Converting sunlight to electricity might no longer mean large panels of photovoltaic cells atop flat surfaces like roofs.

Using zinc oxide nanostructures grown on optical fibers and coated with dye-sensitized solar cell materials, researchers at the Georgia Institute of Technology have developed a new type of three-dimensional photovoltaic system.  The approach could allow PV systems to be hidden from view and located away from traditional locations such as rooftops.

“Using this technology, we can make photovoltaic generators that are foldable, concealed and mobile,” said Zhong Lin Wang, a Regents professor in the Georgia Tech School of Materials Science and Engineering.  “Optical fiber could conduct sunlight into a building’s walls where the nanostructures would convert it to electricity.  This is truly a three dimensional solar cell.”

Details of the research were published in the early view of the journal Angewandte Chemie International on October 22.  The work was sponsored by the Defense Advanced Research Projects Agency (DARPA), the KAUST Global Research Partnership and the National Science Foundation (NSF).

Dye-sensitized solar cells use a photochemical system to generate electricity.  They are inexpensive to manufacture, flexible and mechanically robust, but their tradeoff for lower cost is conversion efficiency lower than that of silicon-based cells.  But using nanostructure arrays to increase the surface area available to convert light could help reduce the efficiency disadvantage, while giving architects and designers new options for incorporating PV into buildings, vehicles and even military equipment.

Fabrication of the new Georgia Tech PV system begins with optical fiber of the type used by the telecommunications industry to transport data. First, the researchers remove the cladding layer, then apply a conductive coating to the surface of the fiber before seeding the surface with zinc oxide.  Next, they use established solution-based techniques to grow aligned zinc oxide nanowires around the fiber much like the bristles of a bottle brush.  The nanowires are then coated with the dye-sensitized materials that convert light to electricity.

Sunlight entering the optical fiber passes into the nanowires, where it interacts with the dye molecules to produce electrical current. A liquid electrolyte between the nanowires collects the electrical charges.  The result is a hybrid nanowire/optical fiber system that can be up to six times as efficient as planar zinc oxide cells with the same surface area.

“In each reflection within the fiber, the light has the opportunity to interact with the nanostructures that are coated with the dye molecules,” Wang (left) explained.  “You have multiple light reflections within the fiber, and multiple reflections within the nanostructures.  These interactions increase the likelihood that the light will interact with the dye molecules, and that increases the efficiency.”

Wang and his research team have reached an efficiency of 3.3 percent and hope to reach 7 to 8 percent after surface modification.  While lower than silicon solar cells, this efficiency would be useful for practical energy harvesting.  If they can do that, the potentially lower cost of their approach could make it attractive for many applications.

By providing a larger area for gathering light, the technique would maximize the amount of energy produced from strong sunlight, as well as generate respectable power levels even in weak light.  The amount of light entering the optical fiber could be increased by using lenses to focus the incoming light, and the fiber-based solar cell has a very high saturation intensity, Wang said.

Wang believes this new structure will offer architects and product designers an alternative PV format for incorporating into other applications.

“This will really provide some new options for photovoltaic systems,” Wang said.  “We could eliminate the aesthetic issues of PV arrays on building. We can also envision PV systems for providing energy to parked vehicles, and for charging mobile military equipment where traditional arrays aren’t practical or you wouldn’t want to use them.”

Wang and his research team, which includes Benjamin Weintraub and Yaguang Wei, have produced generators on optical fiber up to 20 centimeters in length.  “The longer the better,” said Wang, “because longer the light can travel along the fiber, the more bounces it will make and more it will be absorbed.”

Traditional quartz optical fiber has been used so far, but Wang would like to use less expensive polymer fiber to reduce the cost.  He is also considering other improvements, such as a better method for collecting the charges and a titanium oxide surface coating that could further boost efficiency.

Though it could be used for large PV systems, Wang doesn’t expect his solar cells to replace silicon devices any time soon.  But he does believe they will broaden the potential applications for photovoltaic energy.

“This is a different way to gather power from the sun,” Wang said.  “To meet our energy needs, we need all the approaches we can get.”

John D. Toon is manager of the research news and publications office at Georgia Institute of Technology.

