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.”
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.
The theory makes this a potential energy source, but the economics of building the infrastructure to realise it won’t be competitive with fossil fuel or nuclear – just like windmills and solar panel arrays.
Cheap energy is the lifeblood of a thriving global economy. In this circumstance history proves that the rich get richer and the poor of the world get better nourished. The reverse always happens when energy prices are high.
My oh my. the infrastructure costs would be staggering. pipes, pumps, semiconductors, all embedded in the road, where you have to dig up the road itself to effect repairs.
that’s the problem with diffuse energy sources: solar, wind, and “asphalt water warmers.” It takes so much infrastructure to “gather” the energy that it quickly becomes cost prohibitive. And no amount of new technological advances will ever make it cost competitive with small, energy dense fuel sources: hydrocarbon, nuclear.
it’s math. you just can’t make 2+2=4. at least not here in real world outside academia.
Zeke the Sneak says:
November 9, 2010 at 2:18 pm
…Maybe we can try sleeping on hot rocks like snakes do.
Hmm! people often misspell my name. I often thought you did yours, now I know.
Winner of junior science project – now on to the real world.
Phil – Interesting read . However , it made no mention of cost effectiveness . From the photos , I would guess that such projects are hellishly expensive and would probably work only in limited areas . For instance , I doubt the viability of such a system in Minnesota .
Charles S. Opalek, PE says:
November 9, 2010 at 3:16 pm
They claim a 50% reduction in energy costs after installing the system. They also say that the paving cost for the section with the piping is about twice the normal paving cost. I don’t know if the system would be cost effective in the US, as Europe has much higher energy costs. I would suspect that they are increasing the efficiency of the heat pumps by leveraging the apparently small delta t of the asphalt collector (about 10 degrees C) to reduce the delta T they would otherwise have to deal with. I have no personal knowledge of this system, other than having read about something like it some time ago, so I can’t vouch for it or the accuracy of their claims.
Source: http://news.cnet.com/8301-11128_3-9838676-54.html
Photo-voltaic cells embedded in parking lots?
Hmm.
What happens when a car is parked in the lot?
Just asking.
You know, these ideas of distributed low level heat sounds real cool until you figure out the cost of trying to aggregate it into something useful comes into play. Other than heating your shoes it’s just not economical.
Doesn’t anybody ever consult engineers.
Why not just use wind turbines? Vertical shaft, blades parallel to the ground, stick them on the sides of tall buildings where they can catch the thermal updrafts. Don’t the birds already use those air currents?
Hey, they’re Wind Turbines, you can get federal money for them, from research to development to deployment!
Here is an idea to get rid of the UHI… built in one big glycol loop under all the streets in the cities and route that to some big heat exchangers in the country side (next to a rural weather station!!). Voila! No difference in anomaly between urban and cities.
Ray says:
November 9, 2010 at 2:23 pm
“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…
That was my thought as well.
But then I got to thinking: WHAT IF the asphalt is such a good conduction medium that it both gains and loses its heat energy faster than does the water?
If the amount of heat energy transferred to the water was such that the water gained heat while the asphalt lost heat in the process, then it would ~appear~ as he states, but the reality would be that the water was now heating the asphalt.
It’s a thought.
I wonder where the placements were for the thermometric devices?
Well now, I don’t think we should write these guys off so fast…
I used to live in New York and walked every day from Grand Central Station to 9 W. 57th at the bottom of Central Park, rain shine or snow. So let’s do a thought experiment using NY as a model. Hey, we might get a grant!
There are two seasons to consider in our model:
Winter – Just when you need all that solar to melt the snow – It doesn’t show up for weeks! The little that there is, just keeps the slush from freezing into ice and the humans and taxis functional. Thank God for UHI! Drain away that heat to toastify the executive offices of XYZ hedge fund (good science fiction requires the suspension of disbelief in some law, in this case, thermodynamics) and all the people and taxi cabs of NY would be slipping and sliding into one another at a frightening pace. One bunch pumping the heat OUT of the streets for their customers, another dumping more and yet more salt on the roads to keep us all from dying.
