Cybertruck Will Distill Water, Hints Musk!

[TheDarkRanger]

He's been discussing his goal to make quiet home HVAC with HEPA & water distillation system on twitter and followed up with this tweet suggesting that "Maybe Cybertruck will have it …"

Obviously, this feature would be ground breaking in a vehicle and would make the Cybertruck even more useful for overlanding and camping. Imagine powering your campsite with the Cybertruck while distilling water for drinking and cooking.

This is such great news. My ranch's water has a little too much iron for human enjoyment (cows, prairie dogs, and pronghorn don't seem to mind) but if I distill that water from my CyberTrucks (ordered 2) that's yet another game changer for me,

Not to be greedy, but with all that extra electricity on-board, we might as get a desalination-mod-option, while Elon's at it. Next big global shortage on Earth, will be access to freshwater. Then we are only a step away from electrolysis, might as well start practicing and perfecting the truck sized tech that can can split water in Hydrogen and Oxygen.

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[ajdelange]

As noted in an earlier post there won't be any distillation because of the very high energy utilization relative to RO in addition to which RO systems are much simpler. I'll also point out that RO and desalinization are the same thing and that there are portable RO units available for campers/boaters today. It seems unlikely that enough people would want this that it would be offered as an option by Tesla. Perhaps aftermarket but as noted these already exist.

 

[Curacars]

Distilling water requires a heat and cooling source which makes heat pumps ideal for adaptation. You could just distill the water that condenses from the coils to feed the system. It'd make water without having to add anything. There wouldn't be much, if any, residue as condensed water is pretty pure.

I think you're correct, I think Elon is just talking about catching the condensation water that comes from running the AC, so when you are running you car in a high temperature environment and get stuck or something you get a liter of water to stay alive. Probably beats drinking your own urine.

 

[TyPope]

I think you're correct, I think Elon is just talking about catching the condensation water that comes from running the AC, so when you are running you car in a high temperature environment and get stuck or something you get a liter of water to stay alive. Probably beats drinking your own urine.

Probably?!?!?

 

[ajdelange]

Let's keep in mind that there won't be any condensate in xeric locales and that condensate from air conditioning systems is generally pretty yucky. Check what comes out of your home A/C system.

 

[Ehninger1212]

Let's keep in mind that there won't be any condensate in xeric locales and that condensate from air conditioning systems is generally pretty yucky. Check what comes out of your home A/C system.

Water condensation is pretty pure actually. As long as you can keep the collection system clean i wouldn't hesitate to drink it, especially in a pinch. What Tesla is wanting to do with there HVAC water collection in Homes is not revolutionary, but i know Tesla will make the process more simple and thus it will become more common. Rice University here in Texas collects 15 gallons per minute from one of there buildings, i have heard from the engineers that they wouldn't hesitate to use it a potable water however they currently pump it back into the buildings cooling system.

 

[Blue Steel]

I work in HVAC, a typical home AC will generate about a gallon every 4 hours during hot months. That’s in the PNW where humidity is low. Probably generates a lot more water in the South.

And yeah, a lot of customers worry about the water being toxic and being drunk by the their pets or plants, but it’s perfectly fine.

 

[ajdelange]

Yes, the condensed water is pretty pure. It's the stuff that grows in it (e.g. Legionella) that makes it yucky. Ever notice that slightly musty smell that enters the cabin when the A/C is first turned on? That's because the air that flows over the heat exchanger contains dust, salt crystals, mold spores, bacteria etc and they wind up in the condensate. Were the exchanger scrubbed periodically and the collected water filtered (including carbon block) I wouldn't have a problem with drinking it either. Do we really think Tesla would put such a system in its vehicles?

