back to article Google lab proposes solar-powered moisture farming to provide water for billions

Star Wars-style moisture farming could provide safe drinking water for approximately 1 billion people here on Earth, according to research from a Google-owned research lab. Solar-powered atmospheric water harvesting is an untapped source of clean drinking water, a global assessment modelled on hypothetical devices has shown. …

  1. Brewster's Angle Grinder Silver badge

    Tatooine ? Try a planet beginning with "A" (currently in cinemas):

    DEW COLLECTORS or DEW PRECIPITATORS...Collectors or precipitators are egg-shaped devices about four centimetres on the long axis. They are made of chromoplastic that turns a reflecting white when subjected to light, and reverts to transparency in darkness. The color forms a markedly cold surface upon which dawn dew will precipitate. They are used by █████ to line concave planting depressions where they provide a small but reliable source of water.

    1. Throatwarbler Mangrove Silver badge
      Thumb Up

      I was going to suggest the next logical move is stillsuits, but then I thought about how hard it was just to get people to wear masks to prevent the spread of SARS-CoV2. On the plus side, the way the planet is going, the stillsuit refuseniks would quickly die of thirst, so the problem would more quickly solve itself, plus we could throw the refuseniks into the reclamation tank and suck out their water and minerals.

      1. oiseau Silver badge

        I was going to suggest the next logical move ...

        But ...

        Whatever happened to Dean Kamen's Slingshot?

        I once saw a documentary about it (sorry, can't find the link) and apparently it was the solution.

        Seems to have fallen into Coca-Cola's grubby corporate hands.

        "As of 2020, the product does not seem to be in commercial production or wide use. The systems appear to be distributed in partnership with Coca-Cola as a component of EKOCENTER kiosks, of which over 150 have been deployed worldwide."

        Granted, it does need water (in any state) to actually produce drinking water, but it is reported to be quite cheap, durable and ecological.


      2. John Brown (no body) Silver badge

        If it wasn't for the HGV driver shortage, I would have suggested we send wagon loads of dehydrated water concentrate to the relevant locations. On arrival, just add...

  2. Natalie Gritpants Jr

    OK as long as you are not nomadic and have 2m^2 per person of unhindered view of the sky.

    1. Anonymous Coward
      Anonymous Coward

      Just load it on your Banth.. ER water buffalo

      just hang the panel off one side and the condenser off the other :)

      Honestly, you run one of them off a solar car/truck roof, and capture some extra off of the AC evaporator as well. As to fixed locations, as any useful solar system will usually need to be over provisioned if you aren't including a large expensive battery pack, this would be one of a few different ways dynamically user overproduction w/o wasting it for setups that aren't grid connected.

      This isn't how everyone is going to get all of their water, but it would be useful for many as we get more solar on more roofs.

      These ideas often start with a silly all in one version people imagine will be dropped into struggling communities, but the OLPC was the failed version of the Raspberry Pi. My copier rep was talking up their zaibatsu's new condenser based water coolers(but waved off when they heard the tech bay had 4 people it, it was only rated for 2 or three tops). Eventually the designs become modular, and like induction cooktops and direct heat inline water heaters they become commonplace. That also lets people tailor the solution their needs and the area they are in. In places with low humidity, the overflow solar could be sent to desalinization or water reclamation, or used to pump and store well water for use off peak hours. With modular systems, places with excess sun and/or wind may still find use of this tech even in lower humidity areas just because water is locally scarce, heavy, and expensive to haul.

    2. AVR

      Your drinking water is only a part of the water you need and not the largest part. Cooking will take some, washing (your body, clothes, bedding, and probably tableware/cooking utensils) is not something you can do without long-term, and most of all if you want a functioning economy agriculture and manufacturing need lots of water. Talking about supplying people's drinking water needs is so incredibly misleading.

      1. John Brown (no body) Silver badge

        The article is talking about "safe drinking water". If you are living in an area with limited safe drinking water, you don't use that for anything other than drinking or cooking. You use the "not safe to drink" water for everything else. If you don't even have a source of "not safe to drink" water, then the problems are different.

