6 ms·

They should pump water uphill during these surges. California hydropower is constrained by rainfall, so the dams and generators already exist. Pumps cost less t

They should pump water uphill during these surges. California hydropower is constrained by rainfall, so the dams and generators already exist. Pumps cost less than batteries and this process has about an 80% roundtrip efficiency

azurezyq 9y ago
Well, solar farms in CA are mostly in deserts, where hydro reservoirs are not that feasible.
- DiabloD3 9y ago
  Power can be transmitted to areas inside of CA that already have hydro reservoirs or ones at higher elevations can be built.
- rootusrootus 9y ago
  Since it's already wired up to the same grid, does the storage have to be near the generating plant?
  - azurezyq 9y ago
    I think the point of paying AZ to take excess power is to lower the load on CA grids. So long distance transmission cannot solve the immediate problem.
    - deleted 9y ago
      [deleted]
    - iak8god 9y ago
      > So long distance transmission cannot solve the immediate problem. Then how is it getting to AZ?
  - spangry 9y ago
    In most cases the answer is "no, but it helps". Close physical proximity reduces transmission loss (both inward and outward). And hydro storage requires a very specific sort of topography. If you have fortunately built solar energy plants near these sites, great! Otherwise you will probably have to build new transmission infrastructure (likely HVDC), which costs money.
hkmurakami 9y ago
Well we need all the reasons we can get for adding dam capacity.
redthrowaway 9y ago
>this process has about an 80% roundtrip efficiency How is that possible? Even if you assume frictionless pipes and lossless power transmission, that's assuming 90% efficiency for both the pump and the generator.
- dtparr 9y ago
  From https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit... > The round-trip energy efficiency of PSH varies between 70%–80%,[4][5][6][7] with some sources claiming up to 87%.[8]
oconnore 9y ago
If they priced residential power in line with real market rates (in this case negative), I suspect this would not be a problem for long. But we need smart meters first. I would love to be able to have my heat pump run during steep discounts, but in Colorado we currently have a flat 12 hour off-peak (at night -- the opposite of this) with a mild 20% discount.
- Declanomous 9y ago
  It's possible to get a smart meter in Illinois, and I've thought about rigging up appliances to run when rates are negative. However the price feed is lagging by 15 minutes or so. So while you can have a pretty good idea rates would be negative, you can't actually be sure. It's not a huge deal if you are doing something productive with the energy, but if your goal is to make money it's probably not very effective. That being said, it might be productive to rig up your gaming pc to mine bitcoins or fold proteins when the price is close to zero.
  - URSpider94 9y ago
    I'm not aware of any utilities that pass on spot pricing on power to their customers on a minute-by-minute level. Even with smart meters, most just tier the pricing into 2-3 levels per day that stay constant for 6 months or so (here in CA, it resets every summer/winter)
    - Declanomous 9y ago
      Com Ed in Illinois only has two types of metering: standard flat rate, and hour-by-hour. https://hourlypricing.comed.com/ https://hourlypricing.comed.com/ https://www.comed.com/SmartEnergy/SmartMeterSmartGrid/Pages/ForYourHome.aspx https://www.comed.com/SmartEnergy/SmartMeterSmartGrid/Pages/...
- URSpider94 9y ago
  Most customers don't want this. You have to realize that slightly negative costs in some slots (and your power cost would not actually be negative, as it would be more than balanced by the transmission and service costs) would come with eye-poppingly high rates on other days, like 50x the normal rate. Imagine the horrible news stories and "NBC on Your Side" pieces that will come about when someone pops their A/C on at the wrong time and gets a $1000 power bill. Even with smart meters (which we all have already in CA) I don't think residential customers will ever see more than three tiers of time-of-use cost per day, although those hours may shift around. However, utilities already contract with major users like universities and large businesses to shape demand, in return for deep discounts. And, smart home devices like EV chargers and battery storage units will be connected to the grid to provide near-instant capability to suck up excess power, or curtail usage.
Animats 9y ago
They do. Many of the reservoirs of the California Water Project also do power storage. They usually pump up at night and generate in the daytime. Sometimes they can't store more energy because they're full of water, as happened at Oroville Dam this year. Sometimes they don't have enough water. A year ago, some hydro plants in California were down due to lack of water. There's one big pure pumped storage plant in California - Helms, near Fresno.[1] The geography has to be right for pumped storage. You need a high reservoir and a low reservoir near to each other, and since the water levels will change drastically each day, they can't be used for boating or recreation much. Helms has about 1500 meters of elevation difference between the reservoirs. Sites like that are hard to find. Excess solar power isn't a big problem in areas that use air conditioning. Peak A/C load and peak solar output tend to coincide. The big excess power headache is wind, where output varies 4:1 over a day over wide areas. Excess wind generation late at night is common. The best way to understand the power business is to read PJM 101, the introductory training material for the US's largest power grid. Unfortunately, PJM recently put that behind a login. [1] https://en.wikipedia.org/wiki/Helms_Pumped_Storage_Plant https://en.wikipedia.org/wiki/Helms_Pumped_Storage_Plant
- paulsutter 9y ago
  Peak power usage is around 7-8PM, this discrepancy is the source of the duck curve. More storage could allow tons more solar to be installed. https://cleantechnica.com/2014/07/21/utilities-cry-fowl-over-duck-chart-and-distributed-solar-powercrying-fowl-or-crying-wolf-open-season-on-the-utilitys-solar-duck-chart/ https://cleantechnica.com/2014/07/21/utilities-cry-fowl-over... (deepsun - the "no sun" critical event happens every night)
  - _delirium 9y ago
    7-8pm according to that link is the net peak, after solar production has canceled out the original afternoon peak. The problem is that even though solar supply does roughly coincide with the peak of demand, solar production has increased enough that, since about 2013, it's gone past the point of offsetting peak afternoon A/C usage, to now producing an actual net trough in the afternoon hours (you can see the afternoon extremum flips from a local maximum to a local minimum from 2012 to 2014, and just keeps going further down every year since, as peak afternoon solar grows faster than peak afternoon A/C). The new net peak around 7-8pm is because demand has a long tail into the early evening, while solar drops off sharply around 5-7pm. But yeah the end result is that it does cause a problem for grid management if you add more incremental solar, since the original afternoon peak it helped smooth out has long since been smoothed and then some.
gricardo99 9y ago
> California hydropower is constrained by rainfall, so the dams and generators already exist. But there's nothing to pump, at least a good part of the year. The dammed river beds are practically dry during the summer/fall months.
- Maultasche 9y ago
  Plus there are environmental issues where you are pumping water out of places where endangered species are living or spawning. Removing water has an environmental impact, which California already feels due to water already being diverted in large amounts for agriculture or drinking water.

