http://www.sciencealert.com/la-is-dumping-millions-of-small-plastic-balls-into-its-reservoir-to-tackle-the-drought

This is one of those stories that doesn’t make a lot of sense until you’ve heard the science behind it: earlier this week the mayor of LA Eric Garcetti helped to dump 20,000 small black plastic balls into the city’s reservoir. It marks the final phase of a the innovative project, in which a total of 96 million balls have been poured into the 175-acre man-made lake.

The reason? These ‘shade balls’, as they’re known, are actually very effective at keeping water clean and protecting it from evaporation – an issue that those living in Los Angeles and the rest of California are only too aware of right now. Each ball is weighed down with a little water, they’re cheap (costing just 36 cents per unit), and they can last for 10 years before they need to be replaced.

someone here mentioned this a few years ago… wookie? clever

I suspect the cost is 3.6 cents per unit which is more crommulent for a plastic ball.

unless it’s in Grecian Euros

• and they can last for 10 years before they need to be replaced.

Are all these balls the same size, same colour? Wouldn’t it be more economical to have ten different sizes or ten different colours so that you can more easily replace 9.6 million every year rather than the whole lot every ten years?

the colour is part of the plan..

furious said:

• and they can last for 10 years before they need to be replaced.

Are all these balls the same size, same colour? Wouldn’t it be more economical to have ten different sizes or ten different colours so that you can more easily replace 9.6 million every year rather than the whole lot every ten years?

yes, increasing complexity always saves money.

• the colour is part of the plan..

To keep light out they don’t necessarily all have to be one colour, they just need to be opaque…

• yes, increasing complexity always saves money.

Complexity can improve efficiency…

furious said:

• the colour is part of the plan..

To keep light out they don’t necessarily all have to be one colour, they just need to be opaque…

yes, but black would keep the most light out. It can’t even hold light to an orange…

If you had white ones you would probably have to have a billion dollar remediation plan to stop birds eating them thinking they are eggs or something.

does make you wonder how they plan to replace them all… some would surely sink over that time..

furious said:

• yes, increasing complexity always saves money.

Complexity can improve efficiency…

The operation sounds pretty simple, make balls and dump into the lake. If the balls only last ten years I reckon it would be cheaper to have a single sinking fund to remove and replace the whole lot every ten years than an ongoing maintenance and replace program. It’s plastic balls not bridges.

• yes, but black would keep the most light out.

Doesn’t matter what colour an object is, if it prevents light from going through…

furious said:

• yes, but black would keep the most light out.

Doesn’t matter what colour an object is, if it prevents light from going through…

What colour is best to stop uv degradation of the plasticisers?

why black?

why not white?

CrazyNeutrino said:

why black?

why not white?

Minimal reflection

Postpocelipse said:

CrazyNeutrino said:

why black?

why not white?

Minimal reflection

Would be black absorb heat?

How is that beneficial?

and greatest notseethroughableness. or as some would say opaque.

And the primary reason for deploying the hollow balls is more to protect the quality of the water rather than to simply stop it evaporating. In the reservoir water, the naturally occurring bromide was mixing with sunlight and chlorine (added to disinfect drinking water) to create dangerous levels of the the carcinogen bromate. Shade balls should stop that harmful chemical reaction from happening at a large scale, and of course by deflecting the Sun’s rays, they also keep more of the water in liquid form.

from the story.

also not letting sunlight hit the water results in less algae growth.

CrazyNeutrino said:

Postpocelipse said:

CrazyNeutrino said:

why black?

why not white?

Minimal reflection

Would be black absorb heat?

How is that beneficial?

Guessing I’d assume the conduction rate between the balls and the water would provide for heat dissipation without evaporation to the atmosphere. The balls are a heat mediary that separates the atmosphere and the water.

30 million dollars to save 11 gigalitres… seems the economics is marginal.

dv said:

30 million dollars to save 11 gigalitres… seems the economics is marginal.

water supply is reaching critical status in the US in some areas

dv said:

30 million dollars to save 11 gigalitres… seems the economics is marginal.

yea, that’s enough to buy 1.15 bottles of 500mL Mt franklin water (at cost price) for everyone in cali…

AwesomeO said:

furious said:

• yes, but black would keep the most light out.

Doesn’t matter what colour an object is, if it prevents light from going through…

What colour is best to stop uv degradation of the plasticisers?

The carbon black seems to last the longer.

Wonders what will happen in strong winds.

AwesomeO said:

I suspect the cost is 3.6 cents per unit which is more crommulent for a plastic ball.

Given that these need to last ten years and not contaminate the water, I am expecting them to be a bit more expensive that the kind one dumps a toddler in at the mall.

PermeateFree said:

Wonders what will happen in strong winds.

the balls have a small amount of water in them

CrazyNeutrino said:

PermeateFree said:

Wonders what will happen in strong winds.

the balls have a small amount of water in them

If you are sitting in a rubber dingy, your weight acts in much the same way, yet you are still blown all over the place and often at some speed.

PermeateFree said:

CrazyNeutrino said:

PermeateFree said:

Wonders what will happen in strong winds.

the balls have a small amount of water in them

If you are sitting in a rubber dingy, your weight acts in much the same way, yet you are still blown all over the place and often at some speed.

You create a much bigger surface for the wind to act on though, wouldn’t the curved shape of the balls allow the wind to pass over them but not move them very much or perhaps even move them en-masse but not really able to lift them up and out.

Cymek said:

PermeateFree said:

CrazyNeutrino said:

the balls have a small amount of water in them

If you are sitting in a rubber dingy, your weight acts in much the same way, yet you are still blown all over the place and often at some speed.

You create a much bigger surface for the wind to act on though, wouldn’t the curved shape of the balls allow the wind to pass over them but not move them very much or perhaps even move them en-masse but not really able to lift them up and out.

Would be interesting to see.

> someone here mentioned this a few years ago… wookie? clever

Yes, someone did. It could have been me, I don’t remember.