EnergyLarge-scale production of algae-based biofuels poses sustainability concerns
Scaling up the production of biofuels made from algae to meet at least 5 percent — approximately thirty-nine billion liters — of U.S. transportation fuel needs would place unsustainable demands on energy, water, and nutrients, says a new report from the National Research Council; these concerns, however, are not a definitive barrier for future production, and innovations that would require research and development could help realize algal biofuels’ full potential
"Bags" of algae biomass for fuel production // Source: naver.com
Scaling up the production of biofuels made from algae to meet at least 5 percent — approximately thirty-nine billion liters — of U.S. transportation fuel needs would place unsustainable demands on energy, water, and nutrients, says a new report from the National Research Council. These concerns, however, are not a definitive barrier for future production, and innovations that would require research and development could help realize algal biofuels’ full potential.
Biofuels derived from algae and cyanobacteria are possible alternatives to petroleum-based fuels and could help the United States meet its energy security needs and reduce greenhouse gas emissions, such as carbon dioxide (CO2). 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. The number of companies developing algal biofuels has been increasing, and several oil companies are investing in them. Given these and other interests, the National Research Council was asked to identify sustainability issues associated with large-scale development of algal biofuels.
A National Academies release reports that the committee that wrote the report said that concerns related to large-scale algal biofuel development differ depending on the pathways used to produce the fuels. Producing fuels from algae could be done in many ways, including cultivating freshwater or saltwater algae, growing algae in closed photobioreactors or open-pond systems, processing the oils produced by microalgae, or refining all parts of macroalgae. The committee’s sustainability analysis focused on pathways that to date have received active attention. 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.
The committee pointed out several high-level concerns for large-scale development of algal biofuel, including the relatively large quantity of water required for algae cultivation; magnitude of nutrients, such as nitrogen, phosphorus, and CO2, needed for cultivation; amount of land area necessary to contain the ponds that grow the algae; and uncertainties in greenhouse gas emissions over the production life cycle. Moreover, the algal biofuel energy return on investment would have to be high, meaning more energy would have to be produced from the biofuels than what is required to cultivate algae and convert them to fuels.
The committee found that to produce the amount of algal biofuel equivalent to
