Finding a solar solution before the dust settles

With little rain and an abundance of sun, this desert country is just about as good as it gets for solar power. Not surprisingly, therefore, solar stands at the forefront of efforts to develop renewable energy and reduce the UAE's emissions of greenhouse gases while providing an alternative to dwindling supplies of oil. Unfortunately, there is also no shortage of dust. As anyone who lives here knows, dust is the nation's sentinel against inertia: anything immobile is quickly covered, whether hanging laundry, parked cars or solar panels.

Unless regularly removed, accumulated dust can in one month reduce a solar panel's efficiency by 35 per cent, according to some experts, more if there is a dust storm. Making matters worse is that, in addition to the dust that blows in from the desert, the nation's relatively high humidity helps turn fine dust into a sort of crust. "It makes the dust stick," says Lana el Chaar, an assistant professor in the electrical engineering department at Abu Dhabi's Petroleum Institute. "Fans cannot blow it off."

To combat this sticky problem, the Petroleum Institute has enlisted at least 16 of its own students to develop home-grown anti-dust systems. Their assignment: find a way to clean the solar panels without using either lots of precious water or human cleaners whose commutes would themselves consume environmentally unfriendly fuel. Solar power has become serious business in Abu Dhabi, joining a long list of investments - from aluminium and avionics to Formula One racing and French museums - where Abu Dhabi hopes to make its mark globally.

Solar also promises important benefits for the nation's economy. "Using solar power makes sense because if you use solar or other fuel sources for domestic needs it frees up additional hydrocarbons for export," says Simon Williams, the chief economist at HSBC in Dubai. The Government is counting on solar to help shrink the country's carbon footprint. The UAE is already the world's 10th-highest energy consumer on a per-capita basis. Solar will also help address a looming energy shortage. Current estimates project that the country will outstrip its own power supply in just two years.

Abu Dhabi aims to generate at least 7 per cent of its own power from renewable energy by 2020. "Seven per cent is a pretty high number," says Sander Trestain, a vice president at Enviromena Power Systems, a solar developer in Abu Dhabi. With little wind to turn turbines and no rivers to fill dams, Mr Trestain says Abu Dhabi will have to rely largely on solar to meet that goal. Conditions for solar are near perfect, though: Abu Dhabi enjoys roughly eight hours of sunshine a day in the winter; 12 hours a day in the summer. Cloud cover? Almost nil.

At the forefront of the capital's own ambitions is the Abu Dhabi Future Energy Company, also known as Masdar, which has already started investing US$2 billion (Dh7.34bn) into two solar panel factories, one here and another in Germany. Masdar's most ambitious goal, though, is to build in just six years the world's first zero-carbon, zero-waste city in the desert near Abu Dhabi's airport. Plans envision Masdar City becoming home to 50,000 people, with no cars and using 75 per cent less power than a conventional city of the same size.

The sun will provide most of Masdar City's energy. Virtually every building will be coated with solar panels and Masdar plans to build solar thermal plants, which use mirrors to concentrate the sun's rays and boil water to drive turbines. Masdar has already built a Dh185 million, 10 megawatt solar farm to power the city's construction. The farm's 87,777 panels took two months to install and cover 200,000 square metres of land.

Mr Trestain's company, Enviromena, helped design it. After conducting its own tests, he says, Masdar settled on a surprisingly low-tech solution to the dust problem that he calls "two guys with a brush". The crew uses no water, he says, just a four-metre-long brush. And the two employees do not add significantly to the carbon footprint already created by the solar farm's permanent security staff and other employees. The cleaning crew moves through the panels every two to three weeks. "Provided you keep that kind of schedule going there's no measurable output decline," Mr Trestain says.

Indeed, there are some who warn against exaggerating the dust problem. Wolfgang Kessling, a project manager at Transsolar, a German environmental engineering firm, says the UAE's above-average sunshine more than compensates for losses due to dust. And even those who worry about dust say economics may prove a bigger obstacle. "Even if we solved the dust problem tomorrow, solar would still not be cost-effective here," says Nada el Zein, the technology director at Greenlight-energy, an environment consultancy based in Dubai.

While the price of panels is falling, solar-generated power can still be four times the cost of power from coal. In Abu Dhabi, subsidised electricity from natural gas puts solar at an even greater disadvantage: the local utility charges roughly 17 per cent of what it costs to generate solar power. What would help, solar experts say, is a "feed-in tariff" such as in Germany, which requires utilities to buy power from solar producers at a premium to what they pay power plants that use hydrocarbons.

Still, various studies over the past 20 years from Egypt, Saudi Arabia and more recently from the Petroleum Institute have established a link between dust build-up and reduced solar performance. The Petroleum Institute students are not the only ones seeking a solution. Ridha Azaiz, a student in Stuttgart , Germany, set out 10 years ago to solve the dust problem by building a roving robot he dubbed Wallwalker. Wallwalker moves across solar panel arrays, cleaning as it goes. After years of refinements, Mr Azaiz has managed to reduce the robot's weight to just 3kg and moved to Berlin recently to launch a joint venture that will begin marketing it. "We calculated that using Wallwalker is very much cheaper than workmen," he said.

In the meantime, Ms el Chaar's students at the Petroleum Institute are ploughing ahead with solutions of their own, driven in part by a different, but equally grimy problem. The Abu Dhabi Marine Operating Company (ADMA-OPCO) uses solar panels to control equipment on its offshore oil rigs. Dust is an issue. But a bigger nuisance are the droppings left by seabirds. To clean them, ADMA has to send crews to each of its 50-odd wellheads by helicopter.

ADMA donated some solar panels to the Petroleum Institute hoping that they could crack the problem. The result: electronic cleaning mechanisms that automatically clean the panels while shooing away seabirds. One group of Ms el Chaar's students has come up with a Dh3,000 system that uses a rolling sponge to clean off the panels twice a day using water stored in a tank below them. To ward off birds, they devised a motion sensor that sets off a bone-chilling alarm. The team has yet to try it on real birds, but claims it does the trick on humans. "Until now, we're scared by it," says Mohammed Abdul Gallel, the 21-year-old team leader.

A second team produced a more elegant solution using a combination wiper blade and brush controlled by a simple $5 microchip. "You can't imagine how much you can do with this chip," says Eisa al Qubaisi, 22, as he showed off the team's design. The wiper brush cleans the panels twice a day, and swipes the panel again if alighting seabirds trigger its motion sensor. Perhaps most ingeniously, the system will use solar power to pump cleaning water up from the sea and then use the sun's heat to distil it before use.

Now Ms el Chaar says the students are working to combine the best of their projects for ADMA to begin testing their system in the field, using both a sponge and a wiper, the frightening alarm and the solar distiller. "ADMA really likes this because they don't have to worry about the water," she says. "Everything is automatic." [e-mail]