5 ms·

I want to make an orchard on a hill in the maritime pacific northwest. Its a somewhat odd climate where the time that gets hottest is when it also tends to be

by cwkoss 5y ago

I want to make an orchard on a hill in the maritime pacific northwest. Its a somewhat odd climate where the time that gets hottest is when it also tends to be dryest (east coast tends to be wetter when hotter). I wonder if something like this (possibly with less focus on "clean" water - it's rural and breezy, so I don' think raw output would harm trees...) could be suitable for generating summer water for tree irrigation. I wish the overview PDF had more labels...

throwawayboise 5y ago
If it's extracting water from the air, "hot and dry" does not seem to be a good situation. You'd want humid air. Any water condensed from the air is going to be "pure" by most measures. It's essentially distilled water.
- marcosdumay 5y ago
  The purity of the water you get from the air is limited by how much dust is on the air you work with. You can improve it easily by filtering. It's much easier than filtering the final water. But it's not necessarily pure.
- cwkoss 5y ago
  Fair point, I thought part of the energy was being used for purification before I read the overview pdf. The site is ~ 1/4 mile from the ocean, so I think the air won't be totally dry... but just won't get a lot of rainfall. Mostly wondering if there's a good way to 'moisture farm' to keep the soil around trees moist. Ideally with no more power than a small solar panel located right next to the device, so I don't have to run power there (there's well and power at the bottom of the hill... but moisture farming would be cooler than running irrigation :-P).
- outworlder 5y ago
  > Any water condensed from the air is going to be "pure" by most measures. It's essentially distilled water. And you can freely give it for spherical cows to drink in vacuum. Keeping any such device free from contamination is very difficult. Bacteria love the moist environments. Leave it unattended and you have moist dust. Lovely.
  - throwawayboise 5y ago
    So put an air filter on it for the dust and boil or chlorinate the final product. I'm betting it's a lot cleaner than groundwater.
    - thombat 5y ago
      Boiling the final product then gives a process of: evaporate -> condense -> re-evaporate -> re-condense Quite a lot of energy, but at least you can market it as double-distilled, like a fancy spirit.
claudiulodro 5y ago
Orchard on the coast is tricky. I don't know specifically where you're located, but on the Oregon coast the only fruit trees OSU says will grow are apple and cherry (and sometimes pear). I've had better luck going with native bushes where you don't need to worry as much about supplemental water: huckleberry, salal berry, salmonberry, blackberry if you can maintain them, etc. Work with the environment rather than try to force the environment to do what you want. :)
- cwkoss 5y ago
  Yep! Those are all on my list. I'm hoping heavy woodchip mulching can get me enough water retention to keep trees happy (we certainly get plenty of water the other ~9 months of the year!), but some supplemental water during the hot dry summer would probably significantly expand species and variety options. Have a small well that should be able to help some... but looking at permaculture techniques (hugelkulture, swales etc) and possibly moisture farming as a potential way to improve moisture conditions in a 'greener' way then energy intensive pumping. Might try to build a pond high up on the hill to filter down over the dry season. Kind of a paradoxical region, because plants want lots of water when there's lots of sun, and here we generally get one or the other :-/
  - seabrookmx 5y ago
    > try to build a pond high up on the hill This, or tanks (to cut down on evaporation). Pretty common here on the BC coast for people to plumb the gutters of their house and outbuildings to tanks and then use that stored water in the summer for the garden or topping off wells. If you have 9 months of rain/live in a temperate rainforest it's not likely conjuring water out of the air is worth the effort :)
kragen 5y ago
No. The output is orders of magnitude too low. Trees stay cool by evaporating water. The solar energy they're absorbing by doing this is a lower bound on the energy you have to put in to condense that same water out of the air. But tree leaves convert about 75% of the sunlight that hits them into heat (they're a bit more than 75% "efficient" at doing something they don't want) while PV solar panels are only about 21% efficient. So you'd need more than three times as much solar-panel area as tree leaf area for that to work out.
- kragen 5y ago
  As a correction, the paper is about a solar-thermal-driven sorbent system, not a PV-driven system. So you wouldn't need three times as much solar-collector area as tree leaf area, only about equal amounts. That's still probably orders of magnitude too expensive.

