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[Oroville Dam] Please Stop Raining

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  • OrcaOrca Also known as Espressosaurus WrexRegistered User regular
    edited February 2017
    They'll be slowing the outflow through the spillway and then stopping it completely in order to clear debris from the pond at the bottom of the spillway, assisting with repairs, which will allow the hydroelectric generators to function again. Right now, outflow is double the inflow rate so they can continue drawing down the reservoir in preparation for the shutdown. Everything seems to be well in hand for now.

    http://www.sacbee.com/news/state/california/water-and-drought/article135129014.html
    The state Department of Water Resources announced Sunday that with water levels at Lake Oroville reduced to 842 feet, and inflows at a modest 25,000 cubic feet per second, dam operators are confident that shutting off the outflows from the spillway makes sense.

    The spillway has been releasing water the past few days at 50,000 cfs. DWR said it will begin dialing back the flows at 6:45 a.m. Monday, bringing the releases to a halt by sometime in the afternoon. DWR said it plans to keep the outflows at zero “for several days.”

    Dam operators have been moving in equipment to a water channel beneath the spillway in order to remove the pile of mud, concrete and other debris that’s accumulated since the crater developed Feb. 7. The pile is backing water up into the dam’s hydro plant, making it impossible to restart.

    When operational, the hydro plant can release water at 14,000 cfs, “which will allow DWR to better manage reservoir levels through the remaining spring runoff season,” the agency said.

    KRCR TV adds:
    Through the use of water stored in the Diversion Pool and Thermalito Forebay and Afterbay, flows necessary to meet fishery requirements in the Feather River downstream of the dam will be maintained.

    Orca on
  • VishNubVishNub Registered User regular
    edited February 2017
    Water management in areas like that is incredibly complex. They have to balance flood control, irrigation, fisheries, power generation, recreation, drinking water, etc...

    And there's a whole set of laws and guidelines from a host of agencies that they have to follow. Someone is usually screaming at them, I would imagine.

    VishNub on
  • MugsleyMugsley DelawareRegistered User regular
    Here's where power storage -- if advanced enough -- could be a big value. If the power plant hadn't been damaged, it could be storing the excess power/energy created by the constant outflow.

    Yes, I know we are talking about the emergency spillway, which bypasses the dam; but it was stated above that the plant itself can account for 13000 cfs when it's running. If it's running constantly through this entire time, that's a pretty giant buffer to the area's power generation, and potentially lost energy generation if there isn't a sufficient draw on the power grid.

    Yay infrastructure engineering/discussion!

  • TL DRTL DR Not at all confident in his reflexive opinions of thingsRegistered User regular
    Mugsley wrote: »
    Here's where power storage -- if advanced enough -- could be a big value. If the power plant hadn't been damaged, it could be storing the excess power/energy created by the constant outflow.

    Yes, I know we are talking about the emergency spillway, which bypasses the dam; but it was stated above that the plant itself can account for 13000 cfs when it's running. If it's running constantly through this entire time, that's a pretty giant buffer to the area's power generation, and potentially lost energy generation if there isn't a sufficient draw on the power grid.

    Yay infrastructure engineering/discussion!

    Do you know anything about state-of-the-art solutions for power storage? I know battery cells are problematic, and I hear the our local power company uses essentially a kinetic battery; raising a weight when power is cheap and dropping it to turn a turbine when costs are high.

  • MugsleyMugsley DelawareRegistered User regular
    I know fuck-all about power storage, but I wish I did. I'm an engineer, though, so this whole situation is quite intriguing.

  • AiouaAioua Ora Occidens Ora OptimaRegistered User regular
    ... a dam is power storage, one of the most efficient kinds possible.

    life's a game that you're bound to lose / like using a hammer to pound in screws
    fuck up once and you break your thumb / if you're happy at all then you're god damn dumb
    that's right we're on a fucked up cruise / God is dead but at least we have booze
    bad things happen, no one knows why / the sun burns out and everyone dies
  • PhyphorPhyphor Building Planet Busters Tasting FruitRegistered User regular
    Aioua wrote: »
    ... a dam is power storage, one of the most efficient kinds possible.

    It is usually the default power storage, to the point where excess capacity is often used to pump water back uphill if it's less efficient to spin down other plants - hydro dams have startup times of a few minutes

  • MugsleyMugsley DelawareRegistered User regular
    Valid point. I guess I'm just saying that if they were forced to generate power as a safety measure, it would be great if there way a way to somehow capture it "elsewhere," if it wasn't needed on the grid. I'm probably missing a few other mechanisms and features that are glaringly obvious but I haven't done any research. To my knowledge, excess generation is something that power regulators are always working on, since it constitutes a waste.

