Why Are 96,000,000 Black Balls on This Reservoir? on HackerTube: recommended by 2 Hacker News commenters across 2 separate months, 2019–2025.
explainer · evergreen
Veritasium rides a boat across the Los Angeles reservoir covered in 96 million black plastic balls. He explains why they were really introduced, which was not primarily to reduce evaporation.
Referenced as the explanation of shade balls and used in discussions of evaporation and floating covers.
“I thought the engineering at play here was pretty interesting.”
6 Hacker News comments link this video. Each one links back to its thread.
▶ this video Veritasium video about Los Angeles' reservoir black spheres project. They used black because - The goal was light-blocking more than anything else; black worked best - The black pigment held up to the environment (especially UV degradation) better than anything else they tried I expect the second point was the most important thing. Black plastic is very stable.
in “Floating solar panels that track the Sun” · View on HN
In a sort of related/inverse vein, I thought the engineering at play here was pretty interesting. 96 million shade balls on a public water supply reservoir: ▶ this video
in “A Norwegian town built a giant mirror to deflect the sun (2017)” · View on HN
I think that's the wrong way round: climate change causes longer summers and shorter winters, so the problem is one of cooling, not heating. Shade balls[0] could work, but then they'd have to cover part of the lake with that. EDIT: And of course, that also comes with a reduction in total light reaching the lake, which may have different side effects beyond temperature alone. [0] ▶ this video
in “Mixing Is the Heartbeat of Deep Lakes. At Crater Lake, It's Slowing Down” · View on HN
Shading is used in California to prevent evaporation, see for example the well-documented use of "shade balls": [link] Their use in Los Angeles was covered in a Veritasium video that was all over YouTube for a while (97M views): ▶ this video The estimate given when they were added in 2015 – in the middle of a record drought – was that they would prevent the loss of 300 million gallons of water each year.
in “Largest Floating Solar Power Plant Taking Shape on Hydropower Plant” · View on HN
The article describes artificial reservoirs as the water body of choice, which are less complex (partly because they already destroyed the ecosystem that was there) than naturally forming lakes, and has the added benefit of reducing solar driven evaporation in the same vein as this[0] [0] ▶ this video
in “US Army deploys its first floating solar array” · View on HN
Or float those plastic balls [1] on it, like they do for some reservoirs to stop evaporation. It'd take a lot of them, but that'd work and could be both cheaper and more permanent. 1. ▶ this video
in “A man who shoots at birds to keep them off a toxic pit [video]” · View on HN