Quantum Dots May Lead to Rainbow Solar Cell

Quantum Dots May Lead to Rainbow Solar Cell from PhysOrg.com

For the first time, researchers have created solar cells made of different-sized quantum dots, each tuned to a specific wavelength of light. By arranging these quantum dots in an ordered pattern, the scientists hope that they can one day fabricate “rainbow” solar cells, which can efficiently harvest a large part of the useful spectrum of sunlight.

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Daylight Savings Time an Energy Waster

Well, the folks at Congress had their heart in the right place by moving and extending Daylight Savings Time earlier into the spring - but it appears from a recent study that DST actually has a net NEGATIVE effective on energy usage. The culprit - air conditioning.

Hydrogen Fuel Production Takes Leap Forward

Researchers at Penn State University have developed a method using bacteria and common materials to generate hydrogen at previously unachievable levels according to a press release from the National Science Foundation. This work could pave the way for an efficient and net-energy-positive means of producing hydrogen as a fuel source.

"We achieved the highest hydrogen yields ever obtained with this approach from different sources of organic matter, such as yields of 91 percent using vinegar (acetic acid) and 68 percent using cellulose," said principal investigator Bruce Logan, a professor of environmental engineering at Penn State.

Concentrated Solar Initiative Funded

The Department of Energy has released details for funding a two year effort to boost the viability of Concentrated Solar Power (CSP). The goal of the initiative is to make the technology cost-competitive with existing electrical generation methods, with the goal of bringing the cost of generating electricity using CSP down to 10 cents per kilowatt hour power.

Concentrated Solar Power uses an array of mirrors to focus sunlight onto a central receiver, heating its contents and forcing it through a turbine. Currently such efforts require delicate mirrors and protective coatings, and the fluid used is inefficient at transferring heat evenly. Movie fans might recall such a futuristic technology being employed in the 1974 James Bond film “The Man With the Golden Gun.”

The $5.2 million project is part of President George W. Bush’s Solar America Initiative, which has the goal of making solar power a commercially viable technology in a variety of forms by 2015. The DOE recently released details of a new photovoltaic solar research project, in which new technologies for directly turning sunlight into electricity are being studied by a consortium of public and private institutions.

Twelve projects in all are being funded under the grant. Work will be conducted by nine separate private companies in a coordinated effort, with the lion’s share of the funding ($2.037 million) going to Solucar, Inc. of Lakewood, Colorado. Solucar will be looking at development of an advanced trough system for collecting solar power, improved liquid salts for direct heat transfer, and a better polymeric reflector.

Other grant recipients are 3M (St. Paul, Minnesota), Alcoa (Pennsylvania), Brayton Energy (Hampton, New Hampshire), Hamilton Sundstrand (Canoga Park, California), Infinia (Kennewick, Washington), PPG Industries (Pittsburgh, Pennsylvania), Skyfuel (New York, New York), and Solar Millenium (Berkeley, California).

According the DOE, “These projects aim to develop technology that dramatically reduces the cost of CSP power and emphasizes the development of storage technologies.” An additional $7.2 million is available to three of the DOE’s National Laboratories under this portion of the Solar America Initiative for the commercialization of existing technologies.

“Together, these projects will help advance President Bush’s energy initiatives by accelerating the adoption of renewable energy and moving new clean energy technologies into the marketplace,” said Assistant Secretary for Energy Efficiency and Renewable Energy Alexander Karsner.

For more information on the President’s Solar America Initiative and DOE’s commercialization efforts, visit: the Office of Energy Efficiency and Renewable Energy.

Stanford Study Shows Interconnected Wind Farms Reliable

A study by two Stanford University scientists published in the November issue of the Journal of Applied Meteorology and Climate shows that wind power can be made a reliable resource for supplying a portion of the electrical needs of the United States, and not necessarily succumb to the vagaries of the winds that power the turbines. The key lies in interconnecting the wind farms.

Cristina Archer and Mark Jacobson of Stanford say that wind-generated electricity is the fastest growing energy resource in the world, and be made more reliable. "This study implies that, if interconnected wind is used on a large scale, a third or more of its energy can be used for reliable electric power, and the remaining intermittent portion can be used for transportation, allowing wind to solve energy, climate and air pollution problems simultaneously," said Archer, lead author, in a press release from Stanford.

The study looked at 19 sites for wind farms in the Midwestern United States, and looked at the wind patterns for each of the sites. Their conclusion: As more and more wind farms become locked together in a distribution grid, the more reliable wind becomes as a source for electricity.

One supposition of the study was that the entire world’s current electrical demand of 1.8 terrawatts could theoretically be generated using a distributed grid of 890,000 wind turbines of the sort currently being manufactured, without improvements in the technology. There are currently roughly 110,000 electricity-generating wind turbines in operation today, but most of a smaller scale than Archer and Jacobson envision.

Currently, coal-fired electricity generation plants have a reliability factor of 87.5%, meaning they are capable of providing power 87.5% of the time during any one year. The average coal-fired plant generates 1,000 kilowatt-hours (KWH) of electricity, according to a report from Oak Ridge National Laboratory. The Stanford study indicates that 19 individual turbines, connected through a distribution and spaced according to wind patterns, could achieve a similar reliability pattern, while generating 222 KWH.

"The idea is that, while wind speed could be calm at a given location, it could be gusty at others. By linking these locations together we can smooth out the differences and substantially improve the overall performance," Archer said.

Archer is a consulting assistant professor in Stanford's Department of Civil and Environmental Engineering and research associate in the Department of Global Ecology at the Carnegie Institution. Jacobson is a professor of Civil and Environmental Engineering at Stanford.

Archer and Jacobson will present their findings December 13 at the annual meeting of the American Geophysical Union in San Francisco. Their talk is titled "Supplying Reliable Electricity and Reducing Transmission Requirements by Interconnecting Wind Farms."