A Hollywood-based solar startup says that it will soon be able to produce electricity from the sun at costs that are competitive with fossil-fuel generation. The key is the company's dramatic improvement in the performance of concentrated photovoltaic technology.
Sunrgi, which emerged out of stealth mode last week, has created a concentrated photovoltaic system that uses a lens to focus sunlight up to 2,000 times onto tiny solar cells that can convert 37.5 percent of the sun's energy into electricity. Stronger concentrations of sunlight allow engineers to use much smaller solar cells, making it more economical to use higher-efficiency--but higher-cost--cells. Sunrgi, for example, will use cells based on gallium arsenside and germanium substrates.
Paul Sidlo, one of seven founding partners of Sunrgi, says that the system uses four times less photovoltaic material than other approaches, which typically aim for 500 times sun concentration. This includes systems being developed by California rivals SolFocus and Soliant Energy.
"We've miniaturized everything," Sidlo says. "What this leads to is reduced cost, and the big breakthrough here is all about lower cost." The company has also designed its system to be produced on slightly modified computer assembly lines, enabling further savings through high-volume production. The higher efficiency also means that a solar park built with Sunrgi's modules could use one-sixteenth of the space needed with conventional thin-film solar cells, adds Sidlo. The result is lower real-estate costs for developers.
Sunrgi estimates that its system will be capable of producing electricity at a wholesale cost of five cents per kilowatt-hour. Prototypes have been built and tested both in the laboratory and in the field, and the company expects to start commercial production in 12 to 15 months. "It's quite an aggressive claim," says Daniel Friedman, a solar-energy researcher at the U.S. National Renewable Energy Laboratory (NREL). He says that most others in the space are still working toward seven or eight cents per kilowatt-hour. "I can't say Sunrgi won't achieve what it's claiming, but right now, it's just on paper, and costs like that are only going to be a reality at the large manufacturing level," he says. "Even then, the five-cent figure sounds really optimistic."
Arguably the biggest breakthrough for Sunrgi is in the area of heat management, which is essential to any concentrated photovoltaic system. The intense heat created by concentrating the sun so much can reduce both the efficiency and the life of the solar cell. At 2,000 times sun concentration, temperatures can exceed 1800 °C--similar to the heat from an acetylene torch, and hot enough to melt the solar cell.
Cells in such systems are usually cooled through a combination of heat conduction, air or liquid convection, and radiation; the goal is to remove as much of the heat as quickly as possible, says Sunrgi partner KRS Murthy, who has been labeled the "thermal wizard" by his colleagues. "At each stage of conduction, convection, and radiation, we've made an improvement over what others have done," he says.
For example, connected to the bottom of each cell is a small fluid-filled chamber that acts as a heat sink. Murthy says that the fluid contains high-temperature composites and nanomaterials that rapidly remove the heat from the cells. This "super cooling" allows the cells to stay cool enough to work, about 10 to 20 °C above ambient temperatures. Murthy won't say what materials are in the fluid. "It's our secret."
Electronics engineer Thomas Forrester, another founding partner at Sunrgi, says that the chamber isn't filled with much: "We're talking as little as drops of liquid." But it's enough, he says, to absorb the heat and move it to another part of the cell so that it can dissipate rapidly into the environment. Future versions will attempt to capture that waste heat as useful energy. "We have patents pending on other designs that do this," he says.
Simon Fafard, founder and chief technology officer at Ottawa-based Cyrium Technologies, a maker of high-end cells for the concentrated photovoltaic market, says that the heavy-duty heat sinks that Sunrgi relies on leave little room for error during manufacturing. "It also makes testing the cells a bit more of a challenge," he adds.
Forrester says that's why most of the founders of Sunrgi have an expertise in manufacturing. "The question people ask us is, why hasn't any other solar company done this?" he says. "Well, we're taking a different approach that directly applies principles from chip manufacturing. That's one of the keys to our technology."
But other challenges remain. Concentrated photovoltaic systems need direct sunlight to work, meaning that they must be designed to track the sun through the day. Fafard says that Sunrgi's system, at 2,000 times concentration, will need to use tracking with pinpoint accuracy to keep the light focused on the tiny solar cells. He compares it to looking at a star through a telescope: the higher the magnification, the more accuracy is required to keep the star within view of the lens. This makes Sunrgi's system potentially more vulnerable to the elements. "Wind would definitely be bad," says NREL's Friedman. "If the thing is shaking even a little bit, the light will go off the cell."
The need for direct sunlight also means that concentrated photovoltaic systems don't work on cloudy or hazy days when conventional solar systems can at least capture some of the sun's energy. "So it makes the most sense for places like Phoenix, Spain, Australia," says Fafard.
