Stories tagged solar
Solar cells that work at night
Solar cells become ineffective when the sun goes down. At night, the earth radiates heat back toward the sky. Scientists at the U.S. Department of Energy's Idaho National Laboratory are working on a device to turn infrared radiation into electricity.
Nanoantennas convert infrared rays into electricity
Billions of nanoantennas printed onto thin, inexpensive sheets will transform heat energy into electricity. The physics behind this conversion is the same as that of a radio antenna. The only difference between radiowaves and infrared light is wavelength. Antennas 1/25 the size of a human hair resonate when bombarded with heat radiation. If the resulting alternating current can be passed through a rectifier (one way valve) the current can charge up batteries. The infrared rays create alternating currents in the nanoantennas that oscillate trillions of times per second.
"Today's rectifiers can't handle such high frequencies. "We need to design nanorectifiers that go with our nanoantennas," says Kotter, noting that a nanoscale rectifier would need to be about 1,000 times smaller than current commercial devices and will require new manufacturing methods. Another possibility is to develop electrical circuitry that might slow down the current to usable frequencies." Eureka Alert
If these technical hurdles can be overcome, nanoantennas have the potential to be a cheaper, more efficient alternative to solar cells. Computer models of nanoantennas predict up to 92% efficiency (compared to solar cells around 20%).
Learn more in this video, "Harvesting the sun's energy with antennas"
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Splitting water to store electricity: A snapshot showing the new, efficient oxygen catalyst in action in Dan Nocera's laboratory at MIT.Courtesy MIT/NSF
Saving up energy for use at night
Want to be energy independent? Solar and wind energy are great but what do you do when the sun goes down and the wind doesn't blow? Batteries with the needed capacity are very expensive.
Energy can be saved up by breaking water apart into hydrogen and oxygen
Using a surprisingly simple, inexpensive technique, chemists have found a way to pull pure oxygen from water using relatively small amounts of electricity, common chemicals and a room-temperature glass of water. At night that oxygen can be combined with hydrogen (also extracted from water) in a fuel cell to make electricity.
The new process, enabling water to more easily be split, is to use a catalyst consisting of cobalt metal, phosphate and an electrode, placed in water.
"When electricity -- whether from a photovoltaic cell, a wind turbine or any other source -- runs through the electrode, the cobalt and phosphate form a thin film on the electrode, and oxygen gas is produced."
"The new catalyst works at room temperature, in neutral pH water, and it's easy to set up. That's why I know this is going to work. It's so easy to implement," Danial Nocera (MIT news office)
Within ten years
Nocera hopes that within 10 years, homeowners will be able to power their homes in daylight through photovoltaic cells, while using excess solar energy to produce hydrogen and oxygen to power their own household fuel cell. Electric vehicles will also power up from this home system.
Learn more: MIT News
What is the best way to store solar energy?
Solar Two: Heat from the sun is stored in a tower containing molten salt.Courtesy United States Department of Energy What is a good way to store solar energy for when the sun doesn't shine? Batteries are expensive and wear out. Instead of storing electricity, solar thermal systems store heat. A coffee thermos and a laptop computer’s battery store about the same amount of energy. The thermos costs about $5 and the laptop battery $150.
Molten salt at 1000+ degrees
By reflecting sunlight at a tall "power tower", tens of thousands of gallons of molten salt can be heated to very high temperatures (1000 degrees F). The heated salt is used to boil water into steam, spin a turbine and make electric power. By regulating the release of heat, generators can continue to run on rainy days and during the night.
"This technology has been successfully demonstrated and is ready for commercialization. From 1994 to 1999, the Solar Two project demonstrated the ability of solar molten salt technology to provide long-term, cost effective thermal energy storage for electricity generation."
SolarReserve will build solar thermal electric plants
SolarReserve, a company backed in part by United Technologies, is using funding from a U.S. Department of Energy grant to develop utility-scale solar thermal electric generating plants between 100-600 megawatts of electricity. One megawatt is enough power to supply approximately 1,000 US households. Read more at SolarReserves FAQ webpage.
Sources:
New York Times
SolarReserve website (includes a video)
Popcorn shaped dye particles double cheaper solar cell efficiency
Popcorn-ball design doubles efficiency of dye-sensitized solar cells: A close-up of a single ball, taken with a scanning electron microscope. The 300-nanometer sphere is large enough to scatter light. But its insides are made of tiny grains just 15 nanometers across.Courtesy University of Washington Dye-sensitized solar cells, which are more flexible, easier to manufacture, and cheaper than existing solar technologies just got even better.
