Heated Runways | TheaterFire

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thomastwiz@reddit

What if you used the cool water to cool a data center and for it to heat it up. Like a giant water cooled pc

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rocketshipkiwi@reddit

Great idea but how would it work in the summer?

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thomastwiz@reddit

Didn't think of that. Good point.

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satyricom@reddit

The Japanese use heated ground water (hot springs? Geothermal?). Here’s a [cool vid](https://youtube.com/shorts/-MHChHp8g_4?si=0R0y2DeSein-fVUm)

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This is not a crazy idea, [https://www.heatedway.ca/geothermal-heated-driveway/](https://www.heatedway.ca/geothermal-heated-driveway/) . I don't know if the numbers make sense to do this for runways, because large airports are going to be worth running a natural gas line to, and natural gas is cheaper. Also Google, apparently heated runways are not currently a thing. The energy costs are apparently too high to be worth it over plowing and deicing compound the runway.

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JshWright@reddit

Note that's a heat pump, not just "circulating water" that OP is suggesting.

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AwarenessGreat282@reddit

Note: geothermal only means using the earth's heat. It does not mean just hot water. If a pump is used, it is technically still geothermal because the earth's temp, 50F underground, is heating the water.

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JshWright@reddit

I never said that wasn't geothermal... I said it was a heat pump. There are two primary types of heat pumps in use, air-sourced and ground-sourced (i.e. "geothermal"). Both use energy to move heat energy around. It's much more efficient than simply burning fuel or heating a resistor with electricity, but it's still significantly more involved than just pumping some water around.

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AwarenessGreat282@reddit

My reply was about your statement that isn't what the OP said. Just circulating underground water above ground where it will dump heat is in fact, geothermal. You stated "that is a heat pump, not just circulating water".

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JshWright@reddit

I was replying to a comment that included a link a heat pump system used to heat driveways, as opposed to OPs plan to just circulate water. I never used the word "geothermal" at all, let alone claiming either approach was or wasn't "geothermal".

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AwarenessGreat282@reddit

And that article did exactly what the OP described.

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JshWright@reddit

No, it didn't... OP is describing simple circulation of water. That is very different from using water as the heat energy source for a heat pump. Circulating water could \_maybe\_ get you 10C. That's not going to be enough to keep up with snowfall and subzero temps. A heat pump on the other hand can leverage the latent heat in that water to produce temps in the 60-70C range (or higher, but efficiency starts to drop significantly at higher temps)

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AwarenessGreat282@reddit

Uhhh, no. If you do nothing but just circulate water that goes underground, it *will* heat the pavement. And that is how geothermal heating works. The heat is dumped into the pavement, goes back underground, gets heated up again, then circulates back up to repeat the cycle. How do you think geothermal with radiant floor heating works?

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JshWright@reddit

I really don't understand what you're missing here... Do you understand what a heat pump is? The system linked above (in the comment I initially replied to) is a heat pump. It it basically an air conditioner running in reverse, cooling down the water from underground and then releasing the heat obtained from that process into the structure. It is not simply pumping a loop of water. It's a loop of water hooked up to a heat exchanger that is then attached to a compressor and condenser loop. Pumping a loop of water is a thing you could do, but in most of the world it wouldn't get you very much in terms of temperature (10, \_maybe\_ 15C), and wouldn't be enough to keep up with snowfall on a runway. "Heat pump" and "pumping water from underground" are not the same thing.

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AwarenessGreat282@reddit

lol...have you never seen a heated walkway or driveway or radiant floor heating? It's just a circulation pump. That's it. That's how it can be so economical. You just run a simple pump.

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JshWright@reddit

The issue is the source of the heat. In both of those applications the heat is coming from somewhere (burning fuel, running electricity through a resistor, or... in the example linked above... a heat pump). I'm not saying you can't use water circulating to heat a surface. You very obviously can. What I'm saying is that you won't get water that hot enough to keep a runway clear in the winter by simply passively pumping the water deep underground (unless you're in a few very specific locations) and you would instead need to add some equipment with additional cost (like, a "heat pump", a term I'm increasingly convinced you don't know).

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AwarenessGreat282@reddit

What are you talking about? The ground is \~50F once you are below the frost line. Water run through tubes that low will heat to 50F. When it comes back up, it will release that heat to the pavement of the driveway, get colder then go back down to get hot again. Granted, the expense to do it to a whole runway would be enormous mostly because of the way they are built but 100% doable with nothing but lines run through the pavement via pump.

