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Solar Cookers Get Hot

Of all the innovations that could markedly benefit humankind, a reliable solar cooker remains one of the most imperative. Countless people across the developing world still cook their food by burning wood or even cow dung, causing respiratory problems and severe deforestation in some regions.

The quest for a practical solar cooker has gone on for decades and produced dozens of models ranging from $70 cheapies to $400 deluxe models. But none of them have caught on significantly for use in the developing-world because they can’t store heat. Without the ability to store heat, a cooker cannot be used, for example, on cloudy days.

But now a group based at the Norwegian University of Science and Technology (NTNU) in Trondheim is reporting a breakthrough in solar cookers. They say it will lead, within a year and a half, to the production of practical solar cookers that can store enough heat during a sunny day to work for an entire additional day, even if it is cloudy. The breakthrough was recognized with a US $8,000 award from the Norwegian Ministry of Petroleum and Energy this past August.

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Report: Tesla Gigafactory a Well-Played Overreach

Tesla Motors, which this summer announced a partnership with Panasonic to build a battery “Gigafactory,” may be overreaching. A new industry analyst’s report questions whether the demand for the company's electric cars will be big enough within the next five to eight years to warrant the factory’s projected $5 billion investment. 

According to the new report, by 2020 Tesla could be facing substantial overcapacity, with too many batteries and not enough EV cars — and other applications like renewable grid energy storage — to put them in.

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How to Turn Tires Into Batteries for Electric Cars

Scrapped car tires have been used for construction material and recycled into floor mats and shoe soles. Now they might find their way back into hybrid and electric cars, but under the hood. Scientists at Oak Ridge National Laboratory have devised a method to convert tire rubber into a carbon material for lithium-ion battery anodes.

Conventional lithium anodes are made of the graphite, a natural carbon material that is mined. The Oak Ridge researchers, led by materials chemist Parans Paranthaman, have found an alternative waste source for the carbon anode.

In a paper published online in the journal RSC Advances, they outlined a straightforward process to convert waste tire rubber into nanoporous carbon. They first pulverize waste tire rubber into tiny micrometer-sized pieces, which they break down in a hot sulfuric acid bath. The resulting rubber slurry is filtered, washed and turned into a solid cake. Heating the cake in the presence of nitrogen gives a highly porous carbon black material with pores that were less than 2nm in diameter.

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Germany's Grid: Renewables-Rich and Rock-Solid

Last Friday Germany’s grid regulator released the 2013 data for grid reliability, and the figures have renewable energy advocates crowing. The latest numbers (released in German) reveal no sign of growing instability despite record levels of renewable energy on the grid — 28.5 percent of the power supplied in the first half of 2014. In fact, Germany's grid is one of the world's most reliable.

According to the Bundesnetzagentur, unplanned outages left the average German consumer without electricity for 15.32 minutes in 2013, down from 15.91 minutes in 2012 and 21.53 minutes in 2006. The performance, using the power industry's System Average Interruption Duration Index (SAIDI), affirms Germany's place in the top five for grid reliability for European countries.

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Can Solar Power Go Truly Transparent?

The idea of solar windows has been around for some time now, and a number of different approaches—from spray-on solar cells to just really thin film possibilities—are under investigation. Though these are promising, the underlying issue with many of the ideas is that in order for them to work they need to stop some amount of light from getting through the window. And tinted windows are fine, in some situations, but too much tint turns a window into a wall. But not with a new idea out of Michigan State University, where researchers have created a solar concentrator that, if the efficiency is revved up, would provide truly clear, glass-like generators of solar power.

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To Zero Out Data Center Air Conditioner Bills, Build It Next to an LNG Port

Cloud companies have placed their data centers in cold climates — even inside the Arctic Circle — to more easily cool their computing gear. Startup TeraCool proposes that data centers tap into another source of free cooling: liquefied natural gas storage tanks.

Cambridge, MA-based TeraCool has developed a system that marries a source of unwanted heat — data centers — with the largely unused cold available at LNG terminals. With sufficiently large capacity at an LNG port, the company calculates that a data center could cool itself from the surplus cold that’s produced while turning stored liquid gas into pipeline-ready gas. With additional equipment, TeraCool says it could also generate power on-site.

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U.S. Wind Power Growth Stalled in 2013 as Prices Drop to All-Time Lows

A Department of Energy report on wind energy technologies and market status highlights dramatic cost reductions amidst a tenuous and uncertain future for the renewable energy source. Installations of wind power in the United States in 2013 didn't come close to matching the previous few years, and federal policy uncertainty points to a shaky outlook for continued growth.

The industry added 1087 megawatts of new wind capacity in 2013 in the United States, which is amazingly only eight percent of that added in 2012. By the end of 2013 the total installed capacity had reached about 61 gigawatts. It was a down by another measure as well: wind power made up seven percent of all new electricity generating additions, compared with a six-year run before 2013 where that number ranged between 25 and 43 percent.