azurezyq 9y ago

Well, solar farms in CA are mostly in deserts, where hydro reservoirs are not that feasible.

DiabloD3 9y ago
Power can be transmitted to areas inside of CA that already have hydro reservoirs or ones at higher elevations can be built.
rootusrootus 9y ago
Since it's already wired up to the same grid, does the storage have to be near the generating plant?
- azurezyq 9y ago
  I think the point of paying AZ to take excess power is to lower the load on CA grids. So long distance transmission cannot solve the immediate problem.
  - deleted 9y ago
    [deleted]
  - iak8god 9y ago
    > So long distance transmission cannot solve the immediate problem. Then how is it getting to AZ?
- spangry 9y ago
  In most cases the answer is "no, but it helps". Close physical proximity reduces transmission loss (both inward and outward). And hydro storage requires a very specific sort of topography. If you have fortunately built solar energy plants near these sites, great! Otherwise you will probably have to build new transmission infrastructure (likely HVDC), which costs money.

hkmurakami 9y ago

Well we need all the reasons we can get for adding dam capacity.

redthrowaway 9y ago

>this process has about an 80% roundtrip efficiency How is that possible? Even if you assume frictionless pipes and lossless power transmission, that's assuming 90% efficiency for both the pump and the generator.

dtparr 9y ago
From https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit... > The round-trip energy efficiency of PSH varies between 70%–80%,[4][5][6][7] with some sources claiming up to 87%.[8]

oconnore 9y ago

If they priced residential power in line with real market rates (in this case negative), I suspect this would not be a problem for long. But we need smart meters first. I would love to be able to have my heat pump run during steep discounts, but in Colorado we currently have a flat 12 hour off-peak (at night -- the opposite of this) with a mild 20% discount.

