Comment »Posted on Friday 15 August 2008 at 1:06 pm by Jacob Aron
In Climate Change & Environment, Yes, But When?

I love hearing about an idea so good that I can’t help but think “why hasn’t anyone though of this before?” – in this case, using hot roads to generate electricity.

Researchers at the Worcester Polytechnic Institute have been studying ways to extract energy from asphalt, a material used to cover roads which is extremely good at storing heat from the sun. They discovered that when asphalt is exposed to direct sunlight it reaches its highest temperature a few centimetres below the surface. Placing a heat exchanger (such as copper pipes filled with water) at this point would extract the maximum possible energy. The hot water could then be used “as is” for heating purposes, or sent to a generator to produce electricity.

One of the major problems with solar energy is where to put the panels. With this solution, we can effectively reuse existing land. Great Britain has over 3,300 square kilometres of road. Even if only half of this was used for electricity generation, it would be equivalent to demolishing the entire of London and using that instead. That’s quite a lot of spare land!

The building of wind farms is commonly blocked by local residents because they “spoil the view”, but no one will be able to complain about aesthetics in this case because the solar collectors would be underground. Locals would actually benefit in the case of dense urban areas as the extraction of heat cools the asphalt down, reducing the surrounding air temperatures in the process.

I think this an extremely elegant solution to the problem of energy generation – a problem that is becoming increasingly more important. One sticking point could be the question of efficiency. It’s great having all this spare energy generating land, but if it can’t produce enough energy to replace a few power plants then there isn’t much point. The WPI haven’t published any figures on the energy generated, but I will certainly be keeping an eye out for what could be a great future technology.

It could be that in 20 years time we all drive electric cars powered by the very roads that they drive on. What a great idea.

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