MONDAY 09 MARCH, 2009 |
Solar Energy: Turning Carbon Dioxide To Methane
According to researchers at Penn State University, carbon dioxide emissions
intensive industries could convert CO2 to a wide variety of hydrocarbons, such
as methane. While methane is a powerful greenhouse gas, it's a useful one that
can be used for fuel.
The researchers state that while recycling of carbon dioxide into a high
energy-content fuel is an attractive option, the process is energy intense and
useful only if a renewable
source can be used for the purpose - and solar energy appears to be
The "solar powered" carbon dioxide recycling system uses titanium
dioxide nanotubes treated with nitrogen and coated with a thin layer of copper
and platinum to convert a mixture of carbon dioxide and water vapour to methane.
Professor Craig A. Grimes and his team used natural sunlight to test their
nanotubes in a chamber containing a mix of water vapor and carbon dioxide and
exposed the co-catalyst sensitized nanotubes to sunlight for 2.5 to 3.5 hours;
when the sun produced between 102 and 75 milliwatts for each square centimeter
The team found that using outdoor, visible light, a 20-times higher yield of
methane could be achieved compared to previously published laboratory tests that
use intense artificially generated ultraviolet exposures.
The chemical conversion of water and carbon dioxide to methane is seems relatively easy in theory - one carbon dioxide molecule and two water molecules become one methane molecule and two oxygen molecules. However, attempts have had very low conversion rates as the process requires
an efficient photocatalyst that uses the maximum energy available in sunlight.
The researchers are now working on converting their batch reactor into a
continuous flow-through design that they believe will significantly increase
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