By using particles shaped like popcorn, University of Washington researchers were able to increase solar cell efficiencies from 2.4 up to 6.2 per cent. The porosity of the large balls (300nm) allowed light to penetrate into the layers and bounce around between balls increasing absorption. Each balls surface was made of smaller spheres (15nm) increasing the effective surface area. One gram of this material has a surface area of 1000 square feet.
The research used the pigment zinc oxide, which is of lower efficiency than the commercially used titanium oxide, but easier to work with during experiments. Titanium oxide layers are expected to show similar gains. While titanium oxide cells currently have a record efficiency of 11 percent, the researchers hope that by using the new method they can by far surpass this old record, possibly even surpassing silicon cell efficiencies. Such progress could make silicon cells, used for decades, obsolete, replaced by cheaper, more efficient, flexible cells.
Source; University of Washington News
Silicon solar obsolete soon?Courtesy D. O. E.
NanoSolar, cheaper than coal
Renewable energy becoming cheaper than fossil fuels may happen soon. Today, Nanosolar CEO Martin Roscheisen says his startup took a step in that direction by shipping its first thin-film solar panel (via TechCrunch). In a blog post, Roscheisen claims his company has produced
“the world’s lowest-cost solar panel – which we believe will make us the first solar manufacturer capable of profitably selling solar panels at as little as $.99/Watt.”
Electricity from a new coal burning plant costs about $2.10/watt.
Nanosolar can change the world
Popular Science gave Nanosolar's Powersheets the top technical innovation of the year award. The NanoSolar website provides this list of news and events:
- Nanosolar ships first panels.
- Nanosolar secures 647,000 sqft of manufacturing space.
- Nanosolar raises $100,000,000; building factory.
- IBM's top manufacturing executive joins Nanosolar.
- Google founders invest in Nanosolar.
You can watch a video showing how NanoSolar photocells are manufactured (via KQED).
Making the world a better place
A philanthropic arm of the Google Foundation called Goggle.org drawing upon its nearly $2 billion in Google stock will invest "hundreds of millions" in companies specializing in renewable energy, co-founder Larry Page said.
"If we achieve these goals, we are going to be in the (electricity) business in a very big way," Page said. "We should be able to make a lot of money from this."
One gigawatt of renewable energy
Google's plan, known as RE< C, is to develop a gigawatt of electricity from renewable energy sources that will be cheaper than electricity produced from burning coal. Google is betting its R&D dollars on advanced solar thermal power, wind power, and enhanced geothermal technologies. Google's headquarters already draws some of its power from one of the country's biggest solar power installations.
"Cheap renewable energy is not only critical for the environment but also vital for economic development in many places where there is limited affordable energy of any kind," added Sergey Brin, Google Co-founder and President of Technology.
Google.org grants and investments
Two companies Google.com is working with are eSolar Inc. and Makani Power Inc. By focusing sunlight with mirrors, eSolar Inc. hopes to generate utility-scale power cheaper than with coal. Makani Power Inc. is developing high-altitude wind energy extraction technologies (Get more information via pdf downloads by clicking the company names).
"Google.org's hope is that by funding research on promising technologies, investing in promising new companies, and doing a lot of R&D ourselves, we may help spark a green electricity revolution that will deliver breakthrough technologies priced lower than coal." (Nov 27 Google press release)
Sources & resources: Yahoo News and Google.com and FAQ
The World Solar Challenge is a solar
Solar powered race car: Source: Panasonic World Solar Challenge image gallery powered-car race over 3021 km (1,877 miles) through central Australia from Darwin to Adelaide. Started in 1987 by Hans Thostrup, this race was held every three years until 1999 when it was switched to a two year event. It's an energy efficiency challenge, all about creating a balance between sustainable speed and endurance, energy management and strategic planning.
Optional new rules require fewer solar cells
Entrants to the 2007 race chose between racing in the Adventure and Challenge classes.
Challenge class cars were restricted to 6 square meters of solar collectors (a 25% reduction), driver access and egress were required to be unaided, seating position upright, steering controlled with a steering wheel, and many new safety requirements were added. Competitors also had to adhere to the new 130 km/h speed limit across the Northern Territorial portion of the Stuart Highway. Click here see more rules.
Dutch Nuon Solar Team wins again
This year the Dutch Nuon Solar Team scored their fourth successive victory with Nuna4 in the challenge class averaging 90.07 km/h under the new rules, while the Ashiya team with their car Tiga won the race in the adventure class under the old rules with an average speed of 93.53 km/h.