That’s because electricity is nonexistent in Gathungu’s hometown of Njoro, in northwest Kenya. Landlines and other forms of communication are not as efficient, so Gathungu and millions of others in emerging nations rely on mobile phones. Charging the phones can be a headache in towns and villages where electricity is scarce.

Gathungu’s troubles may soon be over, though.

Kenya’s biggest mobile phone company, Safaricom Ltd., launched the nation’s first solar-charged phone this month. The handset comes with a regular electrical charger and a solar panel that charges the phone using the sun’s rays, company CEO Michael Joseph told CNN by telephone.

Retailing at about $35, the phones were manufactured by Chinese telecommunications company ZTE Corp. Safaricom plans to make an initial supply of 100,000 phones available.

“People are excited about these phones,” Joseph said. “I expect to be sold out in a week.”

Eco-friendly phones have been touted by several companies at global trade shows, but most have not been launched yet.

Samsung unveiled a solar-powered phone at the Mobile World Congress in Barcelona, Spain, earlier this year and introduced its first sun-powered phone in India in mid-June. The company expects its Solar Guru model to perform well in India, another country where electrical supply can be erratic.

Unlike many technological innovations, the solar phone is making its big splash in developing nations, where the need is the greatest. After the Solar Guru is in circulation in India, Samsung said, it plans to launch similar phones in other Asian markets, Europe and Latin America.

For the time being, Kenyans are happy to serve as early adopters.

“The power crisis here has been going on for ages,” Joseph said, adding that the Safaricom phone’s solar panel is small and portable, unlike charging devices some Kenyans now use.

Only about 1.3 million of Kenya’s 37 million people are connected to the national electrical grid, said Migwi Theuri, a spokesman for Kenya Power and Lighting Co. The east African nation, which gets most of its energy from hydro-generation, has been undergoing power rationing after a three-year drought.

Despite the limited availability of power, Kenya has one of the most vibrant cell phone markets in Africa, analysts say. An estimated 17 million Kenyans use mobile phones.

Some charge phones on bicycle-run generators, Joseph said. Or like, Gathungu, they pay businesses in major cities to charge their phones, sometimes waiting an entire day.

“There’s an enormous need for a device like this,” Joseph said of the solar phone, which can charge during talk time, as long as there are rays.

“They will continue to charge on natural light, even on cloudy days,” he added.

Gathungu plans to buy one of the new environmentally friendly phones. For him, it’s a matter of money and convenience. He earns 4,000 Kenya shillings ($53 dollars) a month as a waiter. Charging his phone for 50 shillings (70 cents) a week adds up. The solar phone would pay for itself, Gathungu said.

Until he buys one, he’ll keep making the trek to the shopping center every Sunday afternoon after church. He wouldn’t go into further detail about his mobile phone woes, not wanting to waste his battery charge on the call.

What state might be number two? Surely some other large southerly state. Arizona? Maybe sunshine-state Florida?

Not even close. Number two for solar electric power, and number one in total solar installations on a per capita basis, is small and not-so-sunny New Jersey, more known environment-wise for its abundance of Superfund sites. What’s perhaps most remarkable is how quickly the state got to the runner-up spot, from six solar installations only seven years ago to 4,340 today. Even in the throes of the recession, solar installers (120 of them today, versus two at the turn of the millennium) are reporting booming business.

“It’s just really taken off,” says Dan Potkay, president of New Jersey-based Brite Idea Energy, a solar installation company. Solar panels are not only appearing on residential rooftops, but on schools, churches, convention centers, and gyms, and as electricity-generating roofs over stretches of paved parking lots. Ground-mounted farms of solar panels are even planned for at least two of those infamous (albeit now cleaned-up) New Jersey Superfund landfills.

That all still pales in comparison to the solar revolution in Germany. Since it began a major push in 2000, Germany has become the most solar-powered nation in the world. With about one-fourth the United States’ population, it has six times more solar installed, including more than 300,000 residential rooftop systems, along with multi-megawatt commercial systems. That amounts to half the world’s total solar capacity — and in a country that enjoys sunshine about on a par with Oregon.

There’s a lesson here. The solar booms in Germany and New Jersey were not about abundant sunshine, but about subsidies. Both the European nation and the northeastern U.S. state kick-started their programs by providing early adopters with solid guarantees of economic returns on their investments. Taxes were not raised to accomplish this. Instead, utilities were allowed to raise rates minimally on all rate payers in order to subsidize those who were ready to move on installing solar systems.