Flash forward to Summer
Look down on NY during the Summer. How much pavement do you see lit by the sun? Why, it’s a sea of taxi cabs – all madly absorbing that useful solar energy and they using (gasp) fossil fuels to air condition the gained heat back into the air, making it even more miserable for us pedestrians. SO… if the taxis could be equipped with these new fangled energy collectors in their roofs, it could be sent away to air condition XYX hedge fund’s executive washrooms. Oh wait, cars don’t have wires. Oh wait, no problem – car tires could be impregnated with a conductive compound and each side of each lane could be an opposite polarity contact, using the same compound in the asphalt! YES.
Or, we could just paint all the roofs of all the cabs silver and harvest the gains as less fossil fuel used in the first place.
See, there are answers to these difficult questions…
M in Panama
Wait, don’t scoff. There is merit in these musings.
The eggheads will always bring numbers into the equation. Efficiencies, soo yesterday, RoR yawn, job relocations and that, pesky Canadian Gadfly, SMc is totally uncool when he applies Forensic techniques and logic to the auditing of planet-saving, peer-reviewed studies that prove mankind is as lethal to our planet as DDT is to Malaria.
I like the pizziks
Darn the fingers fumblings of an I-phoner! The point that I, so poorly: tried to make was that the most efficient utilisation of UHI is to point the probes towards the pavement, the parking lot or the air-con.
A billion dollars later, we can still come up with the meme. More research needed. Another couple of Mega$ in the cup boss, and ….
Take a time-out and read this essay: http://www.energytribune.com/articles.cfm?aid=2469
It begins: “Ed. note: A few weeks ago, I had the pleasure of hearing William Tucker speak at a conference in Washington, DC. His explanation of E = mc2 was the best I had ever heard. Even better, Tucker explained how Einstein’s equation applied to renewable energy sources like wind, solar, and hydro. His lecture was a revelation. It showed that the limits of renewable energy have nothing to do with politics or research dollars, but rather with simple mathematics. During a later exchange of emails with Tucker, I praised his lecture and suggested he write an article that explained E = mc2 and its corollary, E = mv2.”
Jonesy and Wang would point out that with only 0.05 degrees UHI, such nonsense will never work.
That’s the trend over a century, not the offset. Cities warm 0.5C more per century than rural areas. But the offset is a different story. Cities are often 5C to 10C warmer than the surrounding countryside.
I just checked the specific heat capacity of asphalt and water at http://www.engineeringtoolbox.com/specific-heat-capacity-d_391.html
For asphalt, it is 920 J/kgC and for water it is over 4 times as much at 4186 J/kgC.
So the numbers do not support the statement, at least with respect to water: “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.”
As has been correctly pointed out by others, water cannot GET hotter than asphalt. Could this have been a misrepresentation of what was meant? Could it have been intended to say that after both had been forced to cool after sundown, the water retains heat longer than asphalt? And could the higher temperature of the water then be used in some productive way?
“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.”
Just one question for these researchers:
If the sun is not hot enough to melt accumulated ice on the bridge how is it going to heat up the asphalt enough to warm the water in the pipes which is to be piped to the bridge to melt the accumulated ice?
Is there a substance inhaled or ingested at colleges that selectively lowers the IQ of just academics? Something sprayed from low-flying planes or shipped in with textbooks or goods used mostly by professors. Or maybe added to the coffee at the college cafeteria, or combined with their ivy maintenance spray chemicals. “Egghead-B-Gone” (whatever it is) has struck again.
Werner Brozek says:
November 9, 2010 at 7:50 pm
The problem is that bodies in contact with each other must have thermal equilibrium. The only way for the water to get hotter than the asphalt could only be done with some sort of one way insulator that let the heat move towards the water but not the other way around. This sort of material does not exist. The asphalt is in thermal equilibrium with the water and vice versa. If the water is hotter the heat will move from the water to the asphalt. The source of heat is from the top of the asphalt towards its bulk (where the pipes are). It is thermodynamically impossible for the water to become the source of heat unless the pump is heating the water or the turbulence induced by the pump.
I would have thought it would be easier to work on the air con systems of buildings to produce power than wondering around on the roads.
James.
I dont see any reason why every surface and every rooftop in a city isn’t producing power for that city. It makes a whole lot more sense then flattening miles of desert or mountaintops for “earth friendly” solar and wind. Will it solve our energy problems.. probably not unless you have a pwr source that can be easily dialed down and back for times when the wind wont blow or the sun isn’t out. It seemed to me that Portland or Seattle was trying a pilot program very similar, wonder how that ever came out.
