AUG 17

I actually go to WPI. I like that people are trying to find ways to harness power from any means they can, but I'm not sure about this one. I saw the same thing in a story about a place in england I believe. They were using it to heat an office building though, which seems like an OK approach too. The question is, what happens when the roads have to be repaved? In areas where their si winter, the frost cracks the road all over the place (Worcester is a prime example, the roads in this city suck). This will surely mess with the conductive tubing. In areas where there is no winter (like southern california), the road would get too hot, and the asphalt would remelt. As it is, concrete is used in some warmer climates. Also, copper must not be used, otherwise we would have vultures tearing up the roads for a few pounds of copper to recycle like they do in buildings that are not currently occupied.

And what about the urban heat island affect? Making road hold even more heat energy and having them stay hotter longer would drastically increase the urban heat island and force folks to use more power for AC. And get less rain as the heat makes systems jump over the cities (don't know if that is scientifically true, just something I have noticed living in cities). Sounds problematic to me.

When I was doing a project in Grade 10 English about the future and I focused on transportation, I was asking myself why hasn't somebody done this yet. It makes perfect sense because when the sun shines down on asphalt it does get frickin' hot but also when cars drive over it creates friction and more heat. I'm glad somebody has finally put my plan into action.

in response to the frost heaves mentioned above, a road that is built properly in new england will not have this issue, because they are suppose to be built with the base below the frost line, but rarely does a town or city do this because the upfront cost is too much, its easier to be cheap up front and have longer term expenses because nobody adds it up.

the concern on the heat island effect is valid, but i think if they do it right heat would be taken out of the road thus not allowing it to escape at night...

As long as there the heat is extracted is the crucial piece of that. Even if some is extracted, there will still be some percentage of heat loss to the air. This happens anyway, but increasing the temperature of the road would increase this effect.

The Food Monster
http://thefoodmonsterblog.blogspot.com

What kind of efficiencies are they going to get out of this, because I can't see it being high enough for its bennifits over normal solar power to matter.

It also seems like to install this technology, you would either have to tear up a current road (/parking lot) to replace it, or build a new road, so it doesn't seem like would have that wide an application.

Overall, it just doesn't sound like a practical idea.

This is an EXCELLENT idea!! I actually was just thinking about how you could turn roads and parking lots into solar collectors!
Just imagine how many square feet of roads and parking lots are in the world!!! You could get places like Walmart, Target, Kmart, Shopping Malls, etc to put these into their parking lots!



@Jeff Court
Don't be such a naysayer. There are thousands of brilliant scientists and engineers who will work out the details and overcome minor obstacles such as the ones you mention. I believe this is possibly one of the best renewable energy ideas I have seen in a long time.

And to the guy who wrote:
"And what about the urban heat island affect? Making road hold even more heat energy and having them stay hotter longer would drastically increase the urban heat island and force folks to use more power for AC"

HELLO?? Did you miss the whole heat exchanger part?? Who cares if they increase the heat capacity of the road, they are EXTRACTING it via the copper pipes (or most likely a cheaper, more efficient heat exchanging processes).

In fact they could probably use some type of thermocouple to directly create electricity from the heat!

I think it would probably be better to simply retrofit highways and roads in hot places, and not remove the reflective properties of the road. A simple malfunction in the heat extraction system and you've got cars melting into the ashphalt in carparks.

Solar energy is taking over the energy sector. The idea is catchy but I would repeat what other commenters said; heat island effect is an issue.
http://www.socialbridges.org/

I don't see the heat island effect as being that big of a problem, mainly because the roads in big cities don't see much light anyway because they're always covered in cars, or in the shadows of large buildings (although it is a reason why this would be a good idea in some urban areas).

And in the long open stretches of road in the dessert where this process would be most efficient, there aren't many buildings nearby that could utilise it.

The heat island effect may not be such an issue, since the whole point of this is to transfer as much heat out of the pavement as possible (like a liquid cooled road) in order to generate power.

As long as the heat island effect doesn't become an issue (which I think Yoshi makes a good point about it not) this is brilliant. The heat of the asphalt is one reason I hate driving or being on strip mall wastelands, so if we can put that to work it would be a beautiful thing. Go WPI.

There needs to be more safety/collateral testing done, of course, but also there's a big question about the ROI involved in tearing up road and installing piping, then repaving the road with the altered material. The permits involved coupled with the intensive labor cost and co-ordination with the DoT could make the sunk cost relative to the payback rate less than concentrated PV or traditional solar thermal. Definetly worth the research, but if I were a VC I wouldn't fund a start-up based on this because the unknowns are still too profound.

In the suburbs many people have driveways. The driveway is necessarily close to the house. This may be an alternative to solar collectors on a roof, as not all roofs are suitable for solar collectors (e.g. shading, direction, permits). A residential driveway has less stress than a road (no heavy traffic), and is close to potential heat sinks like domestic hot water and pools.

Indeed I've been looking at this myself for quite some time now.

I wouldn't attempt it until my driveway needs resurfacing anyway which will be quite some time.

Also I would not likely use copper because of cost and would need a way to ensure it is not crushed if close to the surface.

