Countering climate change with cool pavements:
Pavements are an abundant urban surface, covering around 40 percent of American cities. But in addition to carrying traffic, they can also emit heat.
Due to what’s called the urban heat island effect, densely built, impermeable surfaces like pavements can absorb solar radiation and warm up their surroundings by re-emitting that radiation as heat. This phenomenon poses a serious threat to cities. It increases air temperatures by up as much as 7 degrees Fahrenheit and contributes to health and environmental risks — risks that climate change will magnify.
In response, researchers at the MIT Concrete Sustainability Hub (MIT CSHub) are studying how a surface that ordinarily heightens urban heat islands can instead lessen their intensity. Their research focuses on “cool pavements,” which reflect more solar radiation and emit less heat than conventional paving surfaces.
[...] Cities like Los Angeles and Phoenix have already conducted sizeable experiments with cool pavements, but the technology is still not widely implemented. The CSHub team hopes their research can guide future cool paving projects to help cities cope with a changing climate.
[...] “We can build cool pavements in many different ways,” says Randolph Kirchain, a researcher in the Materials Science Laboratory and co-director of the Concrete Sustainability Hub. “Brighter materials like concrete and lighter-colored aggregates offer higher albedo, while existing asphalt pavements can be made ‘cool’ through reflective coatings.”
CSHub researchers considered these several options in a study of Boston and Phoenix. Their analysis considered different outcomes when concrete, reflective asphalt, and reflective concrete replaced conventional asphalt pavements — which make up more than 95 percent of pavements worldwide.
Journal Reference:
Hessam AzariJafari, Xin Xu, Jeremy Gregory, et al. Urban-Scale Evaluation of Cool Pavement Impacts on the Urban Heat Island Effect and Climate Change [open], Environmental Science & Technology (DOI: 10.1021/acs.est.1c00664)
(Score: 2, Funny) by Rosco P. Coltrane on Thursday August 26 2021, @08:45AM (1 child)
The only cool pavement in LA is in Hollywood and it's called the Walk of Fame.
(Score: 0) by Anonymous Coward on Thursday August 26 2021, @05:36PM
The Walk of Shame is pretty cool, depending on your perspective.
(Score: 2) by looorg on Thursday August 26 2021, @09:32AM (2 children)
Pavement is cooled with snow. Get some. It sucks to walk around in. But the pavement is cool. I wish it was a bit warmer so they it wouldn't get all slushy and they wouldn't need to pour salt and sand on it so you don't have to resort to the penguin walk.
Perhaps a radical idea out be less pavement and roads and more parks?
Is there some drawback to reflective asphalt? What and were does things get reflected? So the asphalt becomes cooler but where does the heat go. It just doesn't magically go away (law of conservation all that jazz).
(Score: 0) by Anonymous Coward on Thursday August 26 2021, @10:05AM (1 child)
> It just doesn't magically go away
That's why it's called "reflective" -- the heat (IR radiation, long wavelength light) is reflected back to the sky. Or, if there is a building nearby, part of it is reflected onto the building.
(Score: 5, Informative) by hendrikboom on Thursday August 26 2021, @01:42PM
If the material is really reflected, the energy goes up and away and into space as light -- mostly the same frequencies that came in. It's the absorbed energy that turns into heat, and then into infrared, which is trapped in the atmosphere by greenhouse gases and turned back into heat.
(Score: 5, Insightful) by bradley13 on Thursday August 26 2021, @11:55AM (8 children)
So, the conclusion of the article is simple: concrete has a higher albedo than asphalt, and therefore should be used to build roads and parking lots. It's best with a reflective coating. For the goals of the article, we could have predicted these results without any expensive experiments.
But...
First problem: manufacturing concrete has a massive climate impact, plus we already have a global shortage of suitable sand. Meanwhile, asphalt is one of the most recyclable materials in existence.
Second problem: Reflective? Imagine driving on a road when the sun is low, if the road itself is a reflective surface. This occasionally happens after a rain - it's not fun, because you can't see a damned thing. Having this all the time would be hugely dangerous.
Everyone is somebody else's weirdo.
(Score: 5, Informative) by hendrikboom on Thursday August 26 2021, @01:44PM
Need diffuse, not specular reflection.
Pavement materials provide diffuse reflection; water provides specular at near-tangent angles.
Unless, of course, you pave roads with mirrors.
(Score: 4, Informative) by Thexalon on Thursday August 26 2021, @04:16PM (4 children)
And the real kicker is that there are easier ways to reduce urban heat island, like:
1. Paint black rooftops white (this one was suggested by then-Energy Secretary Stephen Chu).
2. In climates where this is possible, plant trees and other greenery.
And some bigger moves to be considering:
1. Change zoning rules to reduce the required size of parking lots, and incentivize retailers to shrink existing parking lots in favor of greenspace.
2. Build structures with solar panels above the major roadways. Remember that "solar road" nonsense of a few years ago? Except this time, in a way that actually works and doesn't have 18-wheelers running over it.
3. Build and improve public transit and bicycling infrastructure so that there's less need for people to hop in their cars to go everywhere.
"Think of how stupid the average person is. Then realize half of 'em are stupider than that." - George Carlin
(Score: 3, Insightful) by RS3 on Thursday August 26 2021, @05:45PM (3 children)
All good ideas. Why aren't these already the standard?
