From the University of Rhode Island, some ideas on putting waste city heat to good use. They seem to recognize what most climate scientists don’t. There’s a lot of heat in cities.
URI researchers aim to harvest solar energy from pavement to melt ice, power streetlights, heat buildings
KINGSTON, R.I. – November 9, 2010 – The heat radiating off roadways has long been a factor in explaining why city temperatures are often considerably warmer than nearby suburban or rural areas. Now a team of engineering researchers from the University of Rhode Island is examining methods of harvesting that solar energy to melt ice, power streetlights, illuminate signs, heat buildings and potentially use it for many other purposes.
“We have mile after mile of asphalt pavement around the country, and in the summer it absorbs a great deal of heat, warming the roads up to 140 degrees or more,” said K. Wayne Lee, URI professor of civil and environmental engineering and the leader of the joint project. “If we can harvest that heat, we can use it for our daily use, save on fossil fuels, and reduce global warming.”
The URI team has identified four potential approaches, from simple to complex, and they are pursuing research projects designed to make each of them a reality.
One of the simplest ideas is to wrap flexible photovoltaic cells around the top of Jersey barriers dividing highways to provide electricity to power streetlights and illuminate road signs. The photovoltaic cells could also be embedded in the roadway between the Jersey barrier and the adjacent rumble strip.
“This is a project that could be implemented today because the technology already exists,” said Lee. “Since the new generation of solar cells are so flexible, they can be installed so that regardless of the angle of the sun, it will be shining on the cells and generating electricity. A pilot program is progressing for the lamps outside Bliss Hall on campus.”
Another practical approach to harvesting solar energy from pavement is to embed water filled pipes beneath the asphalt and allow the sun to warm the water. The heated water could then be piped beneath bridge decks to melt accumulated ice on the surface and reduce the need for road salt. The water could also be piped to nearby buildings to satisfy heating or hot water needs, similar to geothermal heat pumps. It could even be converted to steam to turn a turbine in a small, traditional power plant.
Graduate student Andrew Correia has built a prototype of such a system in a URI laboratory to evaluate its effectiveness, thanks to funding from the Korea Institute for Construction Technology. By testing different asphalt mixes and various pipe systems, he hopes to demonstrate that the technology can work in a real world setting.
“One property of asphalt is that it retains heat really well,” he said, “so even after the sun goes down the asphalt and the water in the pipes stays warm. My tests showed that during some circumstances, the water even gets hotter than the asphalt.”
A third alternative uses a thermo-electric effect to generate a small but usable amount of electricity. When two types of semiconductors are connected to form a circuit linking a hot and a cold spot, there is a small amount of electricity generated in the circuit.
URI Chemistry Professor Sze Yang believes that thermo-electric materials could be embedded in the roadway at different depths – or some could be in sunny areas and others in shade – and the difference in temperature between the materials would generate an electric current. With many of these systems installed in parallel, enough electricity could be generated to defrost roadways or be used for other purposes. Instead of the traditional semiconductors, he proposes to use a family of organic polymeric semiconductors developed at his laboratory that can be fabricated inexpensively as plastic sheets or painted on a flexible plastic sheet.
“This is a somewhat futuristic idea, since there isn’t any practical device on the market for doing this, but it has been demonstrated to work in a laboratory,” said Yang. “With enough additional research, I think it can be implemented in the field.”
Perhaps the most futuristic idea the URI team has considered is to completely replace asphalt roadways with roadways made of large, durable electronic blocks that contain photovoltaic cells, LED lights and sensors. The blocks can generate electricity, illuminate the roadway lanes in interchangeable configurations, and provide early warning of the need for maintenance.
According to Lee, the technology for this concept exists, but it is extremely expensive. He said that one group in Idaho made a driveway from prototypes of these blocks, and it cost about $100,000. Lee envisions that corporate parking lots may become the first users of this technology before they become practical and economical for roadway use.
“This kind of advanced technology will take time to be accepted by the transportation industries,” Lee said. “But we’ve been using asphalt for our highways for more than 100 years, and pretty soon it will be time for a change.”
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Jonesy and Wang would point out that with only 0.05 degrees UHI, such nonsense will never work.