In theory, subsidized sales lead to growing manufacturing scales and falling costs and, eventually, a day when renewables can compete directly with dirtier, and often imported, fossil fuels. Solar remains expensive compared to fossil-fuel-based energy, but theory and reality have continued to converge, with prices dropping by about 20 percent with each doubling of world production, moving steadily toward parity with dirtier fuels.

In a world threatened economically as well as environmentally by rising greenhouse gas emissions, dozens of other nations and several U.S. states have also begun to turn to various subsidy schemes for renewables, many of them using Germany’s approach as a model.

Although it also began with a version of straight-up subsidies, New Jersey has turned to a different approach, issuing credits that can be traded like stocks or bonds on a free-floating market. A few other states, and Great Britain, have attempted more modest versions of this market-based model, but New Jersey’s is the most aggressive attempt yet. And while the state’s solar boom is still on, the effort is too new for anyone to know if the approach will prove as successful as Germany’s over the long run.

The Germans built their world-beating program for solar and other renewables around a direct subsidy called a feed-in tariff. The approach is simple and straightforward: install solar panels on your roof, pump the power into the grid, and for 20 years you’ll get a guaranteed payment for each kilowatt hour you feed in; with solar, that’s presently about five times the going wholesale rate for nuclear power. Wait a year or two to install your system, and, assuming solar costs have fallen, expect a slightly smaller payment, although still a level and predictable sum.

Since Germany began its aggressive push, several other nations, including 17 other European states and more than 20 other nations around the world have adopted or announced feed-in tariffs, including, just weeks ago, China. The province of Ontario and a small scattering of U.S. states and even two American cities have adopted versions of the tariff approach.

Program designs, though, vary by nation, state or province, or city. Some attempts have been more successful than others.

Spain offers a bit of both triumph and trouble. In 2007 it mandated high tariff payments that turned out to be so generous that they quickly blew up a solar bubble. Although the government originally projected that the program would lead to 400 megawatts of installations by 2010, the program’s first 18 months saw 3,000 megawatts installed in the sunny nation. With no provision to automatically step down the tariff if it proved to be overly generous, Spain almost instantly blew past even Germany, becoming the world’s largest solar market for 2008, but at a cost to utilities of some $26 billion.

The world’s solar panel manufacturers, including a host of new companies in China, went boom mode themselves, cranking out shipments just for Spain that were large enough to fill entire container ships. But because costs for the program were rising far more than planned, by the summer of 2008 the Spanish government announced it would cut the tariff by 30 percent. It also put a firm cap of 500 megawatts on installations for all of 2009. Boom became sudden bust. In the midst of a developing world recession, 20,000 jobs in Spain’s nascent solar industry vanished.

In North America, tariffs have been slower to take off. But this year Ontario modified a modest existing tariff program to make it more attractive. And the city of Sacramento’s municipal utility has a limited program, as does the municipal utility for the city of Gainesville, Florida. Vermont, Washington, and California have instituted tariff programs at the state level (but in California only for commercial-size projects), and several other states are discussing this approach.

Feed-in tariffs aren’t the only subsidies now in play in the United States. There is no national tariff program (a bill has been introduced in Congress, but passage seems unlikely), but the 2009 stimulus bill extends a hefty 30 percent federal tax credit to solar customers through 2016. Commercial installations also can be depreciated for tax purposes on an accelerated basis.

Among the states, which regulate their own electric utilities, there’s a dizzying hodgepodge of approaches to providing solar and other renewable energy incentives, of both the stick and carrot variety. Stick-wise, more than two dozen states have developed “renewable portfolio standards” that require their utilities to hit certain targets — x percent of generation from renewable sources by year y — for instance. A few offer rebates on installed solar systems; in California, for example, homeowners are eligible for rebates under the state’s “million solar roof” initiative.

Most states allow “net metering,” meaning utilities must buy back unused power (electricity generated, say, on an afternoon when a house is unoccupied). It means that the owner’s meter can, essentially, spin backwards when there is excess power. (Although in some states the owner receives only the wholesale, not retail, rate; in general a monthly or annual electric bill can only go down as far as zero owed).

