Desalination @ 1/10 Power, 1/2 Cost wins MIT competition

[h20man]

Interesting news of a new way of getting drinking water from the winner of an MIT 100K USD competition:

(their first target market is sailors)... https://www.nona-technologies.com/

Solar-powered desalination device wins MIT $100K competition







Nona Desalination is developing a compact water-desalination device that requires less electricity than a cell phone charger.
 
Zach Winn | MIT News Office

Publication Date:
May 16, 2022

The winner of this year’s MIT $100K Entrepreneurship Competition is commercializing a new water desalination technology.

Nona Desalination says it has developed a device capable of producing enough drinking water for 10 people at half the cost and with 1/10th the power of other water desalination devices. The device is roughly the size and weight of a case of bottled water and is powered by a small solar panel.

“Our mission is to make portable desalination sustainable and easy,” said Nona CEO and MIT MBA candidate Bruce Crawford in the winning pitch, delivered to an audience in the Kresge Auditorium and online.

The traditional approach for water desalination relies on a power-intensive process called reverse osmosis. In contrast, Nona uses a technology developed in MIT’s Research Laboratory of Electronics that removes salt and bacteria from seawater using an electrical current.

“Because we can do all this at super low pressure, we don’t need the high-pressure pump [used in reverse osmosis], so we don’t need a lot of electricity,” says Crawford, who co-founded the company with MIT Research Scientist Junghyo Yoon. “Our device runs on less power than a cell phone charger.”

The founders cited problems like tropical storms, drought, and infrastructure crises like the one in Flint, Michigan, to underscore that clean water access is not just a problem in developing countries. In Houston, after Hurricane Harvey caused catastrophic flooding in 2017, some residents were advised not to drink their tap water for months.

The company has already developed a small prototype that produces clean drinking water. With its winnings, Nona will build more prototypes to give to early customers.

The company plans to sell its first units to sailors before moving into the emergency preparedness space in the U.S., which it estimates to be a $5 billion industry. From there, it hopes to scale globally to help with disaster relief. The technology could also possibly be used for hydrogen production, oil and gas separation, and more.

I AM IN NO WAY ASSOCIATED with this company.......

 

[AnIdiot]

Loving the choice of size comparison... for those unfortunate souls unfamiliar with US measures and packaging... what's "a case of water"?

 I see they describe it as "one cubic foot" (helpful!)... so, ~30litres... size, if not shape, of a small backpack. Or do they mean the weight (~11Kg) of the above case?

Looks interesting, anyway...

 

[hoektron]

Details are a bit skimpy on their website - absolutely nothing about power requirements. Not surprising since this is a new product in development.

I does say no membrane to clean and no pickling required. That would be nice.

Not sure I would want to be a guinea pig on this for something so mission critical (especially on passages) where proven, low power alternatives already exist.

Kudos to them for pushing the boundaries tho.

 

[CapDave]

Former hard-tech startup investor here - I've seen multiple shots on this goal. It's basically electrodialysis of water, first theorized in 1890 and now used commercially in various applications including desalination and some other specialized applications. For desalination, compared to RO, it can be better in brackish water (up to 3,000ppm) and in places where you need very high feed recovery. For salt water @ 35,000 ppm without feed quantity restraints, not so much. To treat water with high TDS like that you need many "layers" of ion exchange membranes, and the hydraulic overhead becomes daunting, and the membrane cost starts to drown (no pun) the business case, and membrane fouling becomes an operational challenge, and those are just the headlines. Nobody publishes their failures, so youngsters try the same things over and over without knowing why previous shots on goal failed and without a novel or innovative approach to the root causes of failure. That's why you need cynical old guys like me around.....

