Report Warns of ‘Unsustainable’ Demands on Resources
Scaling up production of biofuels made from algae to meet at least 5% – approximately 39 billion liters – of U.S. transportation fuel needs “would place unsustainable demands on energy, water, and nutrients,” says a report issued today by the National Research Council and National Academy of Sciences.
“However, these concerns are not a definitive barrier for future production, and innovations that would require research and development could help realize algal biofuels’ full potential,” states a summary of the Sustainable Development of Algal Biofuels in the United States report.
Algal biofuels offer potential advantages over biofuels made from land plants, including algae’s ability to grow on non-croplands in cultivation ponds of freshwater, salt water, or wastewater. Their impact depends “on the pathways used to produce the fuels… Most of the current development involves growing selected strains of algae in open ponds or closed photobioreactors using various water sources, collecting and extracting the oil from algae or collecting fuel precursors secreted by algae, and then processing the oil into fuel.”
Large amounts of water are needed, as are large amounts of nutrients (and energy), and significant amounts of land.
NAS researchers found that found that to produce the algal biofuel equivalent to 1 liter of gasoline, between 3.15 liters to 3,650 liters of freshwater is required, depending on the production pathway.
Siting and Recycling Are Key
Absent aggressive recycling, production of the aforementioned 39 billion liters of algal biofuels would require 44% to 107% of the total nitrogen use and 20% to 51% of the total phosphorus use in the U.S.
“Crucial aspects to sustainable development are positioning algal growth ponds close to water and nutrient resources and recycling essential resources,” NAS says.
“For algal biofuels to contribute a significant amount of fuels for transportation in the future,” the committee said, “research and development would be needed to improve algal strains, test additional strains for desired characteristics, advance the materials and methods for growing and processing algae into fuels, and reduce the energy requirements for multiple stages of production.”
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Source: National Research Council