Hey All, what do you think about his idea?:
On a crowdfunding site (say like kickstarter.com), start a crowdfunding drive to raise USD1,000,000 in prize money. This prize money will be awarded to the first person or team that can provide conclusive empirical proof showing manmade CO2 is responsible for global warming. This competition will run for 2 years. All submissions will be checked and verified by statistical experts.
Once and for all, let’s settle this global warming argument. At the end of the competition, we will get a conclusive answer one way or the other.
If one million people contribute $1 each or 100,000 people contribute $10 each, we will have the needed prize money.
I love the hope-raising post and love the hope-dashing comments even more.
Of course it’s a daffy, expensive business, this search for alternative energy, but when you consider the potential gain on a long punt…
What exasperates me is the insistence on converting experimental to mainstream without justification. Recently I walked across much of France. I was inspired by the sight of the aging hydro-scheme on the Allier River, and by the long established nuclear reactors on the Garonne. A meeting with a retired geothermal electrician enlightened me on the great usefulness of geo-thermal…and the great limitations of the same.
These industries, the products of daring, independent and practical spirits, were in sharp contrast to the wind-turbines uselessly disfiguring the Aubrac Plateau: perfect symbols of the European Union, where everyone spends everyone else’s money, and everyone thinks everyone won’t notice.
To me, it doesn’t matter if these R. I. guys waste some money on silly lab experiments and sillier pilot programs. They tell me medieval alchemy led to some solid modern chemistry. But every time someone declares an experimental technology to be a “solution”, we start tipping the billions the wrong way. Paradoxically, it’s the people with too much enthusiasm for alternatives who are shutting the door on the future and its viable alternatives.
George E Smith
I think you are being a bit too cryptic in your reference to CARNOT heat engines. The Carnot engine is entirely hypothetical, so is an ideal solution for warmists – they should all get on their Carnot cycles and pedal happily into the sun.
Nevertheless, the subject of heat engines, and in particular the Stirling engine, is relevant to this discussion, as its use is being proposed for use in microgeneration projects and thus could be used to generate power (mechanical and subsequently electrical) as a consequence of temperature differentials between hot asphalt and cooler adjacent areas.
Another alternative is the use of thermopiles, generating electricity directly, providing a more robust solution that PV arrays.
correction, 1st para: “pedal happily into the sunset.”
The ideas described in the article are worth pursuing but as has already been pointed out similar work has been done elsewhere. Phil mentioned an old project in the Netherlands. In Britain, despite our cloudy skies, work is also been done in this field. The article below mentions car parks and school playgrounds as been suitable places for thermal energy storage.
Thermal Energy Storage using ThermalBanks to store heat energy
http://www.icax.co.uk/thermal_energy_storage.html
The idea of storing heat in this way certainly seems more sensible than covering large parts of the British countryside with solar panels – something that is seriously being considered by the government!
Solar mania will cast a shadow over Britain, Daily Telegraph 8 November 2010
http://www.telegraph.co.uk/earth/energy/solarpower/8116609/Solar-mania-will-cast-a-shadow-over-Britain.html
Perhaps the reason for the solar panel idea is to make wind power look good! At least Britain, being an island, tends to be windier than many parts of the European mainland but the idea of using agricultural land to generate solar energy instead is beyond belief.
Going back to the asphalt idea I don’t know why so many people on this blog are keen to rubbish it. One of the most ridiculous criticisms is that if the idea were worthwhile the market would have already exploited it. That argument could be used against any idea.
Whatever you think of the debate about anthropogenic global warming ideas for reducing our dependence on oil, gas and coal, and for exploiting non-polluting sources of energy deserve serious consideration. They do not deserve to be rubbished by cynics who are trying to prove how smart they are.
I’d far rather see money spent in this sort of area than on telling us we’re all gonna fry and it’s all our own fault. At least it is adding to the sum of our knowledge.
Correct me if I’m wrong, it takes as much energy to heat water from 0-10C as it does from 10-100C. If that’s right, it could be very useful.
John Kehr says:
November 9, 2010 at 2:50 pm
My immediate thought exactly – low grade heat is close to useless unless it is very conveniently located near the few things that can actually make use of it.
The idea of running water pipes close to the surface in asphault has so many immediate obvious problems I almost spit my coffee when I read it. Have the morons ever seen asphault roads being paved, repaired, and how they wear under normal use? Almost everyone I should think has seen these things happening and it doesn’t take any skill to imagine how difficult it would be to place and maintain water pipes and how the surface would wear differently. Mind bogglingly stupid.
