New low cost, highly effective way to produce fresh water

[StuM]

Originally Posted by contrail

Actually, the first Spectras made eight gallons per hour with a draw of 8 amps per hour, .

How many amps did they draw per minute to make 8 gallons per hour?

[StuM]

Originally Posted by contrail

A good Spectra watermaker will get you a gallon and a half for those same 20 watts.

20 Watts for how long?

[col50]

Originally Posted by contrail

Actually, the first Spectras made eight gallons per hour with a draw of 8 amps per hour, which is every bit as efficient as the one's today. And the original Recovery Engineering Power Survivors (now Katadyn) made 1.4 gallons for 4 amps. So, this new technology has a way to go. I hope they do make it, but they are overstating their advantages, for the moment.

There is no such thing as amps per hour.
One amp = 6.242 X 10^18 electrons per second.
If you draw a current of 8 amps for one hour, you have used 8 amp-hours.
If you draw 8 ams at 12 volts you have used 96 watt-hours (8X12). If you draw the same 8 amps at 24 volts for on hour, you have used 192 watt-hours.
Watt-hours are energy; amps are not. It takes energy to do work, not amps.

[ItDepends]

Originally Posted by Caleb_Grey

They've been working on it for 10 years and millions of dollars and all they have to show for it is 2 gallons a day and a $100,000 prize they gave themselves, oh and 10x the energy use of a typical desalination device.

And, almost as important as the "prize", a PRESS RELEASE. It helps generate buzz among those people who do not have the engineering chops to recognize puffery when they see it.

"It was in the news, it must be true!"
"Any day now. Just a few more research grants..."

If I had a dollar for every great discovery that has been trumpeted on this forum that has never come to pass, I'd have a new Spectra watermaker of my own--that actually works.

I think you'll find that pretty much all the time if somebody actually makes a great breakthrough that is an order of magnitude better than anything else, they make it and they sell it. They don't issue a press release telling you how smart they are. Unless you are Elon Musk, then you do both.

[Kelkara]

so much negativity on this thread ... the breakthrough they made is in distilling water processed out of air ... not really applicable to boats since the sea is a much more plentiful source of water to process.

[ItDepends]

So often things seem so nice and easy. A great breakthrough has been made, and the smart people publishing the article have found a way around the laws of physics that everyone else has to obey.

Until you let an engineer read the fine print. Somebody who actually understands the conservation of energy, and that the 2nd Law of Thermodynamics forbids getting a free lunch from the universe--no matter how much you WISH for it.

Reversing entropy (turning water from a vapor to a liquid, for example!) ALWAYS takes an external input of energy. Always. It's the law.

All the fancy words about polymer membranes and adsorption and release sounds great, but when you understand there HAS to be an energy input to the system, you start looking for it. And there it is:

To release the absorbed water the membrane has to be "...gently heated to 60C"!

Assuming an ambient temperature of 30C, that "gentle heating" will take 34 W-hrs of energy per liter of water produced, and that is making the very generous assumption there is no energy other than the specific heat of water needed. Now you have very hot water and you have to find a way to prevent it all from evaporating away before you can cool it down.

Unless you can find a way to recover most or all of this energy or make it for free way cheaper than solar panels make electricity, it's not energy competitive with existing desalination technology--except maybe as an emergency water supply.

My watermaker (NOT a Spectra) uses 25 Amps at 24 Volts to make 40 Liters per hour of fresh water. That's 40 liters per 600 W-hrs, or 15 W-hrs per liter. Color me very unimpressed by the system invented by the boys at MIT.

[Kelkara]

"it's not energy competitive with existing desalination technology"

Its not meant to be ...

and I imagine desert dwellers far from the sea are not impressed with spectra's technology.

[Mad Multi]

Firget that here is the newest best tech.

https://www.thedailybeast.com/mit-engineers-created-a-portable-device-that-zaps-seawater-to-make-drinking-water

[GordMay]

Originally Posted by ItDepends

So often things seem so nice and easy. A great breakthrough has been made, and the smart people publishing the article have found a way around the laws of physics that everyone else has to obey.

Until you let an engineer read the fine print. Somebody who actually understands the conservation of energy, and that the 2nd Law of Thermodynamics forbids getting a free lunch from the universe--no matter how much you WISH for it.

Reversing entropy (turning water from a vapor to a liquid, for example!) ALWAYS takes an external input of energy. Always. It's the law...

Ginsberg's Theorem (a re-statement of the three laws of thermodynamics)
1. You can't win.
2. You can't even break even.
3. You can't get out of the game.
4. THE LAW OF ENTROPY: The perversity of the universe tends towards a maximum.

[CaptTom]

Originally Posted by Mad Multi

Firget that here is the newest best tech.

https://www.thedailybeast.com/mit-en...drinking-water

Seems like more techno-babble to me. Key points:

He also explained that he wants to tackle challenges beyond desalination including detecting and removing contaminants in water such as heavy metals and disease-causing pathogens like viruses and bacteria.

That's kinda important. I think that needs to be solved before the big announcement.

desalination...only operates on a large scale, such as a big plant

Thousands of cruisers have dis-proven that point.

[desalination is] an inefficient process for places in the world such as California where 'the water demand is always fluctuating.'

Fresh water is pretty easy to store, making fluctuating demand a non-issue. It almost seems like someone lifted this whole idea from a story on renewable energy, where matching demand to supply really is a problem.

[GordMay]

Originally Posted by GordMay

Ginsberg's Theorem (a re-statement of the three laws of thermodynamics)
1. You can't win.
2. You can't even break even.
3. You can't get out of the game.
4. THE LAW OF ENTROPY: The perversity of the universe tends towards a maximum.

Physicists Rewrite the Fundamental Law That Leads to Disorder
The second law of thermodynamics is among the most sacred in all of science, but it has always rested on 19th century arguments about probability. New arguments trace its true source to the flows of quantum information.
➥ https://www.quantamagazine.org/physi...ocket_discover