The Water Abundance X-Prize was recently awarded to the Skysource/Skywater alliance for:

... developing an easily deployable high-volume water generator that can be used in any climate, meeting the competition parameters of extracting a minimum of 2,000 liters of water per day from the atmosphere using 100 percent renewable energy, at a cost of no more than two cents per liter.

And that sounds great! However, I've had a hard time nailing down actual numbers about energy usage. That leaves me with two questions:

  • How much input energy is required per litre of produced freshwater? And how does that compare to energy required by a desalination plant?
  • What is the quantity of greenhouse gas emissions (per litre of water) that are produced when the water generator is operating under ideal conditions?

There's a little bit of information on their FAQ:

Energy ranges from less than .4KWH/Liter to over kWh depending upon climatic conditions.

And that's just as they've written it. The upper limit is indeed missing.

From their products page, the smallest model consumes 0.8-1.8 kW, and generates 30 (presumably US) gallons per day at most. The largest model consumes 4.1-8.2 kW, and generates 300 gallons per day at most.

1 US gallon is about 3.8 litres, so the largest model generates about 47 litres an hour. At 8kW consumption, that's 0.17 kWh/l. Note that this doesn't match their other figure. I can't reconcile their FAQ with their products-page data.

And energy use per litre of potable water will vary hugely depending on humidity and temperatures. For somewhere cold and arid, energy consumption is going to be very large per litre of potable water. And for now, there aren't any customer data reports that I could find, so there's no information of how it actually performs in the real world.

  • That is substantially worse than desalination which returns 300 litres per kWh. – Nic Oct 24 '18 at 2:35
  • @Nic true, but this doesn't need to be near an ocean to work. They might even work on Tatooine. – LShaver Oct 24 '18 at 14:53
  • @LShaver That's very true, but I wonder why SkySource claims that "Skywater machines are much cheaper and more efficient than water desalination" Source. – Nic Oct 24 '18 at 16:34
  • @Nic since they don't back that up there's no way to know. Perhaps they're just looking at small scale desalination? – LShaver Oct 24 '18 at 19:21
  • Small scale desal can be very efficient, though - yachts use reverse osmosis systems and the more manual ones rival the big plants (at least on energy consumption). SkySource seems to be one of those "wait and see what happens when they become commercially available". – Code Abominator Oct 24 '18 at 21:58

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