Comment by hnmullany | Hacker News Reader

Comment by hnmullany | Hacker News Reader

Apart from whether the economics make sense brine disposal from desalinization is a big issue. Waste with high salt concentrations can wipe out marine life - it would be nice if this piece took the issue a little more seriously. It's a continuing problem in the Canary Islands which are dependent on desalinization plants:

"Rejected brine is a serious threat to marine ecosystems, causing negative effects on both flora and fauna. This is especially so when the optimal initial high dilution capacity is lacking in the discharge system. Consequently, brine discharge plumes spread over large areas of the sea floor and modify the structure and distribution of benthic communities such as seagrass habitats. ... Rejected brine disposal costs are between 5 and 33% of the whole desalinization process, depending on the characteristics of the brine, its pretreatment level before disposal, disposal method, and volume"

from: Jiménez-Arias, D., Morales-Sierra, S., García-Machado, F.J., García-García, A.L., Luis, J.C., Valdés, F., Sandalio, L.M., Hernández-Suárez, M. & Borges, A.A. 2020, "Rejected brine recycling in hydroponic and thermo-solar evaporation systems for leisure and tourist facilities. Changing waste into raw material", Desalination, vol. 496, pp. 114443.

There should definitely be a plan for the brine.

I'm optimistic we could:

* Build ocean pipelines that disperse brine over much larger volumes of water to minimize impact on wildlife

* Dump the brine water in engineered desert fields where it will evaporate and deposit salt reserves.

In general, we should be aware of the whole lifecycle of a solution, and optimistically believe we can solve each problem with more work.

> Dump the brine water in engineered desert fields where it will evaporate and deposit salt reserves.

Honestly, the Salton Sea would be a great place to dump the brine. It would keep the water levels up and reduce the respiratory issues caused by drying, and any ecosystem to be destroyed has been thoroughly destroyed for decades.

Nix the "turn the manmade salt lake to a manmade fresh lake" plan, and use the created freshwater for agriculture directly, or send it off to LA, or do anything with it that isn't "refill the accidental lake that already has evaporation and pollution issues". It's a salt lake, use it as one.

This is something I still don't understand about the original plan: Where is the Salton Sea expected to get more water from on an ongoing basis? If you keep extracting from it and not refilling it, it's just going to keep getting smaller and saltier. Agriculture isn't going to put back out as much as it takes in (the plants need it, after all). Sure, you can drag it out a few more years with desal, but eventually it's not going to be much of a sea, just a salty pile.

AFAICT, water is pumped from both the Sea of Cortez & the Salton Sea to a desal plant. The fresh water is used for irrigation etc, and the runoff from primary use replenishes the Salton.

Huh, I guess I was mistaken that restoration on the Salton Sea was already in progress. I've seen large flocks of birds in and around it and assumed there was food for them in it. But it sounds like no, it's still horrible.

The Salton sea is the home of a huge lithium deposit, and it's unlikely that anything but geothermal and lithium mining will happen there in the near future. Certainly not "restoration" to what it was when it was accidentally created.

My understanding is that the lithium in the salton sea is relatively less accessible than other nearby lithium deposits, such as the new mine starting up in northern Nevada. Sort of nearby I suppose.

Between that and the increasing availability of sodium ion batteries it may never actually be economical to mine the Salton Sea, especially considering people actually live nearby and would be affected by the mine; unlike the mines in northern Nevada.

They'd be mining the brine in which the lithium is dissolved as well as constructing geothermal plants to take advantage of the temperature of the liquid.

Construction is already beginning.

https://www.usatoday.com/story/news/nation/2023/12/07/lithiu...

Is there a way to know how much to care? We do all sorts of things that displace species, so having some way of contextualizing and weighting the harm against the benefit would be helpful.

Seems to me it would initially be a narrowly scoped to the immediate outflow. As the brine dissipates I assume it will be normalized by the rest of the ocean as it's diluted.

However, as with all human endeavours, scaling up will scale up the problem. And we won't pay attention to that until it's a huge issue.

