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back to article MIT boffins on track of portable 60-watt seawater desalinator

MIT boffins say they're on the track of a nifty, portable machine which could turn dirty seawater into enough clean drinking water for several people - using no more power than a lightbulb. Seawater desalination is already widely used, but conventional technologies such as reverse osmosis don't scale down well past a certain …

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There is'nt even a water shortage in the UK

According to the *only* known national survey of it's kind (done in 1976 for some reason) there's plenty of water, but most of it is in Wales.

OTOH Thames water loose as much water per household as they supply to that household.

Thumbs up for this neat piece of tech. Logically whenever you scale things down you should sharpen up voltage gradients a *lot*, just the sort of thing you want to pull salt ions around.

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Coat

"OTOH Thames water loose (sic)as much water per household as they supply"

They do? How/why were they tying the water up in the first place?

In recent years, Thames Water have been digging up shedloads of roads (and leaving so many crazy-looking plastic barriers around that it looks like Mariokart in the 'burbs), in an effort to replace that leaky Victorian pipework.

Hopefully, those dreadful leakage figures will shift.

That said, there have been some interesting papers about entire ecosystems dependant on said leaky Victorian water mains, so go figure, innit?

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The "drought" of 1976...

... was probably the reason that the survey was done.

I remember some friends visiting from Australia who commented that where they lived they'd not had any rain for about five years and they were just considering declaring drought conditions...

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Haiti water

If you look carefully, you'll find that GE has set up at least 5 portable (as in, carry by 2 men before installation) units at water sources in Haiti. These delivery about 5,000l/day from solar energy only.

http://www.gereports.com/solar-powered-water-purification-units-ship-to-haiti

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De-salinisation, not purificuation

I think you'll find those GE installations are water purification plants, not de-salinisation plants. Additional access to the purified sea water could be a huge help.

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This post has been deleted by its author

Happy

"just a shortage of power"

I don't think the Sun will stop shining anytime soon, or the Earth's core going stone cold. At the moment, what we do have is a shortage of taking solar and geothermal seriously. All I see is token government interest, probably to keep climate people happy.

It's hard not to sound like a nutjob when suggesting companies and government really don't want us to have access to 'free' power, which could power things like this free drinking water (and free communication). That would really be the next age of humanity, and it can't come soon enough.

Sorry, sounded like a hippy there as well. Maybe that's the problem. Proponents of all this just sound a bit silly :)

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Pint

Have you tasted desalinated water?

Euughhh! Mind you, if it was the only water available I suppose I could force myself to drink it... but not before the beer.

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Joke

Desalinated water.

Have you tasted salinated water? Even more euughhh factor to that! Though i agree with the beer angle.

Beer

Own pee

Desalinated water

Other lifeboat companion's blood

I foresee at least one benefit of installing these units in a lifeboat.

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Taste

Thats probably because your used to tap water, full of lime and other "bits".

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Pint

You forget one important issue here

It can be made into beer just by adding barley, hops, yeast and time. Can't do that with seawater. How mankind is progressing...

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As it's by the sea....

...is there a portable wave generator that could hook up to it?

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Making waves again.

Is the sea abnormally calm where you live ? Surfing fanatic perchance ?

Why else would you want to generate waves ?

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Oh Dear

Does this mean Gaddafi's pipes are dead in the, erm, water?

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Grenade

WWF

WWF hardline? WTF!

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Coat

WWF hardline

You betcha, it's all the roids and lycra that makes them cross. You need to be good and angry to wrestle pandas, anyway.

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Infinite fresh water.....

"Fresh water is often assumed to be a finite resource in short supply, especially by green campaigners**. But this kind of tech shows that in fact for the vast majority of the human race that lives near the sea this is not the case. "

Just a pity the 'vast majority of the human race' doesn't live near the sea eh ?

"There's no such thing as a shortage of fresh water"

Yes there is, FAPP, be it due to lack of any water, lack of technical resources, funds, expertise or other reasons - don't be an arse Lewis.

"- just a shortage of power."

That helps, where the power can be used to obtain fresh water from somewhere/something, but not otherwise. I get your point, but please don't make such a ridiculous simplification.

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Stop

Actually ...

Half the population of earth lives within 200km of the coast, and two thirds within 400km. Piping water 400km has been a solved problem for about 2000 years.