Regarding practicality arguments...
I think it would be ideal for roads that need replacing and new roads. This may only be a small % of roads, but all roads need to be replaced eventually.

They'd learn from the roads that have been modified, efficiency will likely go up.

If it adds a considerable cost to the road, it should be considered how long it can make electricity and how much it can make. Maybe it'll take 10 years to pay itself off (for the first few generations), but it could still be a good investment (in the very least a good thing to try).

Desert roads could export their electricity.

Hasn't asphalt already been perfected to maximize traction, and tire life? A hotter blacktop would result in excessive tire wear. What they should be looking at is the same technology on rooftops to help heat homes. There is still the problem of areas that have very cold winter.

What about my tires?
Are tires going to start to melt on these roads?
Will this increase the wear and tear on my tires?

Sure the person extracting energy via the extra heat, has something to gain, but how about the extra cost on the wear and tear on the drivers traveling these roads?

I just wanted to add to the pros that... in cities with winter, the increased heat in the roads would likely melt falling snow, as a result reducing the number of necessary snow plows and therefore excess pollution.
right?

This is not new, numerous tests have already been done in the Netherlands using asphalt and using the warmth of summer for the de-icing of the road in wintertime (thus storing the warmth underground) but also to warm houses near the road. Possibilities are endless.

How about the negative effect on tires? Hotter pavement isn't going to be good for the tires/traction.

I don't think the road will get significantly hotter, because although they're absorbing more energy from the sun, they are also transmitting this additional energy away through the copper wiring/piping (or other material with good thermal conductivity).
At least that's the theory, it could easily go either way, not transmitting enough heat, so the roads get hotter, and tires don't last as long, or even transmitting more heat, so the roads will actually be cooler, and tires will last longer.

Also, to the people saying the 'heat island' effect wont happen because the heat is being transferred out of the road, well, unless they build a large heat sink or something deep underground, then the heat is still being transmitted within the city, so would still contribute to the 'heat island' effect.

These years there are invented many new technoligies to produce energy, f.i. blacklight or these new water wave tubes, single system with the only purpose to produce energy.

This street photovoltaic system might be interesting.

However, one of the first bigger probs: Who would be in charge for the administration and responsibility. Anybody likes to lose power in their working sector.

The next are investion costs. Nowadays, there is a ways to keep streets free from ice and snow with this cleaning fluid without damages of the environment by salt. I haven't seen this fluid used on a street, because one salt cellar costs appr. 150000 $ and can't be thrown away so easy.
It's not in the budget.

The same goes for streets. As long as a street has not to be totally rebuilt or is brandnew, this system will not be used as long as it's cheaper to repair the street only.

Sorry for spelling mistakes

I agree with pat. The extra heat would have negative effects on tires.

Considering the layering required, unless the actual composite material is capable of providing the desired results, durability issues are what you would have to sell me on.

Having said that, just using something durable enough on the shoulders of highways, roads, etc., could provide additional daylight power to local municipalities to reduce daylight power requirements from the grid. With a modular gridwork, local repairs can be made when necessary without too much disruption of traffic.

the hippies running across the pavement will burn their feet.

if the asphalt could give off less radiant heat by absorbing it more efficiently, they wouldn't have the problem of overheating tires and could also possibly (if the heat absorption rate is really godly good) take heat out of the atmosphere or at the very least make a cooler asphalt.

Heat Island issue:
if the amount of energy that hits a square foot of land from the sun is the same (energy collecting device or no energy collecting device) then a device which is holding the heat more will not cause a heat island effect. note that the heat island efect is caused by the release of the heat from the road when it should be cool (such as at night) if the heat is being contained then the heat island problem could actually be fixed with this idea.

but I'm not a physicist, i only know a small amount about the conservation of energy (in this case heat energy)

┌█┘ i win.

I'm not concerned about heat issues. The design of the system is to absorb heat, after all. I am concerned with maintenance issues. Roads tend to get well garbled over time, and I have a hard time imagining that pipes running underneath the asphalt will not be extraordinarily difficult to maintain and replace.

There is a company in the UK called http://www.icax.co.uk that specialise in this. So far they have used this in a school and a motorway service station to great effect.

An interesting thought though, if the roads are making money for the city/state by generating electricity it would help pay for the roads. no more tolls?

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The deserts of the south western part of the U.S.A. are our richest natural resource. Heat from the highways here can boil water midday. Turn that heat into steam, then electricity, and you have free power for as long as the sun shines. When America begins to feel the crunch of an oil starved world, and these ideas become cost-effective, this idea and many more ideas that are being kept secret right now will be used to replace the high priced black gold. Until the price of oil forces things to change the status Quo rules, big V-8 gas guzzlers, oil heating of homes, rich Arabs, and overtaxed little guys!

Roads might be impractical but imagine a parking lot. A parking lot might potentially be able to power the businesses it supports during normal business hours.

Re: "...the hippies running across the pavement will burn their feet." 8)

Thought about doing the same thing to heat my pool when I built my house in Florida, but couldn't because I was at the code limit for impermiable surface. Where I live, driveways are shell or gravel for this reason.

