to improve energy security, reduce GHG emissions, and enhance environmental quality. Algal strain development to improve biomass or lipid productivity would clearly increase fuel production per unit resource use and improve the economics of fuel production. Engineering designs to enhance algae cultivation, facilitate biomass or product collection (for example, algal lipid), and reduce processing requirements have the potential to greatly improve the energy balance, reduce GHG emissions, and enhance the overall sustainability of algal biofuels.

SUMMARY FINDING FROM THIS CHAPTER

The environmental, economic, and social effects of algal biofuel production and use have to be compared with those of petroleum-based fuels and other fuel alternatives to determine whether algal biofuels contribute to improving sustainability. Such comparison will be possible only if thorough assessments of each step in the various pathways for algal biofuel production are conducted.



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