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LA is dumping millions of plastic balls into its reservoir to tackle the drought
- abricot 11y ago"in which a total of 96 million balls have been poured" "they're cheap (costing just 36 cents per unit)" Is that really cheap, or is it just because it's in LA?
- venomsnake 11y agoDepends on the ball ... you need to use food grade plastic. And certifications and on and on and on ...
- hkmurakami 11y agoAs sibling poster [1] mentioned, the balls are cheaper (and probably last longer) than the tarp alternative. [1] https://news.ycombinator.com/item?id=10052777 https://news.ycombinator.com/item?id=10052777
- DonHopkins 11y agoSince it's LA, they could have recycled millions of silicon breast implants instead of using plastic balls. ;)
- tristanj 11y agoThey're not dumping plastic balls in order to tackle the drought, they're being dumped because the EPA mandated that all reservoirs be covered. Direct sunlight will cause bromide and chlorine in the water to mix into bromate, a known carcinogen, and the EPA wants to prevent buildup of this compound in the drinking water supply. Covering the reservoir with a tarp is too expensive (costing over $300 million) and plastic balls are a much cheaper option. The evaporation reduction is a secondary benefit, not the primary one, and the article title should reflect this. There's much better coverage of this story here [1] and here [2]. [1] http://www.npr.org/sections/thetwo-way/2015/08/11/431670483/la-rolls-out-water-saving-shade-balls http://www.npr.org/sections/thetwo-way/2015/08/11/431670483/... [2] http://news.nationalgeographic.com/2015/08/150812-shade-balls-los-angeles-California-drought-water-environment/ http://news.nationalgeographic.com/2015/08/150812-shade-ball...
- markyc 11y agodoesn't the plastic + sunlight + heat combination release dangerous chemicals in the water? also, why are they black, doesn't that attract more heat?
- erikb 11y agoThat's also what I was wondering. Touching something wet, being warmed by the sun, and all that, can't be good for the black plastic.
- DonHopkins 11y agoThat's what I thought, too. Shiny silver balls would reflect even more light, and look super-cool!
- fyolnish 11y agoAnd they'd sink
- DanBC 11y agoWhy would they sink?
- easytiger 11y agoBeing balls, they would also reflect that light into the water
- legulere 11y agoActually white balls probably would be better. What you normally reach with specular reflection is around 80% reflectivity. With diffuse reflection (white colour) you can get into the 99.x% range much more easily.
- StavrosK 11y agoThey don't care that much about heat, they care more about sunlight not reaching the water, which black balls are more effective at.
- mattmcegg 11y agowe are so fucked.
- deleted 11y ago[deleted]
- Bootvis 11y agoWhat I don't understand is that they dumped black balls in the reservoir. If you want to keep the water cool to lessen evaporation wouldn't it make sense to use white or reflecting balls so the water stays slightly cooler? I would be glad to know why black balls are chosen.
- cengizkrbck 11y agoblack is best suitable color to deflect UV rays.
- erikb 11y agoNow you just said the opposite of what intuition suggests without any evidence, or even argument. Please elaborate and don't just heat up the discussion!
- DanBC 11y agoBlack is the best colour to absorb UV. You want the UV to not reach the water, so you want whatever is on top of the water to not allow UV past.
- Implicated 11y agoUV + Chlorine = Bromide
- erikb 11y agoDoes that look like an explanation to you? I don't see anything about black. I don't see anything about white. I don't see anything about reflecting materials. I see something from chemistry, maybe? Customer: "Why should I buy the product?" Developer: "Here we had a problem with the inheritance tree. We worked around it with a factory method."
- throwaway_yy2Di 11y agoAccording to a chemist on /r/askscience, the plastics probably contain carbon black [0] as a UV protectant. So it might not be deliberate. (/u/Platypuskeeper) Although I have not seen a specification of what the balls are made of, what I know from polymer chemistry is that the black is quite likely from carbon black (essentially soot), which is used as an additive/filler in polymers (e.g. tire rubber) for multiple reasons but not least UV protection. Carbon black is one of the most (if not the most) effective UV-protective additives, precisely because it absorbs the UV and prevents it from penetrating deeply into the plastic. Plastic without some UV protective additive would degrade pretty quickly in the California sun, not least HDPE which has pretty bad UV resistance. https://www.reddit.com/r/askscience/comments/3gpu6x/why_are_the_shade_balls_in_los_angeles_black_and/cu11268?context=3 https://www.reddit.com/r/askscience/comments/3gpu6x/why_are_... [0] https://en.wikipedia.org/wiki/Carbon_black https://en.wikipedia.org/wiki/Carbon_black
- erikb 11y agoDo they really need to invent that much? It's true that the current situation is maybe the worst they ever faced. But there are a lot of places where water is even more valuable as a resource. Are they also looking into what people in the desert do to keep their water sources alive, etc?
- martin-adams 11y agoI do wonder if it's a different set of challenges. The demand for water in California is probably much greater, rather than adapting everyone's use to the climate. So I suspect the innovation is to sustain the level of water usage that isn't seen in the desert.