This is necessarily a value judgment, isn't it? There are tools like lifecycle analyses and environmental impact reports and threatened species lists that can help estimate/enumerate impacts. But ultimately how much to care is a personal question, and people are going to disagree over whether some small fish or rare owl or fluffy panda is worth more or less than someone's job or a local industry or just some other charismatic species.

Species will always come and go, and they're going to die off faster than we can protect them, sadly. We only get to decide which ones to prioritize, at different personal, local, national, global levels etc.

I would start by wanting to know about the impact and benefit relative to other activities which we already do. Like how's it compare to various flavors of farming?

There's a database for California Environmental Quality Act reports, I think (Environmental Impact Reports? Statements? One is federal and the other is state, can't remember which is which). That probably have similar solar farms you can look at. Not sure about huge desal projects. Maybe overseas?

I'll try to find some analyses this weekend if I can.

The Canaries have 32% of the economy based on tourism, and a good chunk of that depends on the local ecology (scuba, nice beaches, etc.)

If you want to see what a tourism place looks like when you destroy its ecology, you only need look at the abandoned areas around the Salton Sea.

The Salton Sea in its current iteration was created by the failure of an irrigation canal. Before that there was no Salton Sea as we know it or tourist area.

Sure, but that’s beside the point of the question, which is “how do we know salinifying an area enough to kill species is bad”

> RO desal splits the incoming ~3% salinity stream into two halves, one fresh and one ~6% salinity. This concentrated brine is fed to adjacent brine processing facilities (ideally in both countries) that exploit the region’s abundant solar and geothermal energy to extract potentially millions of tonnes of lithium, sodium, magnesium, chloride, and other metals found in sea water. The resulting depleted brine is piped back to the ocean where it is thoroughly mixed with sea water and discharged.

Casey's proposing we mine the brine for useful minerals. You're right he's glossing over details, but a citation addressing the economics of brine disposal with his proposed processing would add more to the discussion.

Basically, I think you could take the Brine and just put it somewhere else. Like, into mine shafts, or into evaporation pools for mining purposes.

the intent of the project is the conversion of a saline lake to freshwater, not the creation of a saline lake.

If you give a mouse a cookie…

...be sure to give it an opt-out pop-up too?

Considering that the brine output of a single large-ish plant might be 150,000m³ per day[1], that's a hell of a mine shaft to take it continuously. The rock with the same volume as a day's brine would weigh a million tons. The entire Aberfan spoil tips were only 2 weeks worth of that much volume (2 million cubic metres).

The gigantic Hambach open-pit mine grows by 0.3km³ a year, so that could take it (but it can't take the Saudi million m³/day plant). By the time the mine is depleted, the resulting 18km³ pit would not be filled by our single hypothetical plant for over 300 years, assuming it won't evaporate. Which leads to:

The evaporation pools might work: they'd "only" have to be 3000 acres (12 km²) to gather the 4GW of solar power at 1kW/m² for 8 hours a day to continuously evaporate that much water daily[2]. Which is certainly large, but not completely impossible. But then there's 2 million tonnes of salt per year which will accumulate continuously over time.

[1] the largest is over a million

[2] not including water not bring a perfect absorber of solar energy or differing insolation

The brine has value too though, and possibly even more than the fresh water, if you extract the salts from it post-evaporation.

Or, just be the world’s biggest producer of pickles

From https://www.frontiersin.org/articles/10.3389/fmars.2022.8451...

“ In general, anthropogenic activities pollute the coastal marine environment, altering the environment’s physiochemical properties and resulting in changes in marine communities. Physiochemical conditions can be altered by the presence of pollutants, hypoxia, organic enrichment, decreased hydrodynamic conditions, and, more recently, brine discharge (de-la-Ossa-Carretero et al., 2016). Salinity elevation in receiving soil and water bodies and the territorial consequences of brine with high total dissolved solids on benthic marine life close to the discharge site are the most important environmental challenges associated with brine disposal (Miri and Chouikhi, 2005; Panagopoulos et al., 2019).”

