5 ms·

Hey everyone, I'm around for a bit to answer any questions you might have :)

jat850 11y ago
How does it taste? :) And what plans do you have for tackling the pH and turbidity level issues? edit Missed the note on turbidity. I'm guessing a follow-up test might show that resolved?
- clayrichardson 11y ago
  It tastes surprisingly good, although not as good as some of the Ozarka bottled spring water I've had, but almost. We're going to try and find another remineralization filter, or we might add electrolyte mix instead. The second lab report was from the isolation of the remineralization filter, and we showed that the turbidity was indeed added by that filter.
  - jat850 11y ago
    That's great! I had missed the test0 procedure text, but it did seem clear after reading it.
zzalpha 11y ago
So... this is basically a dehumidifier. Dehumidifiers typically use some sort of air cooling to reduce water below the dew point to draw water out of the air. And that takes a lot of energy. So what is the purpose of this device? It can't be to provide potable water to areas without it, since those same areas are likely to lack a significant source of power. I don't mean to be overly cynical, but I feel like I'm missing something here.
- exhilaration 11y ago
  https://en.wikipedia.org/wiki/Atmospheric_water_generator https://en.wikipedia.org/wiki/Atmospheric_water_generator I thought the same thing but reading their site led me to the above Wikipedia page which suggests there are other ways to do it than just dehumidification but I'm not sure what method they're using.
  - clayrichardson 11y ago
    For simplicity and adoption, we're utilizing mechanical refrigeration since parts and HVAC(R) skills have been widespread over the past several decades. EDIT: Spelling is hard. Clarification is hard.
- homero 11y ago
  It has Wi-Fi
  - clayrichardson 11y ago
    Indeed. Ideally, we'd like to include a mini-datacenter module, allowing for data storage, streaming, and processing. We'd like to be able to gather metrics from these machines all over the world, and identify trends in things such as the weather, water production and consumption, efficiency, power generation and carbon sequestration, as well as identify opportunities to improve the operation of the machines through software updates.
- clayrichardson 11y ago
  Indeed, it is energy intensive. That can be addressed with the implementation of the power supply module. Ideally, we'd like to use gasifiers and build upon the open source work by http://www.allpowerlabs.com/ http://www.allpowerlabs.com/ If it takes a lot of energy, and we implement carbon-negative power generation, then we increase the rate of carbon sequestration :)
- clayrichardson 11y ago
  It's also going to be the centerpiece for a water-conscious art installation addressing the global water crisis at Burning Man, pulling water out of some of the driest air on the planet :)
- monkmartinez 11y ago
  I agree with you... Why not dig a deep well and run a solar pump? Around Tucson... I have friends that have +400ft. deep wells that cost $60k to install. Seems expensive... but we are talking +35gpm all day long/ Once the well is dug, cased, and the pump is installed there are very little operating costs especially with solar-powered electric pumps. The math for a comparison between a well and this gizmo would be interesting.
  - clayrichardson 11y ago
    I would like to see that comparison as well! I'm not sure how to determine the practicality of well excavation, but my intuition tells me it largely depends on geographically influenced factors. I'll look into that.
  - intron 11y ago
    An AWG is rarely the most efficient solution, but sometimes it's the best solution. If you're not going to be in a particular area for very long, digging a well might not be an option. An AWG can collect water while you're moving -- all you need is access to air. If you find yourself in an area where the water table is contaminated, using an AWG may end up being the safer option. Imagine you're living in space (or a similarly resource-constrained environment): you've got multiple people losing something like 0.5+ L/day (citation needed) to the air through perspiration -- that's valuable water. Moreover, to keep people comfortable, you should make sure your relative humidity stays below 60% (citation needed), so you're going to be pulling it out of the air anyhow. NASA undoubtedly has these systems in place in space, but that doesn't mean we should develop a open source version of the equipment that everyone can collaborate on and improve. TL;DR Sometimes you're willing to trade energy for water. Also, open source.
