Imagine a place where the only energy to be found is clean, reliable solar power. Not happening anytime soon, right? While solar power has become increasingly important, it isn’t yet powering an entire arrive is it? Actually, three tiny islands in the South Pacific are the first islands to rely completely on solar power.

The islands are part of the Tokelau territory, which in the past has relied on imported diesel to meet its power needs. While these are small islands with a population of 1,500 it is still a step in the right direction. New Zealand hopes to continue this trend elsewhere and will co-host a South Pacific clean energy summit next March along with the Tokelau, Tong and Cook Islands.

As our world becomes increasingly reliant on electricity everywhere, it is important to see that clean energy continues as a priority. Now if only an entire country could make the bold move to switching completely to clean energy.

[ source ]

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While solar panels can use stored energy from the day to provide power at night, and solar power is absorbed by higher-end solar panels even when it is cloudy, the panels still work best when the sun is shining its brightest. The solution to a steady supply of solar power even on cloudy days and at nighttime might come in the form of molten salt, which is an excellent conductor of heat.

Last week the Department of Energy offered a $737 million loan guarantee to the Crescent Dunes Solar Energy Project in Nevada. The project includes a 640-foot tall solar power structure and a molten salt-based collection and storage system. The system will capture and focus the sun’s thermal energy by using as many as 17,500 heliostats, which are very focused mirrors. The power plant will aim the heliostats at a focal point in a tower, which will heat up salt to 1,050 degrees Fahrenheit. The salt will be pumped near water to create steam that will run a turbine. The molten salt storage system allows the sun’s thermal energy to be stored for up to ten hours, permitting steady, uninterrupted power despite cloud cover and the disappearance of the sun at night. This method would reduce the need for carbon pollution emitting generators, which currently supplement renewable generation technologies during periods of no or low solar resource.

Once complete, the plant is expected to produce about 500,000 megawatts annually, which is enough to power 43,000 homes and cancel out about 20 per cent of the emissions of a coal power plant. The Crescent Dunes Solar Energy Project, sponsored by SolarReserve, LLC, will be the first of its kind in the United States and the tallest molten salt tower in the world. So far it’s just a proof of concept, but if it works as effectively as claimed, towers full of molten salt might start dotting the horizon, which just might cause as many complaints as wind turbines do.

Photo: Inhabitat

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Researchers at Purdue University have successfully implemented their ultrafast laser scribing technique for thin-film solar cells, a promising innovation that may bring down production costs and boost efficiency of photovoltaics.

Solar panels have long been flat and solid, limiting their placement and usage over the years. But thin-film solar cells are rapidly gaining ground in the market, as the flexible cells can be used as rooftop shingles and tiles, building facades, or glazing on skylights.

The problem with thin film so far has been manufacturing costs and efficiency, both of which are the direct result of the “microchannels” in solar cells. The microchannels, which interconnect solar panels with one another to generate usable amounts of electricity, have traditionally been created using a mechanical stylus – a slow process that often creates imperfect, inefficient cells.

“Production costs of solar cells have been greatly reduced by making them out of thin films instead of wafers, but it is difficult to create high-quality microchannels in these thin films,” said Yung Shin, mechanical engineering professor and director of Purdue University’s Center for Laser-Based Manufacturing. “The mechanical scribing methods in commercial use do not create high-quality, well-defined channels. Although laser scribing has been studied extensively, until now we haven’t been able to precisely control lasers to accurately create the microchannels to the exacting specifications required.”

But the team’s ultrashort pulse laser and its “cold ablation” process has overcome that boundary. The laser uses pulses that only last a quadrillionth of a second, creating precise microchannels very quickly without causing enough heat to damage the film.

“It creates very clean microchannels on the surface of each layer,” said Shin. “You can do this at very high speed, meters per second, which is not possible with a mechanical scribe. This is very tricky because the laser must be precisely controlled so that it penetrates only one layer of the thin film at a time, and the layers are extremely thin. You can do that with this kind of laser because you have a very precise control of the depth, to about 10 to 20 nanometers.

“The efficiency of solar cells depends largely on how accurate your scribing of microchannels is,” added Shin. “If they are made as accurately as possibly, efficiency goes up.”

Thin-film solar cells account for about 20 per cent of watts generated in the photovoltaic market globally, and are expected to account for 31 per cent by 2013. Though, that number may rise quickly once the pulse-laser technique is refined and commercialized over the course of their study.

Their work is being funded by a three-year $425,000 grant from the National Science Foundation.

[Daily Tech via Purdue]

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The solar age is now a day closer thanks to Wladek Walukiewicz and Kin Man Yu at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, who have developed a new full-spectrum solar cell that uses common production methods.

Cheap, common solar panels in production now typically only use a small percentage of the light hitting their surface, as the semiconductor materials in them only respond to certain segments of the solar spectrum. Though highly efficient solar panels that respond to the full spectrum of light have been created in the past, they’ve been unfit for mass production as they’re too complex and expensive to manufacture.

As each semiconductor reacts to a different light wavelength, efficient solar cells use several materials stacked atop one another and wired in a series, each semiconductor taking a portion of the light spectrum. In 2002, Walukiewicz and Man Yu tweaked indium gallium nitrate cells until they were capable of reacting to everything from infrared to ultraviolet — the full light spectrum. The resulting cells, however, were too difficult and costly to manufacture on a large scale.

Two years later, the pair created an alloy of zinc, manganese and tellurium doped with oxygen, creating an entirely different, highly efficient full-spectrum solar panel. But again, it was one unfit for production.

But now they’ve created a new multiband semiconductor alloy, gallium arsenide nitride, which uses the industry’s most common semiconductor fabrication method: metalorganic chemical vapor deposition. Their tests show that the prototype cell based on this new semiconductor reacts strongly with every segment of the solar spectrum.

The results of the breakthrough may not be instant, but this is a large step towards cheap, highly-efficient solar panels and their wide-spread application. Beyond, you know, death rays and such.

[Gizmag]

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