Efficient Device for creating water out of thin air. Aka The fallout water purifer

[Erez]

http://edition.cnn.com/2014/04/24/tech/innovation/machine-makes-drinking-water-from-air/

 

"The system produces 250-800 liters (65-210 gallons) of potable water a day depending on temperature and humidity conditions and Kohavi says it uses two cents' worth of electricity to produce a liter of water."

 

 

"The World Health Organization reports that 780 million people don't have access to clean water, and 3.4 million die each year due to water-borne diseases."

 

 

"Water-Gen's units can produce a liter of water for 1.5 Rupees, as opposed to 15 Rupees for a liter of bottled water."

 

"Another product Water-Gen has developed is a portable water purification system. It's a battery-operated water filtration unit called Spring. Spring is able to filter 180 liters (48 gallons) of water, and fits into a backpack -- enabling water filtration on the go."

[Walsingham]

Solar stills are a far _far_ better idea.

[Blarghagh]

If that really works, that's awesome.

[Fighter]

Sounds too good to be true.

[HoonDing]

T. Howard is a visonary.

[Zoraptor]

You can get some 'free' energy out of heat pumps via entropy, iirc, so in theory you can get very efficient heating/ chilling cycling.

 

The question is whether it works well in appropriate conditions. You want something that produces water well in the dry season when humidity is low and temperatures high, something that produces water well only when humidity is high such as during/ after rain or monsoon is a lot less useful.

[Orogun01]

You can get some 'free' energy out of heat pumps via entropy, iirc, so in theory you can get very efficient heating/ chilling cycling.

 

The question is whether it works well in appropriate conditions. You want something that produces water well in the dry season when humidity is low and temperatures high, something that produces water well only when humidity is high such as during/ after rain or monsoon is a lot less useful.

It works for Florida all year round.

[Zoraptor]

Florida is, basically, a big swamp next to the sea, with appropriate apologies to Floridians for the rather blunt and stereotypical description. Florida does not match many places where water would be needed very closely at all- which are, basically, monsoonal, ie lots of water when there's lots of water, otherwise near desert. Somewhere like Nagpur in India is hundred of km from the sea and has up to 45 degree heats  (up to 35 degree mean daily temperature) in summer with 27% average humidity, and seven months with less than 20mm average monthly precipitation. Tampa, say, does get to an average mean temp of 32 degrees, but average humidity never drops below 69% and it has seven months of less than 70mm rainfall, which is still quite a lot especially if you have high humidity which retards evaporation.

 

So the question is whether that device could efficiently work in Nagpur's significantly different conditions- fundamentally, there's no shortage of water in Florida, just shortage of potable/ fresh water whereas there is, fundamentally, a seasonal shortage of water in Nagpur.

[Orogun01]

No, i'm pretty sure we all know we live in a swamp. Still there are bouts of drought in some places during the summer because of a lack of rain. 

[Zoraptor]

If you're close to the sea you always have relatively high humidity though- take Mumbai for example, it's on pretty much exactly the same latitude as Nagpur but is on the coast rather than inland, has the same monsoonal climate just more extreme (drier when dry, wetter when wet) yet its lowest average humidity is 67%. It's that humidity where the water comes from. Even in drought conditions Florida or Mumbai will get humidity from the sea so there's plenty of 'easy' water to extract, you cannot say the same for inland places with humidity in the 20s.

 

I'm not saying that this device is useless or anything, just that it is likely not to work as well in areas where it would really be useful.

[Orogun01]

But it may create a surplus in nearby areas that lower the transportation cost involved. You pessimists and your half empty glass, should probably get one of those devices see if you can fill it.

[kgambit]

Actually, I'm not impressed in the unit.   Despite the touted improvements in efficiency, it's a hardly a viable solution to water shortages given that the unit's annualized operating cost (excluding maintenance) is prohibitive.