Then there’s the idea of putting photovoltaics on median dividers to power streetlights and signs. Now there’s a nifty idea but it’s hardly original. I have PV hazard lights on my boat dock to help dipthongs like those featured in the OP avoid killing themselves at night by driving into it. That’s still no guarantee though. Someone last year saw the hazard lights and turned toward shore instead of away from shore to go around it. He zipped right over the ramp from shore to dock in about 12 inches of water. It must have launched his boat about 3 feet high. I’m amazed there was nothing more than some boat paint on my ramp, a bit of bent metal and gouged wood, and a few hefty aluminum shavings from his lower unit where it caught the side of the ramp and kicked up. That must have been one “Holy crap! WTF just happened?” moment for that dope.
Roads get too hot in summer and too cold in winter; so what we want is to transfer the warmth from summer to winter (also day to night). There is ample thermal mass directly below each roadway. The problem is getting enough heat deep enough into the ground. The simplest and most reliable technique may be to ram a grid of heavy aluminium rods (~6cm diameter x ~10m long, hexagonal spacing ~1m) down through the surface – carefully avoiding buried utilities! This would roughly double the depth to which heat penetrates and provide significant mitigation of the temperature extremes, at a cost ~£100/m2 (or ~£5000/person in the urban area). For greater effect additional rods could be added at any time. Being completely passive, they would require no maintenance. This would certainly be an affordable system, but whether the benefits would be sufficient to justify it is another matter; I would be inclined to doubt it. Active systems (such as antifreeze flowing through pipes) could shift more heat, but would likely be a maintenance nightmare, so would probably not have a net advantage over the simpler passive arrangements.
paulhan,
Any place where the water consistently reaches 0 Celsius will also require heating for that same water to prevent the precious pipes from bursting or an evacuation system for removing the water which will require electricity for pumps and a holding tank well below the frost line. In Saskatchewan we do geothermal. You obviously do not live any place where winter turns the dugout into a hockey rink. Then there’s the snow cover to deal with as it reflects a whole lot of sunlight… a new use for carbon soot maybe?
Peter Plail says:
November 10, 2010 at 2:08 am
The Carnot cycle describes the theoretical maximum amount of work that can be produced through a temperature gradient. There are a great many quite real engine designs that use the Carnot cycle. For instance the Rankine and Stirling cycles are pratical implementations of the Carnot cycle.
@Peter Plail (con’t)
One of the great practical limitations in exploiting the Carnot cycle is that efficiency greatly improves with larger temperature gradients. A Rankine cycle engine used in a power plant can get up to about 70% efficient when waste heat is extracted and used for a pre-heater. Nonetheless they still must use dry steam at well over 1000F to drive the turbine.
Theoretically much smaller temperature gradients can be exploited but as a practical matter you need larger pistons or turbine fans as the temperature gradient decreases in order to maintain the same efficiency. Early steam engines used pistons the size of 55 gallon drums (or larger) to get just a few horsepower so an engine the size of a small building only generated as much useful work as a small modern lawn mower engine.
For climate study it’s a different story. A thunderstorm is a Carnot cycle engine that uses just a few tens of degrees F temperature gradient. They work on such a small gradient because the expansion chamber is hundreds of cubic miles in size.
Paul Birch says:
November 10, 2010 at 7:34 am
Where many people go wrong, you included, is failing to take into account the energy required to produce the working parts of the design in question. Producing aluminum is incredibly energy intensive. The commodity price of raw aluminum essentially tracks the price of oil. I seriously doubt whether the energy required to produce the aluminum rods you propose would reach break-even during their service lifetime.
Some people have calculated that the energy required to build a nuclear power plant exceeds the energy produced by the plant over its service lifetime. Nuclear plants require a huge amount of concrete and steel both of which, like aluminun, require a lot of energy to produce and also track the price of oil. If that calculation is correct then the ROIC (return on invested capital) is entirely a matter of the basic stock market strategy of buying low and selling high – i.e. the plant is built with an initial investment of cheap energy when cost of capital is low and over its ~25 year service life it sells energy at a more or less constantly rising price that exceeds the cost of capital invested in it.