Copper's conductivity advantage can be overcome by using more surface area of rigid plastic pipe, say every 4 inches for plastic vs every 8 inches for copper.

There are other problems. I areas with sub freezing temps, you can't use water. It will freeze and expand destroying the both the piping and the roadbed. Also you have to find an ecomomic way to convert it to usable energy. There isn't much heat potential in 160 degree water when ambient air is 90. Could be used for home heating supplement in the winter or for heating pools in subtropical areas.

When someone develops an inexpensive means to extract energy/electricity from 70 F heat differential then you're a go.

Will road heat exchangers ever replace our power grid? No. But the best idea for long term energy seems to be a balanced approach that uses many different technologies where appropriate and cost effective.

Say this system pans out (they seem to be very far from a real world ready system). You deploy it gradually as roads get built and repaired to keep capital costs manageable. It wouldn't replace power plants but if you could simply take all the street lights off the power grid it would make a difference.

Will it pan out? Maybe not. But it's good to see people researching new ideas.

develop PV panels that can act as a road suface?

There are a couple of misconceptions that need to be eliminated here:

1. There is no heat problem: In the finished road, the heat is carried away to make electricity. It's only for testing that the researchers are trying to make the roads hot. When the roads are used, they will be cooled to make electricity. Unlike a normal road, with these roads you can adjust their temperature. If you pump the coolant through faster, the road cools down. If you pump the coolant through slower, the roads heat back up. Normal asphalt is just hot: these roads can be cooled down.

2. There is no heat island effect. The same amount of energy strikes all land equally, but white surfaces reflect most of that energy away. Asphalt, however, absorbs the energy and turns it into heat, creating a heat island effect. However, in these roads, the energy is pumped away, keeping the road cool. The end result is the same as if these roads were white. It's true that the energy is being used in the city nearby, which releases the heat again. But this heat would have been released anyway. By using the heat from the roads, you don't need to use more heat from coal. This reduces the total heat in the city. These roads actually help keep us cool.

3. It's expensive to replace roads. However, there are many roads each year that are worn out and will be replaced anyway. These are the roads that we can convert for energy production. To convert a road, you simply need to spread or spray a reflective coating. Then lay down a series of pipes above the coating and pour ordinary asphalt mixed with some quartzite over the top. Now you can finish the road surface. Depending on the materials used in the final plan, this could be very inexpensive and produce a great amount of energy.

All right, those were the main confusions that kept coming up.

Most of the other concerns were real:

People could dig up roads if we use something valuable like copper in the heat exchanger. For many reasons, the heat exchanger needs to be cheap.

Normal wear and tear on the road could crack or damage the heat exchanger. How expensive will it be to repair?

But why not simply lay photovoltaic panels instead?

Here's my response:

* Solar panels would cost more than laying pipes during construction, and probably wouldn't be as durable as a finished asphalt road surface.

* When there are cars on the road, the cars would block out the sun and interfere with solar collectors. This is true of heat exchangers as well, but they can absorb heat from any source, including the heat from the air, from car engines, and the heat generated by cars moving over the asphalt.

* Depending on the materials used, it could be more environmentally friendly to lay pipes. Some very toxic chemicals are created in manufacturing solar panels.

The best idea I've seen for using solar panels is to first concentrate as much sunlight as possible onto a small area and then use an extremely efficient solar collector for that small area.

However, there are limits to how efficient it can be. Solar collectors waste most of the energy they receive (somewhere around 75% is lost). Later, more energy is lost when converting the electricity to heat, and it's difficult to store large amounts of electricity for when you need it.

On the other hand, it's far more efficient to convert sunlight into heat directly. (You know how fast cars heat up in the sun.) And it's comparatively easy to store heat. A thermos tank can keep water hot for a long time. The heat can be used directly for hot water or to heat houses. The extra heat can be converted to electricity.

However, each conversion wastes some of the energy available. If you only need electricity, but not heat, other more direct ways of generating electricity might be the most efficient. But even so, thermal exchanger roads could still be worth having if they're cheap compared to the alternatives.

Solar panels on the road itself wouldn't work. This is because rubber, dirt and other debris would tarnish the surface and block the light. The roads would have to be scrubbed clean constantly and the efficiency of the solar panels would probably decrease more quickly than normal solar panels. Also, large overloaded trucks would probably damage the top layer of asphalt and solar panels/cells/whatever over time.

I like the idea of putting down piping under the roads to collect the heat energy. But how much energy would be needed to circulate the fluid inside the pipes? I don't like the idea of storing the energy for later since energy and thus efficiency would be lost in this process. It would seem more logical to pump the energy immediately into the existing electric grid. Maybe we should instead install metal plates a few inches below the asphalt to transfer the heat to small sterling engine stations alongside the road. These engines could produce electricity and would be connected to the power lines near by.

The ultimate solution with solar technology would be to convert both photon energy and heat energy into electricity at the same time. Photovoltaics and sterling engine technology needs to be combined in order to achieve a higher combined efficiency. But I'm getting off the subject.