Declanomous 9y ago
It's possible to get a smart meter in Illinois, and I've thought about rigging up appliances to run when rates are negative. However the price feed is lagging by 15 minutes or so. So while you can have a pretty good idea rates would be negative, you can't actually be sure. It's not a huge deal if you are doing something productive with the energy, but if your goal is to make money it's probably not very effective. That being said, it might be productive to rig up your gaming pc to mine bitcoins or fold proteins when the price is close to zero.
- URSpider94 9y ago
  I'm not aware of any utilities that pass on spot pricing on power to their customers on a minute-by-minute level. Even with smart meters, most just tier the pricing into 2-3 levels per day that stay constant for 6 months or so (here in CA, it resets every summer/winter)
  - Declanomous 9y ago
    Com Ed in Illinois only has two types of metering: standard flat rate, and hour-by-hour. https://hourlypricing.comed.com/ https://hourlypricing.comed.com/ https://www.comed.com/SmartEnergy/SmartMeterSmartGrid/Pages/ForYourHome.aspx https://www.comed.com/SmartEnergy/SmartMeterSmartGrid/Pages/...
URSpider94 9y ago
Most customers don't want this. You have to realize that slightly negative costs in some slots (and your power cost would not actually be negative, as it would be more than balanced by the transmission and service costs) would come with eye-poppingly high rates on other days, like 50x the normal rate. Imagine the horrible news stories and "NBC on Your Side" pieces that will come about when someone pops their A/C on at the wrong time and gets a $1000 power bill. Even with smart meters (which we all have already in CA) I don't think residential customers will ever see more than three tiers of time-of-use cost per day, although those hours may shift around. However, utilities already contract with major users like universities and large businesses to shape demand, in return for deep discounts. And, smart home devices like EV chargers and battery storage units will be connected to the grid to provide near-instant capability to suck up excess power, or curtail usage.

Animats 9y ago

They do. Many of the reservoirs of the California Water Project also do power storage. They usually pump up at night and generate in the daytime. Sometimes they can't store more energy because they're full of water, as happened at Oroville Dam this year. Sometimes they don't have enough water. A year ago, some hydro plants in California were down due to lack of water. There's one big pure pumped storage plant in California - Helms, near Fresno.[1] The geography has to be right for pumped storage. You need a high reservoir and a low reservoir near to each other, and since the water levels will change drastically each day, they can't be used for boating or recreation much. Helms has about 1500 meters of elevation difference between the reservoirs. Sites like that are hard to find. Excess solar power isn't a big problem in areas that use air conditioning. Peak A/C load and peak solar output tend to coincide. The big excess power headache is wind, where output varies 4:1 over a day over wide areas. Excess wind generation late at night is common. The best way to understand the power business is to read PJM 101, the introductory training material for the US's largest power grid. Unfortunately, PJM recently put that behind a login. [1] https://en.wikipedia.org/wiki/Helms_Pumped_Storage_Plant https://en.wikipedia.org/wiki/Helms_Pumped_Storage_Plant

paulsutter 9y ago
Peak power usage is around 7-8PM, this discrepancy is the source of the duck curve. More storage could allow tons more solar to be installed. https://cleantechnica.com/2014/07/21/utilities-cry-fowl-over-duck-chart-and-distributed-solar-powercrying-fowl-or-crying-wolf-open-season-on-the-utilitys-solar-duck-chart/ https://cleantechnica.com/2014/07/21/utilities-cry-fowl-over... (deepsun - the "no sun" critical event happens every night)
- _delirium 9y ago
  7-8pm according to that link is the net peak, after solar production has canceled out the original afternoon peak. The problem is that even though solar supply does roughly coincide with the peak of demand, solar production has increased enough that, since about 2013, it's gone past the point of offsetting peak afternoon A/C usage, to now producing an actual net trough in the afternoon hours (you can see the afternoon extremum flips from a local maximum to a local minimum from 2012 to 2014, and just keeps going further down every year since, as peak afternoon solar grows faster than peak afternoon A/C). The new net peak around 7-8pm is because demand has a long tail into the early evening, while solar drops off sharply around 5-7pm. But yeah the end result is that it does cause a problem for grid management if you add more incremental solar, since the original afternoon peak it helped smooth out has long since been smoothed and then some.

gricardo99 9y ago

> California hydropower is constrained by rainfall, so the dams and generators already exist. But there's nothing to pump, at least a good part of the year. The dammed river beds are practically dry during the summer/fall months.

Maultasche 9y ago
Plus there are environmental issues where you are pumping water out of places where endangered species are living or spawning. Removing water has an environmental impact, which California already feels due to water already being diverted in large amounts for agriculture or drinking water.