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JshWright@reddit

50F is not going to be be enough to keep up with subzero temps without moving a truly stupendous volume of water. From a practical perspective, you would need a heat pump in order to boost temps enough to accomplish this.

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AwarenessGreat282@reddit

Nope, you don't. Granted, due to the scale of a runway and the massive weight carrying requirement, it's not practical, but it is doable.

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Frederf220@reddit

Arguaby it is a heat pump, just not a *phase change* heat pump.

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SoylentRox@reddit

Fair. Circulating water like that would only work somewhere like Iceland....where there is relatively little air traffic.

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buffalo_0220@reddit

This is not surprising. Runways are long and wide, lots of surface area. I suspect most areas either don't get enough snow to make it worthwhile, or they get so much that the system will be unable to keep up. This technology already exists, some high end homes will heat the driveway to help keep it clear. If it was at all economical the airport would install it.

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Salty_Significance41@reddit

Some sports stadiums use similar tech to keep their field clear. Kansas City Chiefs, for example

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buffalo_0220@reddit

I had forgot about that. I recall a story about Green Bay's field. They need the system, partly to keep it clear of snow, but also to keep the natural grass growing and serviceable in the cold weather.

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GotGRR@reddit

I suspect the thickness of the asphalt is the biggest issue. That's a lot of mass to heat and if you run pipes near the surface, you create structural problems

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DblDtchRddr@reddit

I think that would be the biggest problem. A normal home driveway, at most, needs to support 3 tons. A small prop plane, like a 172, is about the weight of a smalll car, but a private jet jumps straight into the tens of tons. A 777's operating empty weight is 185 tons. On top of that, I can't say I've ever seen someone *drop their car* onto their driveway. Planes...well, that's kinda how they land. Even a buttered landing puts a sudden impact on the runway surface beyond the plane's weight. Even if the runway surface itself doesn't get damaged, a cracked pipe under the concrete shuts down that runway for a while - they'll have to jackhammer up the old concrete, fix the pipe, then lay, cure, smooth, and blend new concrete.

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PatchesMaps@reddit

Plus you're adding a lot of risk if it malfunctions during takeoff/landing operations.

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SoylentRox@reddit

If it stops working ice isn't going to build up that fast, but yes you would need to make the runway able to drain - surface slightly sloped so water drains off it, or channels in the surface - whatever it is you can do without violating the specs for a runway.

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Any-Bluebird7743@reddit

dont people bitch about the cost to fly? or no.

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PatchesMaps@reddit

I wasn't talking about simply if it stops working but if a pipe ruptured.

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SoylentRox@reddit

Pipes are under the runway and the working fluid is antifreeze. Nothing particularly bad will happen.

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Successful-Name-7261@reddit

There is a potential problem with the water left behind by the melt cycle. Water can be slippery and, if it gets extremely cold, frozen water is ice is horrifically slippery!

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SoylentRox@reddit

Right you would have to design the heated runway to basically just stay slight above freezing all the time.

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Any-Bluebird7743@reddit

oh thanks genius. but youll never ever complain about how much a flight costs, right?

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reddit_pug@reddit

Gonna need a nuclear reactor. They need to cool their water anyway.

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satyricom@reddit

Japan also uses a misting system instead of rock salt to keep snow of roads.

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mrkstr@reddit (OP)

We have a couple of bridges in our area that uses a misting system. I think they spray saltwater on the roads? Some kind of anti-Icing agent anyway.

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satyricom@reddit

In Sweden (? Possibly Denmark or Norway - Nordic country where they commonly use geothermal heating), they run it under sidewalks to keep them free of snow.

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mrkstr@reddit (OP)

See, this is what I'm talking about

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skibbin@reddit

Snow is a good insulator. If you have 6ft of snow on a runway, then turn on the heat, you're going to be waiting a long time for it to all be gone. It's far quicker to just push it all out of the way

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Tomj_Oad@reddit

Geothermal is very localized and uncommon. I don't know if anyone actually does but Google says Amsterdam and Zurich are researching it

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Purple-Measurement47@reddit

My uncle has a geothermal loop for his house, they’re quite common, unless you’re referring to dig deep enough to properly heat. How most work is they just go below the frost line, and use a heat pump to move energy out.

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ThellraAK@reddit

Yeah, but I don't think you'd need all that if the goal was to get to 33F

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Dawn_Piano@reddit

Even though 33°F is above the melting temp of water, you need to go a little warmer to melt snow effectively

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Fireproofspider@reddit

>Geothermal is very localized and uncommon. What do you mean localized? If you dig deep enough (a few feet down, forget the details) anywhere on earth you get fairly stable temperature that can be used to heat and cool things.

