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Desalination Is Booming. But What About All That Toxic Brine?
- sandworm101 8y ago>> totaling 141.5 million cubic meters a day, compared to 95 million cubic meters of actual freshwater output from the facilities. Bad news for the environment, to be sure, but things aren’t altogether dire: Desal tech is rapidly evolving, so plants are getting far more efficient, both in the brine they produce and the energy they use. Bad journalism. Bad science. A desal plant is essentially a brine production facility. A more efficient plant won't output less salt. It may be less by water volume but that water will just be all the more salty. This cannot be avoided short of piling the salt up on the land. Brine is bad, but when mixed in with the vast volumes of the oceans is a non-issue. All the brine produced by desal plants is nothing compared to the brine produced by sunlight on the ocean surface. >> "But herein lies opportunity: The discharge can also contain precious elements like uranium." Ya. Um, that is an entirely different story. Uranium from seawater is a thing today even without the brine. Some put the amount of natural uranium in seawater in the billions of tons. Every country in the world suddenly having ready access to a limitless supply of uranium? Desal might be the least thing to worry about.
- flavius29663 8y agoit's indeed a bad article. Probably newer plants will have to dump their brine further away from shore, where it's dissipated easier? What is the effect of the brine on the local ecosystem? Is it on par with the warming of water by thermal plants? The article raises more questions than it answers.
- newyankee 8y agoDoes anyone working in the field know if a 100-1000x reduction in energy consumption of desalination is theoretically possible - using so called promised supermaterials based on graphene/nanotubes etc. or some kind of economies of scale ? Or are we limited by the law of physics here ? I am really skeptical of promise of materials like graphene because although i have heard about magical properties for so many years now i have never heard of practical mass manufacturing completely upending an old school method for something. May be i am not knowledgeable enough. This is one of the technologies that is increasingly important for the future of the earth especially in water poor countries with heavy population. In the large scheme of things it might turn out cheaper to move population closer to the coasts, have desalination plants instead of other solutions to water scarcity assuming renewable energy costs reduce significantly as well along with a lot of surplus.
- flavius29663 8y agoWater evaporated and leaves brine behind, at any temperature above 0C (even below through sublimation). Theoretically I guess you can imagine the sun evaporating the water that you capture, so you could have close to 0 energy input. So there is no physical limit I suppose. But you don't want to wait for the sun, you want to speed up that process, I don't know what the limit is there, when the speed matters (how much does it matter?).
- jartelt 8y agoAnything close to a 100-1000x reduction in energy consumption is unlikely in the next 10-20 years. That said filters have steadily gotten better over the years (better throughput, more durable, etc.) Also, the main thing to focus on is cost of water produced. If you design a new filter that is much more energy efficient but costs 100x more than the standard plastic filter, it may not provide much advantage.
- zozbot123 8y agoThere is a theoretical minimum energy required to desalinate water, because an entropy cost is involved. At room temperature, the cost works out to about 0.8 kWh per cubic meter, and our best systems seem to reach approx. 25% efficiency.
- solarkraft 8y agoThanks. It's quite a bit better than I expected.
- Simulacra 8y agoI think the problem of salt is a much bigger problem than we realize it. It's toxic, you can't burn it for fuel, and you can't really do anything with it except store it. Are there other ways of disposing of salt without repercussions?
- unchocked 8y agoIf only there was a large body of water nearby in which it could be diluted...
- theothermkn 8y agoFrom the fine article: > But a less chattered-about problem is the effect on the local environment: The primary byproduct of desal is brine, which facilities pump back out to sea. The stuff sinks to the seafloor and wreaks havoc on ecosystems, cratering oxygen levels and spiking salt content.
- loco5niner 8y agoThe problem is that is where it currently goes... It is addressed in the article.
- ucaetano 8y agoYes: sell it. Or dilute it. The solution to pollution is dilution.
- gameswithgo 8y ago>The solution to pollution is dilution. For a while. The scale of human population and our increased per capita resource usage starts to make that less often viable.
- gizmo686 8y agoNot for brine. The salt comes from the ocean in the first place, and the water returns to the ocean relativly quickly. Unless something changes and we start to notably change the volume of water in the ocean, dilution is the only way to maintain the ocean chemistry. If we don't, then we would be reducing the salinity as the water returns without the salt.
