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Power Science Technology

Use of Asphalt Paved Surfaces For Solar Heat 110

vg30e writes "It seems that a company in the Netherlands has found a way to use asphalt paved surfaces as solar heat collectors. Flexible tubes under the surface of the road collect heat from asphalt pavement using water as the working liquid. The heated water is stored underground for later use in defrosting the road, or heating buildings. With all the miles of highway in the continental US, this might be a viable way of collecting massive amounts of thermal energy."
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Use of Asphalt Paved Surfaces For Solar Heat

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  • by LWolenczak ( 10527 ) <julia@evilcow.org> on Tuesday January 01, 2008 @07:26PM (#21877648) Homepage Journal
    This could help reduce the overall temperature of blacktop services... which have this side effect in very hot summers of melting.
  • by victim ( 30647 ) on Tuesday January 01, 2008 @07:37PM (#21877742)
    There is apparently a bridge in Fukui [treehugger.com] which does just this.

    Sorry for that link to Treehugger, they are a black hole of links and I would not normally link, but they had the best English language article I could find in 3 seconds of googling.
  • by Anonymous Coward on Tuesday January 01, 2008 @07:49PM (#21877806)
    The article talks about storing energy in ground water. It isn't such a crazy idea. We used to do that kind of thing. Until the 1950s, the conventional way to keep food cool was in an ice box. Ice would be harvested in the winter and stored in ice houses. The ice would be delivered to householders in the spring, summer and fall. It worked well but was labor intensive.

    The idea of storing heat in the summer and cold in the winter is viable technically. The capital costs are impressive though. To keep my house cool over the hot summer months would take many cubic yards of ice. The container would be very expensive but maybe not more than most people are willing to spend on an in-ground pool.

    It could work. Cheap energy allowed us to forget things we used to do. Expensive energy would cause us to bring them back. The ice box, in some form, could easily return.
  • by Anonymous Coward on Tuesday January 01, 2008 @08:31PM (#21878084)
    I use this same technique to heat my pool. When filling it up in the summer I get together all my hoses and connect them. After laying this ultra long on my driveway I simply run water slowly though it from the tap into the pool. The water heats as it travels the hose and by the time it gets to the pool its actually quite warm.
  • by LloydPickering ( 1211110 ) on Wednesday January 02, 2008 @06:28AM (#21880756) Homepage
    I work for a company in the UK who installs road energy systems. Figured I'd finally register a slashdot account to respond to this article after lurking around for so long.

    Here's a link to our supplier's page with installation photos for those curious. http://www.invisibleheating.co.uk/photos-of-asc-installation-g.asp [invisibleheating.co.uk]

    The pipes are filled with anti-freeze rather than water. We use a vegetable based anti-freeze because of it's non toxicity should it leak.

    The system is divided into zones, or sections which converge to a manifold. Each zone can be turned off individually, so if someone does damage a section of pipe, it can be turned off without affecting the rest of the system. Anyone who has underfloor heating should have this in place too.

    We combine the system with geothermal heating and cooling using boreholes. In the summer excess heat from the building, and from the road is 'dumped' into the boreholes raising the average temperature of the local ground. In the winter we abstract the stored heat which then lowers the temperature back down. The entire system is 'closed loop'. We don't touch the groundwater itself at all, although we do also install open loop geothermal systems.

    Inside the building is a heat pump, which (as stated above) works like a fridge, but in reverse. Its basically just a Copeland compressor. It takes in large quantities of water at ground temperature, say 12 degrees C, and compresses that heat into a tank of water (heating it to say 45-50 degrees C) and the water that returns to the ground will exit at something like 6-8 degrees C. Different systems are designed to work with different temperature gradients, so be aware that those are simply example numbers. The larger the difference in temperature, the more efficient the system which is where the road energy comes in. Storing the excess heat in the summer means for example the average ground temp isn't the aforementioned 12 degrees C it's 15 degrees C instead.

    A more layman style description can be made using orange squash. Imagine you have a large volume of orange squash. If you find a way to remove some of the orange dilute from the squash you end up with a weaker orange squash, and a volume of orange concentrate. The heat pump works on this idea, except with heat instead of orange squash.

    On the whole, systems are surprisingly economical for commercial customers. In the UK installing a geothermal heating system will generally have a payback period of around 5 years when compared to a natural gas boiler. The extra benefit is that you also get almost free cooling with the system whereas with a gas boiler you have to put in extra chiller units. As a final economic litmus test...we are installing a road energy and geothermal system for a small medical centre in the UK ultimately paid for by the NHS, and I'm sure even those outside the UK know the NHS is pretty frugal. ;)

  • Re:Cement (Score:3, Interesting)

    by eth1 ( 94901 ) on Wednesday January 02, 2008 @11:55AM (#21882672)
    Actually, here in TX, you could use this to *cool* the roads. The extreme heat tends to crack and buckle the concrete. You'd also get some pretty hot water (even from the light-colored concrete). It's energy, and I'm sure someone could use it!
  • by foniksonik ( 573572 ) on Wednesday January 02, 2008 @11:57AM (#21882684) Homepage Journal
    This article doesn't mention the facts I'm interested in.

    How hot does the water in the pipes get? Is it hot enough that if you swapped out alcohol for the water, the alcohol would turn to steam? (78.3 degrees C) Obviously the surface gets pretty damn hot but does that get through the asphalt into the pipes efficiently enough....

    If so has anyone thought of running a nearby stirling engine to generate actual electricity?

    My thoughts on this were that in a place like California or Nevada, where there are hundreds of thousands of miles of roadway and at least half a year of near cloudless skies, quite a bit of energy could be generated with little or no additional impact on the environment.

    If enough energy was generated you could conceivably even run some public transportation on these roads using an exposed contact system such as a recessed rail... or just run a system parallel to the roads. The cost of transporting the energy to these locations for this use would have dropped to zero thereby making them much more economical.

  • by N3Bruce ( 154308 ) <n3lsy@com c a s t .net> on Wednesday January 02, 2008 @04:08PM (#21886316) Journal
    Well, with the cost of coal [economist.com] being a fraction of the cost of oil, it might just make economic sense from a fuel cost standpoint to bring back the steam locomotives. Of course there will be problems, such as carbon and particulate emissions, boiler maintenance costs, and safety concerns (improperly managed boilers can fail catastrophically) which doomed almost all of the old steam locomotives to the scrapyards over 50 years ago.

    Although there are a fair number privately operated steam railways operating as either scenic railways or rolling museums, both in the US and Europe, the Diesel-Electric locomotive or electrified railways continue to be dominant in most of the First and Second World. The technology exists [internationalsteam.co.uk] for building a new generation of steam locomotives which would address many of the problems of their 19th and early 20th century counterparts, and do it at much greater efficiencies, but there is hardly a groundswell of activity aimed at making this a reality.

Honesty is for the most part less profitable than dishonesty. -- Plato