I think you're being a bit pedantic - of course Lewis isn't saying that as of 0900 this morning fresh water supply is sorted for the whole planet. What he is saying is

1. with enough energy, there's no such thing as a matter* shortage

2. this new technique uses very little energy.

* I could say "water", but this can be extended to almost anything.

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Pedantry

"Half the population of earth lives within 200km of the coast, and two thirds within 400km. Piping water 400km has been a solved problem for about 2000 years."

Part of my point is that the people who talk about a fresh water shortage aren't talking about a shortage of fresh water given an abundant supply of salt/contaminated water. They are talking about a shortage period.

"I think you're being a bit pedantic"

Slightly yes - but I was annoyed at the Apple to Orange comparison, especially as I admire Lewis' attention to detail when analysing the words of others.

" - of course Lewis isn't saying that as of 0900 this morning fresh water supply is sorted for the whole planet. "

No - he seemed to be saying 'with enough energy, if you live by the sea you should be ok'

"What he is saying is

1. with enough energy, there's no such thing as a matter* shortage"

Yes there is - that's the point. There is plenty of energy in many places with severe fresh (or any) water supply problems - that doesn't much if you don't have any water, or the money to acquire the technology, or the expertise to use it and maintain it.

"2. this new technique uses very little energy."

Yes that's great - I have no problem with that or the rest of the article. It was the apparent dismissal of the real problems of fresh water supplies, seemingly to have a quick pop at an organisation, that I objected to.... especially given the excellent stuff normally coming out of the person writing the article - had this come from Orlowski I wouldn't have batted an eye-lid.

* I could say "water", but this can be extended to almost anything.

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Happy

Pessimism

Ok, maybe I'm glass-half-full and you're glass-half-empty (see what I did there? :D )

Sea-water is available in abundance, to two-thirds of the people on the planet. This could be a way to provide fresh water to all these people, given a relatively small investment in energy infrastructure and hardware. It's really good news compared to the prospect of using current technology, infrastructure and fresh water to supply these people.

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Happy

Pessimism

:) My coffee mug does actually read "this glass is now half empty", courtesy of despair.com

However, in all seriousness, I love the tech but my beef was with Lewis' statement that effectively there is no problem with getting fresh water ("Just add POWER !!") which is unfortunately bollocks. He conflates the arguments from people stating there is an issue with getting fresh water supplies available to people *anywhere in the world* with his statement about this tech being of use to people *who live near the coast*.

That is not a fair comparison, and the reason for my issue that part of the article. Apart from anything else, around 60% of the worlds population live > 100km from the coast, and no-one is pumping water to them - and it's a bit far to walk.

That said, I wish these guys all the best, and can see a great deal of uses for it.

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Shortage, what shortage?

You dont have to live by the sea to have salt water, the biggest river system in Australia - the Murray - Darling actually discharges to the sea with water the is saltier than sea water. I'm sure many small communities along its banks would be grateful for this technology.

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Conventional lightbulb?

I for one am deeply suspicious about statements like 15L per hour of water can be produced with the power used by a conventional lightbulb when, by any measure, the power usage of freely available conventional tungstem incandesent lightbulbs run from about 1 to 150 watts (or at least they used to be freely available before the push for low-energy lightbulbs). Wouldn't it just be easier to state the power consumption?

However, a little bit of research shows that large scale reverse osmosis plants can produce drinkable water at 7kWh per 1,000 litres. That would require about 120W to produce 15L per hour of drinkable water (although this will contain about 500 ppm of salt so it isn't that pleasant). As this new system is meant to be less efficient than large scale reverse osmosis then I think this "about the power of a conventional lightbulb" is going to be the 150W sort to produce 15L per hour, not 60W.

Generating 150W of electrical power from a human-powered device is going to be a lot of hard work. Most people will find producing the necessary 200W of mechanical power or so to do this somewhat exhausting after an hour or two (it's equivalent to cycling at about 20mph or so on a decent road bike) and will considerably increase the amount of food intake required (reckon on about 5-600 extra kilo- calories per hour, the human body being perhaps 30% efficient in turning calories into mechanical power). In a hot climate the guy generating this 200W is probably going to have to drink 10% or more of the 15L per hour to sustain the power output.

