The U.S. wind power industry has a lot to celebrate these days. Last year it accounted for 32 percent of all new installed capacity in the U.S., more than any other single fuel. The wind industry also won a hard-fought battle to extend the critical wind power tax credit for another year, and now it looks like scientists at Brookhaven National Laboratory are on the way to solving one obstacle to even more efficient and powerful wind turbines, especially for the offshore wind power sector: development of a low cost superconducting wire based on iron. The new superconductor is more durable and less costly to manufacture than another emerging superconductor based on ceramic materials.
Superconductors do just what the name suggests, delivering far greater potential for high efficiency energy generation, transportation and storage, but they are notoriously fickle.
Generally, superconductors are extremely expensive to manufacture, they require forceful temperature control, and they don’t perform efficiently under the magnetic fields created by wind turbines.
The Brookhaven breakthrough, published last week in Nature Communications, involves fabricating a semiconductor with thin films of iron, the crystalline material selenium and the semi-metal tellurium, three relatively cheap materials (especially the iron).
The low-cost manufacturing process uses laser pulses to vaporize the materials, and the vapor is then collected in precise layers on a substrate. The secret ingredient is a layer of cerium-oxide (a yellowy rare earth powder) in between the substrate and the other three layers. According to Brookhaven physicist Qiang Li:
“…adding layers of cerium-oxide in between the films and substrates dramatically increased the superconductor’s critical current density, or maximum electricity load, as well as the critical temperature at which the material becomes superconducting. That critical temperature threshold rose 30 percent over the same compound made without this layering process—still a very cold -253 degrees Celsius, but it promises significant application potential.”
Er, About that Cerium Oxide
Rare earths like cerium oxide are critical to the future development of the alternative energy industry, including wind power as well as electric vehicles and high-efficiency lighting.
The sticky wicket is that dependency on overseas rare earth sources has proven to be a shaky foundation for long term growth in these industries, as well as in more traditional sectors. Just a couple of years ago, a shortage of cerium dioxide rattled the U.S. glass industry.
Not to worry (at least, not yet). The Obama Administration has several initiatives under way to develop more reliable rare earth sourcing, including the recent establishment of the Critical Materials Institute. The new institute, part of the Administration’s Energy Innovation Hub program, will also be exploring the development of substitute materials as well as new manufacturing and resource recovery strategies.
Magnetic Fields and Wind Turbines
The new superconductor proved to be capable of carrying 200,000 amperes per square centimeter even under an intense magnetic field. In comparison, a typical household circuit breaker will trip at 20 amps.
If the magnetic field issue is starting to ring a bell, you might be thinking of another superconducting wire under development at the University of Houston through a $4 million Department of Energy grant administered by ARPA-E, the agency’s cutting-edge technology division.
Like the Brookhaven project, the Houston research has significant implications for the wind industry in terms of creating a low cost superconductor that performs efficiently even when exposed to a high magnetic field.
Offshore wind power installations would be particular beneficiaries of the new technology, given the massive turbines and long transmission distances involved.
Although the U.S. has been lagging far behind other countries when it comes to offshore wind development, with new superconducting wires in hand it could leapfrog ahead.
That would be especially welcome news for the energy-hungry northeastern states. According to the Department of Energy, practically the entire northeast Atlantic coast is rated as “outstanding” for potential wind power generation.
Image: Courtesy of Brookhaven National Laboratory.
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Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.