I had a great unexpected windfall when the price of oil shot up over the last decade. I happened to have built or purchased a buttload of aluminum, copper, steel, and concrete right around the year 2000 with profits gleaned from selling off my high tech stock portfolio. Little did I realize that in just the course of the next few years the price of those materials would double or triple along with the price of a barrel of oil.
paulhan says:
November 10, 2010 at 4:59 am
Consider yourself corrected. It takes one calorie to heat one gram of water by one degree C. Therefore it takes 10 calories to heat 1 gram of water from 0C to 10C and 90 calories to heat the same gram from 10-100C.
The big energy inputs are in changing one gram of ice at 0C into one gram of water at 0C (334 calories) and in changing one gram of water at 100C into on gram of steam at 100C (2260 calories). Note the temperature doesn’t change at all even though very large amounts of energy are input. These are called, respectively, the latent heat of fusion (melting) and the latent heat of vaporization (boiling). Water is rather unique in the very high latent heat of vaporization which is why steam is used so ubiquitously as a working fluid in various applications involving converting heat to work and in transporting energy from one spot to another.
These same latent heats are also what bedevils climate models as they fail to adequately account for it especially in the heat pump represented by convective cells driven by evaporation at the surface and condensation kilometers higher in the atmosphere.
So the city is warmer Hmmm. well if you extract the heat to make electricity then the homes will need more electricity for heating. There was another project also dumb, but not as dumb, using piezoelectric in the roads, as cars drove by they generated electricity.
Vuk etc. says:
November 9, 2010 at 3:43 pm
Zeke the Sneak says:
November 9, 2010 at 2:18 pm
…Maybe we can try sleeping on hot rocks like snakes do.
Hmm! people often misspell my name. I often thought you did yours, now I know.
@vuk. And Enneagram.
I don’t know where you are getting this snake thing. It’s sneak. S-N-E-A-K.
Of course, for grant money I might like to lay on a warm rock in Cancun, claiming my STUFF is incontrovertible, and hiding my error bars. (No one has ever actually seen me doing it though.) 🙂
Roy says:
November 10, 2010 at 3:16 am
“Whatever you think of the debate about anthropogenic global warming ideas for reducing our dependence on oil, gas and coal, and for exploiting non-polluting sources of energy deserve serious consideration. They do not deserve to be rubbished by cynics who are trying to prove how smart they are.”
Roy, just think about it for 5 minute! It is the pursuit of hare-brained schemes like these that is wasting good money which could be spent of existing technology which is know to deliver, like hydro, natural gas and nuclear. This is were the money needs to be invested if we are to have economic and secure ‘home-grown’ energy supplies for the future.
“”””” Dave Springer says:
November 10, 2010 at 9:22 am
paulhan says:
November 10, 2010 at 4:59 am
Correct me if I’m wrong, it takes as much energy to heat water from 0-10C as it does from 10-100C. If that’s right, it could be very useful.
Consider yourself corrected. It takes one calorie to heat one gram of water by one degree C. Therefore it takes 10 calories to heat 1 gram of water from 0C to 10C and 90 calories to heat the same gram from 10-100C.
The big energy inputs are in changing one gram of ice at 0C into one gram of water at 0C (334 calories) and in changing one gram of water at 100C into on gram of steam at 100C (2260 calories). “””””
And consider yourself corrected also; just a typo I’m sure; but YOUR numbers are more likely Joules per gram; not Calories.
LH of freezing is 80 Cal/gm roughly and about 590 for boiling (at 100 deg C); so your numbers would be in Joules.
Dang ! I have been trying to convert myself from cal to Joules for ages; and there you go giving me the correct nummers.
And this is just a courtesy correction; not a criticism correction; so we don’t pass out incorrect information; those AGW fans, are just waiting for some slipup.
And you’re welcome Dave.
Have any of these people ever had enginnering economics or experience with detailed Life Cycle Cost Analysis? The LCCA for these projects are excessive in the very best case. Research for research sake is great, but leave the applications to engineers and scientist that have to sell this to their clients.
“”””” Dave Springer says:
November 10, 2010 at 8:15 am
Peter Plail says:
November 10, 2010 at 2:08 am
George E Smith
I think you are being a bit too cryptic in your reference to CARNOT heat engines. The Carnot engine is entirely hypothetical
The Carnot cycle describes the theoretical maximum amount of work that can be produced through a temperature gradient. There are a great many quite real engine designs that use the Carnot cycle. For instance the Rankine and Stirling cycles are pratical implementations of the Carnot cycle. “””””
Dang ! and here I thought I had created a really sexy name for something; and you chaps tell me someone else already used it; what a pity !