You pay dearly for that water. In humid places half the load on an A/C system goes to removing water (latent heat) and not cooling air so, in a large building, it might be worth while to try to get some of that energy back as by running that condensate through a high side heat exchanger or spraying it on an outdoor heat exhanger and I expect that is what the Rice people may be doing with it. What else would they do with it? Note that you can increase the efficiency of your home A/C by spraying water on the condenser (outdoor) fins using a kit you can buy which uses the Y wire signal to open a solenoid valve. Edit: Found another one which uses a flap in the outdoor units air stream to open the valve.

What I am really curious about though is what Musk is talking about in this context. Clearly his company has gotten deeply involved in heat pumping technology in the design of the Y's thermal management system and he is probably thinking about the rather large energy savings available in home heating by using geothermal heat pumps. These suck heat out of the ground in the winter and put it back in the summer. But distillation?

Back to the truck: they could collect the condensate, pump it forward and spray it on the radiator up there and in so doing increase the efficiency of the A/C a bit in humid and perhaps even mesic climate areas, But in the desert? No advantage as there is no condensation there (or precious little). I doubt that they would go that far (complexity vs advantage) but they have to do something with the cabin condensate and what they do now is dump it overboard. If you wanted to tap the dump line to bring the condensate into the cabin for whatever reason I guess you could do that but I'm going on record here as recommending against that.

 

[Ehninger1212]

Yes, the condensed water is pretty pure. It's the stuff that grows in it (e.g. Legionella) that makes it yucky. Ever notice that slightly musty smell that enters the cabin when the A/C is first turned on? That's because the air that flows over the heat exchanger contains dust, salt crystals, mold spores, bacteria etc and they wind up in the condensate. Were the exchanger scrubbed periodically and the collected water filtered (including carbon block) I wouldn't have a problem with drinking it either. Do we really think Tesla would put such a system in its vehicles?

You pay dearly for that water. In humid places half the load on an A/C system goes to removing water (latent heat) and not cooling air so, in a large building, it might be worth while to try to get some of that energy back as by running that condensate through a high side heat exchanger or spraying it on an outdoor heat exhanger and I expect that is what the Rice people may be doing with it. What else would they do with it? Note that you can increase the efficiency of your home A/C by spraying water on the condenser (outdoor) fins.

What I am really curious about though is what Musk is talking about in this context. Clearly his company has gotten deeply involved in heat pumping technology in the design of the Y's thermal management system and he is probably thinking about the rather large energy savings available in home heating by using geothermal heat pumps. These suck heat out of the ground in the winter and put it back in the summer. But distillation?

Back to the truck: they could collect the condensate, pump it forward and spray it on the radiator up there and in so doing increase the efficiency of the A/C a bit in humid and perhaps even mesic climate areas, But in the desert? No advantage as there is no condensation there (or precious little). I doubt that they would go that far (complexity vs advantage) but they have to do something with the cabin condensate and what they do now is dump it overboard. If you wanted to tap the dump line to bring the condensate into the cabin for whatever reason I guess you could do that but I'm going on record here as recommending against that.

Yeah, thats why i said they would have to make sure it stays clean (it is done). They have put HEPA filters in vehicles.. i wouldnt put it past them.

You pay dearly to keep your house, building or vehicle cool and comfortable. The condensation run off is a normally wasted by-product. Why not use it?

The water gets pumped back into the system i said, not sprayed on cooling fins or people? That does not work well in Humid climates anyways. The system for most large buildings is not the same as what your house has. These are also not RTU's. They are not Refrigerent based cooling systems, they use water. So Rice uses the water to offset having to use fresh new water from the city water supply.

Geothermal is not efficient for residential use unless you have the space. The wells have to be spaced a certain distance and some places don't allow it because if the well burst you contaminate groundwater, the water being pumped through the system has additives.

Also you have it backwards. Pumping water in front of the radiator (evaporative cooling) would improve cooling in dry climates (Arizona)., Not humid climates (South East Texas).

 

[ajdelange]

You pay dearly to keep your house, building or vehicle cool and comfortable. The condensation run off is a normally wasted by-product. Why not use it?