  3. cyberdemon Silver badge
    Paris Hilton

    > two hypothetical devices: a 1m2 solar panel with a yield of 0.2 to 2.5 litres per kilowatt-hour at 30 per cent relative humidity and a 2m2 solar panel with a yield of 0.1 to 1.25 litres per kilowatt-hour at 90 per cent relative humidity.

    Shouldn't they be quoting that per hour, not per kilowatt hour?

    A 1 m2 solar panel produces about 100W on a good day, not 1kW. So That's a yeild of 0.02 to 0.25 litres per hour at 30% RH.

    And why would a larger panel in much higher humidity produce less water?

    1. Flak


      The Nature article explains the kWh reference as follows:

      In the context of specific yield, we use kWh to denote primary solar energy prior to thermal and other losses, and kWhPV to denote electrical energy supplied to the device from PV panels after conversion.

      Solar irradiance at or the equator can be up to 1.36kW/m2 (at the top of the atmosphere)...

    2. Tom 7 Silver badge

      Is it not strange that it seems harder to get water out of high humidity air than it is to get if from low humidity air? When the humidity is high here it comes out of the air on its own at the slightest temperature drop!

      1. NeilPost Silver badge

        Instead of sucking moisture out of the air - at scale unknown environmental consequences - would solar powered desalination not be a path of least resistance…. Unlimited supply of water - esp. as glacial melt is topping it up at pace.

        1. Androgynous Cupboard Silver badge

          Desalination requires Salinated water to begin with. You’re a long way from that in most of the Sahara.

          1. Tom 7 Silver badge

            True, but how many solar desalination plants are there? Most of them are in oil rich countries where it also happens to be incredibly sunny and yet they use oil! OK I understand there is a need for continuous supply but even in the UK solar concentrators can boil water and istr its not too hard to store.

            1. NeilPost Silver badge

              Visiting friends in Houston whilst the sun was beating down on their roof, they were complaining about their electricity bill to power their AC.

          2. NeilPost Silver badge

            But plenty of Sun for tens thousands of square miles of Solar Farms without wasting arable land elsewhere in the world.

    3. Draco

      It takes energy to extract water from the air

      Why kWh instead of Joules?

      The atmosphere is a HUGE energy exchange system. Energy is put into water, turning it into water vapour. That water vapour is transported by the atmosphere. Energy is removed from the water vapour and it precipitates or condenses out.

      In the places where these systems are being proposed, the atmosphere is not pulling energy out of the water vapour and thus causing it to precipitate. Therefore, the solution is to extract the energy from the water, thus causing it to condense.

      It takes a lot of energy to vaporize water. For example, to vaporize 1kg of water requires:

      2500000J @ 0C

      2453000J @ 20C

      2256000J @ 100C

      In order to condense the water, you must remove that amount of energy. One way of doing this is with a refrigeration system of some sort which moves heat from a cool plate to a hot plate.

      We tend not to use Joules because energy doesn't care about time. We prefer to use a timed measure of energy - such as kWh: 1 kWh = 3600000J of energy over 1 hour.


      Why would you get less water from a higher relative humidity?

      How much water the atmosphere can hold depends on temperature. Consider the following quantities of water in the atmosphere at 100% humidity levels:

      4.89 g/m³ @ 0C

      17.3 g/m³ @ 20C

      30.4 g/m³ @ 30C

      At 0C, 90% relative humidity, the maximum amount of water you could extract from a cubic metre of air is 4.89 x 0.90 = 4.40 grams (about 4.4ml).

      At 30C, 30% relative humidity, the maximum amount of water you could extract from a cubic metre of air is 30.04 x 0.30 = 9.12 grams (about 9.1ml).

      While the paper references to papers it is pulling its number from, it seems the authors are not clear on what they are talking about and don't seem to understand how to present the data in a coherent manner. IMO, it reads like a "publish or perish" filler fluff.


