Nebraska's Solar Potential Bright

By Gabriel Medina

Even though Nebraska has long winters, the sun shines brightly many days a year, which means that solar energy could be a good source of energy in the near future, according to Natale Ianno, who is Blackman Lederer professor in the UNL Department of Electrical Engineering.

"There's a lot of use for solar cells in Nebraska," he said. "We get 250-some days of sun a year here. When you start to rank locations with respect to their availability to solar energy, Nebraska falls into the group 2, which is right below places like Arizona and Hawaii."

Ianno, who is working with his colleagues to create solar cells out of new materials, said that Nebraska farmers could be self-sufficient if they would install solar cells in the roofs of cow feed lots.

"For example, there is a farm in eastern Nebraska where there are cow feedlots and they make ethanol," he said. "They developed a way to convert the remainder of the corn, coupled with algae and cow manure into methane, which then they use to power their ethanol plant. If they'd put solar cells on the roof of their cattle feedlots, they'd be much closer to taking no energy off the grid to generate ethanol."

Ianno said that within the next 20 to 30 years, solar energy will be used much more to provide electrical power generation in the United States. He envisions that in the future there will be more cars with solar cells on the roof, which will control the air conditioner and recharge the battery.

Ianno also believes there will be more houses and even entire residential neighborhoods where electricity will come completely from solar cells. Ianno explained that solar cells will also be more present in space exploration, because it is not practical to use fossil fuels in space and it is difficult to refuel ships or bases whenever it is required.

"Solar cell satellites are an absolutely wonderful thing," he said. "GPS, DirecTV, Satellite TV, all of those things are direct results of solar-cell-powered satellites. So that's a tremendous societal impact."

According to Ianno, the U.S. Army and the Department of Defense are also developing tents covered with solar cells.

"It's excellent in the desert battlefield," he said. "It can power fans, can power recharge of radios and even of soldiers' iPods."

Ianno said these tents with solar cells could even save soldiers' lives because many casualties occur when convoys transport fuel and they are ambushed. So if bases would use solar energy instead of fossil fuels for their needs, those deaths could be avoided.

Solar energy has not been used more frequently in the U.S. because it is still very expensive to produce solar cells and there is an abundance of other useful materials, according to Ianno.

"Natural gas and coal for generating electricity, that's really what solar energy is competing with," he said, "and that's just still very cost-effective."

Ianno pointed out that the U.S. has many decades of coal reserves, as well as natural gas and fossil fuels, so that is one of the reasons why there is not so much investment in solar energy. On the other hand, he said that Europe and Japan don't have an abundance of these materials, so that is why
they rely more on nuclear power and they are investing more in solar energy than does the United States.

Solar Energy and the Environment
Solar energy has many advantages over other kinds of energy, among them that it does not damage the environment, said Ianno.

"The operation of the solar cell is zero environmental impact," he said. "It's pollution free, there is nothing generated by it. There is no gas, no solid waste, nothing."

However, Ianno said that manufacturing solar cells does pollute if they are made with cadmium. That is one of the reasons why he and his team are developing solar cells made of environmentally-friendly materials.

To avoid pollution, when the solar cells' useful lifetime is over, companies that produce them buy them back to recycle them, reuse them or dispose of the materials, according to Ianno.

Solar energy also is safe, unless an external source causes a fire.

"There's no physical or chemical reactions involved in solar energy that make it any kind of a threat to catch on fire, to explode or to release hazardous gases into the environment," Ianno said.

New Development of Solar Technology
Most of the solar cells available in the market have a conversion efficiency of about 20 percent, but Ianno said that the solar cells used in satellites have a conversion efficiency between 30 and 40 percent.

Currently, solar cells are made of materials like cadmium, which is not environmentally friendly, as well as indium, tellurium and gallium, but the supply of those resources will only last about 30 more years, according to Ianno.

For that reason, Ianno and his colleagues are working to develop solar cells made of sulfur and iron, which are plentiful and environmentally-friendly materials.

"Both of those things exist in the earth's crust in general, so they're everywhere," he said. "The challenge is to be able to make a solar structure device that actually has enough efficiency to make it worthwhile to market and to use."

However, Ianno said "sulfur is extremely corrosive and reactive and so you have to deal with that and that presents a set of technological issues that you have to overcome or you can't even make the solar cell."

Ianno and his team are working with new materials- that won't be corroded by sulfur- to build a thin, atomic monolayer of cost-effective substrate in order to develop a cost-competitive and efficient solar cell.

"We want a thin layer of substrate because the iron sulfide needs to be in contact with a metal in order to provide good electrical conductivity for the current and so the solar cell efficiency is high," he explained.

Ianno said this is an extremely complex task, so to develop this new kind of solar cell could take him and his team between 10 and 20 years.

But to achieve that increase in efficiency is a very expensive and complicated process, according to Ianno. He explained that a solar cell converts light energy of the sun into electrical energy.

"The light is absorbed by the solar cell and the photon, which is light energy, is converted into an electron or electronic energy."

Multidisciplinary Research and Funding
UNL's Department of Electrical Engineering is developing solar cells with the Department of Chemistry at the University of Nebraska-Kearney, in a project funded by the Department of Energy, according to Ianno.

Ianno and his colleagues have sent solar cell samples to the Institute of Energy Conversion at the University of Delaware, because they have more facilities than UNL.

In April 2011 the National Science Foundation released a call for proposals in their international research program, which will focus on sustainable energy. So, Ianno and his team will work with the Czech Academy of Sciences in Prague to apply for that program.

Ianno's work with solar cells is funded by the Department of Energy, the Nebraska Center for Energy Science and the Nebraska Research Initiative


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