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A $3B Plan to Turn Hoover Dam into a Giant Battery
- hn_throwaway_99 8y agoThe article says the desired pumping station would be located 20 miles downstream from the dam. Why would it need to be so far?
- progfix 8y agoMy guess is to get an economically height difference to the dam.
- phire 8y agoNo, any extra height to pump water up compared to the height of the dam is just wasted power. They wouldn't do that without a good reason. My understanding is you can't just stick an inlet on the river, otherwise you could only pump water up when the dam was running (defeating the point). You need to build some kind of reservoir. Additionally, with hydropower it's not enough to build a dam above your generators. You also need to get rid of the water exiting your generators fast enough. If there is any restiction on the outflow, the back pressure will decrease the generation capacity. My guess is the distance is needed to meet these requirements. Enough space to let the water slow down, then enough space to build a reservoir.
- progfix 8y agoWhy would it be wasted power? Height difference = stored potential power. I was talking about that maybe 20 miles downstream the pump-size/-energy consumption to stored power is more efficent.
- phire 8y agoBecause the height difference that matters is the difference between the water level in the lake and the turbines. If your pumping station inlet is 20m below the turbines, then any energy used pumping water upto the height of the turbines is wasted, because it can't be recovered when the water comes back down.
- evgen 8y agoIf you look at the topography of the area in google maps you will see that the sides of the canyon are somewhat steep and rugged for quite a ways downstream of the dam. Go a bit further and you find Willow Beach, which has a nice flat run north and then west back to the reservoir. I am guessing that being able to run the pipe using trenching equipment rather than tunneling through canyon walls is a big advantage.
- progfix 8y agoPump storage plants are used all over the world for decades, that they are more efficient than Lithium batteries should surprise no one.
- phkahler 8y agoWhen there is a dam already producing electricity, you just reduce the flow through the dam rather than pumping the water back uphill. That is by far the most efficient way to handle excess generation from other sources in this case. This is a politically driven proposal whose implementation will be a boon to private producers at the expense of taxpayers.
- voidmain 8y agoThis could certainly be a boondoggle, but reducing flow through a dam is limited to storing excess power at the natural flow rate of the river, whereas there is no limit in principle to how fast you could pump water from a big reservoir below a dam to a big reservoir above the dam, or how fast you could draw energy from greatly increased flow through your generators. So pumped hydro storage isn't an inherently silly idea.
- redwood 8y agoThose generators and flow valves likely cannot respond quick enough to the momentary power surges
- snowwindwaves 8y agoA hydro turbine on a dam with no penstocks can probably go from 0-100% in 5 to 10 seconds. The limit is pressure waves in the water conveyance system due to changes in flow through the turbine. If the water conveyance system is only the width of the dam and encased in concrete it is going to have minimal transients compared to a 7km long steel or HDPE penstock on which the time from 0-100% is more like 2 minutes
- IloveHN84 8y agoLooks like the real version of Fallout universe imagined by Bethesda
- lucasjans 8y agoThe political challenges sound immense. The last paragraph in the article sums it up nicely. > "The hurdles are minimal and the negotiations simple, as long as everybody agrees with Nevada" Besides the Hoover Dam/Lake Mead, what other large scale energy storage opportunities exist in the United States?
- mabbo 8y agoThis might sound insane, but the great lakes might work, with a joint Canada-US plan. Raising one of them by a foot would be all you'd need because their area is so huge. If you're willing to look outside the US, a wild but interesting mega project might be to try to do the same thing with the South Aral Sea. Pump water all the way from the Caspian. The North Aral is cut off by a dam/dyke and the south Aral barely exists anymore, causing major economic harm. Fill it with salt water and salt water fish to revive the fishing economy while using it as a giant battery.
- gpm 8y agoNiagara falls (Erie -> Ontario) is already a huge hydro eletric power generator with variable flow. Instead of storing water though they decide how much water to allow over the falls for tourists. More during the day, less at night. Thinking about the terrain, it would probably be relatively easy to setup a dam somewhere that acted as a battery, downstream is basically already a giant bowl... I suspect the tourist industry would complain though.
- ulfw 8y agoThey create more electricity at night when less electricity is generally consumed? Odd. But interesting.
- londons_explore 8y agoThey want niagara falls to look great for tourists. When nobody is looking at night, it pretty much stops.
- phkahler 8y agoThis seems incredibly stupid. If you use excess electricity to pump water backward at the dam, you may as well just shut off the flow through the dam instead. That would be more efficient and cost nothing to implement. If we're talking about so much excess capacity that the dam would be closed AND water pumped back up, that would be interesting. But wouldn't the river go dry? It's not like there's a lake below the dam for that. This whole thing seems more political than practical. I'm guessing the private producers will somehow get a financial benefit from this at the expense of the taxpayer.
