Semiconductor Manufacturing Technique Holds Promise for Solar Energy
Thanks to a new semiconductor manufacturing method pioneered at the University of Illinois, the future of solar energy just got brighter.
Although silicon is the industry standard semiconductor in most electronic devices, including the photovoltaic cells that solar panels use to convert sunlight into energy, it is hardly the most efficient material available. For example, the semiconductor gallium arsenide and related compound semiconductors offer nearly twice the efficiency as silicon in solar devices, yet they are rarely used in utility-scale applications because of their high manufacturing cost.
U. of I. professors John Rogers and Xiuling Li explored lower-cost ways to manufacture thin films of gallium arsenide that also allowed versatility in the types of devices they could be incorporated into. “If you can reduce substantially the cost of gallium arsenide and other compound semiconductors, then you could expand their range of applications,” said Rogers, the Lee J. Flory Founder Chair in Engineering Innovation, and a professor of materials science and engineering and of chemistry.
Typically, gallium arsenide is deposited in a single thin layer on a small wafer. Either the desired device is made directly on the wafer, or the semiconductor-coated wafer is cut up into chips of the desired size. The Illinois group decided to deposit multiple layers of the material on a single wafer, creating a layered, “pancake” stack of gallium arsenide thin films.
“If you grow 10 layers in one growth, you only have to load the wafer one time,” said Li, a professor of electrical and computer engineering. “If you do this in 10 growths, loading and unloading with temperature ramp-up and ramp-down take a lot of time. If you consider what is required for each growth — the machine, the preparation, the time, the people — the overhead saving our approach offers is a significant cost reduction.”
Next the researchers individually peel off the layers and transfer them. To accomplish this, the stacks alternate layers of aluminum arsenide with the gallium arsenide. Bathing the stacks in a solution of acid and an oxidizing agent dissolves the layers of aluminum arsenide, freeing the individual thin sheets of gallium arsenide. A soft stamp-like device picks up the layers, one at a time from the top down, for transfer to another substrate — glass, plastic or silicon, depending on the application. Then the wafer can be reused for another growth.
U.S. Postal Service, GridPoint ink $28M deal
Arlington, Va.-based GridPoint Inc. will supply energy management technology for as many as 2,250 post offices, under a contract designed to help the U.S. Postal Service meet its energy savings targets, the company announced today.
Under the agreement, USPS will install GridPoint’s hardware and software in 750 medium-sized facilities in the first year, with options to add that number in each of two additional years to reach 2,250 sites in total. The maximum value of the contract is $28.7 million.
GridPoint Executive Vice President John Clark said the installations would include hardware that allows users to more finely control the operations of heating, cooling and lighting systems, and software that provides visibility into how individual components and the whole system are using energy. “We give our customers both a speedometer and a tachometer for their energy use to see how they’re doing, as well as a gas pedal and a brake,” he said.
The system is compatible with other vendors’ smart grid tools through a compatibility standard called BACnet, which would allow USPS to roll the resultant data in with information collected from other compliant tools for a big-picture view, Clark said.
The system to be used splits control between local users and central planners, Clark added. A key feature allows a central facilities manager to set the default temperature for a number of linked facilities, but lets a local manager temporarily override that setting. If on-site employees want to increase the air conditioning level, for example, they can temporarily cool the facility more, but the setting eventually resets to the central office-approved default.
Clark said a pilot at 16 USPS facilities in North Carolina showed that from a user-acceptance perspective, long-term changes to climate control systems need to be made slowly.
First U.S. freshwater turbine farm proposed for Lake Erie
General Electric Co. and Lake Erie Energy Development Corp. announced plans today to build the nation’s first offshore, freshwater wind farm near Cleveland.
GE will provide five wind turbines and maintenance services for the 20-megawatt project, company officials noted at a wind energy industry conference in Dallas.
Lake Erie Energy Development Corp. (LEEDCo), a nonprofit economic development corporation launched last year, is evaluating candidates to build the project. The project, which would cost roughly $90 million to build, would be located about 7 miles north of Cleveland in the waters of Lake Erie.
LEEDCo President Lorry Wagner said his organization is evaluating three teams of companies to build the wind farm and begin producing power by late 2012. He declined to name the companies.