 

[accnick]

Former hard-tech startup investor here - I've seen multiple shots on this goal. It's basically electrodialysis of water, first theorized in 1890 and now used commercially in various applications including desalination and some other specialized applications. For desalination, compared to RO, it can be better in brackish water (up to 3,000ppm) and in places where you need very high feed recovery. For salt water @ 35,000 ppm without feed quantity restraints, not so much. To treat water with high TDS like that you need many "layers" of ion exchange membranes, and the hydraulic overhead becomes daunting, and the membrane cost starts to drown (no pun) the business case, and membrane fouling becomes an operational challenge, and those are just the headlines. Nobody publishes their failures, so youngsters try the same things over and over without knowing why previous shots on goal failed and without a novel or innovative approach to the root causes of failure. That's why you need cynical old guys like me around.....

If it sounds too good to be true, it probably is. This sounds like maybe a brackish water solution.

RO is used on a massive scale in parts of the Middle East.

 

[alphafb552]

Heard about this a few weeks ago, still very much in prototype stage. Production after 30mins was just barely a single cup of water...

It'll be a few years before this becomes a viable option to RO

 

[chester]

Former hard-tech startup investor here - I've seen multiple shots on this goal. It's basically electrodialysis of water, first theorized in 1890 and now used commercially in various applications including desalination and some other specialized applications. For desalination, compared to RO, it can be better in brackish water (up to 3,000ppm) and in places where you need very high feed recovery. For salt water @ 35,000 ppm without feed quantity restraints, not so much. To treat water with high TDS like that you need many "layers" of ion exchange membranes, and the hydraulic overhead becomes daunting, and the membrane cost starts to drown (no pun) the business case, and membrane fouling becomes an operational challenge, and those are just the headlines. Nobody publishes their failures, so youngsters try the same things over and over without knowing why previous shots on goal failed and without a novel or innovative approach to the root causes of failure. That's why you need cynical old guys like me around.....

so true, so true!  

 

[socalrider]

I always joke that if I could get clients to pay me a commission based on $$ saved from not doing stupid stuff I tell them not to do, I'd be retired... sadly nobody wants to pay consultants lots of money to tell them not to do stuff.

 

[mckenzie.keith]

Very early days for this. I know from experience that many things announced in the "early days" phase are never heard from again. For example, I wish I had a dollar for every press release I have read promising new battery technology better than lithium ion batteries. Or new super high efficiency solar panels.

Also, 100k US dollars is nothing. Not even one year of salary for one person. So they will need a lot more money (like 10 to 100 million or something) to get off the ground.

I think saying it is a year or two away from market is pretty optimistic. They are probably 5 years away from market assuming they get funded and the technology works.

But if they can produce drinking water from seawater for less power than RO that will be great.

 

[socalrider]

But if they can produce drinking water from seawater for less power than RO that will be great.

There are some fundamental laws-of-physics stuff that dictate how much energy it takes to pull salt out of water (efficiency goes up with water temp).  That's the first place I'd look if I were doing diligence - surprising how many technologies I evaluate violate a fundamental.  I wonder how much more efficient you can actually get compared to an Energy Recovery Systems pressure recovery device or, at a smaller scale, a Spectra Clark pump.  I am very skeptical that the answer is actually 10x.  

The answer's probably somewhere in here if anyone cares to do the digging...

 

[El Borracho]

There are some fundamental laws-of-physics stuff that dictate how much energy it takes to pull salt out of water …. The answer's probably somewhere in here if anyone cares to do the digging...

Yes. I recall posting some power details about that a couple of weeks ago in a related thread about this hyperbole. The Spectra system used far less power that that published by the developers of this thing. Quite close to the theoretical minimum power. They will need to do much better. A small Spectra is not much bigger than a suitcase … whatever size that is. 

 

[mckenzie.keith]

Yes. I recall posting some power details about that a couple of weeks ago in a related thread about this hyperbole. The Spectra system used far less power that that published by the developers of this thing. Quite close to the theoretical minimum power. They will need to do much better. A small Spectra is not much bigger than a suitcase … whatever size that is. 

What might be interesting is putting  a high-pressure low-flow energy recovery pump on non-spectra watermakers. I wonder if something like that could be retrofitted. It seems like it should be possible to use a conventional pump before the membrane and then put a totally independent energy recovery pump after the membrane instead of a restriction valve. Spectra wouldn't need this, obviously. But for the rest, it would be nice to recover some of the pressure flow energy for battery charging or just offsetting the power consumption of the main pump.