 

Using India as the test case, here's the breakdown:

 

From the company website.  The GEN-350G ground atmospheric water generator produces 450 liters/day (120 gallons/day) at conditions of 25°C and 55% RH.  The unit requires 0.310 kWh (under those conditions) to produce 1 Liter of pure potable water.  Zoraptor's comments on the relative efficiency of the unit under extreme conditions are pertinent but let's just use the idealized operating conditions.

 

The UN suggests that we need 20-50 litres of safe freshwater a day for drinking, cooking and cleaning.  That's 100 to 250 litres per day for the average family in India*.  I'm going to use 150 L/day as the average.  That is slightly higher than Indian government standards for rural India (135 L per day as of 2011) but less than the UN average of 175 L/day. 

 

The average cost for electricity in India is ~7 cents per KwH. (That comes pretty close to matching the 2 cents per liter  the article quotes  i.e. 7 cents/KwH x 0.310 Kwh/L = 2.17 cents/L)

 

So the yearly per family energy cost is 150 L/day x 365 days/yr x 0.310 KwH/L x 0.07 $/KwH = $1,188 per year

 

The only problem is that the average per family annual income in India is $1,219.   The majority of families in India simply can't afford one and that's excluding all the maintenance and upkeep not to mention the 7 year lifespan of the unit. 

 

It's probably a decent unit for emergencies and when you're less concerned about cost but as a long term solution to water shortages, not so much. 

 

If you want to carry the analysis further, you can check out these two sites:

 

http://phys.org/news156506896.html#jCp

 

http://physics.ucsd.edu/do-the-math/2012/10/the-energy-water-nexus/#sthash.u5fC1OLX.dpuf

 

Those two sites calculate the energy cost of a regional purification and filtering system at 1.39 x 10^-3 KwH/L and 1.06 x 10^-3 KwH/L respectively.  Roughly 1/2 of 1% of the KwH cost of the GEN-350G.

 

*The average family size is India may actually be closer to 4.  Running the analysis on that assumption makes the Un average and Indian government estimates almost the same.  Using the UN average of 140L/day reduces the annual cost by about 7% but doesn't change the conclusions.

Edited August 26, 2014 by kgambit

[Orogun01]

But for aid groups that might work in the area it would help them set up a local operation rather than having to import water from somewhere else.

[Erez]

 

From the company website.  The GEN-350G ground atmospheric water generator produces 450 liters/day (120 gallons/day) at conditions of 25°C and 55% RH.  The unit requires 0.310 kWh (under those conditions) to produce 1 Liter of pure potable water.  Zoraptor's comments on the relative efficiency of the unit under extreme conditions are pertinent but let's just use the idealized operating conditions.

 

The UN suggests that we need 20-50 litres of safe freshwater a day for drinking, cooking and cleaning.  That's 100 to 250 litres per day for the average family in India*.  I'm going to use 150 L/day as the average.  That is slightly higher than Indian government standards for rural India (135 L per day as of 2011) but less than the UN average of 175 L/day. 

 

The average cost for electricity in India is ~7 cents per KwH. (That comes pretty close to matching the 2 cents per liter  the article quotes  i.e. 7 cents/KwH x 0.310 Kwh/L = 2.17 cents/L)

 

 

We are talking about purified drinking water here. an average person in hot areas would drink 3-5 liters a day per person, you can use more efficient ways to cook and clean.  In my country 75% of the agriculture uses waste water with more than 80% of the country water consumption being recycled.  Like already mention earlier here, this machine is humidity based so in wont be effective for people living in the desert unless they start planting trees. Unfortunately many countries whom are suffering from lack of water are doing exactly the opposite.

[kgambit]

But for aid groups that might work in the area it would help them set up a local operation rather than having to import water from somewhere else.

 

Agreed or for interim disaster relief (where the units or similar ones have already been used such as the Phillipines).

 

@Erez  Even if you restrict the usage to simply drinking water (which runs against both Indian and UN guidelines) to reduce operating costs, the unit itself is still cost prohibitive for families.  I found much less efficient units which produce for smaller quantities of water running 2400$ and up.