But what are you going to use it for? It's real value is in that some of the enthalpy of condenstation, which you paid for, can be recovered.

The water gets pumped back into the system i said, not sprayed on cooling fins or people? That does not work well in Humid climates anyways.

Yes, actually it does. The SVP of water at 150 °F is about 4 psia and that of air at 100 °F about 1. Thus if the RH is 100% at 100 °F and the heat exchanger surface at 150 °F there is a 3 psi gradient and the spray will clearly evaporate carrying superheat away with it.

The system for most large buildings is not the same as what your house has. These are also not RTU's. They are not Refrigerent based cooling systems, they use water.

How do they use water? Swamp cooling? Isn't Houston much too humid for that? Is it a phase change system (water is otherwise known as R718)? Now Cornell uses cold water from Lake Cayuga to air condition much of its campus. Is this system taking water from the gulf? I wouldn't begin to know how to design a phase change system based on water but it's clear the low side would have to be at tenths of a psia in order to get boiling near 50 °F and, presumably, the high side would have to be at about 4 psig for 150 °F exhaust which would permit transfer to ambients above 120 °F. In any case using cool condensate to remove superheat could save energy (perhaps as much as 50 BTU/Lb if 50 ° superheat could be transferred back to the condensate.

While I am very interested to know how the Rice system works my he primary concern here is the CT. It will no doubt use R134a which definitely could benefit from desuperheating by spraying the condensate (about 10 BTU/lb for 15 ° superheat removed) on the condenser. This is where the value in the CT cabin AC condensate lies but clearly you won't get much benefit in dry climates.

Geothermal is not efficient for residential use unless you have the space.

Geothermal is very efficient for residential but of course if you don't install it for whatever reason you won't obtain the benefit.

The wells have to be spaced a certain distance and some places don't allow it because if the well burst you contaminate groundwater, the water being pumped through the system has additives.

Individual jurisdictions have their individual codes but with vertical wells not much space is required. There are lots of installations on residential sized lots. Then there is, of course, the possibility that the wells could be installed under the house. Don't know if codes allow this. The main problem with geo is the expense (augmented when vertical wells are used). I am certain that this is what Musk is talking about as it is in alignment with his overall goal of eliminating fossil fuel use. Consuming 1 kW of electricity one gets about a quarter ton of heat with an electric heater. With a geo heat pump he gets about a ton. If half or more of that kW comes from solar panels then clearly that's a pretty cheap (and clean) ton. Geo pumps are the neatest thing since sliced bread for residential heating. The problem is the cost but that has never bothered Elon. I think he is hoping that just as he has gotten the cost of a BEV down to near parity with ICE he will get the cost of geothermal home HVAC to parity with A/A and pure electric heat. He's going to have to come up with a less expensive way of sinking wells. Maybe the Boring company ties in.

Also you have it backwards. Pumping water in front of the radiator (evaporative cooling) would improve cooling in dry climates (Arizona)., Not humid climates (South East Texas).

Nope. Works in either as I explained above. In the xeric climate, though, you wouldn't bother with the heat pump. Just spray the water on a fibre blanket and blow air over it and into the house. In case you aren't familiar with this the device is called a "swamp cooler". Haven't seen one in quite a while though. SVP of water at 100 °F is about 1 psia as noted above but in the xeric environment the vapor pressure of water in the air is much lower than that but clearly the gradient can't be more than 1 psia. This is less than the gradient with the 150 ° condenser in a refrigerant based system (3 psia) but it does work (and uses much less electricity).

To get back to the auto application: these were used in cars too. In some parts of Australia distances were sometimes expressed in units of "waterbags" though more frequently in "tinnies".

One last comment: The additive in geo groud loop water is propylene glycol which is GRAS.

 

[TyPope]

But what are you going to use it for? It's real value is in that some of the enthalpy of condenstation, which you paid for, can be recovered.

