Plugging into the sun: Masdar's solar dream

Masdar City, on the southern coast of the United Arab Emirates (UAE), which the institute is part of, is an eco-city built on a large scale and primarily powered by Shams 1, one of the largest concentrated solar power plants in the Middle East. The plant is contributing to Abu Dhabi’s goal of raising its renewable energy power generation to seven percent by 2020. 

Sand and dust are a major impediment to optimal use of the sun’s energy in the country. In 2012, Masdar Institute launched the Research Center for Renewable Energy Mapping and Assessment to analyze the emirates’ solar and wind energy resources. The resulting UAE Solar Atlas showed that the attenuation and scattering of solar irradiation caused by airborne dust means that the country’s direct normal irradiance (DNI), a measure of solar radiation, is significantly less than that of Spain and some southern states in the US, for example. Satellite data using a conventional model employed by other countries had previously overestimated the UAE’s DNI by 15%.

“Having an accurate understanding of your available solar resources is the first step in deciding which kind of technology to go with,” explains Matteo Chiesa, associate professor of materials science and engineering and head of the Laboratory for Energy and Nanoscience at Masdar Institute. Shams 1, which became operational in early 2013, was designed around this new data. 

Masdar Institute is currently producing a similar atlas for Saudi Arabia based on the methodology used for the UAE Solar Atlas, says Chiesa, who is originally from Norway.

His lab is involved in several solar energy research projects. 

The accumulation of dust on solar panels affects their efficiency so Chiesa is investigating the incorporation of aluminum nanoparticles into special coatings for solar panels that will give them a “self-cleaning” property. By applying the coating, water droplets accumulating on the panels gather dust and, due to the hydrophobic property of the coating, attempt to run off the panel, thus cleaning it. 

Because the UAE is near the equator, however, solar panels lie horizontally, compared to northern countries where they are placed at an angle to catch the sun’s rays. This makes it difficult for the water droplets to slide off the panels in the UAE. Chiesa is testing the application of an electric field to the panels, a method called electrowetting, to help the sand-collecting water droplets slide off. 

The electrowetting behavior of liquids was described as early as the late 1800s. But the term was first coined in 1981. Chiesa says the choice to use electrowetting must be weighed up very carefully in terms of cost and energy use.

He explains that most companies in the UAE employ people to wash solar panels with water – at a relatively low cost. “So these are issues that, as a researcher, I am struggling with,” he says.

Ammar Nayfeh, associate professor of electrical engineering and computer science and head of the Nano Electronics and Photonics Lab at Masdar Institute is investigating ways to make solar panels more efficient. Along with counterparts at the Massachusetts Institute of Technology (MIT), Nayfeh’s team is working on incorporating germanium into silicon-based solar cells to boost their efficiency. 

“The fundamental base of the solar cell is called the p-n junction which is based on silicon material,” explains Nayfeh. Silicon, he says, can only make use of part of the sun’s spectrum. As a result, solar cells are not as efficient in using the sun’s energy as they could be. Nayfeh says his team has developed what he calls a novel idea to combine silicon with germanium, allowing cells to use more of the electromagnetic spectrum and thus become more efficient.

“Right now it’s all theoretical in the sense that we haven’t done the full fabrication of the ultimate [hybrid solar cell]. We’ve done steps of it now…and hopefully we’re going to get the result we get in the simulation,” he says.

Nayfeh’s team is also investigating how gold nanoparticles in various sizes reduce the reflectivity of solar cell surfaces, thus increasing the amount of light that enters them. Their recently-published study showed that a larger nanoparticle size reduced reflectivity from about 23% to 18%.

Samuele Lilliu, an Italian post-doctoral micro-systems engineering researcher,  established Masdar OPV, the first laboratory for organic electronics in the UAE. 

In collaboration with the University of Sheffield, the University of Cardiff, and New York University Abu Dhabi, Lilliu’s team is studying a new class of materials for solar cells called organic-inorganic lead halide perovskites. 

“Perovskite solar cells are very interesting because, in less than five years, the efficiency of these devices jumped from 3.8% to about 19.3%. This never happened in solar cell research,” he says.

Our objective is to understand the link between the morphological and structural properties at the nanoscale and the macroscopic opto-electrical properties of the devices.

“Our objective is to understand the link between the morphological and structural properties at the nanoscale and the macroscopic opto-electrical properties of the devices. This will help us achieve a better understanding of the physics behind the fabrication processes, as well as new ways to improve the efficiency of solar cells,” he says.

They are using grazing incidence x-ray diffraction to understand how crystals in treated solar cells are oriented at the nanoscale, whether they are oriented parallel or perpendicular to the substrate, or if they organize in some other way. They also analyze the degree of crystallinity of the materials. Once this is done, the team will try to correlate the type of treatment they use on cells with the way it affects their structural and macroscale properties. This will allow them to assess their efficiency.

Much of this work is being done at the European Synchrotron Radiation Facility in Grenoble, France. Lilliu’s synchrotron work on perovskites has turned up some interesting results that he hopes to publish soon.

Masdar offers its researchers unsurpassed opportunity to decide what research they want to be involved in and access to funding for their projects. 

“Compared to Europe, where you’ll find harsh competition and complex procedures for accessing research funds, here it’s relatively easy to access research funds and collaborate with companies,” says Lilliu. 

However, Lilliu says, the center of research activities in his field are still concentrated in Europe and the USA. He hopes that in the next few decades, researchers will play a role in creating a shift towards the Middle East. “For example, there aren’t synchrotrons in the region, which means that we need to travel often for our research, and sometimes it might take a while to get supplies from Europe and the US.”

There is “reluctance” from peer-reviewed journals to consider papers coming from the Middle East, Chiesa says. This reluctance, in his opinion, is justified in many cases, he says, due to the general lack of scientific tradition in the region. Masdar, Chiesa explains, has taken the route of employing younger researchers who build their laboratories and research projects from scratch. This provides them with tremendous opportunity. The downside, however, is that they cannot leverage the names of better-known scientists or of a well-established institution to get their research recognized. 

In addition, Nayfeh says one of the challenges is creating a culture of entrepreneurship. “In Silicon valley, that is the norm, right? You do research and you make a company and if it fails it fails, if it doesn’t it doesn’t,” Nayfeh explains. “Here they don’t have that attitude. There’s no such thing as failure, so everything has to succeed. That’s kind of our big goal here. Students come, they graduate, they make companies, and they drive the economy to move from an oil-based economy to more of a knowledge-based/research-based economy,” he says. “It takes time.”

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