“They’re all U.S.-based companies, but each group has different types of international experience, whether it’s developing offshore wind or oil and gas,” Wagner added.
The developer would be responsible for inking a power-purchase agreement.
GE will build the turbines in Europe, but LEEDCo officials hope the Lake Erie project spurs the industrial conglomerate to eventually build turbines in Ohio. LEEDCo has set a goal of generating 1,000 MW of cost-competitive wind power from Lake Erie by 2020, while leveraging the region’s manufacturing base.
“It’s not about putting just 20 megawatts in the water, it’s about 2020,” Wagner said.
LEEDCo’s founding partners include the Cleveland Foundation, city of Cleveland, Cuyahoga and Lorain counties, and NorTech.
Climate change threatens the diversity of small mammals
A period of rapid warming that ended roughly 11,700 years ago has had lasting changes on the diversity of small mammals in northern California, according to a new study.
While many ecologists have warned that climate change could eventually drive many species to extinction, the authors of the new study say their work shows that warming can bring about more subtle, but enduring, changes.
Fossils excavated from northern California’s Samwell Cave, at the foot of the Cascade Range, show that warming — and the arrival of humans — at the end of the Pleistocene Epoch changed the balance of the area’s small mammal populations.
More adaptable, “weedy” species like deer mice became more common, while species that were already less abundant became even rarer.
“If we only focus on extinction, we are not getting the whole story,” said lead author Jessica Blois, a postdoctoral researcher at the University of Wisconsin, Madison, in a statement. “There was a 30 percent decline in biodiversity due to other types of changes in the small-mammal community.”
The effects are still apparent today, Blois and her co-authors found, based on their examination of the small mammals present near the cave today.
The scientists say their work suggests that future climate change could have unanticipated consequences for the diversity of small mammal species, which perform important functions like aerating soil, dispersing seeds and providing prey for larger animals.
The study was published Sunday in the journal Nature Geoscience.
Gov. Deval Patrick: Cape Wind energy will be worth it
Gov. Deval Patrick yesterday stoutly defended a multibillion-dollar rate agreement for Cape Wind electricity, saying it will provide ratepayers with a stable source of renewable energy.
Patrick’s comments came as Cape Wind Associates and Nstar met yesterday about a possible long-term contract for Cape Wind’s electricity from its proposed offshore wind farm. The two sides yesterday declined comment on the substance of the talks.
Cape Wind has already signed a long-term agreement with National Grid, which agreed to pay Cape Wind about double the price of today’s electricity.
Asked if expensive offshore wind was appropriate when land-based wind is only half the cost, Patrick said “we need a variety” of clean-energy fuels. “We need it all,” Patrick told a reporter before a speaking event at the Suffolk University Law School.
Patrick said the Cape Wind-National Grid agreement will cost the average user of 550 kilowatts about $1.59 a month, though critics say the price will be far higher for large users of electricity.
The Department of Public Utilities is reviewing the Cape Wind-National Grid agreement. The agency would also review any pact with Nstar.
China Huaneng Signs $1.2 Billion Wind-Turbine Accord
China Huaneng Group, the country’s largest power producer, agreed to buy wind turbines from six domestic suppliers for 8.06 billion yuan ($1.2 billion) in total to meet rising demand for clean energy.
The Beijing-based parent of Hong Kong-listed Huaneng Power International Inc signed a framework agreement yesterday with suppliers including Sinovel Wind Group Co. and Shanghai Electric Group for the purchase of 1,800 megawatts of generating units, China Huaneng said in a statement on its website today.
China wants at least 15 percent of its energy to come from renewable sources including wind by 2020. Investment in renewable energy in the world’s biggest polluter reached $6.5 billion in the first quarter, the most for any country, New Energy Finance said on April 12. Huaneng Power posted a 41 percent gain in profit during the period.
The other wind-turbine suppliers include Dongfang Electric Corp., China Shipbuilding Industry Corp., Zhejiang Machinery and Electrical Group and a Guangdong-based manufacturer, according to the statement. The six turbine makers will each supply about 300 megawatts of capacity, China Huaneng said.
China Huaneng plans to have 20,000 megawatts of wind-power capacity by 2020, or about 10 percent of its total estimated generating capacity by then, according to today’s statement. The group currently has 2,800 megawatts of wind-power capacity.