But Peter; What is this all about ? “””your reference to CARNOT heat engines.””” Can you point me to my reference to “CARNOT heat engines ” . Only thing even close I could find was this :-
“”””” I would call it the “CARNOT” Energy source; has a sort of norty connotation to it; should really sell !! “””””
Now I think that a “heat engine” might require an “energy source”; but I wouldn’t say an energy source was a heat engine; and it looks like I didn’t.
Sometimes it is really hard to find words, that are simple for people to read; maybe everyone is texting so much that nobody even bothers to read any more.
But thanks for the hint on that Carnot thing; maybe I will look it up.
Has someone offered a new multimillion dollar X-prize that I haven’t heard about? From the tenor of a multitude of recent press releases it would seem that something has seriously incentivized the academic community to come up with schemes to generate the world’s most expensive Btu or Kilowatt. If Prof. Lee’s class of engineering students took more than a half hour to come up with at least 50 reasons why this project was a complete waste of time and resources, he really ought to give back his paycheck.
As an alternative I suggest we recruit a bunch of homeless guys, station them on bridge decks with sacks of currency and Bic lighters and have them sprinkle any ice that appears with flaming bills. If we restrict the denominations to 10s or 20s it should be just about as economically sensible as this scheme.
Dave Springer says:
November 10, 2010 at 9:04 am
“Where many people go wrong, you included, is failing to take into account the energy required to produce the working parts of the design in question. Producing aluminum is incredibly energy intensive. The commodity price of raw aluminum essentially tracks the price of oil. I seriously doubt whether the energy required to produce the aluminum rods you propose would reach break-even during their service lifetime.”
I have not “failed to take into account the energy required”. That is automatically included in the cost I gave. Since the technique is intended to ameliorate temperature extremes, not generate power, the notion of energy break-even has no relevance. You might just as well ask whether a television set reaches break-even. Nor, as totally passive objects, would the rods have any “service lifetime”; they’d last for thousands or even millions of years. For what it’s worth, such rods could be expected to transfer the quantity of energy required to manufacture them in roughly 100 years.
“Some people have calculated that the energy required to build a nuclear power plant exceeds the energy produced by the plant over its service lifetime. ”
Nonsense. Energy break even should take a few days’ operation at most.
@Dave Springer, @george E. Smith
Thank you both very much. I stand corrected :-). If George E. Smith’s figures are correct, then to go from freezing to 10C and 10C to 100C would take the same amount of energy, but I hold my hands up, I meant it the way that Dave interpreted it.
Paul Birch,
Why not just use existing ground source heat pump technology instead of the rods?
Djozar says:
November 10, 2010 at 12:53 pm
“Why not just use existing ground source heat pump technology instead of the rods?”
Because passive rods don’t require maintenance. Heat pumps, with fluid filled pipes, would be difficult to engineer with adequate reliability (think of the hammering the road and its substrate gets from heavy traffic).
Problem: Roads freeze at night.
Heat source: Sunshine.
Heat storage device: Water
As Werner Brozek’s comment pointed out the specific heat capacity of water is four times that of asphalt. So any road engineer with a little spare cash can place plastic food containers of water (they don’t have to be pipes) under the road surface, and close enough to the surface to pick up some of the daytime warming and release it at night.
Loads of savings on gritting lorries. (The engineer won’t save on snow ploughs because no warmth is going to melt the amount of snow that needs a snowplough, and hey – if it’s snowing the road isn’t black anymore and will not absorb heat during the day!)
This is easy, cheap stuff. But hang on! The road will collapse under the first lorry unless we start to engineer these containers out of steel. Rust-less steel. And the road must stay absolutely flat – not settle around these containers as the asphalt consolidates.
Oops – so now it’s starting to look expensive. It’s starting to look like every long road has to be constructed to the same engineering standards as a short length of bridge.
So we’ve established this is a non-starter. Next !
Surely the KISS principle still applies, even to these junior school scientists?
“””” paulhan says:
November 10, 2010 at 12:43 pm
@Dave Springer, @george E. Smith
Thank you both very much. I stand corrected :-). If George E. Smith’s figures are correct, then to go from freezing to 10C and 10C to 100C would take the same amount of energy, but I hold my hands up, I meant it the way that Dave interpreted it.
