News Article
MIT Opens New 'window' On Solar Energy
Cost
effective devices expected on market soon. The technology could be
used to convert glass buildings into big energy plants. Scientists
from the Massachusetts Institute of Technology (MIT) have developed a
way to coat substrates most effectively.
Imagine windows that not only provide a
clear view and illuminate rooms, but also use sunlight to efficiently
help power the building they are part of. MIT engineers report a new
approach to harnessing the sun's energy that could allow just that.
The work, to be reported in the July 11
issue of Science, involves the creation of a novel "solar
concentrator." "Light is collected over a large area [like
a window] and gathered, or concentrated, at the edges," explains
Marc A. Baldo, leader of the work and the Esther and Harold E.
Edgerton Career Development Associate Professor of Electrical
Engineering.
As a result, rather than covering a
roof with expensive solar cells (the semiconductor devices that
transform sunlight into electricity), the cells only need to be
around the edges of a flat glass panel. In addition, the focused
light increases the electrical power obtained from each solar cell
"by a factor of over 40," Baldo says.
Because the system is simple to
manufacture, the team believes that it could be implemented within
three years, even added onto existing solar panel systems to increase
their efficiency by 50 percent for minimal additional cost. That, in
turn, would substantially reduce the cost of solar electricity.
In addition to Baldo, the researchers
involved are Michael Currie, Jon Mapel, and Timothy Heidel, all
graduate students in the Department of Electrical Engineering and
Computer Science, and Shalom Goffri, a postdoctoral associate in
MIT's Research Laboratory of Electronics.
"Professor Baldo's project
utilises innovative design to achieve superior solar conversion
without optical tracking," says Dr. Aravinda Kini, programme
manager in the Office of Basic Energy Sciences in the U.S. Department
of Energy's Office of Science, a sponsor of the work. "This
accomplishment demonstrates the critical importance of innovative
basic research in bringing about revolutionary advances in solar
energy utilization in a cost effective manner."
Solar concentrators in use today "track
the sun to generate high optical intensities, often by using large
mobile mirrors that are expensive to deploy and maintain," Baldo
and colleagues write in Science. Further, "solar cells at the
focal point of the mirrors must be cooled, and the entire assembly
wastes space around the perimeter to avoid shadowing neighbouring
concentrators."
The MIT solar concentrator involves a
mixture of two or more dyes that is essentially painted onto a pane
of glass or plastic. The dyes work together to absorb light across a
range of wavelengths, which is then re-emitted at a different
wavelength and transported across the pane to waiting solar cells at
the edges.
In the 1970s, similar solar
concentrators were developed by impregnating dyes in plastic. But the
idea was abandoned because, among other things, not enough of the
collected light could reach the edges of the concentrator. Much of it
was lost en route.
The MIT engineers, experts in optical
techniques developed for lasers and organic light emitting diodes,
realised that perhaps those same advances could be applied to solar
concentrators. The result: A mixture of dyes in specific ratios,
applied only to the surface of the glass, that allows some level of
control over light absorption and emission. "We made it so the
light can travel a much longer distance," Mapel says. "We
were able to substantially reduce light transport losses, resulting
in a tenfold increase in the amount of power converted by the solar
cells."
This work was also supported by the
National Science Foundation. Baldo is also affiliated with MIT's
Research Laboratory of Electronics, Microsystems Technology
Laboratories, and Institute for Soldier Nanotechnologies.
Mapel, Currie and Goffri are starting a
company, Covalent Solar, to develop and commercialize the new
technology. Earlier this year Covalent Solar won two prizes in the
MIT $100K Entrepreneurship Competition. The company placed first in
the Energy category ($20,000) and won the Audience Judging Award
($10,000), voted on by all who attended the awards.
clear view and illuminate rooms, but also use sunlight to efficiently
help power the building they are part of. MIT engineers report a new
approach to harnessing the sun's energy that could allow just that.
The work, to be reported in the July 11
issue of Science, involves the creation of a novel "solar
concentrator." "Light is collected over a large area [like
a window] and gathered, or concentrated, at the edges," explains
Marc A. Baldo, leader of the work and the Esther and Harold E.
Edgerton Career Development Associate Professor of Electrical
Engineering.
As a result, rather than covering a
roof with expensive solar cells (the semiconductor devices that
transform sunlight into electricity), the cells only need to be
around the edges of a flat glass panel. In addition, the focused
light increases the electrical power obtained from each solar cell
"by a factor of over 40," Baldo says.
Because the system is simple to
manufacture, the team believes that it could be implemented within
three years, even added onto existing solar panel systems to increase
their efficiency by 50 percent for minimal additional cost. That, in
turn, would substantially reduce the cost of solar electricity.
In addition to Baldo, the researchers
involved are Michael Currie, Jon Mapel, and Timothy Heidel, all
graduate students in the Department of Electrical Engineering and
Computer Science, and Shalom Goffri, a postdoctoral associate in
MIT's Research Laboratory of Electronics.
"Professor Baldo's project
utilises innovative design to achieve superior solar conversion
without optical tracking," says Dr. Aravinda Kini, programme
manager in the Office of Basic Energy Sciences in the U.S. Department
of Energy's Office of Science, a sponsor of the work. "This
accomplishment demonstrates the critical importance of innovative
basic research in bringing about revolutionary advances in solar
energy utilization in a cost effective manner."
Solar concentrators in use today "track
the sun to generate high optical intensities, often by using large
mobile mirrors that are expensive to deploy and maintain," Baldo
and colleagues write in Science. Further, "solar cells at the
focal point of the mirrors must be cooled, and the entire assembly
wastes space around the perimeter to avoid shadowing neighbouring
concentrators."
The MIT solar concentrator involves a
mixture of two or more dyes that is essentially painted onto a pane
of glass or plastic. The dyes work together to absorb light across a
range of wavelengths, which is then re-emitted at a different
wavelength and transported across the pane to waiting solar cells at
the edges.
In the 1970s, similar solar
concentrators were developed by impregnating dyes in plastic. But the
idea was abandoned because, among other things, not enough of the
collected light could reach the edges of the concentrator. Much of it
was lost en route.
The MIT engineers, experts in optical
techniques developed for lasers and organic light emitting diodes,
realised that perhaps those same advances could be applied to solar
concentrators. The result: A mixture of dyes in specific ratios,
applied only to the surface of the glass, that allows some level of
control over light absorption and emission. "We made it so the
light can travel a much longer distance," Mapel says. "We
were able to substantially reduce light transport losses, resulting
in a tenfold increase in the amount of power converted by the solar
cells."
This work was also supported by the
National Science Foundation. Baldo is also affiliated with MIT's
Research Laboratory of Electronics, Microsystems Technology
Laboratories, and Institute for Soldier Nanotechnologies.
Mapel, Currie and Goffri are starting a
company, Covalent Solar, to develop and commercialize the new
technology. Earlier this year Covalent Solar won two prizes in the
MIT $100K Entrepreneurship Competition. The company placed first in
the Energy category ($20,000) and won the Audience Judging Award
($10,000), voted on by all who attended the awards.