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Tomj_Oad@reddit

Nah. Yes it gets hotter as you go down, but that's waaaay down. And that's not geothermal as it's meant in this kind of thing You need rock close to the surface hot enough to boil water to do real geothermal power and heat

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AwarenessGreat282@reddit

Huh? You can have a trench dug 10ft deep, lay coils and you will have geothermal system.

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Fireproofspider@reddit

That's not what I mean. If you get below where the ground is frozen, the ground temperature would be above 0 and that would be enough to melt ice over time through heat exchange. I have a friend who uses this to heat up his rooms in the winter and cool them in the summer. I think he dug about 6ft to bury the water loop.

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JshWright@reddit

Your friend is almost certainly using a heat pump. The temps you get at that depth are warm enough to operate a heat pump, but not "melt ice just by circulating water" temps.

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Purple-Measurement47@reddit

which uses a ground loop to pull geothermal energy, using a heat pump.

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JshWright@reddit

Yes...? Isn't that what I said?

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Fireproofspider@reddit

It's just a water loop. Basically it's 3-4m down, and temperature is stable around 10-15oC. So he runs water on a long water loop underneath his property and uses it to heat up his rooms to that temp in the winter. As some other poster said though, if you needed to warm up a driveway, you'd need a large loop and a pump to move the water around and it might not be worth it financially.

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Several-Judgment4917@reddit

I heard a company is inventing a new way to dig much further down much further using plasma or something

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buildyourown@reddit

You get stable temps that you can use for a ground loop heat pump, but that takes electricity. For a runway, it's way cheaper to just plow it with trucks. Geo thermal is when you have actual hot water that you can tap. Iceland uses it in power plants and to heat every building.

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duskfinger67@reddit

Geothermal energy can be harvested almost anywhere. Some places, such as Iceland, have sufficient volcanic activity that boiling water is freely available for direct heat exchange, and I agree that it is localised. But a ground-source heat pump can harness geothermal energy pretty much anywhere, you will struggle to make it cost-effective in some places due to the composition of the ground, but it is still possible. I agree that ground source heat pumps are slightly more complicated than OP's proposed "circulated water from deep down", but the principle is perfectly viable.

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feel-the-avocado@reddit

It would be quite expensive for the large amount of area that needs to be heated. If we take a standard residential driveway, they typically advise about 500 watts per square metre. The runway at our local airport serving a population of 150,000 people, one of the taxiways and half of the gate parking area - so to accommodate 6 aeroplanes is about 4,500 square metres. Thats 2.25 megawatts of electricity. In terms of cost, if they negotiated a very good rate with electricity retailers, it would cost about $450 per hour to run. It would probably take about 4 hours to start up and melt any snow on top though. So i could imagine it might be useful during bad weather that flights could be delayed to arrive within a window of a couple of hours so they only have to run it for say 5 hours. If its a larger city then maybe they could offer passengers the option of rescheduling for a slightly more expensive flight if the airport needed to charge each passenger an extra $10 per person arriving to run the heaters. You mention geothermal heating - in many places its just not feasible as they would need to drill incredibly deep to reach heat. It really only works in areas which we would consider to be geothermally active zones - where there are geothermal features near the surface, they wont have to dig too deep to reach heat if the airport is nearby.

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Penis-Dance@reddit

Cheaper to plow and de-ice.

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kensteele@reddit

This right here; no company is ever going to spend that kind of money on tech. That's why we're still in the sam spot as we were in the 90s, 80s, 70s, even the 60s. Nothing will ever change.

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rademradem@reddit

The cement used for runways is extremely thick. You cannot just put pipes with circulating coolant under it like you can for a driveway. The heat would have to pass through a huge thick mass of cement before that heat gets to the surface to melt the snow. If the pipes are embedded into the cement rather than under it, it would weaken the runway strength which also cannot be done.

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NUMBerONEisFIRST@reddit

The sidewalks at work are heated.

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The_ApolloAffair@reddit

This sort of thing is possible, but it requires a tremendous amount of maintenance and tubing. [Holland, Michigan has a snowmelt system that covers 10 acres of roads and sidewalks around the downtown.](https://www.holland.org/snow-free-holland/) It was funded in large part by private donors and business taxes. But really the only thing making it viable is the fact that there is a city owned power plant nearby so they can get waste heat for free. Without that or geothermal (rare to find easily), heating water for snowmelt is incredibly expensive.

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shootdowntactics@reddit

Not sure if you can build a solid enough runway slab while introducing all the little pipes that would be needed.