  - dsr_ 11y ago
    If you're digging a new well, you should see if you can do a ground source heat pump to get heating and cooling out of it at the same time. Most of the startup cost is in digging the heat exchange loop. https://en.wikipedia.org/wiki/Geothermal_heat_pump https://en.wikipedia.org/wiki/Geothermal_heat_pump
- extrapickles 11y ago
  There are rotary desiccant dehumidifiers that do not cool the air, but heat it. They operate by sucking air through a part of a rotating desiccant drum then exhausting it. At another spot, they heat and blow air through the desiccant, recharging it. The heavily moisture laden air is ran through a radiator where the moisture condenses out. If you have a source of low/medium grade heat, these can operate for the cost of running a few fans. This type works actually can operate in colder climates as they can work down to near the freezing point of water, where the cooling type cannot operate when the dew point is below the freezing point of water.
  - clayrichardson 11y ago
    Whoa. That is cool. Where can I read more about this, and are there any designs available to peruse?
    - extrapickles 11y ago
      The technical term for them is adsorption dehumidifier. Here is a video of a guy tearing down a typical household unit and he explains the basics of operation: https://www.youtube.com/watch?v=mR57FhytzFk https://www.youtube.com/watch?v=mR57FhytzFk
  - bb101 11y ago
    We have a couple of Meaco DD8L desiccant humidifiers - they are fantastic. Quiet, efficient and they each suck a few litres of water out of the air each day.
  - intron 11y ago
    Enhancement request: support for desiccant module
    - clayrichardson 11y ago
      I will definitely look into that, and probably test a commercially available model or two. If you end up beating me to it: https://github.com/openawg/openawg/pulls https://github.com/openawg/openawg/pulls
- kragen 11y ago
  Let's quantify "a lot of energy": the dehumidification part is 210 watts per person. Maybe Clay can provide actual power consumption numbers that include the other parts of the system, such as filtration. Typical coefficients of performance for air-source heat pumps, like air conditioners or dehumidifiers, are around 2; that means for every 2 joules of heat that it removes from the cold reservoir, it consumes a joule of electrical energy (dumping it as heat into the hot reservoir along with the heat it's pumping). The enthalpy of vaporization of water, at almost 41kJ/mol, is huge compared to the specific heat of air or even water itself, so that's a good approximation to how much heat you need to extract to condense the water. Water's molar mass is about 18 g/mol (two hydrogens of 1.0001 or so and an oxygen of 15.9994) so that works out to about 2.3kJ/g. At 10¢/kWh, this means your water costs 6.3¢/ℓ or US$78000/acrefoot. This is a lot cheaper than bottled water, and a lot more expensive than what farmers can afford to pay for irrigation water, and a lot more expensive than reverse osmosis desalination, which I think is around $8000/acrefoot. (Corrections welcome!) If we figure that a person needs 8 ℓ / day for cooking, drinking, and bathing (more or less what we use at Burning Man; if you're somewhere less hot and druggy then you might need less) which is about 210 watts. If a photovoltaic panel produces a 24-hour average of 13 W/m², which is what a friend of mine in England is getting, you need about 16 square meters of photovoltaic panels to power the device, which costs about US$2000 at this point. That's well within the bounds of feasibility, although it's a big enough asset to be a temptation to thieves. So when you say, "I feel like I'm missing something here," I agree: you were missing quantitative understanding of the subject, and as a result your quantitative conclusions were completely wrong, even though they were based on correct qualitative understanding.
  - toomuchtodo 11y ago
    Love your math. Something to consider is the excessive amount of wind power being generated in certain parts of the world right now. If you can't move that power somewhere, could use it to extract fresh water from the atmosphere rather than curtail production.
  - clayrichardson 11y ago