      Data on Heat of Vaporization:

      Data on Maximum Water Content vs Air Temperature:

      1. cyberdemon Silver badge

        Re: It takes energy to extract water from the air

        Er, I didn't say they should be quoting it in Joules. You are the only person on this page to have said Joules.

        My point was: The Googlers quote their hypothetical contraption as extracting 0.2 litres per kilowatt hour, because it sounds better than 0.02 litres per hour with a 100W panel, or 0.25L/day with 12 hours per day of sunlight.

        > it seems the authors are not clear on what they are talking about

        Or: They don't know what they are talking about. They chucked some numbers into an "AI" and it spat out some nonsense and they published it.

    4. Patrick R

      I read that as 1 hypothetical device.

      1m^2 that would yield 0.2 to 2.5 /kWh at respectively 30% to 90% relative humidity.

      Why doubling the surface would halve the yield remains a good question ...or an error.

      I guess the original device is in fact 2m^2 and the author tried to reduce to 1 but got mixed up.

      So the line above would be for a 2m^2 device and translate to "0.1 to 1.25 litres per meter square per kWh".

      1. John Brown (no body) Silver badge

        Yeah, i've seen very clever people get confused about what 2m^2 is. Is it a square, 2m on a side or a square of 1.414m per side?

        1. cyberdemon Silver badge

          If that really is the case here, then these clowns shouldn't be publishing papers.

          It's straight out of the "desperate marketing" department. Oh shit there's a big climate conference on and everyone suddenly cares about the planet but our datacentres are churning hundreds of megawatts just to spy on our userbase. Quick, do something 'green' with the computers before anyone notices!

  4. Anonymous Coward
    Anonymous Coward

    Hang on ...

    surely if you precipitated moisture somewhere, then there is less to precipitate elsewhere ?

    So all this idea would do is move the droughts around ?

    1. cyberdemon Silver badge

      Re: Hang on ...

      As long as you only drink it, it's not so bad. Most of the water we drink comes back out in our breath. The rest is sweat and urine. And drinking water is "a drop in the ocean" compared to agricultural demands.

    2. Anonymous Coward
      Anonymous Coward

      Re: Hang on ...

      Oh my no.

      The idea is to take something that anyone with land has always gotten for free -- rain -- and replace it with something Google can monetise. If rain never falls, then not only will "underserved people without access to clean water" have to pay for drinking water but so will everyone else. It's probably the most evil idea ever conceived, the ultimate tragedy of the commons. How long until they find a way to take all the oxygen out of the atmosphere too?

      1. Matthew 25

        Re: Hang on ...

        "How long until they find a way to take all the oxygen out of the atmosphere too?"

        Who do you think created space?

    3. Brewster's Angle Grinder Silver badge

      Re: Hang on ...

      I think it's very unlikely this water was going to form rain clouds. The changing atmospheric and oceanic currents will be far more important in determining who gets droughts and who gets deluges. And, overall, a warmer atmosphere holds more moisture.

      Perhaps it steals water that would have precipitated as dew so the vegetation in the immediate vicinity becomes a little more water-stressed and the micro-climate a little more arid. It's certainly worth checking the numbers. But I think you'll need vast farms of these to the nudge the dial.

    4. Anonymous Coward
      Anonymous Coward

      Keep the scale of things in mind

      that on a world covered in 2/3 ocean, the total amount of water in the air is a MASSIVE. Trees do the same thing on scale that is far outside what is being discussed with these devices.

      If you scale the use of this technology well past the point of reason, you could have a measurable impact by pulling water out the air, but you will have already hit impacts scaling land use, and the impact of manufacturing the devices and (hopefully) recycling most of them.

      Most places will have literal tons of water in the air these devices are extracting liters and kilos from. Even if scaled to the point they are having a real net impact, they would also be offsetting other things like trucking water, single use bottles, desal and all the other ways we currently get water.

      1. John Brown (no body) Silver badge

        Re: Keep the scale of things in mind

        "Most places will have literal tons of water in the air these devices are extracting liters and kilos from."

        Yes, those of us in wetter climes generally can't even conceive of the "weight" of the fluffy clouds floating over our heads.