Sidlo says that Sunrgi will initially be targeting utility-scale developments and is in talks with strategic partners, including manufacturers. The company is currently self-funded but says that it is talking with top venture capitalists.
Jennifer Chu, Technology Review, March/April 2008 http://www.technologyreview.com/read_article.aspx?ch=specialsections&sc=emerging08&id=20248
Then, a few years ago, Marin Soljačić, an assistant professor of physics at MIT, was dragged out of bed by the insistent beeping of a cell phone. "This one didn't want to stop until you plugged it in for charging," says Soljačić. In his exhausted state, he wished the phone would just begin charging itself as soon as it was brought into the house.
So Soljačić started searching for ways to transmit power wirelessly. Instead of pursuing a long-distance scheme like Tesla's, he decided to look for midrange power transmission methods that could charge--or even power--portable devices such as cell phones, PDAs, and laptops. He considered using radio waves, which effectively send information through the air, but found that most of their energy would be lost in space. More-targeted methods like lasers require a clear line of sight--and could have harmful effects on anything in their way. So Soljačić sought a method that was both efficient--able to directly power receivers without dissipating energy to the surroundings--and safe.
He eventually landed on the phenomenon of resonant coupling, in which two objects tuned to the same frequency exchange energy strongly but interact only weakly with other objects. A classic example is a set of wine glasses, each filled to a different level so that it vibrates at a different sound frequency. If a singer hits a pitch that matches the frequency of one glass, the glass might absorb so much acoustic energy that it will shatter; the other glasses remain unaffected.
Soljačić found magnetic resonance a promising means of electricity transfer because magnetic fields travel freely through air yet have little effect on the environment or, at the appropriate frequencies, on living beings. Working with MIT physics professors John Joannopoulos and Peter Fisher and three students, he devised a simple setup that wirelessly powered a 60-watt light bulb.
The researchers built two resonant copper coils and hung them from the ceiling, about two meters apart. When they plugged one coil into the wall, alternating current flowed through it, creating a magnetic field. The second coil, tuned to the same frequency and hooked to a light bulb, resonated with the magnetic field, generating an electric current that lit up the bulb--even with a thin wall between the coils.
So far, the most effective setup consists of 60-centimeter copper coils and a 10-megahertz magnetic field; this transfers power over a distance of two meters with about 50 percent efficiency. The team is looking at silver and other materials to decrease coil size and boost efficiency. "While ideally it would be nice to have efficiencies at 100 percent, realistically, 70 to 80 percent could be possible for a typical application," says Soljačić.
Wireless Light
Marin Soljačić and
colleagues used magnetic resonance coupling to power a 60-watt light bulb. Tuned
to the same frequency, two 60-centimeter copper coils can transmit electricity
over a distance of two meters, through the air and around an obstacle.
1. Resonant copper coil attached to frequency converter
and plugged into outlet
2. Wall outlet
3.
Obstacle
4. Resonant copper coil attached to light bulb
Who: Marin Soljacic, MIT
Definition: Wireless power technology transmits electricity to
devices without the use of cables.
Impact: Any low-power device, such
as a cell phone, iPod, or laptop, could recharge automatically simply by coming
within range of a wireless power source, eliminating the need for multiple
cables—and perhaps, eventually, for batteries.
Context: Eliminating
the power cord would make today’s ubiquitous portable electronics truly
wireless. A number of researchers and startups are making headway in this
growing field.
Other means of recharging batteries without cords are emerging. Startups such as Powercast, Fulton Innovation, and WildCharge have begun marketing adapters and pads that allow consumers to wirelessly recharge cell phones, MP3 players, and other devices at home or, in some cases, in the car. But Soljačić's technique differs from these approaches in that it might one day enable devices to recharge automatically, without the use of pads, whenever they come within range of a wireless transmitter.
The MIT work has attracted the attention of consumer-electronics companies and the auto industry. The U.S. Department of Defense, which is funding the research, hopes it will also give soldiers a way to automatically recharge batteries. However, Soljačić remains tight-lipped about possible industry collaborations.
"In today's battery-operated world, there are so many potential applications where this might be useful," he says. "It's a powerful concept."
