Tuesday, July 22, 2014

It looks like I forgot to post this on radiative cooling

Daytime radiative cooling

http://nanotechnologytoday.blogspot.com/2013/03/ultrabroadband-photonic-structures-to.html

Ultrabroadband Photonic Structures To Achieve High-Performance Daytime Radiative Cooling. A Stanford team has designed an entirely new form of cooling panel that works even when the sun is shining. Such a panel could vastly improve the daylight cooling of buildings, cars and other structures by radiating sunlight back into the chilly vacuum of space.

Homes and buildings chilled without air conditioners. Car interiors that don't heat up in the summer sun. Tapping the frigid expanses of outer space to cool the planet. Science fiction, you say? Well, maybe not any more.

A team of researchers at Stanford has designed an entirely new form of cooling structure that cools even when the sun is shining. Such a structure could vastly improve the daylight cooling of buildings, cars and other structures by reflecting sunlight back into the chilly vacuum of space.

“People usually see space as a source of heat from the sun, but away from the sun outer space is really a cold, cold place,” explained Shanhui Fan, professor of electrical engineering and the paper’s senior author. “We’ve developed a new type of structure that reflects the vast majority of sunlight, while at the same time it sends heat into that coldness, which cools manmade structures even in the day time.”

The trick, from an engineering standpoint, is two-fold. First, the reflector has to reflect as much of the sunlight as possible. Poor reflectors absorb too much sunlight, heating up in the process and defeating the purpose of cooling.


Ultrabroadband Photonic Structures

The second challenge is that the structure must efficiently radiate heat back into space. Thus, the structure must emit thermal radiation very efficiently within a specific wavelength range in which the atmosphere is nearly transparent. Outside this range, Earth’s atmosphere simply reflects the light back down. Most people are familiar with this phenomenon. It’s better known as the greenhouse effect—the cause of global climate change.

Cooling solar cells

I found this, which is a follow-on to my previous post on radiative cooling

http://www.osa-opn.org/home/newsroom/2014/july/self-cooling_solar_cells/



By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers led by Shanhui Fan, an electrical engineering professor at Stanford University in California has found a way to let solar cells cool themselves by shepherding away unwanted thermal radiation. The researchers describe their innovative design in the premiere issue of The Optical Society's (OSA) new open-access journal Optica.
Solar cells are among the most promising and widely used renewable energy technologies on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the Sun into usable electricity.
Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is due to solar cells overheating.
Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however—either by ventilation or coolants—would be prohibitively expensive and at odds with the need to optimize exposure to the Sun.
The newly proposed design avoids these problems by taking a more elegant, passive approach to cooling. By embedding tiny pyramid- and cone-shaped structures on an incredibly thin layer of silica glass, the researchers found a way of redirecting unwanted heat—in the form of infrared radiation—from the surface of solar cells, through the atmosphere, and back into space.
"Our new approach can lower the operating temperature of solar cells passively, improving energy conversion efficiency significantly and increasing the life expectancy of solar cells," said Linxiao Zhu, a physicist at Stanford and lead author on the Optica paper. "These two benefits should enable the continued success and adoption of solar cell technology."

By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers led by Shanhui Fan, an electrical engineering professor at Stanford University in California has found a way to let solar cells cool themselves by shepherding away unwanted thermal radiation. The researchers describe their innovative design in the premiere issue of The Optical Society's (OSA) new open-access journal Optica.
Solar cells are among the most promising and widely used on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the Sun into usable electricity.
Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is due to solar cells overheating.
Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however—either by ventilation or coolants—would be prohibitively expensive and at odds with the need to optimize exposure to the Sun.
The newly proposed design avoids these problems by taking a more elegant, passive approach to cooling. By embedding tiny pyramid- and cone-shaped structures on an incredibly thin layer of , the researchers found a way of redirecting unwanted heat—in the form of infrared radiation—from the surface of solar cells, through the atmosphere, and back into space.
"Our new approach can lower the operating temperature of solar cells passively, improving significantly and increasing the life expectancy of solar cells," said Linxiao Zhu, a physicist at Stanford and lead author on the Optica paper. "These two benefits should enable the continued success and adoption of ."


Read more at: http://phys.org/news/2014-07-self-cooling-solar-cells-boost-power.html#jCp
Scientists may have overcome one of the major hurdles in developing high-efficiency, long-lasting solar cells—keeping them cool, even in the blistering heat of the noonday Sun.
By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers led by Shanhui Fan, an electrical engineering professor at Stanford University in California has found a way to let solar cells cool themselves by shepherding away unwanted thermal radiation. The researchers describe their innovative design in the premiere issue of The Optical Society's (OSA) new open-access journal Optica.
Solar cells are among the most promising and widely used on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the Sun into usable electricity.
Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is due to solar cells overheating.
Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however—either by ventilation or coolants—would be prohibitively expensive and at odds with the need to optimize exposure to the Sun.
The newly proposed design avoids these problems by taking a more elegant, passive approach to cooling. By embedding tiny pyramid- and cone-shaped structures on an incredibly thin layer of , the researchers found a way of redirecting unwanted heat—in the form of infrared radiation—from the surface of solar cells, through the atmosphere, and back into space.
"Our new approach can lower the operating temperature of solar cells passively, improving significantly and increasing the life expectancy of solar cells," said Linxiao Zhu, a physicist at Stanford and lead author on the Optica paper. "These two benefits should enable the continued success and adoption of ."