At what cost, huh? If any of these were cost-effective, the market would have brought them to commercialization long before this.
And, “water even gets hotter than the asphalt?” Uh, no. That indicates either you violated the second law of thermodynamics, or your measuring instruments are wrong. Guess which one it is?
Sheesh. Where are the adults to supervise such “research?”
REPLY: Bear in mind that the person who wrote this press release for URI is likely not well versed in science. Note my caveat on the photo caption. – Anthony
“According to Lee, the technology for this concept exists, but it is extremely expensive. He said that one group in Idaho made a driveway from prototypes of these blocks, and it cost about $100,000.”
Well at least they letting us know with press releases that they are looking into how society can bankrupt itself and go back to pre-technological sources of heat. Maybe we can try sleeping on hot rocks like snakes do.
UHI is good for warming surfacestations where temperature is measured, let’s just leave it at that. These are the good old days.
“My tests showed that during some circumstances, the water even gets hotter than the asphalt.”
Either his pump is heating the water or the zeroth law of thermodynamic is false…
Well actually the area is not being heated by the pavement; it is being heated by the sun. The asphalt pavement just absorbs more of the solar energy than would say grass or trees; and it is the absorption of more solar energy that causes the temperature to be higher.
That black asphalt also is radiating more thermal LWIR energy than would grass or trees.
There is nothing wrong with having black asphalt gathering more solar energy so the place gets hotter; nothing at all.
BUT !! Don’t go using that higher Temperature that you read in that asphalt jungle as an appropriate Temperature for some place out in the ocean 1200 km away from your parking lot. Measure the Temperature out in that ocean place, instead of taking a wild ass guess that it should be the same as your parking lot.
Mother Gaia knows the temperature of every single atom or molecule so she doesn’t ever use the Temperature of one as a good guess for the Temperature on another one.
That is why Mother Gaia, ALWAYS gets the overall Temperature correct; it’s uncanny; she NEVER misses !
“If we can harvest that heat, we can use it for our daily use, save on fossil fuels, and reduce global warming.”
If they refrained from mentioning the reduction of Global Warming as their objective I would have taken them much more seriously.
Unfortunately all these great ideas end at the same problem and that’s how to store the heat.
All the rest is an old cow.
“URI Chemistry Professor Sze Yang believes that thermo-electric materials could be embedded in the roadway at different depths – or some could be in sunny areas and others in shade – and the difference in temperature between the materials would generate an electric current. “
Did they forget? The sun moves during the day, and it moves from month to month.
Shadows then also move: And such shadowns mean that the incident light is a sine-cosine function ever-changing as well with time. So, any given shadow zone must be duplicated because it will later become sunny, and any sunny zone at any time of the day becomes shaded earlier or later in the day. Early of later in the season.
Did these guys ever go to Houston? Mobile, AL? Disneyworld? Are they locked into their ivory tower north-New England fantasy of perpetual motion machines of UHI0induced heat transfer – when the UHI is from induced heat energy itself? Do they understand that vast areas of the country don’t need snow removal? That vast areas of the country fight sun half the heat – because it heats up the building and requires additional AC half the year; and then welcomes sun because it heats the building and reduces heat costs the other half of the year?
Also: Melting snow is best done by simple sunshine. But you can’t get grants for sunshine.
—…—
By the way, this concept of roads generating power through embedded plastic sheets and internal continuous cast panels was a science fiction story several years ago. Should they be sued for plagiarism? Or merely give back their research grants?
As to the thermo-electric or other converter from the Temperature differential ; to real usable energy output; I can suggest a good trade name for your machine.
I would call it the “CARNOT” Energy source; has a sort of norty connotation to it; should really sell !!
You can actually get a University Chair (well Professor Title) just for teaching this stuff; Obviously I went to School about 50 years too soon ?
“Another practical approach to harvesting solar energy from pavement is to embed water filled pipes beneath the asphalt and allow the sun to warm the water. The heated water could then be piped beneath bridge decks to melt accumulated ice on the surface and reduce the need for road salt. The water could also be piped to nearby buildings to satisfy heating or hot water needs, similar to geothermal heat pumps. It could even be converted to steam to turn a turbine in a small, traditional power plant.”
Huh?