New Jersey’s continuing solar boom depends most heavily on its alternative approach to subsidies. When the state kicked off its solar program in 2002, it relied on a small “societal benefits” charge on all ratepayers’ bills to provide a simple, straightforward rebate that amounted to about 60 percent on solar installations, combined with a full retail net metering (backwards-meter) mandate. But by 2007, the program had become so popular that it was overwhelming available funds.

In the hope that market efficiencies could help control costs over time, the state has turned not to a tariff-style guarantee, but to a complex approach that relies on a floating, market for tradable solar renewable energy credits (SRECs).

An oversimplified version: install a solar system on your roof (or install a commercial system on a warehouse or in a field) and each year you’ll earn SRECs based on how much power your system generates annually — one credit for each 1,000 kilowatt hours. You can then turn around and sell your credits back to companies that generate power for the state’s grid. The companies can use the SRECs to help them meet state renewable portfolio standards that steadily ramp up to a mandate requiring that 22.5 percent of their energy come from renewables by 2021.

The credits are actually sold by brokers on an electronic market, like stocks or bonds, at whatever price the market will bear. At the moment, the market is bearing a fabulous price. It takes a calculator to work through the complexities, but with SRECs currently selling for just under $700, and the federal tax credit as well as a reduced state rebate in play, a homeowner in the state can pay for a solar system in four years or less.

After the system is paid for, there’s the promise of not only free, clean energy but of SREC profits for years to come. (SRECs are expected to decline in value over time, but could still be worth multiple thousands of dollars annually to the owner of a residential solar system, and far more to owners of large commercial installations.)

Some other states, including Maryland, Delaware, and Pennsylvania have also begun to turn to SRECs, although so far those programs are providing a far less generous payout: in the $200 to $250 range. (The divergence appears to be occurring mostly because New Jersey is wielding a bigger stick, assessing a high “alternative” charge as a de facto penalty if companies do not hit their benchmarks.)

In an email, Doyal Siddell, chief spokesman for New Jersey’s Public Utility Commission suggested that his agency had decided the SREC approach was a way to avoid the “significant downsides” of German or Spanish-style tariffs “with regard to cost exposure to ratepayers, budgeting for uncertain expenditures and… inflexibility in adjusting to market changes such as falling equipment costs.”

But at least one industry insider is skeptical that it will be a real improvement.

Dolores Phillips, executive director of the Mid-Atlantic Solar Industries Association, a regional trade group, worries that New Jersey’s SREC market makes the economics of going solar too unpredictable, suggesting that the alluring SREC-based economics of 2009, especially at New Jersey’s high rates, could be a “fluke.”

Phillips pointed to a May, 2009 report by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) that cited “stability and certainty” as key benefits of feed-in tariffs. In particular, the NREL study noted that since risk raises the cost of financing, a safe, predictable income stream means lower costs overall.

Clearly, properly-designed, feed-in tariffs had the desired effect in Germany, ramping up manufacturing and, in doing so, driving down costs. It’s simply too soon to tell if the U.S. states moving toward a market-based approach are onto something better.

A California company hopes to store solar power by focusing thousands of mirrors on millions of gallons of liquefied salt. An artist’s rendering of such a solar plant is shown here.

The holy grail of renewable energy is a solar power plant that continues producing electricity after the sun goes down.

A Santa Monica, Calif., company called SolarReserve has taken a step toward making that a reality, filing an application with California regulators to build a 150-megawatt solar farm that will store seven hours’ worth of the sun’s energy in the form of molten salt.

Heat from the salt can be released when it’s cloudy or at night to create steam that drives an electricity-generating turbine.

The Rice Solar Energy Project, to be built in the Sonoran Desert east of Palm Springs, will “generate steady and uninterrupted power during hours of peak electricity demand,” according to SolarReserve’s license application.

So-called dispatchable solar farms would in theory allow utilities to avoid spending billions of dollars building fossil fuel power plants that are fired up only a few times a year when electricity demand spikes, like on a hot day.

SolarReserve is literally run by rocket scientists, many of whom formerly worked at Rocketdyne, a subsidiary of the technology giant United Technologies. Rocketdyne developed the solar salt technology, which was proven viable at the 10-megawatt Solar Two demonstration project near Barstow, Calif., in the 1990s.

