Asphalt is very dark in color and therefore absorbs most of the sun's energy as heat. If you've every tried to walk barefoot on a hot summer's day across blacktop you can certainly testify to the thermal energy present.

I saw another post recently that proposed making roads out of photovoltaic cells. I think this is a step in the right direction, but the cost of production, the low efficiency, the frailness of the devices, and the need for direct exposure to the sun's electromagnetic waves is very constraining.

So I propose to use Peltier devices, or the Seebeck effect to be more specific, to generate power by using the temperature differential between the asphalt of the roadway and the underlying bedrock/clay.

You've probably heard about peltier devices and know that they are usually made of n-type and p-type silicon. This makes them costly. But with the vast amount of roadways in the US alone, efficiency could take a hit by a factor of 10 or more from the commercials peltier devices sold, and still generate enough energy to be comparable to today's US power consumption.

I imagine with a little research by materials scientists, we could come up with an environmentally friendly, inexpensive, and large-scale peltier device for use underneath the roads of the future.

Power to the people!

I've included some links you can check out to learn more about the Peltier, Seebeck, and Thompson thermoelectic effects. :) enjoy.
-- kumpf, Oct 04 2005

Intro to Thermoelectricity http://www.chem.cor...3/thermo/intro.html
[kumpf, Oct 04 2005]

The Science Behind Thermoelectrics http://www.its.calt...cs/science_page.htm
[kumpf, Oct 04 2005]

Some Common Seebeck Coefficients http://www.efunda.c.../thmcple_theory.cfm
[kumpf, Oct 04 2005]

Info on Commercial Peltier Devices http://www.tetech.com/techinfo/
[kumpf, Oct 04 2005]

The Peltier / Seebeck Effect http://www.answers....tier-seebeck-effect
[kumpf, Oct 04 2005]

I don't think thermoelectrics will handle the stress of the road traffic.
-- Madai, Oct 04 2005


The top and bottom layers would be made of metal, which could hold up to the stresses of traffic with no problem. The center layer would probably be made of something similar in nature to sand or hard plastic... That's up to the materials science people that know a lot more about that than I do. However, some poking around at different sites suggested that all you really need is low electrical resistivity and high thermal resistivity. There's got to be a few materials out there that fit that bill. :) I hope.. :)
-- kumpf, Oct 04 2005


The energy conversion efficiency of a peltier unit is quite low, and with relatively low temperature differential, the power produced per sq ft of roadway will be minimal. Not enough to be cost effective.

Also, the reason roads are made of asphalt and concrete is because these materials are durable and cheap. A peltier device is neither.
-- RunVentura, Oct 04 2006


Not to mention the bonus effect of instant heat to melt off ice and snow, just by reverse feeding in current.
-- neelandan, Mar 22 2011



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