See All 10 Emerging Technologies 2008
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Tyler Hamilton, Technology
Review, January 22, 2008
http://www.technologyreview.com/read_article.aspx?ch=specialsections&sc=batteries&id=20090&a= Earlier this month, a stealthy startup that says its ultracapacitor-based energy storage system could make conventional batteries obsolete took a small step toward proving its many skeptics wrong. The company, EEStor, based in Cedar Park, TX, has made bold claims about its technology but has so far failed to deliver a working commercial product. However, an agreement announced this month with Lockheed Martin, based in Bethesda, MD, suggests that the company could be making progress--at least enough to convince a major defense contractor that the technology has merit. The agreement gives Lockheed an exclusive international license to use EEStor's power system for military and homeland-security applications--everything from advanced remote sensors and missile systems to mobile power packs and electric vehicles. The technology, Lockheed said in a statement, "could lead to energy independence for the Warfighter." Lockheed has not seen a working prototype but said that qualification testing and mass production of EEStor's system is planned for late 2008. Lockheed would not disclose the terms of the partnership. "We fully intend to work with EEStor this year to prototype and demonstrate this technology for the soldier," says Lionel Liebman, Lockheed's manager of program development in its applied research division. "We're looking at a lot of applications where the EEStor application can help." EEStor says that its patented system is a nontoxic, safe, and lower-cost alternative to conventional electrochemical battery technologies, offering ten times the energy density of lead-acid batteries. The company also claims that its system allows rapid and virtually unlimited charging and discharging without significant degradation of the unit. (See "Battery Breakthrough?") But many experts have been skeptical, citing the difficulty of working with the material at the core of the company's system: a ceramic made of barium-titanate. A lack of news from the company has only fed the skepticism. The last public announcement from EEStor came last January, when it revealed that it had made high purity barium-titanate powders on its first automated production line. But the company has so far failed to deliver units of its storage product to minority investor ZENN Motor, a company based in Toronto that plans to use it in electric vehicles. Originally, the devices were to have shipped in the first half of last year. EEStor chief executive Richard Weir declined to comment on the development of the technology and the agreement with Lockheed. But he told Technology Review in an e-mail message that he's anticipating another "technical news release in the near future," at which time he would be open to discussing EEStor's progress in more detail. ZENN chief executive Ian Clifford remains optimistic. "Every restatement of delivery time has been for good reasons," he says, suggesting that the Lockheed announcement and the due diligence that led to it "add credibility to the technology." He's now expecting delivery of the energy-storage unit in mid-2008. And it won't be a prototype, he emphasizes: it will be a mass-produced commercial product. "This is about commercialization, not hitting technology roadblocks. We're in constant contact with EEStor, with regular visits to their site. We always come away from every meeting much more excited that this is going to happen." ZENN has already switched to a different motor in its current low-speed electric vehicle, partly in anticipation of the new energy storage technology. "We're first in line," says Clifford. "We understand we'll be taking the first product off the production facility being built right now." Liebman, who says that he has visited EEStor's facility in Cedar Park and was impressed, also expressed confidence in the company. He notes that EEStor's approach so far allows for a rapid ramp-up in production. "I think it's very real," he says. 6) Autra Makes Solar Thermal Simple and
Cheap
Tekla Perry, IEEE Spectrum, May 2008, http://www.spectrum.ieee.org/may08/6200
Solar-thermal power has never seemed as technologically smart as photovoltaic technology. After all, a Neanderthal man could warm himself in the sun, but it took Einstein to explain the photoelectric effect. But these days the idea of using sunlight to heat fluids to generate electricity is suddenly looking like a bright idea. At least 10 solar-thermal power plants are being developed for installation in the United States, and another 17 are under construction or being planned in Algeria, China, Egypt, Israel, Mexico, Morocco, South Africa, and Spain. With a typical plant generating somewhere between 50 and 500 megawatts, that's a lot of clean power due to come online. (New photovoltaic installations worldwide totaled a record 2826 MW in 2007, according to Solarbuzz.) There are lots of ways to build a solar-thermal system, parabolic troughs or dishes being the most familiar. But a former Australian academic, David Mills, founder of the solar-thermal firm Ausra, in Palo Alto, Calif., thinks he has a better idea, and at least one major utility—Pacific Gas & Electric, in San Francisco—agrees. In November, the utility signed an agreement to purchase power generated by a 2.6-square-kilometer 177-MW power plant Ausra is building in the Nevada desert. Ausra says it has many more such deals in the works. Mills's design, called the Compact Linear Fresnel Reflector, uses much less land than others. The mirrors appear to be solid but are actually made up of many smaller, movable reflectors, each with a slight curve. The system uses nearly flat mirrors at ground level that focus the sun's light onto water-filled steel tubes. When the water boils, it directly drives a steam turbine to