Science says algae energy not viable
A report out today from the National Research Council (NRC) of the U.S. National Academies says that large-scale production of biofuels from algae is untenable with existing technology, as it would require the use of too much water, energy, and fertilizer. To improve matters, the report's authors suggest that the U.S. Department of Energy (DOE), which supports much of the research in the field, should conduct assessments of proposed technologies that examine sustainability at all stages of fuel production, including growing or collecting algae and harvesting their oil and converting it into transportation fuels.
...Obama has suggested that we could replace 17 percent of our imported oil with algae based biofuels. The science says such a project would not be sustainable with current technology. BTW, where do you suppose they get all that nitrogen for fertilizer? It is mostly made by processing natural gas. Some is available from manure, but the amount required for the large algae farms would not be sustainable.
But there are many different approaches to growing algae, such as growing the microscopic plants in shallow outdoor ponds, or in enclosed plastic tubes called bioreactors. And the industry is far from settled on a single approach. No matter what the strategy, however, the NRC committee concluded that current technology scaled up to produce 39 billion liters a year—approximately 5% of U.S. transportation fuel needs—would require an unsustainable level of inputs. Current technologies, for example, need between 3.15 liters and 3650 liters of water to produce the amount of algal biofuel equivalent to 1 liter of gasoline, the panel concluded. (That's potentially less than the estimated 5 liters to 2140 liters of water required to produce a liter of ethanol from corn, but more than the 1.9 liters to 6.6 liters of water needed to produce a liter of petroleum-based gasoline.) Growers would also have to add between 6 million and 15 million metric tons of nitrogen and between 1 million and 2 million metric tons of phosphorus to produce 39 billion liters of algal biofuels. That's between 44% and 107% of the total use of nitrogen in the United States, and between 20% and 51% of the nation's phosphorus use for agriculture.
While one of the arguments for algae is that it is not a food product, its production would take from the fertilizer available for food crops.