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PatchesMaps@reddit

You can already get a heated driveway. The problem isn't the feasibility but the practicality. A heated runway would add cost during construction,operation,and maintenance while actually increasing risk since a broken pipe under the runway would require the runway to be shut down while the problem is located, excavated, and repaired. Oh and the biggest deal breaker of all, what if a steam pipe broke underneath the runway while a plane was taking off or landing? It could potentially lead to the death of hundreds of people.

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sidaemon@reddit

We hated geothermal roads in the town I grew up in and it was cool. It was just downtown but we'd get a fair amount of snow there and downtown would be totally free of snow!

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nanerzin@reddit

Those systems work very well but it is all extra heat coming off boilers in buildings. Makes tons of sense, might as well use the 50°f water to melt snow since it will be reheated again for boilers anyway. Cold areas that stay below freezing for weeks don't use the excess heat because the cost to reheat the water doesn't make financial sense. I had to excavate steam lines in ND and MN. They were typically 2-5' deep and had an insulation cap to retain heat.

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sidaemon@reddit

These were straight up geothermal. We even had a house with geo heat and it was AMAZING. My wife could cook the house at like 80 all winter long and the bill would be like a hundred bucks when it was 20 degrees outside.

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trighap@reddit

I am not an expert at all, but I do know that runways are complex things that have a lot of requirements already, such as handing extremely significant weights, extreme wear and tear, constant cleaning (airliners leave significant amount of their tire rubber all along the runway), etc. They might not easily handle additional hardware such as heated wires or pipes.

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RainbowCrane@reddit

Zero actual physics math involved here, but yes, I have to imagine runways are rated for an impact force of several times the actual stationary weight of a max load plane, just to ensure that in the event of an uncontrolled landing the runway doesn’t collapse into some underground infrastructure and worsen the accident. I know that the oft-cited reason for slow changes to aircraft design is that safety regulations are written in blood, I’m sure that applies to runways as well.

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ATLien_3000@reddit

The airport snow plow drivers' union is going to fight that one tooth and nail.

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AckerHerron@reddit

A 2500m x 20m runway is about 15 acres of surface area. That’s an extremely large surface area to heat.

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Dirtbagdownhill@reddit

Sure but where does the water go if there's snow and ice surrounding it. Eventually you have a polished ice landing strip surrounded in icy dams

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soulmatesmate@reddit

My subdivision and like everywhere in the USA has this system of pipes for collecting and draining away rainwater. It works even in winter with snowmelt.

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Dirtbagdownhill@reddit

I also live somewhere with drains but they are not infallible, the roads are often terrible when the temps are right around freezing but involve thawing and refreezing. It wouldn't be acceptable for a landing airplane, that's why there are specialized machines to clear runways

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cjt09@reddit

It’s worth noting that runways have a *huge* surface area. The airport near me has over half of a square kilometer of paved runways. With any sort of notable snowfall, clearing the runways would require many gigawatt-hours of energy to melt all the snow. That is a *lot* of energy, and to actually be useful you also need enough power to deliver all that energy over a reasonable timeframe.

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Shrimp_Richards@reddit

They do something similar to this at the transit station by my old work. It basically stops being effective if it snows more than about .5in/hr and/or is really cold. Could be useful in addition to regular plowing but at that point you're adding millions to a project that you'll still end up having to plow. I imagine from an engineering perspective you'd have to bury the pipes deep into the runway to keep them sturdy enough for planes landing which would also decrease their effectiveness.

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Not_me92@reddit

Airport expert here. Not going to happen. Mostly due to strength requirements, mixing of concrete and asphalt pavement types, and cost. Plows, brooms, and chemicals such as alcohol and E-36 are cheaper and proven to work. Some airport have looked at putting deicing chemical sprayers around but I don’t know of an example of them on an airfield.

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nhorvath@reddit

runways are really big this would be prohibitively expensive to run. and you still need the snow removal equipment and personnel for the ramps and taxiways.

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Prof01Santa@reddit

You want to use steam a little above atmospheric pressure. Surround it with the heavy concrete runway, and you can keep the runway temperature at 35-40°F. It will be expensive.

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Riptide360@reddit

Ohare has a limited heated bridgeways. Oslo has limited geo thermal terminal heating. As climate change exacerbates harsher winters and hotter summers the use of heating and cooling systems for runways will likely grow, so not a crazy idea at all.

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lawnmower303@reddit

They do do this in places. Iceland, I believe. They also have pipes running under the footpaths to keep them free of ice in the winter. Does help that they have an abundance of geothermal heating, of course.

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