generate electricity. Typical solar-thermal systems use heat transfer; water- or oil-filled tubes pass the heat to another system, which then boils water to drive steam turbines. “I have a favorable opinion of [Ausra's] technology, largely because of the relative simplicity of manufacturing flat mirrors compared with parabolic mirrors. Also, because the mirrors are closer to the ground, they are less subject to wind loads,” says Michael Locascio, a senior analyst with Lux Research, in New York City. Last April Ausra powered up the production line at a 12 000-square-meter manufacturing plant in Nevada. It's the first facility in the United States dedicated to producing the components of solar-thermal systems, including reflectors, towers, and specially insulated steel tubes. The new factory can build enough equipment to fill more than 10 km2 with solar-thermal collectors annually, enough to produce 700 MW of power or to power 50 000 homes. Eventually, Mills expects Ausra to sell equipment to others; for now, Ausra will consume the output. Ausra sounds like a young company on the fast track, and in a way it is. It got its first round of venture capital financing last year—US $43 million. But in another way, Ausra's been slowly building for decades. Mills has been working with solar energy since the 1970s. Back then he was a principal research fellow at the University of Sydney, doing work in optics. There he started a research program to develop advanced coatings for evacuated-tube solar collectors, cleverly constructed glass tubes that let solar energy in but don't let heat out. Today his tubes are widely used in water heaters in China. In 2006, John O'Donnell, a serial technology entrepreneur, contacted Mills. At first Mills told him, basically, to get lost. But O'Donnell was persistent, and in October of that year, he convinced Mills to come to California for a meeting with venture capitalists. Just three months later, Mills left the house in Sydney where he'd lived for more than 20 years and moved to Palo Alto; his wife and children followed a month later. These days he heads up R&D for Ausra; until recently he ran the company's engineering efforts as well. “I'm 61,” he says. “It's a bit late in life to do a start-up, but when you work at something all your life, you do hope something comes of it and that you can influence change.” 7) Conoco-Philips Energy
Prize
Subject: [global-energy] Conoco-Phillips Energy Prize
Press Release, May 13, 2008,
http://www.conocophillips.com/Tech/energyprize/index.htm For Immediate Release The ConocoPhillips Energy Prize is a joint initiative by ConocoPhillips and Penn State that is designed to recognize new ideas and original, actionable solutions that can help improve the way the United States develops and uses energy. In 2008, the program will award up to $300,000 in cash prizes and focus on generating innovative ideas and solutions that help in three areas: * Developing new energy sources, including new ways to develop alternative energy. * Improving energy efficiency, such as new methods to significantly reduce the amount of energy consumed in the United States. * Combating climate change, including solutions that reduce greenhouse gas emissions. It is our hope that by creating an open forum for new energy ideas, we can create a path to a more secure and environmentally conscious energy supply for future generations. 8) JAXA Testing Space Solar Power
System
[Source: Hokkaido Shimbun] Pink Tentacle, Feb. 8,
2008
For decades, scientists have explored the possibility of using
space-based solar cells to power the Earth. Some see orbiting power
stations as a clean and stable energy source that promises to slow global
warming, while others dismiss the idea as an expensive and impractical
solution to the world’s energy problems. While the discussion goes on,
researchers at the Japan Aerospace Exploration Agency (JAXA) have begun to
develop the hardware.
JAXA, which plans to have a Space Solar Power System (SSPS) up and running by 2030, envisions a system consisting of giant solar collectors in geostationary orbit 36,000 kilometers above the Earth’s surface. The satellites convert sunlight into powerful microwave (or laser) beams that are aimed at receiving stations on Earth, where they are converted into electricity. On February 20, JAXA will take a step closer to the goal when they begin testing a microwave power transmission system designed to beam the power from the satellites to Earth. In a series of experiments to be conducted at the Taiki Multi-Purpose Aerospace Park in Hokkaido, the researchers will use a 2.4-meter-diameter transmission antenna to send a microwave beam over 50 meters to a rectenna (rectifying antenna) that converts the microwave energy into electricity and powers a household heater. The researchers expect these initial tests to provide valuable engineering data that will pave the way for JAXA to build larger, more powerful systems. JAXA says the orbiting solar arrays, which have the advantage of being able to collect energy around the clock regardless of the weather on the ground, will need to transmit microwaves through the earth’s atmosphere at frequencies that are not affected by the weather. The researchers are now looking at using the 2.45GHz and 5.8GHz bands, which have been allocated for use with industrial, scientific and medical devices. JAXA ultimately aims to build ground receiving stations that measure about 3 kilometers across and that can produce 1 gigawatt (1 million kilowatts) of electricity — enough to power approximately 500,000 homes. For More Information Charter for a Space Solar Satellite Company http://www.sspi.gatech.edu/letter%20to%20chairman%20gordon.doc Provided as a public service by www.IntegrityResearchInstitute.org
where a new website awaits the unwary visitor! Also, a FREE "Progress
in Future Energy" DVD 30-min. is available upon request (email: "Free DVD"
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