Now this technology might be useful in extremis, but I have severe doubts over the practicality. Large numbers of micro-desalination units would have to be held in stock and distributed at the time of the disaster and it will take time and training to set up. If the purpose is to save lives, then it's almost certainly going to lose out in the short term to direct distribution of drinkable water and the idea of using large amounts of human energy to desalinate water when the required food supply is likely to be in short supply is unlikely.

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Anonymous Coward

@Arkasha

Yes I have when it was provided in saudi arabia. There was one tap of 'sweet water' in the house, for drinking, desalinated to IIRC 50 PPM of salt, the rest were desalinated to IIRC 2000 PPM and were for washing. Sweet water tasted quite acceptable, the 2000PPM stuff was distinctly brackish but still swallowable.

BTW *nothing* would lather in that washing water, your hair felt permanently stiff and one's skin a bit... odd.

@Craig 12: energy is everywhere, just not in the cheap, concentrated form we're accustomed to. I hope that changes.

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Mmmm

Sounds like the water in Santa Barbara.

Which, for one of the richest places on Earth, is particularly squalid. Hard enough you can practically stand a spoon upright in it. Distinctly salty and with the refreshing aftertaste of the local oilfields.

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2000 PPM!?!

I can't imagine anyone would actually call that desalinated. A concentration like that puts it squarely in the middle of the brackish camp as it's a bit over 5% the concentration of plain ocean water. I suspect, like everything else, it's far easier to get the first ~95% of the salt out and a damn site harder to get that last 4.85%.

They answered the "does it work" question but now they need to answer "how do we sell it?"

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We live near the ocean

@ Tim

I believe about 75% of the human race live within 50 miles of the ocean

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Belief

"I believe about 75% of the human race live within 50 miles of the ocean"

I admire your belief, even in the face of reality.

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Go

Hmm

Combine this with those mini reactors I read about today and perhaps we might be able to survive the next few years.

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ermm

For lifeboats you already have reverse osmosis pumps. Maybe not as efficent in watts/litre but you can drive them mechanically - it's just like a big bike pump, but a lot less to go wrong.

Most microfluidics stuff has a real issue scaling upto the industrial scale. It's pretty easy to build prototypes from silicon and PMA but when you want the silicon wafers to mate up with stainless pipes and o-ring seals the engineering and tolerances get expensive.

Then you have the issue of cleaning, servicing, flushing the filters etc - all tricky on large scale reverse osmosis plants but much worse on a tiny portable device. It will probably turn out to have to have disposable cartridges where you simply throw away the microfludics part making it too expensive for anything other than western hikers or military.

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A fair bit of point missing going on here

The point of these new units is that they are easily portable.

'Proper' reverse-osmosis or evaporation plants are huge, using lots of power. So they're very hard to transport to the place that needs them - you need to take a big generator (maybe 1000kVA), plus the big purifier unit.

Going by the ones on the last cruise liner I worked on, that's roughly two 40-foot ISO shipping containers for a usable system, plus the fuel oil to run the generator for however long you need to go for.

So to get it to where it needs to be, you need two container lorries and a fuel bowser - or a few trips with a very big helicopter.

These 'new' devices are small and can be run off a very small generator, of the kind you see in B&Q - A single 1kVA gennie would run several of these devices.

So you could throw 'a few' of these new purifier systems into the back of a transit van or pick-up truck.

Much easier and therefore faster to get out to somewhere that needs them.

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Overkill

I seem to remember a solar powered water purifier that cost about 10p to make - simple inflatable tent of black and clear plastic that worked extremely well from about twenty years ago. One the size of a wheel would be working in the KW region.

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Pint

Solar Distillation...

...is cheap for small capacities. Any enclosure, clear on top and black on the bottom will do.

Once past the "emergency" application, systems must be in place to backflush, sanitize, dust, and otherwise maintain* a working system.

It's not just the oceans, many wells in the southwest yield very salty water. Solar pumps can bring the water up, and solar distillation** can make it drinkable. The biggest user of solar pumping is the cattle industry, when you need water the most, there's no wind, but plenty of sun. I would imagine salty wells exist in many areas of the world.

Scaling this simple technology up will benefit from creative engineering and intelligent control.

Earth seen from space is "The Water Planet"

Water, #1 ingredient in 211.

*If you don't do all that, the water get's really nasty.