    That is awesome! We'd love to have a chat with you to better understand your thinking process, perspective, and sources. The pump were using right now consumes 104 W intermittently. For our next prototype, we're going to use a condenser unit from a walk-in freezer (1168W), a split A/C unit to pretreat the air (560W) MinnowBoardMax (15W), duct fan (208W), etc.
monkmartinez 11y ago
Not likely to work well in place like Tucson, AZ... due to the consistently low relative humidity or am I reading this wrong? Right now, for example in Tucson, AZ: humidity at 14% with a temperature of 76F and dew point of 24F. High will be 90F :( with Humidity around 6% mid-afternoon.
- clayrichardson 11y ago
  Interesting. With 32.2C ambient, 14% RH, 1.35C DWP, the absolute humidity is 4.78 g/m^3 With 24.4C ambient, 14% RH, -4.80C DWP, the absolute humidity is 3.12 g/m^3 Absolute humidity here is specified as grams of water per cubic meter of air. This is similar to the AH at BRC. Our current model assumes a DWP of -10C — 10C, so we can predict similar performance. We're not taking into account volumetric capacity and the thermal interface of the heat exchangers. If you know anyone able to help point us in the right direction with those calculations, it would be much appreciated! Our current understanding is the enthalpy of vaporization + fusion for water is (2257 + 333.55) = 2590.55 J/g we want to pull out of the air. This is assuming we can process enough air, since the dew point is below freezing a fair amount of the time. This is by using this equation specified in the NASA technical note [0]: =((0.21668*((TMPC+273)^-1))*((DWPC+273)^-4.9283)*(10^(23.5518+(-2937.4/(DWPC+273)))))*1000 [0]: http://www.nasa.gov/centers/dryden/pdf/87878main_H-937.pdf http://www.nasa.gov/centers/dryden/pdf/87878main_H-937.pdf EDIT: Formatting is hard. Added source. Clarification.
  - FiatLuxDave 11y ago
    Physicist here. I'm confused why you are using the enthalpy of fusion in your calculation, since your project does not appear to be freezing the water after condensation. Also, you seem to be using the enthalpy of vaporization from boiling at 100 C in your calculations, which is incorrect for use around 30 C. A better way to calculate your energy needs would be to look at a steam table, such as the one on Wikipedia's water data page, then take the deltaHvap. This is the accurate enthalpy of vaporization. https://en.wikipedia.org/wiki/Water_%28data_page%29 https://en.wikipedia.org/wiki/Water_%28data_page%29 In theory you need to add the amount of energy to cool the air/vapor mixture to the dew point. However, this amount will likely be small enough to be within your experimental error. For low humidity applications (like Burning Man), you can assume you are cooling mostly air, which is around 1.2 Joules/K per m^3. At 30 K temp differential, and humidity of 4 g/m^3, this is only 9 joules per gram water, or pretty much negligible. So, you are looking at a deltaHvap of around 2420 to 2450 J/g in this temperature range. This is reasonably close to your original estimate of 2590 J/g, and the good news is that the error is in your favor.
gravypod 11y ago
Have you thought about using an attached TEG [1] and a few 9volts to increase the amount of water produced as an optional strap-on. [1] - https://en.wikipedia.org/wiki/Thermoelectric_generator https://en.wikipedia.org/wiki/Thermoelectric_generator
- clayrichardson 11y ago
  Interesting. I haven't thought about combining it with the mechanical refrigeration process! I'll run the numbers on that, thanks. The initial proof-of-concept I threw together with spare parts actually used a spare TEC (19911-5L31-15CQ) [0] I had laying around. [1] [0]: http://www.customthermoelectric.com/tecs/pdf/19911-5L31-15CQ_spec_sht.pdf http://www.customthermoelectric.com/tecs/pdf/19911-5L31-15CQ... [1]: https://openawg.github.io/2016/01/27/blueice-alpha.html https://openawg.github.io/2016/01/27/blueice-alpha.html
  - gravypod 11y ago
    That's basically the same thing as what I'm asking. I'll be happy to read the numbers when you get it going.
Mithaldu 11y ago
I have a question about your website. While trying to figure out what exactly you're doing i browsed around a bit and eventually ended up here: https://openawg.github.io/#about https://openawg.github.io/#about Which has a bunch of footnotes, many with one footnote per concept, where the footnotes are almost all wikipedia articles. Why don't you just link the words instead?
- clayrichardson 11y ago
  Ah, that makes sense, thank you for the feedback. When I was drafting it in Google Docs, I was using footnote annotations, and I just copypasta'd it over.