United Technologies has licensed the technology to SolarReserve and will guarantee its performance — a crucial advantage for the startup when it seeks financing from skittish bankers to build the Rice solar farm.

As many as 17,500 large mirrors — each one 24 feet by 28 feet — will be attached to 12-foot pedestals. The mirrors, called heliostats, will be arrayed in a circle around a 538-foot concrete tower.

Atop the tower will sit a 100-foot receiver filled with 4.4 million gallons of liquid salt. The heliostats will focus the sun on the receiver, heating the salt to 1,050 degrees Fahrenheit. The liquefied salt flows through a steam-generating system to drive the turbine and is returned to the receiver to be heated again.

SolarReserve isn’t the only developer planning to tap molten salt to store solar energy. Abengoa Solar, for instance, intends to use salt storage at its 280-megawatt Solana solar trough plant outside Phoenix.

That project, however, will heat tubes filled with synthetic oil to create steam and transfer some of the heat to salt-filled storage tanks. By using salt for both steam and storage, SolarReserve can generate higher-temperature steam, which will allow the Rice power plant to operate much more efficiently, according to Kevin Smith, SolarReserve’s chief executive.

“Consequently, our system can capture three times the energy for the same pound of salt,” Mr. Smith wrote in an e-mail message. “Plus they have additional ‘bolt on’ equipment, plus multiple heat transfer steps to go from oil to salt to oil and then to steam for electricity generation.”

SolarReserve’s plant will be built on private land — the site of a former World War II-era Army airfield — near the desert ghost town of Rice. The company will air-cool the power plant, avoiding controversies over water use that have dogged other solar projects.

But the height of the solar tower — 653 feet when a maintenance crane is attached to the top — could generate resistance from conservationists worried about the impact of the project on desert vistas. A proposed SolarReserve power plant in Nevada ran into resistance from Air Force officials concerned that the tower would interfere with radar at a nearby military base.

The company said it is negotiating with California utilities to buy the electricity generated from the Rice project and expects the solar farm to go online in October 2013, barring unforeseen delays.

Iosa Ghini Associati has designed the Energy Belt, a sleek solar-powered monorail system for Bologna, Italy that will connect the airport to the city center. The system’s smoothly sculpted lines run above the countryside, providing great views for travelers. The monorail will also provide infrastructure for other uses, namely a pedestrian walkway alongside the tracks and a solar system that runs along the rail’s southern face.

The Energy Belt was designed to speedily move people from the main train station in Bologna out to the airport with only one intermediate stop at Lazzaretto. It crosses over one major highway, spanning the stretch of road in a graceful arc. At each station a metal screen covered in vegetation protects passengers from the elements, and also helps filter the air, provide natural insulation and shade the platform.

The system is designed to operate using solar energy captured by photovoltaic panels placed at each monorail station and along the track’s south-facing side. Since the solar system installed directly on the monorail infrastructure, the landscape below is not disturbed with extra equipment. Running at a height from 7 meters up to 25 meters, the Energy Belt monorail is supported by slender piers, giving the system a very small footprint along its 5,084 meters of track.

Solar powered, direct, convenient, and fast – the monorail system offers an enticing option for travelers looking to take it easy rather than driving to the airport. Its highly probable that a monorail would be more expensive than a ground level light rail system, but where’s the novelty and graceful architecture in that?

Imagine a cool breeze blowing from your window! ‘Blind Air Conditioner’ is an innovative air conditioner that can also function as a blind. ‘Blind Air Conditioner’ is installed on the window itself like a blind, thereby emphasizing the image of a window on a breezing morning. ‘Blind Air Conditioner’ challenges the old design by combining the functionality of both an air conditioner as well as a foldable blind.

I absolutely love the idea of marrying solar power with air conditioning but I’m still unsure of how this would actually function as a proper air conditioner. Because of condensation, won’t it make a drippy, wet mess like standard window AC units, and furthermore, where will the water drip since there is not an outside component to the device? Will the built-in solar panels be powerful enough to provide enough juice to an energy-guzzling appliance like an AC unit? Can you really raise and lower hefty techno-blinds with built-in solar panels and air conditioning capabilities? Isn’t this more of a souped-up bladeless fan?

Hmmph. I’d like to think something like the Blind Air Conditioner would be possible in the not-so-distant future but there needs to be a few functionality kinks worked out if this concept reaches a second phase. When next summer hits and my own electric bills skyrocket, I’m going to certainly dream of cool, solar-powered breezes.