**Water distilled by solar collectors is VAPOR DISTILLED. The $.75 per gallon stuff is STEAM DISTILLED. Using a Sears Still, i consume $.25 2.5 KWH of power to make 1 gal of water.

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could you .....

Power it with a solar panel? 15L of water an hour would provide a reasonable amount of irrigation for salt tolerant plants. Mind you, how long could your run it for continuously.

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Coat

Brilliant idea!

Do none of you realise what this could mean to the starving nations of the earth?

They'd have enough salt to last forever.

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Safe to say

These guys are about to become stupidly rich just as soon as the Pentagon can find the chequebook.

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Paris Hilton

Shortage of power and...

"There's no such thing as a shortage of fresh water - just a shortage of power."

... and desalinators.

I'm thinking that in some places, give people a single huge desalinator and a power source to drive it, and someone will take both apart for scrap because it suits them.

But give everyone a small, cheap desalinator they can power themselves, and they'll fight to defend it, although that shouldn't be necessary if it doesn't contain any scrappable parts and if it's reliable enough that everyone who might want to steal it already has one. That's where I see this device might be headed.

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FAIL

only power!?

as others have pointed out - this article misses the point of the technology. fresh water is never in short supply providing you've got a coast line and enormous amounts of power. RO plants are springing up around the world for precisely that reason. the problems with RO are precisely that of energy. they are hideously expensive to run, particularly if they're going to use green power and not contribute to 'burning' through our limited fossil or nuclear energy supplies.

if it's even less efficient than ROs then this seems like a useful gadget but with precisely zero relevance to global water supplies.

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Slingshot

What is the status of Dean Kamen's Slingshot program?

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Solar

"just a shortage of power"

"I don't think the Sun will stop shining anytime soon, or the Earth's core going stone cold. At the moment, what we do have is a shortage of taking solar and geothermal seriously. All I see is token government interest, probably to keep climate people happy."

Solar will work, but it sounds like this device itself would be pretty small and portable, while a 60W solar setup (I just looked it up) is about 4 feet wide, 5 1/2 feet tall, a foot thick, and weighs about 60 pounds. That's without any battery etc. to steady out the power supplied to the device. Not insurmountable, but it does mean it's not like there'll just be a unit with a little solar panel on it to power itself.

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Enormous amounts of power ... hardly

Enough drinking water for 15 people using 60 watts ... that's not enormous. It's the output of a smallish solar panel. 50cm square would do, if the sun is shining.

How efficient is this, compared to the low-tech way of making drinking water using the sun? Better, I hope. An emergency DIY solar still consists of a plastic-lined hole in the ground, that you fill with vegetation or (saltwater OK) wet rags. You put a bowl in the middle, cover the hole with another plastic sheet, put a stone and a bit more seawater in the middle of the cover sheet. The sun vaporises water on the inside and the outside. The outside evaporation produces a cooler spot on the plastic, the inside vapour condenses on the cool spot, and drips into the bowl.

On a bigger scale, one could either build a solar-thermal power station to run a desalination plant, or boil saltwater in the solar-thermal plant, get some electricity from the steam, and then condense the steam into drinking water. Again, I wonder which is more efficient?

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Ah, Massachusetts seawater

So they used "Massachusetts seawater purposely contaminated with 'small plastic particles, protein and human blood'" for their test? Is this just boffin-speak for "we dipped a pint from Boston Harbor"?

Of course, as a lad growing up on the Massachusetts shore I ended up swallowing a fair bit of the stuff from time to time, and it did me no harm, aside from the occasional spot of brain damage. But tell that to kids these days...

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Anonymous Coward

"just a shortage of power"

Ah, another typical “technology will solve everything” article.

I am sure this technology is very useful, and millions/billions could use it. On the other hand, mostly in industrialised countries, maybe we should focus on restoring untainted fresh water systems, and use cleaning technology before pollutants are discharged, so we have a purer environment to live in, rather than creating sewage rivers, and then having to filter out some of the diluted crap we put in, while the rest gently flows past our offended eyes and nostrils.

No. I am not member of “hardline” WWF or any other NGO.

Calling WWF hardline while you routinely make articles about the almighty, ruthless, corrupt, unpunished US (and other’s) armament industry would be funny if it weren’t so sad and so deadly. If the WWF is hardline, what do you call these guys? I don’t recall you making any judgement.

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