- unchocked 8y agoIt came from the ocean. Put it back in the ocean.
- lightbyte 8y agoFrom TFA: >The stuff sinks to the seafloor and wreaks havoc on ecosystems, cratering oxygen levels and spiking salt content. >Because this stuff is denser than typical seawater, it sinks to the seafloor and disrupts vibrant communities of life, which find themselves wanting far less salt and far more oxygen. >But brine is more than just hypersaline water—it can be loaded with heavy metals and chemicals that keep the feedwater from gunking up the complicated and expensive facility. “The antifoulants used in the process, particularly in the pretreatment process of the source water, accumulate and discharge to the environment in concentrations that can potentially have damaging effects on the ecosystems,” says Jones.
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- loco5niner 8y agoThat's exactly what the article is about. Putting it back in the ocean is the problem.
- CyberDildonics 8y agoThis article is terrible. It contains lots of exaggerations and conflates all sorts of problems like the assumption that all energy usage means burning fossil fuels.
- makerofspoons 8y agoAquion Energy is making salt water batteries, that could be a good use for this stuff: http://aquionenergy.com http://aquionenergy.com
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- plainOldText 8y agoSadly their FAQ states they’re in the process of rebuilding their business as a consequence of filing for bankruptcy.
- makerofspoons 8y agoThat is unfortunate, but considering the opportunity presented by the need for grid-level energy storage for renewables or even by the need for domestic energy storage for solar as well as the apparent availability of materials it could be an attractive area for innovation.
- ip26 8y agoI'm still kind of shocked lead acid is faring so poorly when it comes to grid storage. One of the oldest (the oldest?) battery chemistries, well understood, really cheap, mostly safe, simple, durable, serviceable, recyclable. (sidenote, submarine warfare was, for decades, powered by lead acid) It's chief disadvantages are low power density and low power to weight ratio, neither of which matter for grid storage. It just seems to have all the hallmarks of traditional industrial solutions. But, of course, lithium ion has the same advantage ubiquitous silicon semiconductors have- massive, massive economies of scale and endless R&D dollars.
- dzhiurgis 8y agoLead acid doesn't handle (input or output) current so well. Perhaps 5x or so than lithium.
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- lawrenceyan 8y agoUse the waste byproduct for molten salt energy storage: https://www.maltainc.com https://www.maltainc.com. Not only efficient, but profitable even to do so.
- partingshots 8y agoIs there any constraint on what types of salt or salt compounds are usable for energy storage? Or does it not really matter for the most part?
- lawrenceyan 8y agoNot really, though a commonly used thermal salt is the eutectic mixture of 60% sodium nitrate and 40% potassium nitrate, which can be used as liquid between 260-550 °C. Table salt, or sodium chloride, has a melting point of around 800 °C. So it really depends on what attributes your looking for.
- StreamBright 8y agoWhat about http://news.mit.edu/2015/shockwave-process-desalination-water-1112 http://news.mit.edu/2015/shockwave-process-desalination-wate...?
- dbatten 8y agoThis article talks about newer technologies being "more efficient" in terms of the brine they produce, by which they seem to mean that you get more fresh water with less brine production. How is this possible? Your input has a certain amount of salt and water in it, right? How do you take out the same amount of water, but leave less salt behind? Am I missing something?
- empath75 8y agoI imagine you recycle brine into seawater somehow.
- dwighttk 8y agoI think they are using the technology on brackish water instead of seawater, less brine in -- less out, but more water out.
- mjevans 8y agoI believe they're ignoring the concentration of salt in the brine, instead only counting the volume of 'highly salty water' that is output.
- solarkraft 8y agoTL;DR No inherent terrible problem, just issues as it scales. With sea levels rising there's not going to be a global shortage of water.
- nanomonkey 8y agoI'm curious what the mineral content is of the brine water. There are a few cyanobacteria, like spirulina, which thrive in alkaline water that other algae can't handle. One could likely use the run off to process high nitrogen content sewage water and produce spirulina which could be used for food, oil and ethanol production.
- powera 8y agoI'm disappointed this article talks so much about brine, and so little about the even-more-dangerous Dihydrogen Monoxide that is a result of the process. This is a very bad article - pure FUD.