- erikb 11y agoHm, okay. I guess that's the American Way to approach such a problem.
- ZeroGravitas 11y agoI wonder if floating solar PV was considered as an alternative/complementary solution that might pay for itself over time: http://www.eastgreenenergy.co.uk/for-business/products/floating-solar-pv/ http://www.eastgreenenergy.co.uk/for-business/products/float...
- WalterBright 11y agoI wouldn't be surprised if the balls increased the evaporation rate, for the simple reason that it will increase the surface area of the water (the balls will rotate in the water, bringing wet surfaces up). Black balls will also heat up more, causing more evaporation.
- redcalx 11y ago> Black balls will also heat up more, causing more evaporation. Question. Overall, is the heat absorption of the black balls greater than open water? I imagine it's about the same, but perhaps the issue is that the balls are concentrating the heat at the surface, and on the surface of the rotating balls. So it does seem like the evaporation rate could well be higher. I suppose it comes down to the mean rotation rate of the balls.
- rdlecler1 11y agoSmart thinking. The balls could be slightly weighted to avoid this issue, albeit this could mean the balls collect a rim of sludge more easily.
- redcalx 11y ago> the balls collect a rim of sludge more easily Not sure if that's a massive issue, that would probably seal the water off even more effectively. That makes me think that this whole balls idea will limit gas exchange too, i.e. much reduced oxygen absorption, but I guess if they want no life in the reservoir that's not an issue. Overall though I can't help feeling like there are going to be some significant unintended consequences with this scheme.
- WalterBright 11y agoThe weighting won't prevent them from sloshing around due to wave action and getting the upper surfaces wet anyway.
- SamReidHughes 11y ago
- undersuit 11y ago10 Year lifetime? Just the lifespan of these plastic balls being beaten with sunlight?
- david-given 11y agoThis may seem like a silly question, but... Why on earth are you chlorinating the water in the reservoir? I've never seen any other country that does that. Isn't it a really, really terrible idea? Environmentally ghastly because you kill everything in the reservoir, expensive due to chlorine loss, subject to side effects (like this one), and ideally suited to breeding chlorine-resistant bacteria... not to mention giving you nigh-undrinkable water! I'm from the UK, and we chlorinate our water pretty heavily, but even we don't do this. (I now live in Switzerland. Water in Zürich is purified via activated carbon, live biofilm and ozonation. The water which comes out of the tap is unchlorinated and is better and more drinkable than most bottled mineral water.)
- aquadrop 11y agoLooks like 3d simulation example came to life :) But seriously, why balls are used? They say it's cheap but 36 cents doesn't look too cheap on the hundreds of millions scale. Wouldn't it be better to use sheet-like form? It will be covering space more efficiently.
- allendoerfer 11y agoI think the story sounds a bit ironic: So you are essentially dumping objects made out of chemicals, you had to drill wholes in the ocean ground to get, into a lake, because you found out that the chemicals you dumped into it earlier kill you when the sun shines on them. You also think that this might help you with the water shortage caused by unsustainable use of resources. To me this all sounds like we arrived at a local maximum here. This simply cannot be the way to do this. Maybe we should start over.
- icebraining 11y agoUnless you have a better idea, I don't see how the criticism is useful.
- allendoerfer 11y agoI would stop trying to beat nature and instead try to play along with it. There is no need to waste that much water on farming in California. It is ridiculous to do this when you have a population density like the US has. There is just so much more suitable space all over the country.
- Asbostos 11y agoBut we protected ourselves from diseases with the chlorine. That's a massive win. Then we discovered there's a new risk of disease with the bromate, so we protect ourselves from that too. Isn't this basically how most technology develops? We keep getting better and better off because of it.
- legulere 11y agoThere are countries that don't use chlorine: Switzerland, Austria, Germany, Sweden, ... and they're regularly touted as having the best tap water quality in the world.
- moftz 11y agoOzone purification is cheap but could allow for future contamination if there is backflow or possibly a leak in the water mains. Chlorination prevents anything from growing in the water from the filtration plant to your home. One problem that major coastal cities have is that they collect water from streams that have already been polluted and are on their way out to the ocean. The US has a lot of these cities, 40% of the population occupy the coasts which is only 10% of the country. The cities in the US that typically are regarded as having the best tap water are midwestern cities, ones that do not have a coastline and tend to get cleaner water from natural sources. Switzerland, Austria, and Germany are exactly the same. They are very central countries with nearby access to Alpine runoff water, the water they get is pretty unmolested when compared to what the Potomac River supplies to Washington DC.
- utuxia 11y agohttp://imgur.com/JagJndf http://imgur.com/JagJndf
- Bohahahaha 11y agoThis chlorine everywhere in the US astonishes me. When visiting I'm not able to drink (non bottled) Coke b/c of the bad and intense chlorine taste.
- rdlecler1 11y agoThe article title is misleading. If we assume water price of $1000/acre-foot, then they spending ~$30m today to save 10x$2m over the next ten years. Water Davis are clearly a by-product benefit (as the article states) and the balls are not being used to tackle drought.