You are browsing the archives of MIT.

PV panels on the Mars rover Spirit were covered with dust over a two-year period. Credit: NASA/JPL.

Self-cleaning surfaces aren’t a particularly novel idea, and self-cleaning glass commercial products made by companies, such as Saint Gobain, have been around in various products for at least five years – but at a premium price. These technologies use a TiO₂ coating to photocatalyze organic dust that is then washed away by humidity and rain. However, for some dusty (e.g., nonorganic) materials, even this self-cleaning system doesn’t work.

The cost and performance problems with these existing systems are unfortunate, especially when it comes to photovoltaic solar panels and mirrors, particularly when one considers that many utility-scale solar energy systems are being located in desert areas that are prone to large amounts of non-organic dust. In some of these regions, even dragging out a hose or water truck to rinse off PV panels and mirrors is not practical nor economically feasible.

The effects of the dust on these solar energy system are tangible. “A dust layer of one-seventh of an ounce per square yard decreases solar power conversion by 40 percent,” explains MIT visiting professor Malay K. Mazumder. “In Arizona, dust is deposited each month at about four times that amount. Deposition rates are even higher in the Middle East, Australia and India.”

Mazumder knows something about dust. He has worked with NASA on a similar but more difficult problem: Extraterrestrial dust. When the problem is dust on surfaces somewhere lacking Earth’s atmosphere and weather – say, Mars or the moon – terrestrial technology just won’t cut it. Lunar dust was nasty stuff for astronauts to deal with and is described as tiny pieces, sharp and interlocking pieces of glass or coral that is everywhere on the lunar surface.

According to NASA, Mars dust isn’t quite so bad, but still a big problem:

Dust is also ubiquitous on Mars, although Mars dust is probably not as sharp as moon dust. Weathering smooths the edges. Nevertheless, Martian dust storms whip these particles 50 m/s (100+ mph), scouring and wearing every exposed surface. As the rovers Spirit and Opportunity have revealed, Mars dust (like moon dust) is probably electrically charged. It clings to solar panels, blocks sunlight and reduces the amount of power that can be generated for a surface mission.

NASA knew that dust interference with solar panel function could be catastrophic for Mars missions. Working with the agency, Mazumder and other researchers developed a novel self-cleaning solar panel technology for use in lunar and Mars missions.

Now, Mazumder says the time has come to apply the same technology on earth. “Solar panels powering rovers and future manned and robotic [NASA] missions must not succumb to dust deposition. But neither should the solar panels here on Earth,” he says

Mazumder describes the technology he has in mind as having three parts. The first part is thin layer of transparent, electrically sensitive material on the glass or plastic covering of a solar panel. The second part is a sensor to monitor dust levels on the surface of the panel. The third part is a system to send a brief electric charges over the surface of the panel. Because, like the stuff on moon and Mars, most Earth dust carries an electrical charge, delivering alternating electric fields acting through the thin layer on the panel dislodges, carries and deposits dust particles off and away from surfaces.

According to a news release, Mazumder says a two-minute process removes about 90 percent of the dust deposited on a solar panel. Further, his approach requires only a small amount of electric power, which can easily be supplied by the panel.

At the end of each week, I end up with a list of a bunch of stories I started to write about, or started to investigate or didn’t even get that far even though the topic looked intriguing, but, I had a meeting to go to …

Anyway, it’s Friday, and rather than have these stories evaporate into the ether, I’ve close out each week by providing some raw links to some of these orphan tales. Check ‘em out:

Retrograde melting property of silicon demo’d by MIT team may yield new purification process

Haier Power Pad takes energy from shower water and returns it to hot water system

Study: Solar power is cheaper than nuclear

Scientists at MIT, Intel and other facilities are researching microstructures in hopes of replacing lithium-ion batteries with nanoscale ultrapowerful capacitors. If successful, the new materials could be mass produced in volumes to power systems ranging from mobile devices to electric vehicles to smart grid storage units.