        "They may look light and fluffy, but those big white things floating overhead are pretty hefty. A typical cloud has a volume of around 1km3 and a density of around 1.003kg per m3 – about 0.4 per cent lower than that of the surrounding air, which is why they float. So cranking through the maths, that means that a typical cloud weighs around a million tonnes."

    5. the Jim bloke Silver badge

      Re: Hang on ...

      If the water being removed from the atmosphere -actually- was being removed from the system, say, by being put into a pipe and sent a hundred kilometres away, then it could be a problem, but pulling it out of the air and feeding it through a human is but a temporary detour on the grand adventure that is a water molecules existence. There are probably water molecules floating around that have existed since before life developed.

      Efficiency achieved will vary with the relative humidity, so drought conditions will still be a crisis, especially as temperatures increase, but it is a form of recycling... - the 10 million litres your city of 2 million inhabitants consume in a day will be exhaled and sweated out to be available again tomorrow, less any piped away in sewerage -( maybe keep your treatment plants nearby and upwind for maximum recovery)

      Hydrogen as a fuel replacement will synergise with this technology, so win win there.

      From a civic planning perspective (so ignoring poor people) providing urban water features such as ponds and fountains will improve the efficiency of these, and reduce the amount of services needing to be connected to each building (sewers still required).

      Even poor quality water could improve the local humidity, as you are basically using the atmosphere to distil the water.

    6. adam 40 Silver badge

      Re: Hang on ...

      I'm with you.

      If you suck it out of the air, and the wind moves it on, that's dry and hot air for your neighbour to suck on, and he won't be able to do the same, no matter how much you sweat it back out from what you drink, which will be instantly reabsorbed by your own device.

      This can only be used on a small scale with probably 200m separation between individual dehumidifiers or else the yield will be very poor.

      Any sweat that does waft downwind will also make the next dehumidifier's output, well, a bit tangy. Eeewww.

  5. Aristotles slow and dimwitted horse

    It's a blue planet...

    I'm probably not aware of some large scale industrial limitation of them, but...

    Seeing as 70% of the Earths surface is covered with water, why can't they put their many billions of dollars into inventing or building a more efficient industrial scale desalination plant / watermaker? The Schenker one I inherited on my sailing boat makes about 25-30 litres per hour and is perfectly drinkable.

    OK, sure... it does draw about 15A amps @ 12v, but my high output alternator and solar array take care of this.

    1. cyberdemon Silver badge

      Re: It's a blue planet...

      15A @ 12V is 180W, which is the same as you'd get from the quoted 2 square metre panel anyway.

      And 25 litres/hour is 10 to 100 times what this google contraption produces.

      So.. Yes. It's all a load of hot, arid air.

      1. Anonymous Coward
        Anonymous Coward

        Re: It's a blue planet...

        The advantage of your boat is that you are sitting about 0.5 metres above your source of water. If you have to pump the water up from a saline aquifer at 10s of metres down, let alone from the nearest ocean, the energy costs of desalination are dwarfed by your pumping costs.

    2. Anonymous Coward
      Anonymous Coward

      Re: It's a blue planet...

      > Seeing as 70% of the Earths surface is covered with water, why can't they put their many billions of dollars into inventing or building a more efficient industrial scale desalination plant / watermaker?

      Because it's already been done: de-salination is already relatively cheap and efficient. The problem is that seas are at sea-level, the consumers are both above sea-level and far inland, and water is heavy. So getting it to those who need to drink it is literally an uphill struggle.

      When that distribution cost is taken into account, local moisture farming starts to make sense.

      1. Aristotles slow and dimwitted horse

        Re: It's a blue planet...

        Yeah ok, point taken... but none of the major industrial countries and cartels seem to have a problem spending billions on oil and gas pipelines where their profits are concerned do they.

        With my seers hat on I'm going to predict that fresh water is going to become one of the two most valuable commodities on this planet (if it isn't already) and without it - civilization is going to fall apart a lot quicker than with a few petrol shortages.

