The prototype solar reactor that directly converts the
Sun's rays into fuel
Because conventional
photovoltaic panels produce electricity directly from
sunlight, the energy they generate must either be used as it is
produced or stored – either in batteries or by using the
electricity to produce a fuel that acts as a storage medium for
the energy. Now U.S. and Swiss researchers have developed a
prototype device that directly converts the Sun’s rays into
fuels that can be stored, allowing the energy to be used at
night or transported to locations where it is needed.
A
BBC report citing a paper appearing in the journal
Science describes how the prototype device uses a
quartz window and cavity to focus sunlight into a cylinder lined
with cerium oxide. Cerium oxide, also known as ceria, is
hygroscopic (meaning that it attracts and holds water molecules
from the surrounding environment) and will also absorb a small
amount of carbon dioxide. As the sunlight heats the ceria, it
thermochemically breaks down the water and carbon dioxide pumped
into the cylinder to produce carbon monoxide and hydrogen that
can be converted to a liquid fuel.
The resultant hydrogen could be used as fuel for hydrogen
fuel cell vehicles such as those being developed by a number of
automakers, including
Hyundai and
Honda, while a combination of hydrogen and carbon monoxide
could be used to create syngas – a combustible gas that has less
than half the energy density of natural gas but is often used as
a fuel source or as an intermediate for the production of other
chemicals. The researchers say the device can also be used to
produce methane.
With cerium being the most abundant “rare-earth” metal, the
developers of the device from the
California Institute of Technology and the Swiss Federal
Institute of Technology say it would be economically feasible to
use the technology on a large scale.
Although currently, the prototype is not very efficient, with
the fuel created harnessing between just 0.7 and 0.8 percent of
the solar energy put into the device. This inefficiency is
because most of the energy is lost through heat loss through the
reactor’s wall or through the re-radiation of sunlight back
through the device’s aperture. However, the researchers believe
that a commercially viable device with efficiency rates of up to
19 percent is possible by using better insulation and smaller
apertures.
Via
BBC
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