According to EE Times, Intel researchers have been working on “ultracapacitors with a greater energy density than today’s lithium batteries.” Intel is looking into producing these nanoscale ultracapacitors in high-volume manufacturing.

“It’s way too early to announce any results, but we are taking what we think is a fresh look at building ultracapacitors using our expertise in nanomaterials fabrication and high volume manufacturing,”says Intel lab director Tomm Aldridge.

MIT’s Laboratory for Manufacturing and Productivity is working on a multitude of micro- and nano-scale manufacturing techniques. For example, researchers at the Precision Compliant Systems Laboratory at MIT are looking into multi-axis nanopositioning systems.

The PCSL describes nanopostitioners as “electromechanical systems that position and orient components with [nanometer]-level accuracy.” While not directly related to the manufacture of nanoscale ultracapacitors, this technology may be able to include Intel’s nano-scale ultracapacitors on smaller-scale circuit boards, making electronics smaller.

Also in conjunction with it’s Energy Innovation Summit, ARPA-E is promoting a new, brief video about the photosynthesis/photocatalysis energy storage ideas of MIT’s Daniel Nocera and his company, Sun Catalytix. Nocera has received $4 million form ARPA-E to continue the development of his prototypes.

Nocera’s catalyst consists of cobalt metal, phosphate and an anode, placed in water. When electricity from a photovoltaic cell is run through the catalyst, the cobalt and phosphate form a thin film on the electrode’s surface, creating oxygen gas. When combined with a cathode capable of producing hydrogen gas from water, the two electrodes create a system that mimics the way plants use sunlight to split water and create energy during photosynthesis. This catalyst works at room temperature

For more information on Nocera’s work see:

Nocera makes more news with electrolysis gains

More about Nocera’s electrolysis catalyst

Catalyst discovery unlocks low-cost solar storage

(Either JavaScript is not active or you are using an old version of Adobe Flash Player. Please install the newest Flash Player.)

Charles Vest, president of the National Academy of Engineering and president emeritus of MIT, was the 2009 Frontiers of Science & Technlogy–Rustum Roy Lecturer at the recent ACerS Annual Meeting and MS&T’09 conference.

“This is the most exciting time for engineering and science in human history. A new generation of engineers will be inspired by the great human challenges of this century. Globalization and the changing nature of science and technology are driving change and opportunity in higher education, R&D and innovation. R&D spending is smeared nearly uniformly around the world, and new players are rapidly emerging. Higher education is globalizing in both planned and unplanned ways, enabled by information technology and driven by economic and social change. Our innovation system may be due for another major transformation. Do our universities have new responsibilities? Can we pull it off?”

Vest earned a B.S. in mechanical engineering from West Virginia University in 1963, and M.S.E. and Ph.D. in mechanical engineering from the University of Michigan in 1964 and 1967, respectively. He joined the faculty of UM as an assistant professor in 1968, where he taught in the areas of heat transfer, thermodynamics and fluid mechanics, and conducted research in heat transfer and engineering applications of laser optics and holography. He became an associate professor in 1972 and a full professor in 1977.

Vest’s administrative duties at UM included associate dean of engineering from 1981 to 1986. He was dean of engineering from 1986 to 1989, when he became provost and vice president for academic affairs. In 1990 he became president of MIT and served in that position until December 2004. He then became professor and president emeritus.

As president of MIT, Vest was active in science, technology and innovation policy; building partnerships among academia, government and industry; and championing the importance of open, global scientific communication, travel and sharing of intellectual resources.

Vest was a director of DuPont for 14 years and of IBM for 13 years, was vice chair of the U.S. Council on Competitiveness for eight years and served on various federal committees and commissions, including the President’s Committee of Advisors on Science and Technology during the Clinton and Bush administrations. He serves on the boards of several nonprofit organizations and foundations devoted to education, science and technology.

In July 2007 he was elected to serve as president of NAE for six years.