        1. iron Silver badge

          Re: It's a blue planet...

          Do YOU want to pay £1.43 per litre* for WATER? Can everyone in Africa afford £1.43 per litre?

          There is a reason oil companies are happy to use pipelines in a way that wouldn't work for other liquid goods.

          * Current UK price for petrol (gas).

          1. Spacedinvader

            Re: It's a blue planet...

            A bottle of mineral water isn't far off that price...

            1. Anonymous Coward
              Anonymous Coward

              Re: It's a blue planet...

              and sometimes, in an emergency, a truck load of bottled water is the right way to go - but moving the 130 kilos of water a typical person uses each day is a serious game..we use about 30 to 60 times more water per head just domestically than petrol -let alone that needed by agriculture, industry etc.

          2. Anonymous Coward
            Anonymous Coward

            Re: It's a blue planet...

            Here in LA even re-bottled city tap water goes for about that, and spring water is more, even with the exchange rate. But you raise a fair point that the bigger the financial incentive the more pipe gets laid.

            We should have voted in the desalinization project that game up on the ballot a decade ago, but we have complicated history with water rights here in Los Angeles. (complicated in the standard American meaning they were acquired by means of fraud, murder, and in some cases dynamite based diplomacy). So LADWP was fighting pretty hard to quietly block it.

            Desalinization works at scale, and in a city that has faced 35 years of some level of water rationing out of 40, we can afford getting a decent fraction at least from the local seawater instead of draining 5 other states dry. We currently are pulling water from Colorado to the almost the Oregon border.

            There have been large scale proposals to use either the Salton sea drainage or laguna Salada in Mexico, but the upfront costs have stalled. Both sites have high solar potential, good climate, and ample space for brine management. The companies trying to extract lithium at Salton seem to be deterred by other large projects that might be "distracting" to their own ambitions. The laguna salada is on the wrong side of the border for one, and dealing with the local government isn't any easier than the NIMBYs stateside. That said these are projects than can and should happen, but don't need to happen at any cost, either financial or envionmental.

          3. katrinab Silver badge
            Paris Hilton

            Re: It's a blue planet...

            Brent Crude costs around $85 for a 159 litre barrel. That is about 39p per litre. Tax is about 82p per litre.

            That leaves 22p for refining, distribution, and retail costs.

            1. adam 40 Silver badge

              Re: It's a blue planet...

              Ahh and no profit for the poor oil companies? Ahh diddums, poor things...

          4. John Brown (no body) Silver badge

            Re: It's a blue planet...

            "Do YOU want to pay £1.43 per litre* for WATER? Can everyone in Africa afford £1.43 per litre?"

            Petrol/diesel is highly taxed in most non-producing countries, and also in some producing countries. In some of the big producing countries, it's dirt cheap. The downside is that in some of those high producing oil economies, they have low levels of water, so water can cost as much if not more than petrol.

            Without the tax on fuel, petrol is cheaper than bottled mineral water, at least here in the UK :-)

        2. Anonymous Coward

          Re: It's a blue planet...

          It's already happening. The Chicago Mercantile Exchange sells futures contracts for California water allowing investors to speculate on water prices.

  6. IGotOut Silver badge

    Great idea in theory

    It's not like human geoengineering has caused far more problems that its solved before.

    How are the cane toads in Australia going?

    Or the Scottish forests planted on "useless" bogland?

    How about the desalination of the Dead Sea?

    It's a great idea but has to be thought out VERY carefully.

    1. Jimmy2Cows Silver badge

      Re: geoengineering

      It's hardly geoengineering. The amount of water even a vast number of these devices could remove from the atmosphere is tiny compared to the total amount of water vapour therein, even locally, and most of it will be returned to the environment in less than a day. I fear you're comparing apples to oranges.

      Agreed that some well-intentioned human endeavours can have drastic negative side effect, but this doesn't seem like one of them.

  7. wiggers

    Absolute not relative humidity

    The actual amount of moisture in the air is measured as absolute humidity, g/m³.

    Relative humidity is simply the ratio of the actual moisture content compared with the maximum for that temperature and pressure.