How does it taste? :) And what plans do you have for tackling the pH and turbidity level issues? edit Missed the note on turbidity. I'm guessing a follow-up test might show that resolved?

clayrichardson 11y ago
It tastes surprisingly good, although not as good as some of the Ozarka bottled spring water I've had, but almost. We're going to try and find another remineralization filter, or we might add electrolyte mix instead. The second lab report was from the isolation of the remineralization filter, and we showed that the turbidity was indeed added by that filter.
- jat850 11y ago
  That's great! I had missed the test0 procedure text, but it did seem clear after reading it.

zzalpha 11y ago

So... this is basically a dehumidifier. Dehumidifiers typically use some sort of air cooling to reduce water below the dew point to draw water out of the air. And that takes a lot of energy. So what is the purpose of this device? It can't be to provide potable water to areas without it, since those same areas are likely to lack a significant source of power. I don't mean to be overly cynical, but I feel like I'm missing something here.

exhilaration 11y ago
https://en.wikipedia.org/wiki/Atmospheric_water_generator https://en.wikipedia.org/wiki/Atmospheric_water_generator I thought the same thing but reading their site led me to the above Wikipedia page which suggests there are other ways to do it than just dehumidification but I'm not sure what method they're using.
- clayrichardson 11y ago
  For simplicity and adoption, we're utilizing mechanical refrigeration since parts and HVAC(R) skills have been widespread over the past several decades. EDIT: Spelling is hard. Clarification is hard.
homero 11y ago
It has Wi-Fi
- clayrichardson 11y ago
  Indeed. Ideally, we'd like to include a mini-datacenter module, allowing for data storage, streaming, and processing. We'd like to be able to gather metrics from these machines all over the world, and identify trends in things such as the weather, water production and consumption, efficiency, power generation and carbon sequestration, as well as identify opportunities to improve the operation of the machines through software updates.
clayrichardson 11y ago
Indeed, it is energy intensive. That can be addressed with the implementation of the power supply module. Ideally, we'd like to use gasifiers and build upon the open source work by http://www.allpowerlabs.com/ http://www.allpowerlabs.com/ If it takes a lot of energy, and we implement carbon-negative power generation, then we increase the rate of carbon sequestration :)
clayrichardson 11y ago
It's also going to be the centerpiece for a water-conscious art installation addressing the global water crisis at Burning Man, pulling water out of some of the driest air on the planet :)
monkmartinez 11y ago
I agree with you... Why not dig a deep well and run a solar pump? Around Tucson... I have friends that have +400ft. deep wells that cost $60k to install. Seems expensive... but we are talking +35gpm all day long/ Once the well is dug, cased, and the pump is installed there are very little operating costs especially with solar-powered electric pumps. The math for a comparison between a well and this gizmo would be interesting.
- clayrichardson 11y ago
  I would like to see that comparison as well! I'm not sure how to determine the practicality of well excavation, but my intuition tells me it largely depends on geographically influenced factors. I'll look into that.
- intron 11y ago
  An AWG is rarely the most efficient solution, but sometimes it's the best solution. If you're not going to be in a particular area for very long, digging a well might not be an option. An AWG can collect water while you're moving -- all you need is access to air. If you find yourself in an area where the water table is contaminated, using an AWG may end up being the safer option. Imagine you're living in space (or a similarly resource-constrained environment): you've got multiple people losing something like 0.5+ L/day (citation needed) to the air through perspiration -- that's valuable water. Moreover, to keep people comfortable, you should make sure your relative humidity stays below 60% (citation needed), so you're going to be pulling it out of the air anyhow. NASA undoubtedly has these systems in place in space, but that doesn't mean we should develop a open source version of the equipment that everyone can collaborate on and improve. TL;DR Sometimes you're willing to trade energy for water. Also, open source.
- dsr_ 11y ago