- tonyedgecombe 8y agoI'm not sure why you are being downvoted, you are correct. If the normal state of the dam is to generate electricity then the obvious response to excess supply is to stop the flow. No need to pump anything back uphill unless the excess exceeds the normal capacity of the dam.
- brokensegue 8y agonope. maybe read the article and you'll get it
- mmt 8y ago> If the normal state of the dam is to generate electricity It isn't, at least not in the sense that you likely mean. That seems to be a common misconception about the Hoover Dam. Its ability to generate electricity is completely secondary to its primary purpose: controlling the flow of water (e.g. flood control, irrigation). Unless/until there is a lower reservoir (as proposed by the project in the article) that takes over that primary function, changing the flow through the dam for any electricity-related reasons is simply not an option.
- maxerickson 8y agoIt depends an awful lot on the lag between demand and excess supply. It might use the noon sun to pump water that was used to meet morning demand.
- OliverJones 8y agoThere's a pumped-water electricity storage facility near where I live, called Northfield Mountain. It entered service in 1972 and has been in use since then. When electricity demand is low, the grid operator uses the excess to pump water uphill. When electrity use is high, the water flows back down into the Connecticut River. Horthfield Mountain can deliver just over a gigawatt of energy for eight hours with the generators running at full bore. It was originally built as a complement to the (now-decomissioned) Vermont Yankee nuclear power plant. That plant generated 0.6 gigawatts continuously, and functioned most efficienty if it wasn't ramped up and down to meet instantaneous demand. So, the storage facility provided a way to vary the power output from the grid. The Times piece contained these words: ...utility-scale lithium-ion batteries cost 26 cents a kilowatt-hour, compared with 15 cents for a pumped-storage hydroelectric project. The typical household pays about 12.5 cents a kilowatt-hour for electricity. It's a little misleading. The 26 cents and 15 cents figures are for capital expenditure to build storage capacity, which can then be used over and over (for 45 years in Northfield Mountain's case). The 12.5 cents is for a kilowatt hour consumed. Also, I fear the 12.5 number represents lazy journalism. The current residential rate in Los Angeles is 17.8 cents/kWh, and in New York City (home of the Times) it's 21.0 cents/kWh. Rates vary a LOT geographically. I hope journalists can learn to understand energy economics better, because they are a way for the rest of us to learn about them. And learn about them we must when fossil fuel use diminishes.
- iamgopal 8y agoAlso they fail to mention cyclic efficiency and life cycle cost. Hydrolic storage are most efficient with their short comingss being too large and location dependaance.
- CydeWeys 8y agoThe 26 cent figure for a kWh of storage must be the cost per cycle, and assuming it gets thousands of cycles. 1 kWh of Li-ion battery capacity is orders of magnitude more expensive than 26 cents.
- nimos 8y ago26/15 is the estimated cost per kwh. Really there is a huge variance, especially for pumped storage because because of highly variable capital cost. Capital costs are in the 100s-1000s dollars for kw of pumped storage.[0] [0]http://large.stanford.edu/courses/2014/ph240/galvan-lopez2/ http://large.stanford.edu/courses/2014/ph240/galvan-lopez2/
- delinka 8y agoNit: Lake Mead is the battery. Hoover's generators are extracting power from that "battery" constantly. The plan from TFA: Take water that's already passed through the generators at Hoover and, using solar and wind power, pump it back upstream into Mead to be processed again. This gives us the ability to supplement hydro with solar and wind. I guess if this is more efficient than other batteries, it's not a completely crazy idea. It does, however, have potential negative impact on downstream ecosystems. Also: I assume that we don't extract 100% of the available potential from the dammed water: how much water flows past generators (instead of through them) and how does that change when upstream water supply changes? How much of a decrease in this "loss" can we get from this solar/wind plan?
- ridgeguy 8y agoAt Hoover Dam, 100% of the river flows through the turbines with no bypass. The dam was originally built for flood control. Power generation is driven by downstream water demands. [1] [1] https://en.wikipedia.org/wiki/Hoover_Dam#Operation https://en.wikipedia.org/wiki/Hoover_Dam#Operation "The entire flow of the Colorado River passes through the turbines."
- Someone 8y agoBut it isn’t 100% efficient in converting potential energy into electricity. Even if the generators were 100% efficient, resistance in the pipes leading to the turbines slow down the water, not all the water hits the turbine blades, the water that does doesn’t transfer all its energy (the water would have to have zero speed after the turbine to do that, and the turbines would have to be at the bottom water level)
- ridgeguy 8y agoUnderstood. I took the OP's "how much water flows past generators" to address whether all the dam's outflow goes through the turbines or whether some is diverted around them. The former is the case. The latter only happens when spillways are in use, which is rare.
