Monday, October 29, 2012

Microwaves: Useful For Your Leftovers and Solar Energy

Posted By on Mon, Oct 29, 2012 at 9:08 AM

The appliance that heats your day-old Chinese food could hold the key to making solar energy mainstream. Engineers at Oregon State University have applied microwave heating to solar energy technology in a way that could lead to a manufacturing process that uses less energy and fewer resources.

The engineers opted for microwave heating—as opposed to conventional heating in an oven—to reduce the time it takes materials to bond into a working solar cell. While the reaction time with conventional heating can be anywhere from 30 minutes to 15 hours, microwave heating can achieve the same results in minutes or seconds, said head researcher Greg Herman.

This innovative approach, paired with a compound of non-toxic elements, enabled the OSU engineers to create thin-film photovoltaic products that turn sunlight into power.

The elements used to make the compound—copper, zinc, tin and sulfur—aren’t harmful to humans. That’s noteworthy, said Herman, an associate professor at OSU, because “a lot of what’s used [in solar technology] isn’t benign.”

Cost effectiveness is another plus to this research. Developing solar technology can become an expensive endeavor, especially when using pricey elements such as indium and gallium. In this case, however, all the components used are “viewed as low cost, very abundant materials,” Herman said.

And where will this discovery lead? Although there are many ways to construct solar cells, Herman said the thin-film photovoltaic method that he and his team opted for is promising largely because it’s cost-effective. Major companies such as IBM have already voiced their interest in using similar technology, Herman said.

In the thin-film method, tiny layers of photovoltaic material are placed on substrates, such as plastic or glass. This technique requires fewer resources than using crystalline silicon, the traditional method of constructing solar cells, Herman said.

Although this is a positive step, the efficiency of solar technology still needs improvement in the industry as a whole, said Dr. Richard Powell, professor emeritus of optical sciences and materials science at the University of Arizona. Efficiency refers to the percentage of solar energy harnessed that can be converted into usable energy.

Developing solar energy technology today is a Catch-22 scenario where a benefit comes at the expense of something else. The OSU engineers reduced manufacturing costs, for example, but the tradeoff was less efficient solar devices. Upping the efficiency, however, is not a cheap undertaking, Powell said.

Despite the fact that the OSU researchers didn’t significantly improve the efficiency of solar cells, their methods were inexpensive. Using microwave heating was also a new twist, Powell said.

As society advances, the demand for clean energy increases every day. To make solar energy attractive to businesses and industries, the materials and manufacturing process must be less harmful to the environment and produce less waste, Herman said.

But making technology affordable—a goal of Herman and his team—is also crucial. “You have to drive down the cost for it to work on a commercial level,” Herman said.

At the moment, Powell said, it’s still cheaper to burn fossil fuels than it is to produce solar energy. For this reason, Herman said, renewable energy needs to be an important part of any national or international energy policy.

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