👤11thEarlOfMar🕑6y🔼219🗨️71

(Replying to PARENT post)

Graphene can do almost anything except exit the lab. I hope to see my grandchildren see its benefits one day.

https://www.reddit.com/r/askscience/comments/6tzy80/graphene...

👤bariswheel🕑6y🔼0🗨️0

(Replying to PARENT post)

One of the key questions for desalination is how good can it get. It turns out that many desalination plants are probably close to the thermodynamic limit [1, 2], which means that even with new technologies it's likely energy costs aren't going to go down by an enormous amount. The Ars review suggests the best we can do is a factor of 3-4x, which is nice, but if we're expecting this to solve all our water needs we may have another thing coming. For reference, the cost of water is as low as $25 per acre-foot [3] in CA, and the most recent desalination plant in San Diego is on the order of $2000 per acre-foot [4]. Even some of the other estimates in [3] suggest that the average cost of water is something like $7-800 per acre-foot, which would put us right around where the thermodynamic limit suggests the floor of desalinated water would be.

Obviously this is great new tech and more water purification technologies are always needed, but given the physical boundaries it's unlikely we'll be able to use desalination as the only solution to water crises. We should still be figuring out ways to be more efficient about water use.

[1] https://arstechnica.com/science/2011/08/desalinization-is-th...

[2] http://science.sciencemag.org/content/333/6043/712

[3] http://www.cpuc.ca.gov/uploadedFiles/CPUC_Public_Website/Con...

[4] https://www.mercurynews.com/2014/05/29/nations-largest-ocean...

👤entee🕑6y🔼0🗨️0

(Replying to PARENT post)

"scientists also needed to demonstrate the durability of the membranes under prolonged contact with seawater and ensure the membrane was resistant to "fouling" by salts and biological material (which requires existing barriers to be periodically cleaned or replaced)."

Er, yes. All they have is an experimental membrane that won't pass salt. Lots of those exist. Can you backwash it and get the salt out? It has to handle concentrated brine in reverse. Plus whatever other crud is in the incoming water. Most of the headaches of real desalinization plants revolve around those issues. Fragile membranes are a big issue.

This is in Nature Nanotechnology, not Desalinization, which has a more practical orientation.

👤Animats🕑6y🔼0🗨️0

(Replying to PARENT post)

Not to rain on the parade, but is there any example of graphene being used at scale to do anything? I feel like I've heard about graphene for the last 20 years and how it's going to be a miracle material, but we have little to show for it besides some nice lab results
👤omosubi🕑6y🔼0🗨️0

(Replying to PARENT post)

This is a component -- what's the device model? The energy cost of crossing that gradient will continually increase (you could use gravity, but you still have to clean the briny side).

The of course brine disposal is a problem.

Don't get me wrong -- I love this work -- but it's just part of the solution.

For a lot of people in poor, hot regions a simple evaporator of concrete with a glass top is surprisingly effective, both cap ex and op ex (both pretty low, though they assume a tiny cost of labor).

👤gumby🕑6y🔼0🗨️0

(Replying to PARENT post)

What is it about every HYS in the Science section that attracts the population control nutters? We all add one to the total. Those screaming for our numbers to be reduced fail to notice a small part of the solution to the problem every time they look in the mirror.
👤QuamStiver🕑6y🔼0🗨️0

(Replying to PARENT post)

Does anyone have a solution by now on what to do with the millions of tons of salt which are produced by desalinating water?

I read that right now the salt is just dumped somewhere being a huge burden for flora and fauna.

👤Jakob🕑6y🔼0🗨️0

(Replying to PARENT post)

Might want to attach the (2017) label, although I hadn’t heard of it until now.
👤snazz🕑6y🔼0🗨️0

(Replying to PARENT post)

What can't graphene do?
👤chrisweekly🕑6y🔼0🗨️0

(Replying to PARENT post)

Osmotic pressure is still a thing and semipermiable membranes already exist. Will be intersting to see what the actual benefits are compared to what already exists.
👤salty_biscuits🕑6y🔼0🗨️0

(Replying to PARENT post)

I have heard about graphene being some kind of holy water in the last decade quite a few times. Sadly, it seems only possible to recreate amazing results lab wise.
👤SunnyS🕑6y🔼0🗨️0

(Replying to PARENT post)

Has there been any progress on it? Seems to be just a lab experiment
👤wolfi1🕑6y🔼0🗨️0

(Replying to PARENT post)

Seriously this was news 5 years ago.
👤AltmousGadfly🕑6y🔼0🗨️0

(Replying to PARENT post)

Taokey?
👤bkmeneguello🕑6y🔼0🗨️0

(Replying to PARENT post)

Excellent news I need a desalinator for my boat and this should bring down there ridiculess costs, can't wait to see the production model. This will revolutionize fresh water production for many dry third world countries and make a lot of revenue for Britain
👤Amendeson530🕑6y🔼0🗨️0