Rare Earth Prices

In the New York Times, Keith Bradsher paints a picture of the troubling economic situation that's emerging in the rare-earth market. Prices of these metals, which are found in small amounts in a wide range of high-tech products, have been skyrocketing. Manufacturers hope for some relief from new supplies from a processing plant in Malaysia that's currently under construction. But, Bradsher reports, the Malaysian Atomic Energy Licensing Board has asked its operator, Lynas Corporation of Australia, for additional documentation before approving it. (Rare-earth processing leads to an accumulation of radioactive elements that also occur in the deposits.)

In spite of soaring prices of these elements, the rare-earth supply problems have been invisible to consumers—it hasn't affected the prices we pay for smartphones, for example. That's because in most applications of rare earths, only trace amounts are used. That's not true, though, of electric- and hybrid-car motors or wind turbines. The Prius, for example, uses a kilogram of rare earths. Bradsher notes that while the price of the Prius has gone up, Toyota has attributed this to increased demand for the car, not increased demand for the necessary rare-earth neodymium.

Thermoelectric Materials

In Science Now, Robert F. Service reports on efforts to do something useful with thermoelectric materials, which can convert heat into electricity. Waste heat is everywhere—car exhaust pipes, computer chips, etc.—and this inefficiency has been tormenting engineers for a long time. But efforts to make use of that waste in materials that can convert heat into electricity haven't gone very far. Service provides a nice summary of these efforts and explains how researchers have now made one of the most common thermoelectric materials more efficient.

Today the Boeing 787 "Dreamliner", said to be 20 percent more efficient, 60 percent quieter, and significantly cheaper to maintain, passed a huge milestone as it finally took off and landed.

Watching the televised takeoff of the 787--after two years of delays brought on by manufacturing errors and structural problems--brought back some memories. Six years ago I visited Boeing's rain-drenched tarmacs and vast hangars in Everett, WA, to report a feature for Technology Review on the then-new project to build what was dubbed the "7E7" commercial jet.

The idea was to gain an edge on Airbus by offering a midsized super-fuel-efficient jet, with better jet engines, and reduced weight enabled by far wider use of composite structural materials as well as fewer bulky pneumatic control systems.

In 2003 Boeing engineers and executives spoke excitedly about how the 7E7 would take collaborative Internet-enabled design and widely distributed manufacturing processes to new heights. Designers around the world would collaborate on the same master file over the Internet. Then subcontractors around the country and world would get a copy of those files, whip together big chunks of the structure, and ship those chunks back to Everett. Boeing would simply snap together the parts. No problem. "We call it our Lego airplane," Frank Statkus, Boeing's vice president of technology and processes, joked to me at the time.

The improved computer design process was meant to eliminate problems. Previously, Statkus explained, a supplier would sometimes "have to digitize our picture to tell his machine how to build it. This translation sometimes caused errors."

Well, of course, Boeing didn't squeeze out all the errors. Production was hampered by ill-fitting parts and structural problems that led to five delays, extending the commercial delivery date two years (it's now scheduled for late 2010). In 2008, for example, the company found that parts of the center wing box--the massive structure at the center of the plane, extending to two-thirds of the wingspan--required stiffening with new brackets, which in turn forced the re-routing of some wiring. The component--15 meters long and 5 meters wide--had been designed and built by Boeing, Mitsubishi Heavy Industries and Fuji Heavy Industries, in Japan. And, earlier this year, Boeing also had to resolve another structural issue.

Back in 2003, Mark Jenks, Boeing's director of technology integration told me that the plane was "the future. It really is. It's a huge deal for us. If we get it wrong, it's the end. And everyone here knows that."

After today's historic flight, and with orders for 840 planes already taken, the hard part may finally be done.

Silicon solar cells built on a nanostructured substrate (top left) have a surface patterned with nanoscale domes (top right). The scale bar in both electron-microscope images is 500 nanometers. The diagram shows the layers of the device, from bottom to top: a quartz substrate, a reflective layer of silver, a transparent conducting oxide, the active layer of amorphous silicon, and another oxide layer. Credit: ACS/Nano Letters

The accumulation of dust on the surface of a solar cell can block light and cut into cell efficiency. Researchers at Stanford have demonstrated that solar cells patterned at the nanoscale with domed structures absorb more light and, as a bonus, are self-cleaning.

The nanoscale patterning is not just on the surface of the cell but is applied to every layer. The cells are built on a substrate patterned with nanoscale cones. The bottom layer is a film of silver 100 nanometers thick that acts as an electrical contact and a light reflector; atop this is a film of amorphous silicon sandwiched between transparent conducting layers. Though the substrate is jagged, the accumulation of layers results in domed structures that happen to resemble the mushroom-like structures other researchers have been developing for self-cleaning surfaces. An added layer of hydrophobic molecules makes the cells nearly superhydrophobic: water droplets roll along the surface, pulling dust away with them.

These nanodome structures not only repel water, but help trap light. Because they're so small--about 500 nanometers in diameter--the nanodomes interact with light in a cool way, absorbing 94 percent of all light from the infrared to the ultraviolet. A flat solar cell made from the same materials absorbs only 65 percent of light in the same broad spectrum. So far the overall power conversion efficiency of the cells is 5.9 percent. The lead researcher, Stanford materials science professor Yi Cui, says these patterning techniques could be applied to other solar materials. This work is described online in the journal Nano Letters.