Read more at: http://phys.org/news/2014-07-self-cooling-solar-cells-boost-power.html#jCp
Scientists may have overcome one of the major hurdles in developing high-efficiency, long-lasting solar cells—keeping them cool, even in the blistering heat of the noonday Sun.
By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers led by Shanhui Fan, an electrical engineering professor at Stanford University in California has found a way to let solar cells cool themselves by shepherding away unwanted thermal radiation. The researchers describe their innovative design in the premiere issue of The Optical Society's (OSA) new open-access journal Optica.
Solar cells are among the most promising and widely used on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the Sun into usable electricity.
Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is due to solar cells overheating.
Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however—either by ventilation or coolants—would be prohibitively expensive and at odds with the need to optimize exposure to the Sun.
The newly proposed design avoids these problems by taking a more elegant, passive approach to cooling. By embedding tiny pyramid- and cone-shaped structures on an incredibly thin layer of , the researchers found a way of redirecting unwanted heat—in the form of infrared radiation—from the surface of solar cells, through the atmosphere, and back into space.
"Our new approach can lower the operating temperature of solar cells passively, improving significantly and increasing the life expectancy of solar cells," said Linxiao Zhu, a physicist at Stanford and lead author on the Optica paper. "These two benefits should enable the continued success and adoption of ."


Read more at: http://phys.org/news/2014-07-self-cooling-solar-cells-boost-power.html#jCp
Scientists may have overcome one of the major hurdles in developing high-efficiency, long-lasting solar cells—keeping them cool, even in the blistering heat of the noonday Sun.
By adding a specially patterned layer of silica glass to the surface of ordinary solar cells, a team of researchers led by Shanhui Fan, an electrical engineering professor at Stanford University in California has found a way to let solar cells cool themselves by shepherding away unwanted thermal radiation. The researchers describe their innovative design in the premiere issue of The Optical Society's (OSA) new open-access journal Optica.
Solar cells are among the most promising and widely used on the market today. Though readily available and easily manufactured, even the best designs convert only a fraction of the energy they receive from the Sun into usable electricity.
Part of this loss is the unavoidable consequence of converting sunlight into electricity. A surprisingly vexing amount, however, is due to solar cells overheating.
Under normal operating conditions, solar cells can easily reach temperatures of 130 degrees Fahrenheit (55 degrees Celsius) or more. These harsh conditions quickly sap efficiency and can markedly shorten the lifespan of a solar cell. Actively cooling solar cells, however—either by ventilation or coolants—would be prohibitively expensive and at odds with the need to optimize exposure to the Sun.
The newly proposed design avoids these problems by taking a more elegant, passive approach to cooling. By embedding tiny pyramid- and cone-shaped structures on an incredibly thin layer of , the researchers found a way of redirecting unwanted heat—in the form of infrared radiation—from the surface of solar cells, through the atmosphere, and back into space.
"Our new approach can lower the operating temperature of solar cells passively, improving significantly and increasing the life expectancy of solar cells," said Linxiao Zhu, a physicist at Stanford and lead author on the Optica paper. "These two benefits should enable the continued success and adoption of ."


Read more at: http://phys.org/news/2014-07-self-cooling-solar-cells-boost-power.html#jCp

Saturday, May 1, 2010

Future of robotocs for human augumentation

Dean Kamen give and excellent presentation that explains how his group is designing hardware for physically disabled veterans. This is a must watch.


http://www.youtube.com/watch?v=rNgqQNovWTc

Monday, April 12, 2010

Fusion?

I don't know if this will ever pan out, but it might be a start...

New hope for ultimate clean energy: fusion power


(PhysOrg.com) -- Imagine if you could generate electricity using nuclear power that emitted no radioactivity: it would be the answer to the world's dream of finding a clean, sustainable energy source.

Monday, January 21, 2008

And reality strikes

I have a personal bias that causes me to wish that the world will be a better place in the future. Unfortunately it looks like we will be going through a rough patch before we get there. In the USA we have a monetary situation where it is extremely likely that our elected officials will cause a DEPRESSION, instead of allowing the market correction that needs to occur.
Part of the problem is the insatiable addiction to oil, and the fact that we are currently using everything that can be pumped out of the earth. Global warming is another piece, and global pollution and the wholesale resource depletion, both on land and at sea is another.
The hope that I have is based on the possibility of nuclear fusion research, which is proceeding after the death last year of Dr. Robert W. Bussard.