Opening the Window for Solar Power

By using windows as solar panels, city buildings will be able to produce most of the electricity they need. Source: Lofty

We now know that burning fossil fuels is causing big changes in the climate. To limit the damage caused by our energy intensive lifestyles we need to look for alternative ways to generate electricity. Solar power is just one of the many ‘green’ energy sources, but it requires a large area for collecting the sun’s rays. A skyscraper in the city doesn’t have much space for roof-top solar panels but they do have a lot of window space. These windows could be used for energy production thanks to a new innovation in solar technology.

While traditional solar panels are made using silicon, a group from Flinders University in South Australia are producing solar cells using carbon nanotubes. As the name suggests, carbon nanotubes are made from carbon atoms arranged in a tubular shape. They’re also ridiculously small with widths approximately 10 000 times thinner than a human hair and lengths between a nanometre (one billionth of a metre) and 18 centimetres.

As well as being incredibly small, they have a bunch of other properties which make them pretty darn amazing. They have the highest tensile strength of any known material (in theory, a 1mm thick cable of nanotubes could hold 6 tonnes of weight) while still being very light. They can also conduct heat and electricity, much like metal, and react in a bunch of funky ways with light and other forms of electromagnetic radiation (I’m not smart enough to explain the specifics of this).

The group from Flinders University have produced small solar cells by taking these carbon nanotubes, applying a bit of chemistry magic and then sticking them between two thin sheets of glass that are treated to help conduct electricity. The hope is that this technology could be used to turn entire windows into solar panels that turn the sun’s energy into electricity, while still letting through light.

Solar panels that use silicon require a lot of energy to make and are still only 10-20% efficient. This means it can take several years for the panel to produce the energy required to make it in the first place. Carbon nanotubes are much cheaper and easier to make and incorporating them into windows means that they don’t take up any extra space.

These solar windows could be included in existing building designs during construction or when the windows are being replaced without adding significantly to costs. While they would not be able to provide all the electricity for the building, but they would certainly reduce the use of fossil fuel generated electricity.

But before you get too excited, the carbon nanotube solar cells produced in the lab and are only 1cm² in size. The researchers will next look to expand these cells to industrial size but it will still be another 10 years before they become a commercially viable product. Until then, you’ll just have to appreciate the other benefits of your windows, like the nice view they give you of the outside world.

References:
Bissett, M., Barlow, A., Shearer, C., Quinton, J., & Shapter, J. G. (2012). Comparison of carbon nanotube modified electrodes for photovoltaic devices. Carbon, 50(7), 2431-2441. doi:10.1016/j.carbon.2012.01.065

News aricles from Science Alert and The Conversation

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