Sustainable Development of Algal Biofuels in the United States (2012)Board on Agriculture and Natural Resources
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Biofuels made from algae are gaining attention as a domestic source of renewable fuel. However, with current technologies, scaling up production of algal biofuels to meet even 5 percent of U.S. transportation fuel needs could create unsustainable demands for energy, water, and nutrient resources. Continued research and development could yield innovations to address these challenges, but determining if algal biofuel is a viable fuel alternative will involve comparing the environmental, economic and social impacts of algal biofuel production and use to those associated with petroleum-based fuels and other fuel sources. This report was produced at the request of the U.S. Department of Energy.
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- 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 fuels 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.
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. - An energy return on investment (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; freshwater, 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.
- Algal biofuels have the potential to contribute to improving the sustainability of the transportation sector, but the potential is not yet realized. Additional innovations that require research and development are needed to realize the full potential of algal biofuels.
- Algal strain development is needed to enhance traits that contribute to increasing fuel production per unit resource use, reducing the environmental effects per unit fuel produced, and enhancing economic viability. Improvements in biomass or product (lipid, alcohol, or hydrocarbons) yield, culture density, nutrient uptake, ease of harvest, and photosynthetic efficiency are some of the improvements that would improve sustainability of algal biofuels.
- Engineering solutions to enhance algae cultivation, to facilitate biomass or product collection, and to improve processing of algae-derived fuels can increase the EROI and reduce the GHG emissions of algal biofuel production.
- 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.