Lots more detail in the article on studies of specific populations as well as discussion of mitigations and alternatives.

We just simply don't need that much brine for useful minerals -- it's a huge cost and you'll be left with massive piles of mostly useless salt.

On one of my hard drives, I've got an engineering / construction plan for a moderately sized intake + discharge for a small RO facility that would've passed muster in Australia, which has pretty reasonable environmental protections. Round numbers - the intake would have cost $25 million and the discharge more like $75 million. You need a massive structure to be able to emit that brine back into the environment in a way that doesn't just nuke the surrounding marine life. Huge pipes + check valves + cascading discharges, all either on the ocean floor if there aren't reefs and other sensitive areas or even worse from a cost perspective, tunneled out to a depth that can handle the amount of salt.

Seawater is ~35g/L of TDS - the author is talking about 5 million acre feet of desal - what's that, 20 million tons of salt annually?

This is doable. Many coastal wastewater systems already have large pipes that extend miles to sea (1), and that's a rounding error compared to the many more miles of pipe routing sewage to the plant (2, pg A-3)

(1) https://www.wateronline.com/doc/new-10-mile-long-sewage-tunn...

(2) https://www.sandiego.gov/sites/default/files/ploovol4_15.pdf

Pipes tend to last a long time, in large part because it's relatively straightforward to manage the chemistry problem in the pipes.

https://slimemoldtimemold.com/2021/08/02/a-chemical-hunger-p...

This guy claims that Lithium may be partially responsible for some weight gain in our population, but also, that desalination plants cause extra lithium as well.

If it was mined out, that would be viable, but if not...

It's probably not lithium.

And despite the initially valid-seeming high hopes for their amazing scholarship, currently it looks that they are too crackpot-y :/

https://www.lesswrong.com/posts/7iAABhWpcGeP5e6SB/it-s-proba...

https://www.lesswrong.com/posts/NRrbJJWnaSorrqvtZ/on-not-get...

Out of the edit window, but this seems like a nice summary of the current understanding of the hypothesis: https://manifold.markets/LarsDoucet/will-the-contaminant-hyp...

Will the contaminant hypothesis of modern obesity be judged true by expert consensus before 2032? 8% yes 92% no

In an environment where solar and geothermal electricity are abundant enough to make this work, it would be far easier to condense water straight from the air by refrigeration.

I think you’re underestimating how much less efficient that is.

It worked for Uncle Owen

:D and if you scale this to the point where the amount of water vapor in the atmosphere is affected, you can also use some of the abundant energy to boil the ocean to replace that water vapor. :) Same net effect (water is taken from the ocean and salt is not) without actually moving the salt back and forth.

If you desalinate 1 gallon of seawater, and then mix the brine with 10 gallons of seawater, the salt content of that seawater has increased ~10 percent.

If that’s still too much, use 20 gallons.

It’s a matter of spending energy on pumps, but it’s totally doable.

Also, the ocean salt content will not be increased by this, since the desalinated water will eventually make it back to the ocean.

But where are you getting that pure seawater from? If it's anywhere near the outlet, there's a scale at which the concentrated brine will affect the salinity of your inlet.

Yes, some pipes are needed. Beyond that, you rely on ocean currents. .

Yeah, but if you’re pulling in water and disposing it from a specific region, eventually the water that you’re pulling in is progressively saltier, and you’re compounding the saltiness of that area.

I’m sure that ocean currents will eventually equalize the salt, but if you’re continuously dumping salt into a specific area, it’s going to make that region of the ocean saltier.

You need pipes to spread it out. And I think you may be underestimating the scale and force of ocean currents. Every tide probably moves more water than California uses in a year.

I don't think the ocean is equally saline everywhere: https://salinity.oceansciences.org/maps-global.htm

On average it's pretty close, but you can definitely get impacts from increased local salinity: https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.16859 (just random ecamples)

https://www.scientificamerican.com/article/slaking-the-world... (view in incognito)

Okay fair point.