by cwkoss 5y ago

throwawayboise 5y ago

If it's extracting water from the air, "hot and dry" does not seem to be a good situation. You'd want humid air. Any water condensed from the air is going to be "pure" by most measures. It's essentially distilled water.

marcosdumay 5y ago
The purity of the water you get from the air is limited by how much dust is on the air you work with. You can improve it easily by filtering. It's much easier than filtering the final water. But it's not necessarily pure.
cwkoss 5y ago
Fair point, I thought part of the energy was being used for purification before I read the overview pdf. The site is ~ 1/4 mile from the ocean, so I think the air won't be totally dry... but just won't get a lot of rainfall. Mostly wondering if there's a good way to 'moisture farm' to keep the soil around trees moist. Ideally with no more power than a small solar panel located right next to the device, so I don't have to run power there (there's well and power at the bottom of the hill... but moisture farming would be cooler than running irrigation :-P).
outworlder 5y ago
> Any water condensed from the air is going to be "pure" by most measures. It's essentially distilled water. And you can freely give it for spherical cows to drink in vacuum. Keeping any such device free from contamination is very difficult. Bacteria love the moist environments. Leave it unattended and you have moist dust. Lovely.
- throwawayboise 5y ago
  So put an air filter on it for the dust and boil or chlorinate the final product. I'm betting it's a lot cleaner than groundwater.
  - thombat 5y ago
    Boiling the final product then gives a process of: evaporate -> condense -> re-evaporate -> re-condense Quite a lot of energy, but at least you can market it as double-distilled, like a fancy spirit.

claudiulodro 5y ago

Orchard on the coast is tricky. I don't know specifically where you're located, but on the Oregon coast the only fruit trees OSU says will grow are apple and cherry (and sometimes pear). I've had better luck going with native bushes where you don't need to worry as much about supplemental water: huckleberry, salal berry, salmonberry, blackberry if you can maintain them, etc. Work with the environment rather than try to force the environment to do what you want. :)

cwkoss 5y ago
Yep! Those are all on my list. I'm hoping heavy woodchip mulching can get me enough water retention to keep trees happy (we certainly get plenty of water the other ~9 months of the year!), but some supplemental water during the hot dry summer would probably significantly expand species and variety options. Have a small well that should be able to help some... but looking at permaculture techniques (hugelkulture, swales etc) and possibly moisture farming as a potential way to improve moisture conditions in a 'greener' way then energy intensive pumping. Might try to build a pond high up on the hill to filter down over the dry season. Kind of a paradoxical region, because plants want lots of water when there's lots of sun, and here we generally get one or the other :-/
- seabrookmx 5y ago
  > try to build a pond high up on the hill This, or tanks (to cut down on evaporation). Pretty common here on the BC coast for people to plumb the gutters of their house and outbuildings to tanks and then use that stored water in the summer for the garden or topping off wells. If you have 9 months of rain/live in a temperate rainforest it's not likely conjuring water out of the air is worth the effort :)

kragen 5y ago

No. The output is orders of magnitude too low. Trees stay cool by evaporating water. The solar energy they're absorbing by doing this is a lower bound on the energy you have to put in to condense that same water out of the air. But tree leaves convert about 75% of the sunlight that hits them into heat (they're a bit more than 75% "efficient" at doing something they don't want) while PV solar panels are only about 21% efficient. So you'd need more than three times as much solar-panel area as tree leaf area for that to work out.

kragen 5y ago
As a correction, the paper is about a solar-thermal-driven sorbent system, not a PV-driven system. So you wouldn't need three times as much solar-collector area as tree leaf area, only about equal amounts. That's still probably orders of magnitude too expensive.