Not up on, and no time to research paints / road materials that would reflect UV energy as much as possible.
I'll add: build roofs over parking lots and cover them with PV and/or solar heat collectors.
Cover all large buildings with PV and/or solar heat collectors. (Amazon has done this with their "fulfillment centers", and are building out an all-electric delivery fleet).
Sorry to truckers and truck lobby, but return to rail transport and greatly reduce the use of 18-wheelers (lorries).
(Score: 3, Insightful) by Runaway1956 on Friday August 27 2021, @01:34AM (2 children)
Truck drivers and the trucking lobby only have the influence that they have because the railroads in the US are incompetent. It is not at all unusual for the railroads to lose railcars, sometimes for months at a time.
At the same time, industry demands Just In Time shipping. They want to plan months ahead just which loads will be unloaded onto their docks at what hours. JIT and absolutely minimal warehousing work together to demand that trucks move the goods, and trains just aren't good enough.
Many of today's industrial parks were designed without rail access. Many more have had rail access paved over, so they can get more trucks and trailers into the park.
Despite my affection for trucking, I know that railroads can move freight at a small fraction of the cost of trucking.
If we want to see changes in our freight distribution, we'll need to start by shooting all the MBAs who have screwed up and/or destroyed our manufacturing capacity.
“I have become friends with many school shooters” - Tampon Tim Walz
(Score: 2) by RS3 on Friday August 27 2021, @02:35AM
Yup, as I commented in another discussion, short-term profits over long-term.
But also the pressure for quick shipping, "just-in-time", and a lack of overall logistical coordination. It amazes me how people I've worked for and with just default to overnight shipping; stuff that could be planned.
Company I work at, building butts up to a major rail line. You can see where there had been a loading platform that's long gone.
I don't fly often (any more) but about 20 years ago I happened to be on a plane next to a major CSX VP. We chatted a bit and he told me they never know where the trains are, and if anyone could solve that, they'd be rich. At the time cell phones and GPS wasn't super cheap, but I thought by now someone would have some kind of beacon on every car. It would be quite easy to come up with a GPS system. You can't rely on cell networks over long distances, but it wouldn't be difficult to do something in lower RF ranges that would carry long distances. And/or maybe satellite comms if cell service isn't available. Gosh, it's not that hard people! It would be worth setting up a nationwide RF network. Lower frequencies would be ideal- you don't need much bandwidth and you'd get much longer RF propagation.
(Score: 2) by Thexalon on Friday August 27 2021, @11:43AM
There's an easy-ish fix for this: Keep pushing the cost of or taxes on diesel upwards, and I'd bet that industry would start adjusting their shipping to use less diesel.
But that requires politicians who aren't easily bribed away from doing what's best for the country, so it won't happen.
"Think of how stupid the average person is. Then realize half of 'em are stupider than that." - George Carlin
(Score: 2) by anotherblackhat on Thursday August 26 2021, @05:52PM (1 child)
At least in theory they could find a paint that (mostly) reflected non-visible light (infra-red and ultra-violet).
Also, only paint inside the lanes with "invisible" chevrons, or some other pattern that even when wet makes the lanes more discernible, not less.
Shade seems like a better answer though. Maybe solar panels on road covering awnings — both shade and electricity.
(Score: 2) by vux984 on Thursday August 26 2021, @11:56PM
The cost to paint the entire surface of the road every few years would be extremely high for little benefit.
When you are looking at hundreds of kilometers of road surface, even pennies per square meter is very expensive. Add on driving wear and tear, and weather wear and tear, and after every bit of road maintenance... astronomical.
Shade is a better answer. Plant trees.
Your solar panel idea is also incredibly expensive and comparatively inefficient vs just building solar farms*, but some road shading solar may still be worthwhile in some places.
* The angles of collection would generally be less optimal, their might be some some buildings that cast shade on them part of the day further reducing their effectiveness, the initial construction cost would be higher as you'd need to put them quite high, and construction and maintenance would cost more as it would require more resources and manpower to close roads/lanes, set up cones and traffic direction every time a panel needed repair service, or cleaning, etc, etc.
Here's another really good on paper idea ... but reality, so far at least, is that it's just not viable:
https://interestingengineering.com/solar-roadways-engineering-failure [interestingengineering.com]
(Score: 1, Insightful) by Anonymous Coward on Thursday August 26 2021, @05:44PM (3 children)
Even if experiments with solar cells in the road itself don't work out, you could mount solar panels above the road.
(Score: 1, Insightful) by Anonymous Coward on Thursday August 26 2021, @10:41PM (2 children)
This is my favorite, although that would mean a MASSIVE amount of metal to mount them, or they could re-use telephone polls while burying wires in the ground?
Or rip up lots of roads and add a lot more rail. Encourage car rentals.
(Score: 1, Funny) by Anonymous Coward on Friday August 27 2021, @01:11AM (1 child)
Boats! Turn roads into canals and everyone has to call eachother Cap'n.
(Score: 0) by Anonymous Coward on Friday August 27 2021, @02:03PM
I thought yours was a silly idea until I got this part, now I am sold!
(Score: 0) by Anonymous Coward on Friday August 27 2021, @11:29AM
Ya, that is the answer, just paint everything.
No worries about the environmental impact of what leeches into the water shed.
Will be far easier to ditch rolling over the Earth for transport and move to sky highways with autonomous robotic drones.