Crucially but overlooked so far in these threads, is that the proposal does not have brine exiting on the California coast; it has it flowing into the Sea of Cortez.

That should be an obvious non-starter for anyone remotely familiar with the unique geography and ecology of the area.

It sucks you guys home in on some weird issue for every promising technology.

He literally addresses brine in the article.

It's a community of hackers passionate about the way things work. Picking it apart helps everyone understand the inputs and outputs of a system to understand how feasible it is, and what the tradeoffs are. What would you prefer, a generic "that's nice"?

As far as I can tell, the author just kinda glossed over the brine situation. Some minerals can be sold, but his solution for the excess salt was just to turbulently mix it back into the ocean, if I'm reading correctly. The sibling comments here explain why that isn't trivial (cost and wildlife impacts). I found them illuminating!

He addresses brine, but not the waste products that come from brine, and only addresses it in one sentence:

> The resulting depleted brine is piped back to the ocean where it is thoroughly mixed with sea water and discharged.

This is not nearly as easy as this sentence implies.

Brine is just concentrated seawater. What waste products?

The waste product is brine. It's an extremely salty sludge that's toxic to marine life. In the same way that fresh water is "just" diluted seawater, but pumping millions of gallons of it into a coastal ecosystem would wipe it out.

The pipe should really go a dozen miles out to sea and then get pump-mixed with the destination water

Yes it is. We do it with urban wastewater in thousands of locations around the world. This is not a hard problem, nor is it expensive.

Waste brine is substantially more dense than regular seawater, so it tends to form a coherent layer that doesn't mix easily: it's why waste brine sinks to the sea-bed and spreads out in a layer.

Diffusers are a thing. Fairly well understood.

They provide some detailed and constructive thoughts. What exactly does your comment provide? Some sort of complaint which could be solved by yourself by not going into the comments or not reading theirs, hope this helps you in the future.

Brine discharge is an issue, but the geography of the North American West Coast is favorable for that. In most places the seafloor drops down fairly deep just a short distance offshore. Past about 400 ft / 120 m there is no flora at all, and most fauna is clustered around rock structures. So, the impact of brine discharge can be minimized with careful pipeline siting.

Careful pipeline siting indeed. The author needs to update the proposal to have the brine exiting on the Pacific coast, rather than annihilating the the Sea of Cortez.

Can’t we pipe the seawater inland and then deposit the salt on land?

When it rains, what happens to the run-off from a huge pile of salt?

Surely the massive open air pools of salt used for sea salt production have figured out how this process works.

On the Californian coast, there is already at least https://en.wikipedia.org/wiki/South_Bay_Salt_Works , a sea salt production facility that uses salt pools. They produce 80k tons annually of salt, which means they process 2666k tons of seawater to get that. If that one salt production facility used brine as their source instead of seawater, they would have allowed the facility to produce 2580k tons of freshwater. The "urban" usage of water in California is 10 million acre-feet (ish), so that's not exactly a significant amount.

Your quote doesn't give any evidence it is a big problem. It simply asserts that it is a problem and includes some random factoid about the cost.

Perhaps the net effect is ostensibly positive, given the greening and habitation of that blighted area in CA.

you could use brine for construction (Isreal build a wall along Jordan). Also you can pump it into a ship and dump into Pacific, slowly.

The naive solution is to just dump the brine back into salton sea, its already too salty for marine life, so whats a little more salt?

>flaunt its unequaled excellence by exporting alfalfa to all corners of the globe.

really not sure if this is satir.

Your naive solution just creates an even more gigantic stagnant stinky mess of a Salton "sea". The entire point is to reengineer the salton sea as a beautiful ecosystem and lake by diluting all the salt with 5MAF of RO desalinated water. The added benefit is huge economic revitalization of the entire area. Plus, because of the value of minerals in the brine, and the cost-effectiveness of solar power, it is not as expensive and crazy of an idea as one might think.

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