Yes, actually it does. The SVP of water at 150 °F is about 4 psia and that of air at 100 °F about 1. Thus if the RH is 100% at 100 °F and the heat exchanger surface at 150 °F there is a 3 psi gradient and the spray will clearly evaporate carrying superheat away with it.


How do they use water? Swamp cooling? Isn't Houston much too humid for that? Is it a phase change system (water is otherwise known as R718)? Now Cornell uses cold water from Lake Cayuga to air condition much of its campus. Is this system taking water from the gulf? I wouldn't begin to know how to design a phase change system based on water but it's clear the low side would have to be at tenths of a psia in order to get boiling near 50 °F and, presumably, the high side would have to be at about 4 psig for 150 °F exhaust which would permit transfer to ambients above 120 °F. In any case using cool condensate to remove superheat could save energy (perhaps as much as 50 BTU/Lb if 50 ° superheat could be transferred back to the condensate.

While I am very interested to know how the Rice system works my he primary concern here is the CT. It will no doubt use R134a which definitely could benefit from desuperheating by spraying the condensate (about 10 BTU/lb for 15 ° superheat removed) on the condenser. This is where the value in the CT cabin AC condensate lies but clearly you won't get much benefit in dry climates.


Geothermal is very efficient for residential but of course if you don't install it for whatever reason you won't obtain the benefit.


Individual jurisdictions have their individual codes but with vertical wells not much space is required. There are lots of installations on residential sized lots. Then there is, of course, the possibility that the wells could be installed under the house. Don't know if codes allow this. The main problem with geo is the expense (augmented when vertical wells are used). I am certain that this is what Musk is talking about as it is in alignment with his overall goal of eliminating fossil fuel use. Consuming 1 kW of electricity one gets about a quarter ton of heat with an electric heater. With a geo heat pump he gets about a ton. If half or more of that kW comes from solar panels then clearly that's a pretty cheap (and clean) ton. Geo pumps are the neatest thing since sliced bread for residential heating. The problem is the cost but that has never bothered Elon. I think he is hoping that just as he has gotten the cost of a BEV down to near parity with ICE he will get the cost of geothermal home HVAC to parity with A/A and pure electric heat. He's going to have to come up with a less expensive way of sinking wells. Maybe the Boring company ties in.

Nope. Works in either as I explained above. In the xeric climate, though, you wouldn't bother with the heat pump. Just spray the water on a fibre blanket and blow air over it and into the house. In case you aren't familiar with this the device is called a "swamp cooler". Haven't seen one in quite a while though. SVP of water at 100 °F is about 1 psia as noted above but in the xeric environment the vapor pressure of water in the air is much lower than that but clearly the gradient can't be more than 1 psia. This is less than the gradient with the 150 ° condenser in a refrigerant based system (3 psia) but it does work (and uses much less electricity).

To get back to the auto application: these were used in cars too. In some parts of Australia distances were sometimes expressed in units of "waterbags" though more frequently in "tinnies".

One last comment: The additive in geo groud loop water is propylene glycol which is GRAS.

I'm just going to say this here in the public forum. I like to read your posts. Some of it goes over my head (IE here, not EE) but I enjoy the level of answers you give. Thank you for your posts.

 

[Ehninger1212]

But what are you going to use it for? It's real value is in that some of the enthalpy of condenstation, which you paid for, can be recovered.

Yes, actually it does. The SVP of water at 150 °F is about 4 psia and that of air at 100 °F about 1. Thus if the RH is 100% at 100 °F and the heat exchanger surface at 150 °F there is a 3 psi gradient and the spray will clearly evaporate carrying superheat away with it.


How do they use water? Swamp cooling? Isn't Houston much too humid for that? Is it a phase change system (water is otherwise known as R718)? Now Cornell uses cold water from Lake Cayuga to air condition much of its campus. Is this system taking water from the gulf? I wouldn't begin to know how to design a phase change system based on water but it's clear the low side would have to be at tenths of a psia in order to get boiling near 50 °F and, presumably, the high side would have to be at about 4 psig for 150 °F exhaust which would permit transfer to ambients above 120 °F. In any case using cool condensate to remove superheat could save energy (perhaps as much as 50 BTU/Lb if 50 ° superheat could be transferred back to the condensate.