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For the Shaw brothers, who converted the downtown arts building and community center into a miniature solar power plant two years ago, each reverse rotation subtracts from their monthly electric bill. It also means the building at that moment is producing more electricity from the sun than it needs.

“Backward is good,” said John Shaw, who now runs Shaw Solar and Energy Conservation, a local solar installation company.

Good for whom?

As La Plata County in southwestern Colorado looks to shift to cleaner sources of energy, solar is becoming the power source of choice even though it still produces only a small fraction of the region’s electricity. It’s being nudged along by tax credits and rebates, a growing concern about the gases heating up the planet, and the region’s plentiful sunshine.

The natural gas industry, which produces more gas here than nearly every other county in Colorado, has been relegated to the shadows.

Tougher state environmental regulations and lower natural gas prices have slowed many new drilling permits. As a result, production — and the jobs that come with it — have leveled off.

With the county and city drawing up plans to reduce the emissions blamed for global warming and Congress weighing the first mandatory limits, the industry once again finds itself on the losing side of the debate.

A recent greenhouse-gas inventory of La Plata County found that the thousands of natural gas pumps and processing plants dotting the landscape are the single largest source of heat-trapping pollution locally.

That has the industry bracing for a hit on two fronts if federal legislation passes.

First, it will have to reduce emissions from its production equipment to meet pollution limits, which will drive up costs. Second, as the county’s largest consumer of electricity, gas companies probably will see energy bills rise as the local power cooperative is forced to cut gases released from its coal-fired power plants or purchase credits from other companies that reduce emissions.

“Being able to put solar systems on homes is great, you take something off the grid, it is as good as conserving,” said Christi Zeller, the executive director of the La Plata Energy Council, a trade group representing about two dozen companies that produce the methane gas trapped within coal buried underground.

“But the reality is we still need natural gas, so embrace our industry like you are embracing wind, solar and the renewables,” she said.

It’s a refrain echoed on the national level, where the industry, displeased with the climate bill passed by the House this summer, is trying to raise its profile as the Senate works on its version of the legislation.

In March, about two dozen of the largest independent gas producers started America’s Natural Gas Alliance. In ads in major publications in 32 states, the group has pressed the case that natural gas is a cleaner-burning alternative to coal and can help bridge the transition from fossil fuels to pollution-free sources such as wind and solar.

“Every industry thinks every other industry is getting all the breaks. All of us are concerned that we are not getting any consideration at all from people claiming they are trying to reduce the carbon footprint,” said Bob Zahradnik, the operating director for the Southern Ute tribe’s business arm, which includes the tribes’ gas and oil production companies. None is in the alliance.

Politicians from energy-diverse states such as Colorado are trying to avoid getting caught in the middle. They’re working to make sure that the final bill doesn’t favor some types of energy produced back home over others.

At a town hall meeting in Durango in late August, Sen. Mark Udall, who described himself as one of the biggest proponents of renewable energy, assured the crowd that natural gas wouldn’t be forgotten.

“Renewables are our future … but we also need to continue to invest in natural gas,” said Udall, D-Colo.

Much more than energy is at stake. Local and state governments across the country also depend on taxes paid by natural gas companies to fund schools, repair roads and pay other bills.

In La Plata County alone, the industry is responsible for hundreds of jobs and pays for more than half of the property taxes. In addition, about 6,000 residents who own the mineral rights beneath their property get a monthly royalty check from the companies harvesting oil and gas.

“Solar cannot do that. Wind cannot do that,” said Zeller, whose mother is one of the royalty recipients. In July, she received a check for $458.92, far less than the $1,787.30 she was paid the same month last year, when natural gas prices were much higher.

Solar, by contrast, costs money.

Earlier this year, the city of Durango scaled back the amount of green power it was purchasing from the local electric cooperative because of the price. The additional $65,000 it was paying for power helped the cooperative, which is largely reliant on coal, to invest in solar power and other renewables.

“It is a premium. It is an additional cost,” said Greg Caton, the assistant city manager.

Instead, the city decided to use the money to develop its own solar projects at its water treatment plant and public swimming pool. The effort will reduce the amount of power it gets from sources that contribute to global warming and make the city eligible for a $3,000 rebate from the La Plata Electric Association.