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Silicon Valley Goes Long on Nuclear Fusion

An experimental nuclear fusion company recently raised $1.5 million in venture capital this month, in what is turning out to be a banner year for unconventional fusion fundraising. (As IEEE Spectrum noted last month, another firm, Lawrenceville Plasma Physics recently wrapped a $180,000 IndieGogo campaign to fund an experimental reactor that the company predicts could fuse protons with boron nuclei to generate low-radiation nuclear energy.)

San Francisco-based Mithril Capital Management covered $1.25 million of the total raised by Helion Energy of Redmond, Wash. Ajay Royan, the VC firm's co-founder  says his fund is always on the lookout for what he calls “state-shift companies,” firms that force a sea-change in their industry. Helion, he says, offers the promise of being that rare company.

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Ivanpah Solar Power Tower Is Burning Birds

Imagine you're a bird and you're flying in the Mohave Desert along the California side of the Nevada border and in the distance you see a massive reflective field, kind of like a lake, but more like thousands of puddles hovering together in a herd. You see insects swarming around it. You're hungry and thirsty. Or maybe you're just curious. So, you decide to fly over and see what's up.

Now, stop imagining, because the rest is not very pretty. What our bird has unwittingly stumbled upon is the Ivanpah solar thermal power plant, a circular array of over 300,000 mirrors aligned in such a way as to deliver a concentrated solar beam onto a central water tower. As the bird passes over the facility, its wing feathers begin to curl and singe. Its tail feathers, which it relies upon for aerial lift, ignite and burn. It rapidly loses altitude, trailing a plume of smoke behind it, and suddenly it's more of a comet than a bird.

This is the series of events that researchers at the U.S. Fish and Wildlife Service witnessed last fall at the 377-megawatt Ivanpah power plant and which they describe in an avian mortality report released last month by the California Energy Commission. (KCET, a public television station in California obtained a copy of the report months earlier.) The report, which calls the Ivanpah solar power plant a "megatrap," issues grave warnings about the threat that this relatively new technology poses to all species of birds. It also offers some basic recommendations for how to make solar thermal safer for birds, both at the Ivanpah plant and at future facilities—because, yes, newer, bigger ones are already on the way.

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MIT Researchers Turn Used Car Batteries into Solar Cells

Scientists at MIT have concocted what could become the ultimate in green energy: a solar panel made out of hazardous waste. 

In research paper reported in the journal Energy and Environmental Science, researchers describe a method for making perovskite solar cells using the lead from recycled car batteries. The technique can be done in a low-temperature, benign process that’s simpler than today's methods, they say. And after 18 months of testing, the researchers found that their experimental solar cells matched the efficiency of many commercial silicon cells, MIT said yesterday.

Perovskite is a class of materials that has caught the interest of solar photovoltaic researchers because they have made rapid progress in improving the efficiency of solar cells made from materials in the past three years. Compounds in this group promise to be very cheap and relatively simple to manufacture. One company, called Oxford Photovoltaics, is seeking to make commercial solar perovskite cells that can be applied as coatings on windows and other outdoor building surfaces.

One downside is that the material contains a small amount of lead. Extracting lead from ore is a high-temperature, polluting process that creates lead vapor and dust that’s difficult to contain, the MIT researchers note. And if companies begin to produce perovskite solar cells at large volumes, the materials they would be mining and processing could become a serious health or environmental hazard, they say.

(Two labs recently reported perovskite cells using tin instead of lead, but these are much less efficient.)

The other looming problem with lead is that technologies such as lithium ion batteries are advancing to the point that they could soon displace lead acid batteries in cars and trucks. The result, the researchers fear, is a glut of unwanted batteries containing a huge amount of lead waste.

About 90 percent of lead acid batteries in the United States are recycled, but problems remain. In 2011, the New York Times reported that an increasing number of old car batteries are being exported to Mexico from the United States for recycling, but that the work is done with crude methods that expose people to lead poisoning.

The MIT scientists say they have a better idea. In their paper, they spell out a multi-step process they say will give the lead from all those batteries a second life. They've demonstrated the ability to synthesize perovskite solar material using the electrodes straight out of a used lead-acid battery. Lead from the anode is mixed with nitric acid and the lead oxide (made from the lead dioxide cathode) is mixed in acetic acid. Then each compound is mixed with potassium iodide.

The solutions are then purified and deposited on a thin flexible film, which acts as the substrate for the solar cell. (You can watch a step-by-step video demonstration below.) Because it’s a relatively simple process, the researchers are optimistic that it can work at large scale cheaply. And because each of the perovskite cells are just half a micrometer thick, the researchers estimate that a single car battery could produce enough solar panels to provide electric power for 30 households.

MIT professor Angela Belcher and the paper’s lead author, Po-Yen Chen, say they don’t intend to start a company to commercialize their technology. Instead, they wanted to show people who are developing and manufacturing perovskite solar cells that the lead from old batteries performs just as well as mined lead. 

“This paper is about the excitement in the field of these [perovskite] materials and thinking about the environmental implications of extracting lead,” Belcher says. “The beauty is that this new process is pretty interchangeable with the current production method.”


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