Solar home design competition
Solar Decathlon: The public flocked to see 20 solar powered homes on the National Mall in Washington, D.C. (Credit: Kaye Evans-Lutterodt/Solar Decathlon)The Solar Decathlon is a competition in which 20 teams of college and university students compete to design, build, and operate the most attractive, effective, and energy-efficient solar-powered house. The event took place on the National Mall in Washington, D.C., October 12 - 20.
To compete, the teams must design and build energy-efficient homes that are powered exclusively by the sun. The homes must be attractive and easy to live in. They must maintain a comfortable temperature, provide attractive and adequate lighting, power household appliances for cooking and cleaning, power home electronics, and provide hot water. These houses must also power an electric vehicle to meet household transportation needs.
The Solar Decathlon is 10 contests in one
Ten separate contests were scored, then added together to determine the winner of the Solar Decathlon. Each division below is linked to webpage for more information.
- Architecture 200 points
- Engineering 150 points
- Market Viability 150 points
- Communications 100 points
- Comfort Zone 100 points
- Appliances 100 points
- Hot Water 100 points
- Lighting 100 points
- Energy Balance 100 points
- Getting Around 100 points
Winner: Technische Universitat Darmstadt
This team from Germany came to the Solar Decathlon hoping to have an impact on people, and it's safe to say that this happened. Darmstadt won the Architecture, Lighting, and Engineering contests. The Architecture Jury said the house pushed the envelope on all levels and is the type of house they came to the Decathlon hoping to see. The Lighting Jury loved the way this house glows at night. The Engineering Jury gave this team an innovation score that was as high as you could go, and said nobody did the integration of the PV system any better. Darmstadt was one of seven teams to score a perfect 100 points in the Energy Balance contest. All week, long lines of people waited to get into this house.solardecathlon.org
Learn more about the 2007 Solar Decathlon
A solar powered telephone: And you thought the Death Star was sinister? Well that never destroyed our planet, so no. (photo by redjar on flickr.com)According to Dr. Jesse Aubusel, the Director of the Program for the Human Environment at The Rockefeller University, renewable energy isn’t a super good idea. That is to say, he thinks it’s a pretty bad idea.
Using math and numbers, Dr. Aubusel figures that the amount of land necessary for “green” energy sources makes them extremely impractical, especially when compared to nuclear energy. According to Aubusel, were we to flood all of Ontario (900,000 square km), it would only provide 80% of the energy that Canada’s 25 nuclear power stations could produce. I guess that’s the end of my plans to flood Ontario. Or, to provide enough electricity for New York City, all of Connecticut would have to be turned into a wind farm (although, who’s to say that Connecticut would mind). Also, to grow a single pot of basil, it would take more dirt than there is in my whole room. So no basil.
Aubusel, in this article, always brings the issue back to the matter physical space required for renewable energy, and the number of watts produced per square meter. “Nuclear energy is green,” he states. He’s not referring to its radioactivity, I think, so much as to its relatively small physical footprint, and the potential to use already existing infrastructure.
It might seem to some that this is a pretty simplistic way of looking at things, but we should all make sure that we’re doctors before we disagree.
When asked if he could imagine technology that uses and creates energy more efficiently than those he based his research on, Doctor Aubusel states, “No.” When asked if he could possibly try, he replied, “That’s not really my style.”
Solar cells reduce your electric bill, but they are also very expensive to buy and install. Are they worth it?: Photo by clownfish from www.flickr.com
Some people are installing solar panels on their homes. These panels generate electricity from sunlight. Using the panels will lower your electric bill, and reduce demand from power plants (which often burn coal).
But, are they worth it?
On April 15, the San Francisco Chronicle said yes. They looked at the costs of buying and installing the panels, and weighed it against the benefits (which include getting a tax rebate). They found that, over 25 to 30 years, the average home would save about $33,000.
So, solar panels are a good idea, right? Not so fast! On April 14, the NY Times reported that solar panels never pay for themselves. Even accounting for electrical savings and tax rebates, they are so expensive that you never make your money back.
Well, the two articles can’t both be right. Right? Well, actually, they both seem correct -- but they are based on two very different scenarios:
- Different tax rebates in the two states.
- More sunshine in California, making the panels more useful.
- The panels are almost twice as expensive in NY than in SF.
- The NY Times assumed that, if you didn’t spend the money on panels, you’d put it in the bank or otherwise invest it, where it can earn money for you. The SF Chronicle did not take this into account.
So, whether or not solar panels are a good financial investment depends on a lot of factors. Whether they are good for the environment is much easier to answer – they produce electricity without pollution.
In the future, the debate may be moot – scientists are working on new types of solar cells that use nanotechnology, which may bring the costs way down.