Do they have – or the writer – have any idea of thermodynamics and heat transfer and steam production? We’ve only been doing that since the early 1700’s. And I know of no steam system that ever started with less than 213 degrees F – 100 C.
Or did the URI revoke the Laws of Entropy in their science departments as well? Does Newton’s Law still work in RI?
racookpe1978 says:
Using an ORC system (Organic Rankine Cycle) it would be possible, but as it is said clearly, they think of water. Water in a pipe in winter is not a problem for them apparently!
[Water in an uncovered/unburied pipe in the open air under a bridge in winter very busy conducting its solar heat to the asphalt/steel/grating in the bridge so the bridge doesn’t freeze. (And what is the energy source for the pump, filter, cleaner, and reservoir (that also must not freeze in winter? Robt]
How much money did they get for this? Those all sound like high school science fair projects.
Good luck. The pavement outside my house is in thermal equilibrium with the air at a temperature of 52 degrees F. Of course we could use that for cooling, but the demand in NE for cooling in november is minor at best. Anyway, black pavement is made with asphalt and we all know how awful oil is.
True Story – I was channel surfing the other night and stopped for a minute on an old episode of The Rockford Files – must have been from about 1974 – in it he discusses, AND I KID YOU NOT!!, The Urban Heat Island effect!!
Or we can build a nuclear plant and power the entire city.
http://www.ooms.nl/images/folders/RES%20%28E%29.pdf
Asphalt as a solar collector. Neat.
Yes there is a lot of heat, but it is low grade waste heat. Getting energy from that type of thing is always difficult and expensive. This is the type of heat that power plants use to pre-heat water. That is about all it is good for.
John Kehr
The Inconvenient Skeptic
Not really: Solar heat works only a few hours during the day – Can’t use it (or the very expensive pipes and pumps and heat exchangers it requires) between 3:00 PM and 9:00 AM. So, for 18 hours a day, your investment is wasted. It easier to try to get waste heat from the stack gasses. And even that is uneconomical if the stack gas is less than 300 – 450 degrees F. Robt]
Bit like solar .
Probably works OK in the North African summer.
To heat the shower.
Zeke the Sneak says:
November 9, 2010 at 2:18 pm
…Maybe we can try sleeping on hot rocks like snakes do.
I liked that, now that our Sun has entered into its “Stand By” mode 🙂
BTW it seems that you have tried it!
Anyway, if those snakes are two snakes, then we have the “Caduceus”, which long ago was the representation of the two opposite forces running our universe:
http://www.scribd.com/doc/40514613/Unified-Field-Explained-8
Holy cow!. I just saw all other comments. However, the Dutch idea does not seem as hare-brained as the URI folk, who apparently are trying to re-invent the wheel. The Dutch prototype has apparently been actually built and running for 10 years. That should be sufficient time to see how the actual experience compares to their calculations and what problems has come up that they may not have foreseen. Here is another link that shows that more installations have been made and gives more technical info: http://www.roadenergysystems.nl/pdf/Fachbeitrag%20in%20OIB%20-%20de%20Bondt%20-%20English%20version%2013-11-2006.pdf. Maybe this idea isn’t so crazy after all.
Spray-on infrared solar cells could be used 24/7 and could possibly be more efficient with UHI.
http://news.nationalgeographic.com/news/2005/01/0114_050114_solarplastic.html
““If we can harvest that heat, we can use it for our daily use, save on fossil fuels, and reduce global warming.”
“If we can harvest that heat, we can use it for our daily use, save on fossil fuels, and reduce LOCAL warming.”
There, that’s better.
“But we’ve been using asphalt for our highways for more than 100 years, and pretty soon it will be time for a change.”
Why? Cost effective, easy to work with. LA even uses asphalt (tar pits) for a tourist attraction.
Have these guys ever heard of “Delta T”?
This is like trying to harvest mouse farts for propulsion!
From what I can tell, consensus science doesn’t deny that UHI exists. It denies that UHI increases significantly as cities grow. Specifically, that UHI impacts on the temperature record from the growth of cities around thermometers during the temperature record only amount to .05C/century.
Saying that consensus science doesn’t recognize UHI as existing is like when consensus science popularizers claim that skeptics deny that CO2 absorption spectrum exist.