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Comment by derefr | Hacker News Reader

Any reason that airports in super-hot places like that, don't run heat-transfer coils under their runways, to cool them down with a heat pump like a skating rink does? Runways aren't an order-of-magnitude larger in surface area than skating rinks, so it's not cost. And they wouldn't even need to turn on the heat pump for 3/4ths of the year. Do we just not know how to create heat-transfer coils that wouldn't break from the stress of planes landing "on" them?

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Your comment fascinates me. A normal ice hockey rink is 1,800 square meters. The biggest indoor ice rink in the US is the Schwan Super Rink = 28,000 sqm which consists of 8 separate rinks.

Yuma's 4 runways total 543,000 sqm. At midday those runways are absorbing 543MW of energy from the Sun. So that might require 100-200KW of electricity to run the heat pumps. And then you still need somewhere to dump the heat.

In short, I think the reason they don't cool runways is due to the cost.

There's a ton of comments on HN like this. A quick brainstormed "why don't they just.." as if cooling a runway, building a subway, conducting space travel or doing anything else bound by physics is as trivial just because it is conceptually simple. Might as well ask why you can't ski in your backyard in London because after all it is trivial to add some pipes to your refrigerator.

Also I don't know of any skating rinks that operate outdoors in summer, or to use a more favourable example, something like lowering a surface temperature from 20C to -5C (an ice rink, indoors) vs lowering a surface temperature from 80C to 55C (an assumption for a runway, outdoors). Even Dubai, a major transport hub, much hotter than UK even this week, with cheapish energy costs, little public debate uses other mitigations such as runway materials and scheduling many takeoffs for 2-5AM (there are many costs due to high temperature besides runway degradation).

Then we wonder why when it's hot, it's really bloody hot at airports. Is that sum really right? that an airportsworth of tarmac is like a whole power station pumping its entire output into ground heat? because it looks right to me and it seems like the easy, sensible option is just to rip up the airport...

Isn't a large part of electricity production around making things hot to drive turbines?

Airplanes are very heavy so this may not be physically possible, but if you could run coolant pipes under runways, couldn't that captured heat be used in energy production elsewhere?

Yes. You could heat fluid and use it to generate electricity as you can assume the runway is hotter than the ambient air. But if you look at other solar thermal power stations [0] you can see that they generally use concentrators to get the working fluid very hot for more efficient operation. So a runway based system probably wouldn't be economical even if it were good reuse of space.

0 - https://en.wikipedia.org/wiki/List_of_solar_thermal_power_st...

I’d just douse them with water. It’s not like UK airports and pilots can’t handle wet runway landings.

Hm. An Olympic ice rink is 30mx60m, or 1800m^2. The "largest ice arena complex in the world" (https://en.wikipedia.org/wiki/Schwan_Super_Rink) is 28,000m^2 but has 8 Olympic ice rink, sort of.

Yuma International/MCAS has roughly 540,000m^2 of runway (plus taxiways).

I imagine skating rinks in temperate/hot places are indoors and well insulated. Your solution would work well for an indoor runway.

> Runways aren't an order-of-magnitude larger in surface area than skating rinks,

International hockey rinks are 30m by 60m. My local airport, which isn't that big as far as these things go, has two runways each of size 45m by 2200m. That's 55x larger per runway.

They either use concrete or have different asphalt blends that handle higher temperatures.

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