Yes, the power company will pay the city to use less of its power. That’s because the solar will count toward a state mandate to boost renewable energy production.

“In the typical business model, it doesn’t work,” said Greg Munro, the cooperative’s executive director. “Why would I give rebates to somebody buying someone else’s shoes?”

The same upfront costs have prevented homeowners from jumping on the solar bandwagon despite the tax credits, rebates and lower electricity bills.

Most of Shaw’s customers can’t afford to install enough solar to cover 100 percent of their homes’ electricity needs, which is one reason why solar supplies just a fraction of the power the county needs.

The higher fossil-fuel prices that could come with climate legislation would make it more competitive.

“You can’t drive an industry on people doing the right thing. The best thing for this country is if gas were $10 a gallon,” said Shaw, as he watched two of his three full-time workers install the last solar panels on a barn outside town.

The private residence, nestled in a remote canyon, probably will produce more power from the sun than it will use, causing its meter to spin in reverse like the Smiley Building’s. The cost, however, is steep: more than $500,000.

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Mendez developed a Quantitative Habitability Theory to assess the current state of terrestrial habitability and to establish a baseline for relevant comparisons with past or future climate scenarios and other planetary bodies including extrasolar planets.

“It is surprising that there is no agreement on a quantitative definition of habitability,” said Mendez, a biophysicist. “There are well-established measures of habitability in ecology since the 1970s, but only a few recent studies have proposed better alternatives for the astrobiology field, which is more oriented to microbial life. However, none of the existing alternatives from the fields of ecology to astrobiology has demonstrated a practical approach at planetary scales.”

His theory is based on two biophysical parameters: the habitability (H), as a relative measure of the potential for life of an environment, or habitat quality, and the habitation (M), as a relative measure of biodensity, or occupancy. Within the parameters are physiological and environmental variables which can be used to make predictions about the distribution, and abundance of potential food (both plant and microbial life), environment and weather.

The image above shows a comparison of the potential habitable space available on Earth, Mars, Europa, Titan, and Enceladus. The green spheres represent the global volume with the right physical environment for most terrestrial microorganisms. On Earth, the biosphere includes parts of the atmosphere, oceans, and subsurface. The potential global habitats of the other planetary bodies are deep below their surface.

Enceladus has the smallest volume but the highest habitat-planet size ratio followed by Europa. Surprisingly, Enceladus also has the highest mean habitability in the Solar System, even though it is farther from the sun, and Earth, making it harder to get to. Mendez said Mars and Europa would be the best compromise between potential for life and accessibility.

“Various planetary models were used to calculate and compare the habitability of Mars, Venus, Europa, Titan, and Enceladus,” Mendez said. “Interestingly, Enceladus resulted as the object with the highest subsurface habitability in the solar system, but too deep for direct exploration. Mars and Europa resulted as the best compromise between habitability and accessibility. In addition, it is also possible to evaluate the global habitability of any detected terrestrial-sized extrasolar planet in the future. Further studies will expand the habitability definition to include other environmental variables such as light, carbon dioxide, oxygen, and nutrients concentrations. This will help expand the models, especially at local scales, and thus improve its application in assessing habitable zones on Earth and beyond.”

Studies about the effects of climate change on life are interesting when applied to Earth itself. “The biophysical quantity Standard Primary Habitability (SPH) was defined as a base for comparison of the global surface habitability for primary producers,” Mendez said. “The SPH is always an upper limit for the habitability of a planet but other factors can contribute to lower its value. The current SPH of our planet is close to 0.7, but it has been up to 0.9 during various paleoclimates, such as during the late Cretaceous period when the dinosaurs went extinct. I’m now working on how the SPH could change under global warming.”

The search for habitable environments in the universe is one of the priorities of the NASA Astrobiology Institute and other international organizations. Mendez’s studies also focus on the search for life in the solar system, as well as extrasolar planets.

“This work is important because it provides a quantitative measure for comparing habitability,” said NASA planetary scientists Chris McKay. “It provides an objective way to compare different climate and planetary systems.”

“I was pleased to see Enceladus come out the winner,” McKay said. “I’ve thought for some time that it was the most interesting world for astrobiology in the solar system.”

