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Ask HN: How Can I convert free electricity into water

6 points by callumprentice ↗ HN
We recently moved into a new home in Southern California that has a large lawn and an over provisioned (I think) solar system. This means our water bills are terrifyingly large and our electricity bills are 0.

It occurred to me that there might be a way to extract water from the air using something like an industrial sized dehumidifier and store it for later use in the garden.

Does anyone know of such a thing or are there other options we should be looking at like grey water collection or even drilling a well?

27 comments

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yuppie_scum
Run dehumidifiers and then filter and boil the resulting water
samstave
I, too, choose this guys dead technology!

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(SERIOSULY this is a good idea if elec is free...)

callumprentice
We don’t need to drink the resulting water - I think we’d just it for watering the garden so we could skip the filter/boil steps.
toast0
If it's just to water the lawn, I don't know that you need to boil it? How well a dehumidifier will work is going to depend on your local humidity of course, which varies a lot in socal. Try to get some shade for the dehumidifier to work in, too.

A well might work, depending on where your water table is, but you probably need a drilling permit, and you may need other approvals too, water in California is a complex issue.

I'm anti-bitcoin, but bitcoin/etc turns electricity and gpus/asics into money, and money pays for water, so see if that makes more sense than a dehumidifier (although variations in price mean you might want to switch between things depending on price and workfactors, etc)

callumprentice
Yeah just for the lawn/garden although it might be interesting to extend it to household and even drinking water if I find a good solution.

Fascinating, left field idea about generating money to pay for the water too.

bigiain
Lawns are pretty ecologically unsustainable. I’d be looking for low water use alternatives to lawn, rather than trying to work out ways to temporarily extend the life of your grass.

Did you see this?

https://news.yahoo.com/grassy-lawns-banned-las-vegas-1949502...

callumprentice
Yep. We’ve turned down the sprinklers so much that the grass is turning brown. We may well end up having to replace it with something more drought tolerant.
bombcar
Modern astroturf is surprisingly well done, if you don’t want to do a full desert-style landscaping.
callumprentice
Yes and actually a little bit of the front yard (no idea why) has the artificial stuff and it looks much better than I imagined. I haven’t looked at costs but I expect it’d be expensive to replace everything. I should at least get a quote - thanks for the reminder.
MatthiasPortzel
Dehumidifiers work in areas with humidity, normally not California.
callumprentice
I agree but it’s been surprisingly humid since we got here.
CaliforniaKarl
SoCal has noticeable swings in humidity during the year; if you live in range of the marine layer, also during the day.
callumprentice
We’re about a 15 minute walk from the ocean. Does the marine layer extend that far inland ?
samstave
Magnets.

Just kidding.

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The thing with extracting water, esp when youre in so-cal... is that any evening-dew-harvesting system is going to need to be massive. And likely your terra-forma (topology) is not conducive to passive dew harvestings via nets and such due to moisture-point-heavy airflow not passing through whatever net you have...

Use you're free electricity to build and drill a super deep-aquifer level well.... (Source: my dad owned one of the water companies in california... electricity for pumping/drilling/blah blah... is expensive.)

callumprentice
Got it. Thank you - drilling a well sounds like a non-starter.
bombcar
The main thing “free electricity” would let you do is install a large underground rainwater storage tank that you could pump from.

Be sure to anchor the tank even if buried so it doesn’t pop out of the ground when empty.

callumprentice
It almost never rains here sadly.
DoreenMichele
Look up Earthships and info about how much water you need. My recollection is you can supply a household's water needs for as little as 10 inches of rain per year and most parts of California get at least that much. San Diego gets that much and Fresno gets about 11. Only some parts of the High Desert get less, as little as 6 inches.

But info on Earthships (or perhaps Earth Ships) should be a good place to start educating yourself.

Grey water systems are generally part of the set up for such.

callumprentice
Thank you. Great info. I’ve a feeling not worrying about the electricity side of things and figuring out how to really make use of grey water will be the solution we arrive at but we’ll see.
beardyw
Not sure how you cut your lawn, but letting it grow longer is going to help a lot. If its like a putting green it's way too short. I think the longer grass does moisture harvesting itself.

Please don't use artificial grass. Creatures live in grass, not plastic. We let clover grow and the bees love it, though be careful not to go barefoot that time of year.

callumprentice
We leave it pretty long because it’s apparently very new and we were told that’s what you have to do. The soil is apparently awful though - more sand than soil - so I believe that’s one reason any water we do put on it runs away quickly.

Artificial grass would be a last resort but may be required if the original proposition doesn’t work out. We are lucky enough to have lots of other flowers, shrubs and trees too and there is almost always some bees flying about. It’s magical and our daughter loves it.