SUMMARY FINDINGS FROM THIS AND EARLIER CHAPTERS
Based on a review of literature published until the authoring of this report, the committee concluded that the scale-up of algal biofuel production sufficient to meet at least 5 percent of U.S. demand for transportation fuelsa would place unsustainable demands on energy, water, and nutrients with current technologies and knowledge. However, the potential to shift this dynamic through improvements in biological and engineering variables exists. (See also Chapters 2 and 3 on improvements in biological and engineering variables.)
Sustainable development of algal biofuels would require research, development, and demonstration of the following:
• Algal strain selection and improvement to enhance desired characteristics and biofuel productivity. (See Chapter 2.)
• An EROI that is comparable to other transportation fuels, or at least improving and approaching the EROIs of other transportation fuels.
• The use of wastewater for cultivating algae for fuels or the recycling of harvest water, particularly if freshwater algae are used.
• Recycling of nutrients in algal biofuel pathways that require harvesting unless coproducts that meet an equivalent nutrient need are produced.
A national assessment of land requirements for algae cultivation that takes into account climatic conditions; fresh water, inland and coastal saline water, and wastewater resources; sources of CO2; and land prices is needed to inform the potential amount of algal biofuels that could be produced economically in the United States.
a U.S. consumption of fuels for transportation was about 784 billion liters in 2010. Five percent of the annual U.S. consumption of transportation fuels, which would be about 39 billion liters, is mentioned to provide a quantitative illustration of the water and nutrients required to produce algal biofuels to meet a small portion of the U.S. fuel demand.
Alley, W.M. 2003. Desalination of Ground Water: Earth Science Perspectives. Reston: U.S. Geological Survey.
Baral, A., B.R. Bakshi, and R.L. Smith. 2012. Assessing resource intensity and renewability of cellulosic ethanol technologies using Eco-LCA. Environmental Science and Technology 46 (4):2436-2444.
Batan, L., J. Quinn, T. Bradley, and B. Willson. 2011. Erratum: Net energy and greenhouse gas emissions evaluation of biodiesel derived from microalgae (Environmental Science and Technology (2010) 44 (7975-7980)). Environmental Science and Technology 45(3):1160.
Batan, L., J. Quinn, B. Willson, and T. Bradley. 2010. Net energy and greenhouse gas emission evaluation of biodiesel derived from microalgae. Environmental Science and Technology 44(20):7975-7980.
Benemann, J., P.M. Pedroni, J. J. Davison, H. Beckert, and P. Bergman. 2003a. Technology roadmap for biofixation of CO2 and greenhouse gas abatement with microalgae. Paper read at the Second Annual Conference on Carbon Sequestration, May 5-8, Alexandria, VA.
Benemann, J.R., J.C. Van Olst, M.J. Massingill, J.C. Weissman, and D.E. Brune. 2003b. The controlled eutrophication process: Using microalgae for CO2 utilization and agricultural fertilizer recycling. Paper read at the 6th Greenhouse Gas Control Technologies Conference (GHGT6), October, Kyoto Japan.
BLM (Bureau of Land Management) and DOE (U.S. Department of Energy). 2010. Solar Energy Development Draft Programmatic Environmental Impact Statement (Draft Solar PEIS). Washington, D.C.: Bureau of Land Management and U.S. Department of Energy.
Boyd, C.E., and A. Gross. 2000. Water use and conservation for inland aquaculture ponds. Fisheries Management and Ecology 7(1-2):55-63.
Brentner, L.B., M.J. Eckelman, and J.B. Zimmerman. 2011. Combinatorial life cycle assessment to inform process design of industrial production of algal biodiesel. Environmental Science and Technology 45:7060-7067.
Cai, X.M., X.A. Zhang, and D.B. Wang. 2011. Land availability for biofuel production. Environmental Science and Technology 45(1):334-339.