Mendez presented his results at the Division for Planetary Sciences of the American Astronomical Society meeting earlier this month.

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Scientists at Princeton and Cambridge say that most of the universe is regularly destroyed.  It’s space-time-twisted into black holes, in fact, which is about as utterly destroyed as you can get without pissing off Zeus.  In each destruction cycle only a small seed of habitable space survives, which grows phoenix-like to provide a new universe due to the apparently all-powerful dark matter.

The model is based on M-Theory – an expanded limit of string theory with an extra dimension, making it only slightly less esoteric than studying the symbolism of Chopin’s work in a universe where the Nazis won the war.  I’m not saying that M-theory is poorly understood or developed, but they can’t even agree on what the ‘M’ actually stands for.  Seriously.

In this model, the universe is a region on a multidimensional membrane called a “brane”, and it’s only one of many.  When these branes collide huge regions of our brane get bunched into extremely uninhabitable black holes, with only a small region of space left for us.  Without dark energy to inflate these gaps, a few cycles of this would annihilate everything.

As with all string-theory siblings, it’s an extremely interesting idea with less proof than the “Hitler shot JFK” theory, and the reasons for including dark energy sound suspiciously like “because our math doesn’t work without it.”  Plus, since it deals in six hundred billion year timescales and the End of Almost Everything, it’s slightly less measurable than a unicorn horn diameter.

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Galactic cosmic rays are speeding charged particles that include protons and heavier atomic nuclei. They come from outside the solar system, though their exact sources are still being debated.

Earth dwellers are protected from cosmic rays by the planet’s magnetic field and atmosphere. But outside Earth’s protective influence, cosmic rays can play havoc with spacecraft electronics – they may be responsible for some recent computer glitches on NASA’s Kepler spacecraft, which temporarily halted its planet-hunting observations. They can also damage astronaut DNA, which can lead to cancer.

Now, the influx of galactic cosmic rays into our solar system has reached a record high. Measurements by NASA’s Advanced Composition Explorer (ACE) spacecraft indicate that cosmic rays are 19 per cent more abundant than any previous level seen since space flight began a half century ago.

Solar minimum

“The space era has so far experienced a time of relatively low cosmic ray activity,” says Richard Mewaldt of Caltech, who is a member of the ACE team. “We may now be returning to levels typical of past centuries.”

The sun’s magnetic field normally blocks some of the cosmic rays, preventing them from entering the solar system. But that protection has weakened of late. The solar wind, which helps project the sun’s magnetic field out into space, has dropped in pressure to a 50-year low. And the strength of the magnetic field in interplanetary space is down to just 4 nanoTesla, compared to the more typical 6 to 8 nanoTesla.

The recent weakening of the shield is due to cycles in solar activity. The sun is at a minimum in its 11-year cycle of magnetic activity, and this particular dip is deeper than any other seen in nearly a century.

Extra shielding

That may be a sign that the unusually active sun of the past 100 years or so is returning to the historical norm of lower activity, or even entering a so-called grand minimum of exceptionally low activity that could last centuries.

Scientists can infer variations in the sun’s magnetic activity over the past 10,000 years from the abundance of rare isotopes in Greenland ice cores.

If the increase in cosmic rays is here to stay, it could make long-duration human missions in space more challenging. Astronauts aboard the International Space Station are still close enough to enjoy protection from Earth’s magnetic field, but any sent in future to the moon or beyond will be outside that field.

“The increase is significant, and it could mean we need to re-think how much radiation shielding astronauts take with them on deep-space missions,” Mewaldt says.

Down time

If there’s a long-term increase, it might also make sense to design future robotic missions for extra robustness against radiation, says Roger Hunter of NASA’s Ames Research Center in Moffett Field, California, who manages NASA’s planet-hunting Kepler mission.

It is not clear whether Kepler’s temporary computer glitches were due to cosmic-ray hits, he says. But the spacecraft is designed to be able to recover from such events, going into a safe mode while mission controllers work to restore it to normal operation, he adds.

“Our only concern is will we see more events as a result of the cosmic-ray increase,” he says. Since its launch in March, Kepler has lost 3.5 days of observing time due to glitches that put it into safe mode. However, the mission team always planned for occasional days lost to glitches, and considers up to 12 lost days per year to be acceptable.