A team of researchers at the Massachusetts Institute of Technology has come up with a way to lower the cost of solar energy, by mimicking the same effect that enables greenhouse gases to trap heat in the Earth’s atmosphere. The new technology could eventually lead to powerful concentrated solar energy systems that don’t rely on the huge arrays of mirrors that are required in conventional systems.
Making More Solar Power without Mirrors
Instead of using mirrors, the MIT researchers fabricated a crystalline material arrayed with precisely spaced microscopic holes. Sunlight can enter the holes, but most of the radiation can’t find its way out by the same route. That’s because holes are configured in such a way that the rays must reflect back at precisely the right angle in order to escape. Think of a high-tech lobster trap of nanoscale proportions, and you’re on the right track. David L. Chandler of MIT News compares this approach to the greenhouse effect, in which radiation from the sun is admitted to the Earth’s atmosphere and is trapped there.
Many Routes to Low-Cost Solar Power
According to Chandler, the new material – called photonic crystal – could be manufactured using standard processes that are used to fabricate chips. That could give the new device a cost advantage over mirror-based technologies, which require precise optics to boost efficiency. The idea is that simplicity of manufacturing plays a key role in determining the installed cost of solar power, an approach that President Obama’s SunShot solar power initiative aims to encourage.
No Last Hurrah for Mirrors in Solar Energy
Despite the potential of the new technology, mirrors will most likely remain an important part of the low-cost solar toolkit. Another team at MIT, for example, is developing a low-cost concentrated solar system that positions mirrors on a hillside to focus sunlight downwards. That reduces the amount of pumps, piping and other complexities of conventional systems that aim
sunlight upwards, at a tower. As for optics, the aluminum giant Alcoa is working on concentrated solar systems using low-cost mirrors made of – what else – aluminum, with comes with the advantage that most of the installation could be easily recycled when it’s time for replacement.
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