  If you're digging a new well, you should see if you can do a ground source heat pump to get heating and cooling out of it at the same time. Most of the startup cost is in digging the heat exchange loop. https://en.wikipedia.org/wiki/Geothermal_heat_pump https://en.wikipedia.org/wiki/Geothermal_heat_pump
extrapickles 11y ago
There are rotary desiccant dehumidifiers that do not cool the air, but heat it. They operate by sucking air through a part of a rotating desiccant drum then exhausting it. At another spot, they heat and blow air through the desiccant, recharging it. The heavily moisture laden air is ran through a radiator where the moisture condenses out. If you have a source of low/medium grade heat, these can operate for the cost of running a few fans. This type works actually can operate in colder climates as they can work down to near the freezing point of water, where the cooling type cannot operate when the dew point is below the freezing point of water.
- clayrichardson 11y ago
  Whoa. That is cool. Where can I read more about this, and are there any designs available to peruse?
  - extrapickles 11y ago
    The technical term for them is adsorption dehumidifier. Here is a video of a guy tearing down a typical household unit and he explains the basics of operation: https://www.youtube.com/watch?v=mR57FhytzFk https://www.youtube.com/watch?v=mR57FhytzFk
- bb101 11y ago
  We have a couple of Meaco DD8L desiccant humidifiers - they are fantastic. Quiet, efficient and they each suck a few litres of water out of the air each day.
- intron 11y ago
  Enhancement request: support for desiccant module
  - clayrichardson 11y ago
    I will definitely look into that, and probably test a commercially available model or two. If you end up beating me to it: https://github.com/openawg/openawg/pulls https://github.com/openawg/openawg/pulls
kragen 11y ago
Let's quantify "a lot of energy": the dehumidification part is 210 watts per person. Maybe Clay can provide actual power consumption numbers that include the other parts of the system, such as filtration. Typical coefficients of performance for air-source heat pumps, like air conditioners or dehumidifiers, are around 2; that means for every 2 joules of heat that it removes from the cold reservoir, it consumes a joule of electrical energy (dumping it as heat into the hot reservoir along with the heat it's pumping). The enthalpy of vaporization of water, at almost 41kJ/mol, is huge compared to the specific heat of air or even water itself, so that's a good approximation to how much heat you need to extract to condense the water. Water's molar mass is about 18 g/mol (two hydrogens of 1.0001 or so and an oxygen of 15.9994) so that works out to about 2.3kJ/g. At 10¢/kWh, this means your water costs 6.3¢/ℓ or US$78000/acrefoot. This is a lot cheaper than bottled water, and a lot more expensive than what farmers can afford to pay for irrigation water, and a lot more expensive than reverse osmosis desalination, which I think is around $8000/acrefoot. (Corrections welcome!) If we figure that a person needs 8 ℓ / day for cooking, drinking, and bathing (more or less what we use at Burning Man; if you're somewhere less hot and druggy then you might need less) which is about 210 watts. If a photovoltaic panel produces a 24-hour average of 13 W/m², which is what a friend of mine in England is getting, you need about 16 square meters of photovoltaic panels to power the device, which costs about US$2000 at this point. That's well within the bounds of feasibility, although it's a big enough asset to be a temptation to thieves. So when you say, "I feel like I'm missing something here," I agree: you were missing quantitative understanding of the subject, and as a result your quantitative conclusions were completely wrong, even though they were based on correct qualitative understanding.
- toomuchtodo 11y ago
  Love your math. Something to consider is the excessive amount of wind power being generated in certain parts of the world right now. If you can't move that power somewhere, could use it to extract fresh water from the atmosphere rather than curtail production.
- clayrichardson 11y ago
  That is awesome! We'd love to have a chat with you to better understand your thinking process, perspective, and sources. The pump were using right now consumes 104 W intermittently. For our next prototype, we're going to use a condenser unit from a walk-in freezer (1168W), a split A/C unit to pretreat the air (560W) MinnowBoardMax (15W), duct fan (208W), etc.

monkmartinez 11y ago

Not likely to work well in place like Tucson, AZ... due to the consistently low relative humidity or am I reading this wrong? Right now, for example in Tucson, AZ: humidity at 14% with a temperature of 76F and dew point of 24F. High will be 90F :( with Humidity around 6% mid-afternoon.