    1. Swarthy Silver badge

      Re: Absolute not relative humidity

      While that is true, Relative Humidity describes how easily the water can be extracted.

  8. dvd

    Isn't this just the Waterseer again?

    1. SusiW

      Ahh. Waterseer...


      Bugger! Beat me to it!! lol

      Especially as the 'final iteration' of the "Waterseer" turned out to be a repackaged cheapo Chinese dehumidifier sold at a HUGE markup - that did indeed produce water....... wait for it...........

      That was "unsafe to drink!!"

  9. Tom 7 Silver badge

    I had a big pollytunnel

    and it was far too hot during the day and cold during the night. So I stuck a lot of loose rubble down the centre of the tunnel on a plastic sheet - to stop it going into the soil - and was surprised to discover it produced a considerable amount of water in the mornings. I've often wondered whether daily temperature fluctuations and a combination of shade and chimneys and thermal mass cant produce something far more efficient than using solar panels.

    1. Jellied Eel Silver badge

      Re: I had a big pollytunnel

      It's fairly normal as a survival trick. Peg out a ground sheet, stick a rock in the centre, stick a mug on the ground under the sag, collect water. Slow, but water will condense on the groundsheet, run to the centre and drip into the mug.

    2. Anonymous Coward
      Anonymous Coward

      Re: I had a big pollytunnel

      Yeah, it's just different trade off for yield and space used vs materials cost and the conditions they work in. With the electric condensers you can move the solar element wherever makes sense, the condensers can be more vertical, and the ground underneath could still be used for other purposes(garden, car park, whatever). But if the conditions are right, even planting trees can pull enough water out of the air to start surface streams flowing at lower altitudes.

      I expect that as this takes off that the higher efficiencies they are shooting for will be realized by approaches that leverage both powered and passive elements(much like the cooling towers on the old power plants) and minimize land use.

  10. xyz Silver badge

    I've been trying this for a couple of years

    Without Google obviously and I just cant get it to work. Guess it only works on Star Wars'sets.

  11. gypsythief

    Cloud Fishing!

    I reckon The Chocolate Factory Evil Corp(TM) are somewhat over-thinking this.

    In Chile, they just chucked some nets in the air to catch the clouds, then ran an entire brewery from the water they captured that produces 24000 litres of tasty, tasty beer a year.

    One newer net setup is producing 4000 litres of water per day.

    Admittedly, this method is dependant upon clouds passing by so probably isn't deployable everywhere, but it is a cheap, simple and effective method that works. And they've been using it for 65 years. Do try to keep up, Google Evil Corp(TM).

    And, mmm, beer.

    1. Jimmy2Cows Silver badge

      Re: Cloud Fishing!

      Fine in foggy and low-cloud locations. More arid environments seem less workable for this approach.

      But hey, pick the best solution for the local conditions. Doesn't have to be a mutually exclusive this-one-or-that-one-everywhere thing.

    2. adam 40 Silver badge

      Re: Beer Fishing!

      Yes apparently if you are lucky enough to live next to a brewery, and do this, you can condense beer out of the air.

  12. Anonymous Coward
    Anonymous Coward

    Chile has perfect conditons for low tech water capture.

    The same kind of ecosystem is present on many islands where a higher altitude cloud forest drives most of the fresh water in the ecosystem. These techniques were known and used all the way back in the age of sail. The big difference is that the higher tech systems can work outside the narrower band where cloud or fog banks are forming, and past the morning dew point. So while low tech solutions may beat their efficiency and output under ideal conditions, being able to operate for longer and under less favorable conditions may buy them a seat at the table.

  13. Anonymous Coward
    Anonymous Coward

    How novel

  14. Fixador

    What of using a selective wavelength radiating material - ie emits 'heat' at a wavelength that is clear of atmospheric absorption wavelengths, so the material is cooler than all other local materials/surfaces ( if such a phenoma is possible ) - then water vapour at a relative humidity , might be cooled to, or below its dewpoint on the surface of the radiator material ?

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