While I am very interested to know how the Rice system works my he primary concern here is the CT. It will no doubt use R134a which definitely could benefit from desuperheating by spraying the condensate (about 10 BTU/lb for 15 ° superheat removed) on the condenser. This is where the value in the CT cabin AC condensate lies but clearly you won't get much benefit in dry climates.


Geothermal is very efficient for residential but of course if you don't install it for whatever reason you won't obtain the benefit.


Individual jurisdictions have their individual codes but with vertical wells not much space is required. There are lots of installations on residential sized lots. Then there is, of course, the possibility that the wells could be installed under the house. Don't know if codes allow this. The main problem with geo is the expense (augmented when vertical wells are used). I am certain that this is what Musk is talking about as it is in alignment with his overall goal of eliminating fossil fuel use. Consuming 1 kW of electricity one gets about a quarter ton of heat with an electric heater. With a geo heat pump he gets about a ton. If half or more of that kW comes from solar panels then clearly that's a pretty cheap (and clean) ton. Geo pumps are the neatest thing since sliced bread for residential heating. The problem is the cost but that has never bothered Elon. I think he is hoping that just as he has gotten the cost of a BEV down to near parity with ICE he will get the cost of geothermal home HVAC to parity with A/A and pure electric heat. He's going to have to come up with a less expensive way of sinking wells. Maybe the Boring company ties in.

Nope. Works in either as I explained above. In the xeric climate, though, you wouldn't bother with the heat pump. Just spray the water on a fibre blanket and blow air over it and into the house. In case you aren't familiar with this the device is called a "swamp cooler". Haven't seen one in quite a while though. SVP of water at 100 °F is about 1 psia as noted above but in the xeric environment the vapor pressure of water in the air is much lower than that but clearly the gradient can't be more than 1 psia. This is less than the gradient with the 150 ° condenser in a refrigerant based system (3 psia) but it does work (and uses much less electricity).

To get back to the auto application: these were used in cars too. In some parts of Australia distances were sometimes expressed in units of "waterbags" though more frequently in "tinnies".

One last comment: The additive in geo groud loop water is propylene glycol which is GRAS.

I dont really want to continue to get into this back and fourth with you right now. I work with this stuff everyday, i know what works efficiently and what does not. Also i never said would NOT work i said it doenst work very well.

One thing is for sure.. if it is so dumb as your are claiming.. why is one of the smartest people alive right now working on creating a product that does this?

 

[ajdelange]

I dont really want to continue to get into this back and fourth with you right now.

Your time is your time to use as you see fit but I would ask for one more indulgence. I'd really, really like to know the basic principle on which the Rice system works. No details. Just where the "cold" comes from in a system that doesn't use refrigerant.

I work with this stuff everyday, i know what works efficiently and what does not. Also i never said would NOT work i said it doenst work very well.

I personally would not have the temerity to make such a claim. But here's a simple test: can you interpret a p -H diagram? I don't want an answer to that. It's for you alone to consider. If the answer is no then its unlikely that you will be able to understand why spraying condensate on a condenser does what it does. If the answer is yes then rethink your statement that it wouldn't work very well in a humid environment (and even better in a dry one).

One thing is for sure.. if it is so dumb as your are claiming.. why is one of the smartest people alive right now working on creating a product that does this?

