4 ms·

CAISO has a great live dashboard that you can play around with on the actual real time demand and supply curves. If you switch to previous days, you'll see the

CAISO has a great live dashboard that you can play around with on the actual real time demand and supply curves. If you switch to previous days, you'll see the "duck curve" is already here and not just speculation anymore. https://www.caiso.com/TodaysOutlook/Pages/default.aspx https://www.caiso.com/TodaysOutlook/Pages/default.aspx The issue nowadays isn't so much the depth of the dip in dispatchable (e.g. traditional) generation, but the slope of the ramp back up after the sun goes down (e.g. the "neck" of the duck). Base load natural gas an other fossil generation have a very difficult time spinning up that quickly (CAISO said it was ~11GW over 3 hours yesterday). That's why batteries are such a hot topic in renewables right now. Not so much for storing power for "a rainy day", but for helping load shift during the day to prevent such a steep slope in the evenings. Lithium is pretty good at doing that kind of short, daily-burst storage job.

tialaramex 7y ago
Couldn't you do other types of storage rather than batteries? Pumped storage can do very fast spin-up because gravity doesn't take any time to warm up, nothing to 1.8GW in a few seconds at Dinorwig (in Wales), if you own half a dozen of those then 11GW in 3 hours feels like child's play. Not everywhere has the geography for building power stations inside mountains (which is the only way to do pumped storage that isn't horribly ugly), but the US is huge and seems like there are mountains everywhere you look in some parts, surely some of them are suitable for hiding a pumped storage facility?
- NeedMoreTea 7y ago
  There were two or three backup sites within 15 miles of Dinorwig that were being evaluated prior to it being built. There in case the main site proved impractical or too expensive for some reason. I'd posit there are ample disused quarry sites that could serve a similar purpose scattered around the UK, US and much of the developed world.
- diafygi 7y ago
  Hmmmm, yes, probably. However the reasons for deploying millions of lithium batteries instead of a few dozen pumped hydro stations are likely more political and business reasons than technical reasons. First, it's way easier and faster to just park containers full of batteries wherever you need to shift the energy than to find and build new pumped hydro location then build/upgrade the transmission to the locations where the load shifting is needed. And when you need the load shifting ASAP, you're probably going to opt for the solution that can deployed now, especially when the regulatory reaction to this problem is to adjust prices ("time of use" rates) to discourage people from using power during the slope. Second, battery installers are able to sell directly to consumers, which means they can bypass utility bureaucracy. Many utilities are very slow to adopt "non-wires alternatives" because their business model doesn't incentivize them to building out a distributed, flexible grid, and they are increasingly becoming worried about their generation assets being financially stranded. This means that it's often easier to sell thousands of energy storage units to thousands of homes and businesses, than it is to sell that same thousand units directly to the utility. With pumped hydro, there's no distributed option, so you end up being at the mercy of the utility wanting your product. So yes, you're probably right that pumped hydro is on paper cheaper for addressing the Duck Curve "neck" problem, but this is a case where the difference between theory and reality is substantial for non-technical reasons.
- deleted 7y ago
  [deleted]
- lazyguy2 7y ago
  > Couldn't you do other types of storage rather than batteries? Sure. But they all have their own downsides. Pump air into vast underground tunnels. Pump water into towers. Spin up massive drums as flywheels (this one is my favorite. Spinning weights are incredibly power dense). Lift massive weights. It's all been done. There are companies working on making these things more practical. Meanwhile the power companies have instituted new standards in grid-tied inverters for solar panels that have effectively solved the problem for them. It's based on the frequency of the grid. As the grid becomes over powered it's frequency tends to shift a bit higher. As the grid becomes over loaded the frequency tends to shift a bit lower. By responding to these frequency shifts the grid-tied inverters will either allow electricity to be generated when the frequency falls back slightly, throttle electrical generation when the frequency rises slightly, and then shut off completely when the grid goes down. So the effect is that those expensive solar panel arrays in places were they are