 

[Startracker]

What might be interesting is putting  a high-pressure low-flow energy recovery pump on non-spectra watermakers. I wonder if something like that could be retrofitted. It seems like it should be possible to use a conventional pump before the membrane and then put a totally independent energy recovery pump after the membrane instead of a restriction valve. Spectra wouldn't need this, obviously. But for the rest, it would be nice to recover some of the pressure flow energy for battery charging or just offsetting the power consumption of the main pump.

I'm not a particularly smart person, so there are likely options for this somewhere I have not found, or reasons why not, but I have been attempting to explore this particular rabbit hole recently.  I'd like to find a broken water maker with a salvageable ER unit to play with.  I have a pet theory I wish to test out, and a pump I think may work better for feeding it than the currently used ones, longer life and durability though possibly a bit less efficient.  

I eventually figured out that a spectra pump by another name is called a hydraulic intensifier pump, but I have not found any in the right size/price range.  From the specs I think it is a 1:10 Hydraulic intensifier.  It doesn't recover energy in terms of electricity for example, but simply takes a flow of say 50L/min at 50 PSI, and would output 5L at 500PSI, at least if I understand it correctly, and I am not sure that I do.

 

[mckenzie.keith]

I'm not a particularly smart person, so there are likely options for this somewhere I have not found, or reasons why not, but I have been attempting to explore this particular rabbit hole recently.  I'd like to find a broken water maker with a salvageable ER unit to play with.  I have a pet theory I wish to test out, and a pump I think may work better for feeding it than the currently used ones, longer life and durability though possibly a bit less efficient.  

I eventually figured out that a spectra pump by another name is called a hydraulic intensifier pump, but I have not found any in the right size/price range.  From the specs I think it is a 1:10 Hydraulic intensifier.  It doesn't recover energy in terms of electricity for example, but simply takes a flow of say 50L/min at 50 PSI, and would output 5L at 500PSI, at least if I understand it correctly, and I am not sure that I do.

I think the place where energy is wasted is at the output of the membrane chamber. The pressure in the chamber is super high. The flow is very low, but since the pressure is high, it is still a lot of hydraulic power. Some systems (I believe) just use a restriction orifice (like a disk with a pinhole in it or something) to maintain the high pressure and still allow flow. That is the equivalent of slowing down a motor running at full throttle by putting on the brakes.

The spectra folks have a different pump system that is able to recover some of the wasted energy and use it to run the high pressure pump. That is how they do energy recovery. As far as I know this works well.

But it occurs to me that you could replace the orifice with a pump set up to resist the flow of high pressure water. And use that pump as, basically, a turbine (not exactly but similar idea) to generate electrical power. Of course you would not get as much power as the main pressure pump is using up. But it would be a simple way to recover energy from, maybe, any watermaker and get rid of the orifice that I assume is there.

I am not super up-to-speed on watermakers so some of my assumptions could be wrong.

 

[El Borracho]

The bypass flow does not change pressure (much) in the RO chamber. To maintain pressure some systems use a restriction. There the energy in the bypass flow is all wasted in violence at that restriction. The product flow that exits the RO chamber is at low pressure. Either atmospheric or just enough to reach the water tank. The pressure drop of the product flow is in the membrane itself as a necessary and (mostly) irreducible part of separating the salt. There is no energy to recover there. The principal of the Clark pump is that the energy lost at the bypass restriction can be recovered by essentially using that pressurized flow to help power the pump. Sweet.

Converting that energy back into electricity would seem inefficient.

The low pressure feed pump of the Spectra is a noisy hot beast. I would focus some effort on the waste therein. That is where at least half the energy is wasted in little parts flailing themselves about. Something slower, calmer, and more efficient would be nice. 

