GreenSun Energy
Encyclopedia
GreenSun Energy is a Jerusalem-based Israeli company that has developed a new process for producing electricity
from solar energy. As The Economist
points our, solar energy is a logical development since "Israel is a country with plenty of sunshine, lots of sand and quite a few clever physicists and chemists."
covered by glass plates. In the GreenSun process, it is only the outer edges of the glass
plates that are covered by with thin strips of silicon. The physicists and chemists at GreenSun, led by Renata Reisfeld
, coat the glass with metallic nanoparticle
s and dye
s to cause the sunlight falling on the glass to diffuse sideways toward the edges where the silicon strips turn it into electricity.
A mixture of dyes is used to capture and absorb a wide spectrum of available light. Having absorbed the sunlight, the fluorescent dyes then re-radiate it. Interaction with the metallic nanoparticles turns light into a form of electromagnetic radiation
known as surface plasmon
s. The surface plasmons propagate over the glass surface and are intercepted by the silicon strips at the edges. The company would not reveal which metals are used in the process.
Because the process uses less silicon, it is far less expensive than conventional photovoltaic module
s. It is also more efficient. In a conventional photovoltaic cell, much of the sun's energy is lost as heat because the energy of light varies across the spectrum (red light is less energetic than blue, for example). Only a particular amount of energy is needed to knock an electron
free from the silicon atom
s. If the sunlight is more energetic than necessary, more energy than usual is lost as heat. Sunlight scatters its energy, but the dye/nanoparticle mix in the GreenSun process delivers plasmons and photons of the right energy to knock electrons free more efficiently.
According to corporate spokesmen Eitan Shmueli, GreenSun's photovoltaic panels are capable of producing electricity from low-intensity sunlight on cloudy days and from sunlight that reaches them from any angle. The company claims that can turn the windows or walls of buildings into electricity-generating photovoltaic panels.
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
from solar energy. As The Economist
The Economist
The Economist is an English-language weekly news and international affairs publication owned by The Economist Newspaper Ltd. and edited in offices in the City of Westminster, London, England. Continuous publication began under founder James Wilson in September 1843...
points our, solar energy is a logical development since "Israel is a country with plenty of sunshine, lots of sand and quite a few clever physicists and chemists."
The process
Traditional photovoltaic cells are made from thin sheets of siliconSilicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
covered by glass plates. In the GreenSun process, it is only the outer edges of the glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
plates that are covered by with thin strips of silicon. The physicists and chemists at GreenSun, led by Renata Reisfeld
Renata Reisfeld
Renata Reisfeld is an Israeli Professor of Chemistry and D.H.C. Enrique Berman Professor of Solar Energy at Institute of Chemistry of the Hebrew University of Jerusalem, Israel.-Biography:Renata Reisfeld was born in Poland...
, coat the glass with metallic nanoparticle
Nanoparticle
In nanotechnology, a particle is defined as a small object that behaves as a whole unit in terms of its transport and properties. Particles are further classified according to size : in terms of diameter, coarse particles cover a range between 10,000 and 2,500 nanometers. Fine particles are sized...
s and dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....
s to cause the sunlight falling on the glass to diffuse sideways toward the edges where the silicon strips turn it into electricity.
A mixture of dyes is used to capture and absorb a wide spectrum of available light. Having absorbed the sunlight, the fluorescent dyes then re-radiate it. Interaction with the metallic nanoparticles turns light into a form of electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
known as surface plasmon
Surface plasmon
Surface plasmons , are coherent electron oscillations that exist at the interface between any two materials where the real part of the dielectric function changes sign across the interface...
s. The surface plasmons propagate over the glass surface and are intercepted by the silicon strips at the edges. The company would not reveal which metals are used in the process.
Because the process uses less silicon, it is far less expensive than conventional photovoltaic module
Photovoltaic module
A solar panel is a packaged, connected assembly of solar cells, also known as photovoltaic cells...
s. It is also more efficient. In a conventional photovoltaic cell, much of the sun's energy is lost as heat because the energy of light varies across the spectrum (red light is less energetic than blue, for example). Only a particular amount of energy is needed to knock an electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
free from the silicon atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s. If the sunlight is more energetic than necessary, more energy than usual is lost as heat. Sunlight scatters its energy, but the dye/nanoparticle mix in the GreenSun process delivers plasmons and photons of the right energy to knock electrons free more efficiently.
Economics
GreenEnergy CEO Amnon Leikovich claims that the process, once put into production, could deliver electricity at about double the cost of a conventional power station. Traditional photovoltaic modules deliver electricity at about five times the cost of a conventional power plant. Leikovich hopes that costs can be brought down even further.According to corporate spokesmen Eitan Shmueli, GreenSun's photovoltaic panels are capable of producing electricity from low-intensity sunlight on cloudy days and from sunlight that reaches them from any angle. The company claims that can turn the windows or walls of buildings into electricity-generating photovoltaic panels.
External links
- Green Sun Energy company website
- Audio interview with Renata Reisfeld, CTO and Chief Scientist http://audiovideo.economist.com/?fr_story=7f8b0d5b6ee20f7f5ab080e25d0372559c43bb37&rf=bm