Just an idea that occurred to me during a conversation today. Solar energy is becoming pretty trendy these days, and it seems to be that with how hot roads get, they are basically solar panels. Admittedly thermal rather than electric, but would it somehow be possible to turn this heat into electricity? It seems to be a rather vast untapped resource if so.
Its complex, and expensive, but a great idea. I’ve thought it before.
The only way to do it is to use a thermal cycle with a refrigerant. You need to embed a heat exchanger (tubes) in the road. They need to be able to withstand temperatures, thermal flexing, salt, mechanical loading from cars. There are some issues to overcome.
If you use the right medium it undergoes a phase-change at the operating temperature of a road, that sucks up a TON of energy. You pump in a liquid, pump out a gas. With hot gas you can either run it through some sort of generator, or use it to heat something else up then run the something else through a generator.
So you might think of putting fins on the coils and making them more like long lines. Here in Phoenix AZ the hot summer sun only radiates 1kw/sq-meter. You can compute from the radiation coefficient and the temperature of the pavement what part of that is re-radiated away. Its likely significant. Bottom line: to get meaningful power you must have large area of pavement soaking up light.
There is a good book in thermal system design by Boehme from the 1980′s. You could find it, check it out using inter-library loan, and then put the idea as something in a science fair. If someone likes it, they could support your work, if not you can still earn glory and scholarships. A good heat transfer text would also do you pretty well.
Yes, blacktop absorbs heat. To convert heat into energy, you will have to heat a fluid like water until it turns into steam, and steam can drive an electric generator. This is not working with hot roads. Solar panels are more efficient. Or look up what a heat pump is. That may do very little. If you cannot afford solar panels to generate electricity, you can use the sun to heat up water which you can then use for showers or washing. But to get that heat from roadbeds may not be so efficient.
Keep thinking, though. Your next idea may be a very good one!
References :
Its complex, and expensive, but a great idea. I’ve thought it before.
The only way to do it is to use a thermal cycle with a refrigerant. You need to embed a heat exchanger (tubes) in the road. They need to be able to withstand temperatures, thermal flexing, salt, mechanical loading from cars. There are some issues to overcome.
If you use the right medium it undergoes a phase-change at the operating temperature of a road, that sucks up a TON of energy. You pump in a liquid, pump out a gas. With hot gas you can either run it through some sort of generator, or use it to heat something else up then run the something else through a generator.
So you might think of putting fins on the coils and making them more like long lines. Here in Phoenix AZ the hot summer sun only radiates 1kw/sq-meter. You can compute from the radiation coefficient and the temperature of the pavement what part of that is re-radiated away. Its likely significant. Bottom line: to get meaningful power you must have large area of pavement soaking up light.
There is a good book in thermal system design by Boehme from the 1980′s. You could find it, check it out using inter-library loan, and then put the idea as something in a science fair. If someone likes it, they could support your work, if not you can still earn glory and scholarships. A good heat transfer text would also do you pretty well.
References :
Bachelor of Science in Mechanical Engineering.