 

[socalrider]

Yes - the Clark Pump is one way to avoid just wasting pressure.  Another method used in larger scale desalination is ERS which makes an amazing ceramic turbocharger like thing capable of surviving saltwater and pressure for years and years at high RPM.  Truly a mechanical marvel (like the Clark pump).  

This is all pretty well trodden ground.  I also hate the low pressure pump Spectra uses - I'm sure a quieter pump could be used but not sure if it would be much more efficient.  Pumps in general are really well understood.  

I was trained as a MechE - I quickly got frustrated at how little room there is for innovation in the field!  Most of the major theories were figured out in the 1700's-1800's and most of the major inventions in the 1870-1910, with only a few after that (gas turbine engine being the biggest deal).  The ERS device made my heart go pitter patter when I first saw it 15 years ago or so.  Worth a closer look if you're so inclined.  

: 

 

[mckenzie.keith]

The bypass flow does not change pressure (much) in the RO chamber. To maintain pressure some systems use a restriction. There the energy in the bypass flow is all wasted in violence at that restriction. The product flow that exits the RO chamber is at low pressure. Either atmospheric or just enough to reach the water tank. The pressure drop of the product flow is in the membrane itself as a necessary and (mostly) irreducible part of separating the salt. There is no energy to recover there. The principal of the Clark pump is that the energy lost at the bypass restriction can be recovered by essentially using that pressurized flow to help power the pump. Sweet.

Converting that energy back into electricity would seem inefficient.

The low pressure feed pump of the Spectra is a noisy hot beast. I would focus some effort on the waste therein. That is where at least half the energy is wasted in little parts flailing themselves about. Something slower, calmer, and more efficient would be nice. 

First of all, you can't improve energy wise by a lot on the spectra. They are the ones who are doing it right. That is not what I am proposing. (I mean, other than your idea of improving the low-pressure booster pump).

The brine stream has to be pressurized in order for pure water to reverse osmote through the membrane. I get that the pressure gradient across the membrane is necessary. I didn't know what the "bypass" was called. That is where the brine stream goes after passing by the membrane I guess. My understanding is that the spectra energy recovery pump has a way of not just wasting that power or energy. On a system that does NOT use a spectra energy recovery pump, I am wondering whether you could just place a second pump there, powered on DC, and run it at a low enough voltage to the point where it is able to electrically regenerate, but also maintain 900 PSI for the brine stream near the membrane. However, there may be reduction gears and such that are not shaped properly for reverse direction torque.

While I agree that a recovery system there might be not very efficient, it is still more efficient than wasting 100 percent of the energy in violence as you say. I also embrace your idea of improving the booster pump. Maybe you could use a higher flow pump then run it underspeed with a different volute. Or use a BLDC motor instead of a DC brushed or AC induction motor.

 

[mckenzie.keith]

Yes - the Clark Pump is one way to avoid just wasting pressure.  Another method used in larger scale desalination is ERS which makes an amazing ceramic turbocharger like thing capable of surviving saltwater and pressure for years and years at high RPM.  Truly a mechanical marvel (like the Clark pump).  

This is all pretty well trodden ground.  I also hate the low pressure pump Spectra uses - I'm sure a quieter pump could be used but not sure if it would be much more efficient.  Pumps in general are really well understood.  

I was trained as a MechE - I quickly got frustrated at how little room there is for innovation in the field!  Most of the major theories were figured out in the 1700's-1800's and most of the major inventions in the 1870-1910, with only a few after that (gas turbine engine being the biggest deal).  The ERS device made my heart go pitter patter when I first saw it 15 years ago or so.  Worth a closer look if you're so inclined.  

View attachment 510892 : 

Do you think something like this exists that is small enough to run on a cruising boat?

 

[socalrider]

Do you think something like this exists that is small enough to run on a cruising boat?

I doubt it.  Their smallest unit is ~5,000lph and I suspect most installations are orders of magnitude bigger.  Interesting to think about whether the concept could be scaled down another 1-2 orders of magnitude.  ERS has patented the crap out of their system as I understand so it'd likely have to be them.  Pretty small market to go after but I guess Spectra makes it work.