The state-run company is seeking to set up wind farms in northern China and in coastal areas in the country’s southeast, China Huaneng said. Its unit Huaneng Power plans to spend 1.2 billion yuan on new wind projects this year, Chief Accountant Zhou Hui said on March 25.
Huaneng Power has risen 2.5 percent in Hong Kong trading this year, beating the 12 percent drop in the benchmark Hang Seng Index. The stock was at HK$4.50 at the midday break, down 2.2 percent.
Blair to advise Silicon Valley group on climate
Former British Prime Minister Tony Blair is joining a Silicon Valley business as a senior adviser on environmental issues.
Khosla Ventures announced the association with Blair on Monday during its limited partner summit in Sausalito.
The firm, started by Sun Microsystems Inc. co-founder Vinod Khosla, has invested in companies pursuing alternative fuel strategies and other environmentally-minded technologies.
Menlo Park’s Khosla Ventures has invested companies including Cogenra Solar Inc., which wants to multiply the energy efficiency of solar cells, and Calera, which is converting manmade greenhouse gas emissions into sustainable building products.
Khosla said Blair will advise the companies it invest in on how to meet their business goals.
“He’s going to help us in many areas that techie nerds like us here in Silicon Valley don’t understand and tend to underestimate the importance of,” Khosla said.
Since leaving office three years ago, Blair has urged policy makers and businessmen to work together on environmental problems.
“I’m more and more convinced that unless we connect and align the public policy space with the creativity and ingenuity and innovation of the entrepreneurs, we’re not going to resolve this issue,” Blair said. “The answer to this has got to lie in science and technology.”
It wasn’t disclosed how much Blair would be getting paid in this new advisory role. Blair said he would continue to work on his other projects, including his “Breaking the Climate Deadlock Initiative” in support of an international framework on climate change.
Nuclear Reactor Aims for Self-Sustaining Fusion
In a few years, an experimental nuclear fusion reactor near Moscow could be the first to yield a self-sustaining fusion reaction. If the Italian-Russian project is successful, it would be a key milestone for fusion power.
The proposed reactor is based on a design developed by Bruno Coppi, a professor of physics at MIT, and principal investigator on the reactor project with Italy’s National Agency for New Technologies, Energy and the Environment. Three similar reactors based on the same design have already been built at MIT. Italian and Russian physicists plan to meet on May 24 to chart a course for the new reactor, called Ignitor, in the first such meeting since the two countries agreed to join forces on the project in April.
Ignitor is a tokamak reactor, a doughnut-shaped device that uses powerful magnetic fields to produce fusion by squeezing superheated plasma of hydrogen isotopes. As an electric current and high-frequency radio waves pass through the plasma, heating it to extreme temperatures, the surrounding electromagnetic field confines the plasma under high pressure. The combined pressure and heat causes the hydrogen nuclei to fuse together to form helium in a process that releases tremendous amounts of heat. In a fully functional fusion reactor, this heat would be used to power an electricity-generating turbine.
A much larger, far more complex tokamak fusion reactor–the International Thermonuclear Experimental Reactor (ITER)–is planned for construction in Saint-Paul-lez-Durance, France. ITER, which will be completed in 2019 and ready for full-scale testing in 2026, will be closer to a functioning fusion generator but will not produce a self-sustaining fusion reaction. Ignitor will be a sixth the size of ITER and will test the conditions needed to produce a self-sustaining reaction.
“Ignitor will give us a quick look at how burning plasma behaves, and that could inform how we proceed with ITER and other reactors,” says Roscoe White, a distinguished research fellow at the Princeton Plasma Physics Laboratory.
But Ignitor will only test one key aspect of fusion. “It will give us information that is important, but it won’t give us all the information we need and certainly doesn’t replace ITER,” Steven Cowley, director of the Culham Centre for Fusion Energy in Oxfordshire, U.K. “It’s a demonstration that you can create ignition, but it’s not really a pathway to a reactor.”
Unlike ITER, Ignitor doesn’t include many of the components that a real reactor would require. For example one crucial missing part is the “breeder blanket,” which contains lithium and sits inside the reactor’s magnetic coils, providing a continuous supply of tritium–one of two isotopes fused in the reaction. Ignitor’s design is so compact that there is no room for a test blanket inside its coils.
