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LA is dumping millions of plastic balls into its reservoir to tackle the drought

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Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#61

Post by markyc »

StavrosK wrote: post #32
markyc wrote: post #9

Earlier quoted context omitted.

doesn't the plastic + sunlight + heat combination release dangerous chemicals in the water? also, why are they black, doesn't that attract more heat?

They don't care that much about heat, they care more about sunlight not reaching the water, which black balls are more effective at.

why would black be better than white?

i remember an article stating that the melting ice at the poles is accelerating global warming because the white of the ice used to reflect the light coming towards the water

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#62

Post by erikb »

martin-adams wrote: post #47
erikb wrote: post #10

Do 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?

I 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.

Hm, okay. I guess that's the American Way to approach such a problem.

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#63

Post by redcalx »

WalterBright wrote: post #36

I 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.

> 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.

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#64

Post by StavrosK »

markyc wrote: post #61
StavrosK wrote: post #32

Earlier quoted context omitted.

They don't care that much about heat, they care more about sunlight not reaching the water, which black balls are more effective at.

why would black be better than white? i remember an article stating that the melting ice at the poles is accelerating global warming because the white of the ice used to reflect the light coming towards the water

Because white reflects, black absorbs. White balls wouldn't reflect all light upwards. To put it another way, if you were in the water, looking at the surface, which would be brighter? White balls or black balls?

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#65

Post by rdlecler1 »

redcalx wrote: post #63
WalterBright wrote: post #36

I 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.

> 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…

Smart thinking. The balls could be slightly weighted to avoid this issue, albeit this could mean the balls collect a rim of sludge more easily.

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#66

Post by rdlecler1 »

The 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.

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#67

Post by allendoerfer »

icebraining wrote: post #52
allendoerfer wrote: post #50

I 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…

Unless you have a better idea, I don't see how the criticism is useful.

I 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.

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#68

Post by markyc »

StavrosK wrote: post #64
markyc wrote: post #61

Earlier quoted context omitted.

why would black be better than white? i remember an article stating that the melting ice at the poles is accelerating global warming because the white of the ice used to reflect the light coming towards the water

Because white reflects, black absorbs. White balls wouldn't reflect all light upwards. To put it another way, if you were in the water, looking at the surface, which would be brighter? White balls or black balls?

makes sense :)

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#69

Post by rsfern »

markyc wrote: post #61
StavrosK wrote: post #32

Earlier quoted context omitted.

They don't care that much about heat, they care more about sunlight not reaching the water, which black balls are more effective at.

why would black be better than white? i remember an article stating that the melting ice at the poles is accelerating global warming because the white of the ice used to reflect the light coming towards the water

The problem is specifically the ultraviolet photons in the sunlight, which photoactivate the reaction between bromine ions and ozone to form bromate [1].

The visible color shouldn't matter as much as strong absorbance or reflectance in the UV band. I would guess that they're using a plastic that absorbs UV, or contains a dye that does so.

1: http://www.ncbi.nlm.nih.gov/pubmed/18290477

Re: LA is dumping millions of plastic balls into its reservoir to tackle the drought

#70

Post by moftz »

legulere wrote: post #60
Asbostos wrote: post #57

Earlier quoted context omitted.

But 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.

There 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.

Ozone 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.

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