already popular... are effectively shut off during the peak solar power generation hours. And are turned off completely when the grid itself is shutdown. Lithium batteries represent a unique opportunity for truly distributed power generation. They are just reaching the point, price-wise, were they can be used as a practical way to store energy on a individual small business or household manner. This way individuals themselves can take charge of their own power needs and no longer has to rely on centralized bureaucracies to save the world for them. Unfortunately due to the way grid-tied systems are now required to work it has effectively nullified most of the benefits of having private solar arrays. IF you want to be your own power generator you have to be off-grid to do it. And this the reason this is unfortunate is because almost nobody is building private solar arrays this way. There is a semi-religious belief that grid-tied systems allow a ROI in the form of selling power back to the grid. Also they are built with the assumption that battery backups for the house is too expensive and impractical. All these things are true if you are looking at low-voltage SLA battery arrays and grid-tied standards from 5-10 years ago, but with high voltage lithium power (it's a lot cheaper to convert 300v DC to 240v AC then it is to convert 48v DC to 240v AC), how accounting for energy usage has changed, and how grid-tied systems are being remote controlled by the power company this is not necessarily the truth anymore.
  - rory096 7y ago
    Can you link a cite for those standards for grid-tied inverters? I've never heard of grid-commanded curtailment for home solar — generally those frequency signals are created by the inverter to tell the (AC-coupled) PV to turn off when a house is off-grid and the battery is full.
- rory096 7y ago
  The Bath County Pumped Storage Station in Virginia stores 24GWh. It was built between 1977 and 1985 at a nominal cost of $1.6 billion.[0] If we conservatively take those as 1985 dollars, that's equivalent to $3.9 billion in 2019 dollars, or $162.5/kWh. That's comparable to today's price for lithium ion battery storage (~$176/kWh[1]), even before taking into account the massive real increase in cost of large infrastructure projects over the last 35 years. That said, Dominion Energy recently selected a site for a planned second pumped storage facility, conceptually entering operation in 2030.[2] It's a long way off from construction, but they claim that the current budget is $2 billion.[3][4] [0] https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta... [1] https://about.bnef.com/blog/behind-scenes-take-lithium-ion-battery-prices/ https://about.bnef.com/blog/behind-scenes-take-lithium-ion-b... [2] https://www.roanoke.com/news/local/dominion-narrows-to-tazewell-county-site-for-possible-hydroelectric-facility/article_f8376628-cea2-5cdb-8d4a-7e9b225041da.html https://www.roanoke.com/news/local/dominion-narrows-to-tazew... [3] https://www.dominionenergy.com/company/making-energy/renewable-generation/water/powering-southwest-virginia https://www.dominionenergy.com/company/making-energy/renewab... [4] https://www.nrdc.org/experts/walton-shepherd/dominions-greenwashed-pumped-storage-pipedream-wont-fly https://www.nrdc.org/experts/walton-shepherd/dominions-green...
- phyzome 7y ago
  Pumped hydro needs a pretty specific geographic profile. It's pretty great where it works, but good luck finding good candidate spots. Some people have been working on an approach pulling railcars full of rock up a slope, which should have more location options, but I don't know how the math and economics works out.
  - fluffything 7y ago
    > Some people have been working on an approach pulling railcars full of rock up a slope, which should have more location options, but I don't know how the math and economics works out. Have a link?
    - detaro 7y ago
      https://www.aresnorthamerica.com/article/8736-america%E2%80%99s-first-commercial-scale-rail-energy-storage-project-receives-blm-approval https://www.aresnorthamerica.com/article/8736-america%E2%80%...
    - NeedMoreTea 7y ago
      There's a similar approach that seems promising - dropping a huge weight down disused mine shafts, and winching it back up at times of low demand. It looks to be a lot simpler than the railway wagon approach. The UK has loads of potential sites, I imagine the US does too. A fairly detailed look: http://euanmearns.com/short-term-energy-storage-with-gravitricity-iron-versus-ion/ http://euanmearns.com/short-term-energy-storage-with-gravitr...
  - imtringued 7y ago
    It doesn't. The only gravity based storage mechanisms that work out take their materials from the immediate environment like hydraulic hydro storage which scales up to 2 TWh for a large storage plant.
diafygi 7y ago