clayrichardson 11y ago
Interesting. With 32.2C ambient, 14% RH, 1.35C DWP, the absolute humidity is 4.78 g/m^3 With 24.4C ambient, 14% RH, -4.80C DWP, the absolute humidity is 3.12 g/m^3 Absolute humidity here is specified as grams of water per cubic meter of air. This is similar to the AH at BRC. Our current model assumes a DWP of -10C — 10C, so we can predict similar performance. We're not taking into account volumetric capacity and the thermal interface of the heat exchangers. If you know anyone able to help point us in the right direction with those calculations, it would be much appreciated! Our current understanding is the enthalpy of vaporization + fusion for water is (2257 + 333.55) = 2590.55 J/g we want to pull out of the air. This is assuming we can process enough air, since the dew point is below freezing a fair amount of the time. This is by using this equation specified in the NASA technical note [0]: =((0.21668*((TMPC+273)^-1))*((DWPC+273)^-4.9283)*(10^(23.5518+(-2937.4/(DWPC+273)))))*1000 [0]: http://www.nasa.gov/centers/dryden/pdf/87878main_H-937.pdf http://www.nasa.gov/centers/dryden/pdf/87878main_H-937.pdf EDIT: Formatting is hard. Added source. Clarification.
- FiatLuxDave 11y ago
  Physicist here. I'm confused why you are using the enthalpy of fusion in your calculation, since your project does not appear to be freezing the water after condensation. Also, you seem to be using the enthalpy of vaporization from boiling at 100 C in your calculations, which is incorrect for use around 30 C. A better way to calculate your energy needs would be to look at a steam table, such as the one on Wikipedia's water data page, then take the deltaHvap. This is the accurate enthalpy of vaporization. https://en.wikipedia.org/wiki/Water_%28data_page%29 https://en.wikipedia.org/wiki/Water_%28data_page%29 In theory you need to add the amount of energy to cool the air/vapor mixture to the dew point. However, this amount will likely be small enough to be within your experimental error. For low humidity applications (like Burning Man), you can assume you are cooling mostly air, which is around 1.2 Joules/K per m^3. At 30 K temp differential, and humidity of 4 g/m^3, this is only 9 joules per gram water, or pretty much negligible. So, you are looking at a deltaHvap of around 2420 to 2450 J/g in this temperature range. This is reasonably close to your original estimate of 2590 J/g, and the good news is that the error is in your favor.

gravypod 11y ago

Have you thought about using an attached TEG [1] and a few 9volts to increase the amount of water produced as an optional strap-on. [1] - https://en.wikipedia.org/wiki/Thermoelectric_generator https://en.wikipedia.org/wiki/Thermoelectric_generator

clayrichardson 11y ago
Interesting. I haven't thought about combining it with the mechanical refrigeration process! I'll run the numbers on that, thanks. The initial proof-of-concept I threw together with spare parts actually used a spare TEC (19911-5L31-15CQ) [0] I had laying around. [1] [0]: http://www.customthermoelectric.com/tecs/pdf/19911-5L31-15CQ_spec_sht.pdf http://www.customthermoelectric.com/tecs/pdf/19911-5L31-15CQ... [1]: https://openawg.github.io/2016/01/27/blueice-alpha.html https://openawg.github.io/2016/01/27/blueice-alpha.html
- gravypod 11y ago
  That's basically the same thing as what I'm asking. I'll be happy to read the numbers when you get it going.

Mithaldu 11y ago

I have a question about your website. While trying to figure out what exactly you're doing i browsed around a bit and eventually ended up here: https://openawg.github.io/#about https://openawg.github.io/#about Which has a bunch of footnotes, many with one footnote per concept, where the footnotes are almost all wikipedia articles. Why don't you just link the words instead?

clayrichardson 11y ago
Ah, that makes sense, thank you for the feedback. When I was drafting it in Google Docs, I was using footnote annotations, and I just copypasta'd it over.