Say Paulhan; I think maybe some information got lost in the shuffling.
When you say going from “freezing” to 10 deg C; you should be specific about “which side” of freezing you start from.
Ye; IF you start from x grams of ICE at the freezing point (zero deg C) then it will take 80 Calories per gram; just to go to the OTHER side of freezing; aka ice water and then ten more calories to get you to 10 deg C or 90 Total, and then 90 calories more would take you to the water side of boiling at 100 deg C.
So if you meant starting from ice at zero and ending at water at 100, then you are quite correct; the half way point heat wise is at 10 deg C.
Dave just got his Calories and Joules flipped; but that can happen to anyone.
I think the boiling water to Steam transition is even more dramatic; sicne the latent heat is 590 Cal/g at that phase change; so steam at 100 deg C contains seven times as much heat as water at 100 deg C; which is why steam burns are so deadly. You get a gram of steal at 100 deg C on your skin; and it dumps 590 Calories immediately and then another 63 calories as it cools down to body temperature (37 deg C).
I think it is less confusing if you keep the latent heats at phase changes separated from just temperature changes.
But you were right if you meant from ICE to boiling WATER.
“”””” Paul Birch says:
November 10, 2010 at 12:29 pm
Dave Springer says:
November 10, 2010 at 9:04 am
………………………………..
“Some people have calculated that the energy required to build a nuclear power plant exceeds the energy produced by the plant over its service lifetime. ”
Nonsense. Energy break even should take a few days’ operation at most. “””””
I remember many years ago going to an Electro-Chem Society Convention; and during a session on energy; it was announced that the first Westinghouse reactor to go on line (commercially) had taken 17 years to pay back the total energy capital it took to build; If I remember correctly they were just in the process of refuelling it; and they figured it had another 17 years of service life; before it would be just too costly to maintain.
Maybe they have gotten better since then.
You have to start with ALL of the raw materials being in their natural state ; presumably somewhere on planet earth; and that of course includes whatever equipment and machinery you need to mine those raw materials, and process them, and use in the construction; all of which will get pretty much consumed by the time the project is finished.
We know that stored chemical energy is viable; since that is what got us to where we are today; manual labor would never have done the job.
“”””” Correct me if I’m wrong, it takes as much energy to heat water from 0-10C as it does from 10-100C. If that’s right, it could be very useful. “””””
So Paulhan; the way you actually stated the problem; you didn’t have it correct; you said to heat WATER, not ICE.
I’m sure that you just misread whatever source you originally learned it from.
From ICE to boiling WATER; yes.
From ice WATER to boiling WATER; no
From ICE at zero to STEAM at 100 definitely not.
George E. Smith says:
November 10, 2010 at 3:14 pm
“I remember many years ago going to an Electro-Chem Society Convention; and during a session on energy; it was announced that the first Westinghouse reactor to go on line (commercially) had taken 17 years to pay back the total energy capital it took to build;”
You’re probably misremembering what they actually said (unless they got it wrong themselves). Paying back the total capital required to build a power plant is quite different (in this case wildly different) from merely paying back the energy capital. Since energy costs are ~5% of total costs, but energy ~100% of total output of a power plant, there is a factor of twenty between them. And even this includes the whole of the energy consumed for all purposes (including recreational and discretionary) by everyone employed in building and operating it, or receiving any payment or revenue, not merely the energy that is actually required for its manufacture and maintenance. People promoting an energy technology have a tendency to use the latter when they should be using the former; whereas people opposing an energy technology have a tendency to use the former when they should be using the latter. This is why partisan claims are so absurdly divergent. Even for ridiculously expensive technologies (like current wind and photovoltaic technologies) the time for physical break-even in energy is quite short.
“”””” Paul Birch says:
November 10, 2010 at 4:14 pm
George E. Smith says:
November 10, 2010 at 3:14 pm
“I remember many years ago going to an Electro-Chem Society Convention; and during a session on energy; it was announced that the first Westinghouse reactor to go on line (commercially) had taken 17 years to pay back the total energy capital it took to build;”
You’re probably misremembering what they actually said “””””
I believe I said this was the session on energy; I even remember that one of the papers presented in the session was a paper on Gallium Arsenide Concentrator Solar cells; presented by a chap named Jerry Woodall from IBM (who were doing that research). and since it was a session on ENERGY, and not a session on FINANCE, there was no reason for us to be discussing financing of energy plants. The whole emphasis on concentrator cells was for exactly that reason; that you could save a lot of energy capital with concentrator cells; which in the case of Gallium Arsenide would work well with high efficiency, even at 50 suns concentration.
