April 6, 2009
Pressure pumps up algae biofuel
Put water under enough pressure and
you can turn algae into methane fuel and at the same time pull carbon
dioxide out of the atmosphere.
Supercritical water -- water heated beyond 374 degrees Celsius
and pressurized beyond 218 atmospheres -- is a powerful solvent. Researchers
have been exploring ways of using supercritical water to turn biomass
into fuel over the past decade.
The proposed process uses supercritical water to turn microalgae
into methane and concentrated carbon dioxide. Because the process
separates out and stores carbon dioxide, it ensures that burning the
methane fuel releases less carbon dioxide than the algae absorbs from
The process uses the metal ruthenium to catalyze the reaction.
The process turns 60 to 70 percent of the algae's heating value to
methane. A material's heating value is the amount of energy it releases
Methane can be used in place of natural gas to power vehicles,
generate electricity and provide heat. The concentrated carbon dioxide
can be sequestered underground or under the ocean.
The closed loop system would use nutrient byproducts of the
process and some of the carbon dioxide to feed the microalgae. Some
of the methane would be used to heat the system's reactor.
Gasification of Algae in Supercritical Water for Biofuel Production
and Carbon Capture
Energy & Environmental Science, published online March 20,
Gabriela Anca Haiduc
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system closes the loop -- related research
algae spreads the light -- related research
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April 6, 2009
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