Does what? Distill water in a car? Start by telling us who this smart person is. It is not Elon Musk unless he has said something specific about this in some place or other. What he is quoted as saying here is

[/QUOTE]"I’m dying to do super efficient, quiet home HVAC with HEPA & water distillation. It’s weird, but I really want to do it."[/QUOTE]

This doesn't say anything about distilling water in a car. This is, of course, the internet and so someone is going to grab this and interpret it as meaning that Tesla is going to put a still in the CT. Common sense alone says this is ridiculous. Elon said he wanted to do super efficient, quiet, home HVAC with HEPA & water distillation". Even in realizing that he was speaking of the home environment we have to also take into account that this was just a casual remark in an interview as "super efficient" and "water distillation" do not belong in the same sentence. As I have pointed out here before RO is a much more efficient way to purify water than distillation and easier to maintain thus what he meant to say was that he wanted to get into home appliances that do things like purify water and condition the home's air. That makes sense in terms of the company's overall goal. So what is a super efficient, quite home HVAC with water purification and HEPA? Well, as explained in a previous post it is a geothermal (to include loops ducked in lakes or ponds) based heat pump with HEPA filters in the ducts and an RO system. Would such a system recover the condensate for desuperheating? No, probably not but many systems do use well or mains water to desuperheat thus, in cooling mode, recovering some of the latent heat load into the house's hot water system.

 

[ajdelange]

Never mind my request. The recaptured condensate is used as makeup water for the system's cooling towers and the diagram in the article (about the Rice system specifically) I found makes it clear that the cooling towers are in a conventional refrigerant based arrangement (evaporator, compressor, condenser). As the water gets evaporated (the article strongly implied that the towers are the wet type, even though that "doenst work very well" in a humid place like Houston) some of the enthalpy of condensation is repaid as it would be if sprayed directly onto condenser fins in an automotive system. That energy recovery from condensate is something I had never thought of before and that's why I'm so hyped on this.

Another interesting part of the article about the Rice system pointed out that air conditioning systems are "Legionella amplifiers" to the extent that recovered condensate must not be used even for flushing toilets without treatment.

 

[TyPope]

Your time is your time to use as you see fit but I would ask for one more indulgence. I'd really, really like to know the basic principle on which the Rice system works. No details. Just where the "cold" comes from in a system that doesn't use refrigerant.

I personally would not have the temerity to make such a claim. But here's a simple test: can you interpret a p -H diagram? I don't want an answer to that. It's for you alone to consider. If the answer is no then its unlikely that you will be able to understand why spraying condensate on a condenser does what it does. If the answer is yes then rethink your statement that it wouldn't work very well in a humid environment (and even better in a dry one).

Does what? Distill water in a car? Start by telling us who this smart person is. It is not Elon Musk unless he has said something specific about this in some place or other. What he is quoted as saying here is

"I’m dying to do super efficient, quiet home HVAC with HEPA & water distillation. It’s weird, but I really want to do it."[/QUOTE]

This doesn't say anything about distilling water in a car. This is, of course, the internet and so someone is going to grab this and interpret it as meaning that Tesla is going to put a still in the CT. Common sense alone says this is ridiculous. Elon said he wanted to do super efficient, quiet, home HVAC with HEPA & water distillation". Even in realizing that he was speaking of the home environment we have to also take into account that this was just a casual remark in an interview as "super efficient" and "water distillation" do not belong in the same sentence. As I have pointed out here before RO is a much more efficient way to purify water than distillation and easier to maintain thus what he meant to say was that he wanted to get into home appliances that do things like purify water and condition the home's air. That makes sense in terms of the company's overall goal. So what is a super efficient, quite home HVAC with water purification and HEPA? Well, as explained in a previous post it is a geothermal (to include loops ducked in lakes or ponds) based heat pump with HEPA filters in the ducts and an RO system. Would such a system recover the condensate for desuperheating? No, probably not but many systems do use well or mains water to desuperheat thus, in cooling mode, recovering some of the latent heat load into the house's hot water system.
[/QUOTE]
I think I found something that is confusing about the Cybertruck and distilling... Elon tweeted about HVAC for the home and then someone said something about solar panels and then "Maybe the Cybertruck will have it". Have what? Distilling or Solar? It's hard to follow Elon's train of thought.