PerspectiveChemistry

Algae Under Pressure and in Hot Water

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Science  23 Nov 2012:
Vol. 338, Issue 6110, pp. 1039-1040
DOI: 10.1126/science.1224310

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Summary

Algae grow quickly, can be cultivated to have a high oil (triacylglyceride) content, and can be grown on nonarable land with brackish or salt water. These characteristics make them an attractive source of biomass for renewable biofuels. The U.S. Navy and commercial airlines have demonstrated the use of algal biofuel in ships and planes; blending algal biofuel with ultralow-sulfur diesel fuel reduced the pollutants and particulate matter and improved fuel economy during the operation of a marine vessel on the Great Lakes (1). Algae-derived fuel is very expensive, however, and most of the cost is associated with producing the biomass. The U.S. Navy has contracted to pay $12 million for 450,000 gallons (1.7 million liters) of biofuel, which works out to about $27/gallon or 10 times the U.S. cost of petroleum-derived fuel [see, for example, (2)]. Chemical reactions in hot, compressed water (hydrothermal reactions) and in supercritical fluids can provide new, potentially cheaper paths to renewable fuels from wet algal biomass (3).