  • EncEnc A Fool with Compassion Pronouns: He, Him, HisRegistered User regular
    TL DR wrote: »
    Mugsley wrote: »
    Here's where power storage -- if advanced enough -- could be a big value. If the power plant hadn't been damaged, it could be storing the excess power/energy created by the constant outflow.

    Yes, I know we are talking about the emergency spillway, which bypasses the dam; but it was stated above that the plant itself can account for 13000 cfs when it's running. If it's running constantly through this entire time, that's a pretty giant buffer to the area's power generation, and potentially lost energy generation if there isn't a sufficient draw on the power grid.

    Yay infrastructure engineering/discussion!

    Do you know anything about state-of-the-art solutions for power storage? I know battery cells are problematic, and I hear the our local power company uses essentially a kinetic battery; raising a weight when power is cheap and dropping it to turn a turbine when costs are high.

    This and giant spring coiling are things seriously being discussed for power storage. It's pretty neat.

  • ArdolArdol Registered User regular
    edited February 2017
    There was a really interesting Nova episode about power storage a couple weeks ago. I'm on my phone or I'd try to dig up a link.

    Edit - Here's a link to the episode.

    Ardol on
  • DedwrekkaDedwrekka Metal Hell adjacentRegistered User regular
    Are they still looking at molten salts for power storage or has that moved on?

  • VishNubVishNub Registered User regular
    edited February 2017
    So, this is perhaps a dumb question, but what happens if too much power is generated, absent some sort of energy sink/battery? I assume it goes to heat waste somewhere along the way?

    I'm trying to think about this in terms of V=iR, and V is set by the wires and transformers, R is set by the amount of electrical use, and i is the power generated? But there are several contradictions in that logic pretty much immediately.

    Unrelated (ignore the catfish), but this is a photo from below a hydro plant near me. The difference in energy between the water coming off the spillway (background) and through the plant (foreground) is pretty obvious (flow rates are similar). Hydro power is pretty cool, though I'm generally anti-dam.

    6649B726-B6B8-4BA7-8C48-4B3E243C6BC8_zpsunyyfdq0.jpg

    VishNub on
  • tinwhiskerstinwhiskers Registered User regular
    VishNub wrote: »
    So, this is perhaps a dumb question, but what happens if too much power is generated, absent some sort of energy sink/battery? I assume it goes to heat waste somewhere along the way?

    I'm trying to think about this in terms of V=iR, and V is set by the wires and transformers, R is set by the amount of electrical use, and i is the power generated? But there are several contradictions in that logic pretty much immediately.

    Well its AC power so you have capacitance and inductance, phase and frequency and those ever fun imaginary numbers...

    The easiest way to think of it is that load is basically a break on the system.

    Turbine generator sets are constant RPM designs, they are always intended to be running at say 1800 RPM. So what goes up and down with the load isn't the speed(sort of) it's the torque on the shaft.

    There is a lot of mechanical energy stored in the rotating turbine/generator components, that are electro-magnetically coupled to the grid. When demand increases, that increases the braking effect on the shaft. Turning that stored mechanical energy to electrical. But it also slows the shaft which lowers the frequency output of the generator.

    The plant will then if it can increase the flow into the turbine to get things back to nominal, but now with a higher power output. Or other plants will be signaled to come online or increase their output.

    When demand drops, the opposite happens, and shafts speed up slightly and the plant throttles down. And basically the random stuff on the grid just runs a bit more powerfully. Your toaster would be a bit hotter, your light bulb a bit brighter.

    Hydro is by far the best at load following like this, followed by combined cycle natural gas plants, and this is definitely a problem that has gotten harder and more important as more solar and especially wind power comes onto the grid. And is one of the things helping kill off the older small sized coal plants.

    6ylyzxlir2dz.png
  • VishNubVishNub Registered User regular
    Spillway flow has been stopped to allow detailed inspection of the damage.

    Unfortunately, when you do that very suddenly, there are consequences downstream.
    In a matter of hours Monday, engineers at the troubled dam ramped back outflows on the main spillway from 50,000 cubic feet per second to nothing. The Feather River below the dam is still flowing, though at levels closer to what’s typical in summer, thanks to water releases from a series of small reservoirs below the dam.

    Federal fisheries regulators had urged the state Department of Water Resources, which operates the dam, to taper the spillway releases more gradually to prevent as many fish from getting stranded. DWR officials said they complied with those suggestions as best they could, but haste still had to be a priority.
    When California state biologists crested a sandbar along the Feather River on Tuesday morning, they expected to find at least some of the water that just a day before had raged through the channel, too deep to stand in – and plenty of fish needing to be rescued.

    Instead, to their chagrin, the flows powering down Oroville Dam’s badly damaged main spillway into the Feather River had been throttled back so quickly Monday that the whole sandbar was now dry.

    “Oh, no,” said biologist Alana Imrie.

    :(

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