So I remember what was said and what was said about that Westinghouse Reactor; and they weren’t talking about just obtaining the nuclear fuel.
And I have no partisan axe to grind; I care only about the science. And if they can make energy (available) rather than lose energy; then they will succeed economically; and there’s nothing that will stop them unless it is political.
I’m not much in the habit of mis-remebering; and if I do mis-remember; then I also forget to write about it.
“Ray says:
November 9, 2010 at 10:42 pm
The problem is that bodies in contact with each other must have thermal equilibrium.”
True, but what if we had 10 feet of normal asphalt on the SHOULDER of a highway which alternates between 10 feet of something with a layer on insulation at the bottom and then some sort of plastic water filled jugs mixed with asphalt for the next 10 feet? In the summer, everything may be at 140 F during the afternoon but in the middle of the night, the normal asphalt could be 60 F and the alternate 10 feet could be at say 90 F. Could this differential be used to light a street lamp?
Of course the 10 feet with water filled jugs, or whatever, must be able to handle the odd truck that may have to go on the shoulder. And in places where it gets below freezing, antifreeze would need to be used instead of water.
George E. Smith says:
November 10, 2010 at 7:24 pm
“So I remember what was said and what was said about that Westinghouse Reactor”
OK. So then they got it wrong (as I said before) . Whether they realised it or not, they were referring to or basing their statement on total costs (and probably including one-off research costs at that).
“And if they can make energy (available) rather than lose energy; then they will succeed economically; and there’s nothing that will stop them unless it is political.”
No, you’re making the same mistake again; conflating energy with total costs. Energy break-even and economic pay-back are two very different things. You can have either one without the other.
To be economically viable a general purpose utility power plant needs to repay its physical energy input many times over (at least 20 fold and typically of order 1000 fold). Specialised power sources may be viable at much lower ratios – in extreme cases well below unity (cf. primary cell batteries, which deliver much less energy than went into making them, but still sell well for powering electric torches).
“”” Paul Birch says:
November 11, 2010 at 4:28 am
George E. Smith says:
November 10, 2010 at 7:24 pm
“So I remember what was said and what was said about that Westinghouse Reactor”
OK. So then they got it wrong (as I said before) . Whether they realised it or not, they were referring to or basing their statement on total costs (and probably including one-off research costs at that). “””””
Well Paul; when I go to a scientific conference, I tend to start off with the assumption that the speakers do know what they are talking about.. Some times that turns out to be not so; early research is often corrected by later results; but it would appear that you know what they were computing was not correct.
Now all I have to do, is to figure out how you get somebody to do something; for which you have to pay real money; and for doing which, they consume NO energy.
So all we have to do is alter our economy to one which does valuable things at the expenditure of no energy; then our energy problems will be solved; we don’t need any !
Actually, all of my electric torches these days, use rechargeable batteries; and my flashlights too.
George E. Smith says:
November 11, 2010 at 10:42 am
“Now all I have to do, is to figure out how you get somebody to do something; for which you have to pay real money; and for doing which, they consume NO energy.
So all we have to do is alter our economy to one which does valuable things at the expenditure of no energy; then our energy problems will be solved; we don’t need any !”
Oh dear, why do people keep jumping to the conclusion that “less” means “none”? Nobody is claiming that it takes no energy to build a reactor, merely that the amount it takes is small compared to the amount it produces. Some energy is required in the production of all economic goods, as is some material, some capital, some land, some labour. But the relative amounts of each can be varied over a wide range, depending on the relative costs. The optimal production process (for a given time and place) is that which minimises the total cost per unit output – not that which minimises the cost of any one of those factors of production (such as energy) alone.
“Actually, all of my electric torches these days, use rechargeable batteries; and my flashlights too.”
There is still a very large market for primary cells. They are better than rechargeables for torches, unless you use them regularly. Rechargeables tend to have much higher self-discharge rates, which not good for a device that has to work straight out of the cupboard after being left unused for long periods.