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- pwagland 8y agoDespite that this was submitted four hours earlier than https://news.ycombinator.com/item?id=17637437 https://news.ycombinator.com/item?id=17637437 , that one has more comments, at least at the moment.
- rkuska 8y agoThere was an episode on planet money about this. https://www.npr.org/sections/money/2018/06/15/620298266/episode-848-the-world-s-biggest-battery https://www.npr.org/sections/money/2018/06/15/620298266/epis...
- booleanbetrayal 8y agoThe Bath County Pumped Storage Station has been doing a similar thing since '85 and can be characterized as the largest battery in the world. https://en.m.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station https://en.m.wikipedia.org/wiki/Bath_County_Pumped_Storage_S...
- thezilch 8y agoNPR's Planet Money recently had a good story about alternatives to traditional batteries in "#848 The World's Biggest Battery" https://www.npr.org/templates/transcript/transcript.php?storyId=620288114 https://www.npr.org/templates/transcript/transcript.php?stor...
- simonswords82 8y agoDuplicate of this https://news.ycombinator.com/item?id=17637437 https://news.ycombinator.com/item?id=17637437
- microtheo 8y agoA similar project has been on construction in Europe https://de.m.wikipedia.org/wiki/Nant_de_Drance https://de.m.wikipedia.org/wiki/Nant_de_Drance Cost of $2B. I had the chance to visit the caverne where the turbines will be, really amazing engineering!
- rurban 8y agoPump storages are already all over Europe for decades. The most famous one being Kaprun/Austria, built by the Nazis in the 30ies. They are all over the Alps, as the green party lets them. Those pump storages provide the very expensive peek electricity all over Europe, needed for the spikes in the morning and noon. Nevada probably didn't need it back then, Hoover Dam was built for flood protection, and since then the levels are too low to work efficiently as pump storage. But since peek energy is in high demand they think it over.
- jcranmer 8y agoThe elephant in the room that I'm surprised wasn't mentioned is that there's no spare water in the Colorado. The Colorado River Compact allocated more than 100% of the current flow of the Colorado River to the different states (and a separate agreement adds up Mexico as well too), and it's at the point where a "good" winter snowpack means that the water level doesn't fall instead of providing meaningful recharge. The snow in 2016-2017 meant a return to 2014's low, but 2014 itself saw a miserable 20-foot fall in lake levels that there's no prospect for reversing. So where will the water to pump into the lake come from?
- davidf18 8y agoThe line that I noticed in the article is that the dam is only 20% used. They should fix that first, since hydroelectric power is green power. Best to ensure hydroelectric works first since it is far cheaper than wind and solar. Power from hydroquebec (used in NYC) is 4.5 cents US (about 6 cents CAN dollar), so they should fix the river so that Hoover Dam works at full capacity instead of 20%. http://www.hydroquebec.com/residential/customer-space/account-and-billing/understanding-bill/residential-rates/rate-d.html http://www.hydroquebec.com/residential/customer-space/accoun...
- londons_explore 8y agoThe water is pumped from lower down the river to higher up the river. No water is lost in the process - you can still use that same water for feeding almond trees or whatever you guys like to use it for.
- tener 8y agoThere are likely to be some losses still, but true that probably not a lot of them.
- lstodd 8y agoFirst, the water is lost - because evaporation over the large area of the reservoir only increases with its area, which increases with its level Second, the scheme decreases flow, and that means level of the downstream. This means negative effects on ecosystems downstream. Third, large hydroelectric dams require subordinate downstream reservoirs to tackle exactly the second problem - keep the downstream flow of the system (of the two+ dams) at least at some acceptable level to hide the variations in the main dam's outflow which are due to daily/weekly/monthly/yearly fluctuations in inflow and power requirements. Fourth - hydroelectric turbines require some amount of backpressure to operate. If the backpressure (that is the level of water downstream of the dam) gets too low, they can't operate unless risking damage. (that's actually the original reason behind the subordinate downstream dams) So the project just does not make any sense. Where are they going to get the water?
- envoked 8y agoAfter moving to the Columbia Gorge I became fascinated with the dams and energy production on the Columbia. Over the last 75ish years the whole river has been turned into a battery through a series of dams and reservoirs. The scale is astonishing - Grand Coulee itself produces ~6800 megawatts (about 3x of Hoover Dam). For those interested [A River Lost: The Life and Death of the Columbia](https://www.amazon.com/River-Lost-Life-Death-Columbia/dp/0393316904 https://www.amazon.com/River-Lost-Life-Death-Columbia/dp/039...) is a great book documenting the creation and long term implications (from cheap electricity for the Manhattan Project, to agriculture, to the collapse of the Salmon population) of the project.