Replying to my own comment with a more meta comment: I'd also like to point out that the Duck Curve is a good example of the class of problem in the energy transition that seem like a major blocker at first and is often pointed to by detractors to using solar energy, but isn't really. Since these types of problems take years to manifest, it can be being broken down into smaller prioritized problems (such as addressing the slope problem of the "neck") that we, the cleantech sector, can individually figure out and deploy solutions to without stopping progress decarboninzing the grid. If you just keep solving thousands of these smaller problems over time, eventually you'll end up solving the overall problem. In a time where it's politically infeasible to do big things (e.g. building hundreds of nuclear generators), the cleantech sector has for the most part been making progress through incremental solutions that over time will get us where we need to go. I have no doubt that we'll solve the Duck Curve problem, but it will likely be one step at a time, not large strategic changes, which to outsiders make it seems like the problem is still a "blocker". Anyway, this is what fighting climate change looks like, and as an engineer, it's tons of fun to know that if you just keep solving problems, you'll wake up one day in a 100% clean energy world that you helped create.
saagarjha 7y ago
> Base load natural gas Sorry, what? Natural gas spins up quickly and is frequently used in “peaking” power plants, while coal and nuclear provide the actual base load.
- NeedMoreTea 7y ago
  Not if you look at how it is becoming more common to use in Europe, as renewables are increasingly adopted. In the UK, with around 20% of capacity possible from nuclear, 20% from wind, gas is the largest source that makes up any shortfall from renewables and nuclear. Coal is generator of last resort kicking in after using the international interconnects. Both of those non-traditional uses are down to simple economics - it's not economic to use coal unless there is literally nothing else available. It's reached a point where the couple of remaining UK coal plants are paid a small subsidy to stay idling, ready for spin up rather than cold start, for days or weeks on end without actually providing power to the grid. Coal will be entirely gone before 2025. Gas is getting to that point, but for now, it's the bulk of UK generation. Peaking is mostly Dinorwig and the other pumped storage scattered around the UK, along with the secondary ability to disconnect the highest industrial users - around 10% of supply I think - they get a discount on rate for accepting an interruptible supply to help manage the grid.
- jonas21 7y ago
  Yeah, I think the bigger issue with natural gas peaking plants is that it's not an efficient use of capital to build and maintain a plant that only gets used for a few hours a day.
boulos 7y ago
Thanks for this pointer! I asked this in my comment about wind, but wanted to ask you: why is a renewal dip (and generation response) so different from several GW of planned maintenance? The renewal dips are actually quite predictable as well.
- diafygi 7y ago
  Hmmmm, I think the difference is that the dip will be ever-increasing to the point where it completely eliminates the need for fossil-based generation. California (and many other places) have 100% carbon-free energy mandates over the next few decades, so this isn't a once-in-a-while situation where you can just ramp up a bit more at other facilities to get by for the maintenance window.
scythe 7y ago
Japan has forty years of experience with energy storage actually: https://en.wikipedia.org/wiki/Sodium%E2%80%93sulfur_battery#Japan https://en.wikipedia.org/wiki/Sodium%E2%80%93sulfur_battery#... >one of four battery types selected [...] as part of the "Moonlight Project" in 1980. They have 2600 MWh of installed grid energy storage capacity as NaS batteries: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7804322 https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7804322 >According to NGK, the company has delivered NAS battery systems with a total output of 530 MW and storage capacity The power generation shortfall on the Duck curve is about 10000 MW. So Na-S capacity has reached 5% of that. But it's a start, and it's cheap, and it's been shown to work. Plus, growth in these kinds of industries can be supralinear.

tialaramex 7y ago

Couldn't you do other types of storage rather than batteries? Pumped storage can do very fast spin-up because gravity doesn't take any time to warm up, nothing to 1.8GW in a few seconds at Dinorwig (in Wales), if you own half a dozen of those then 11GW in 3 hours feels like child's play. Not everywhere has the geography for building power stations inside mountains (which is the only way to do pumped storage that isn't horribly ugly), but the US is huge and seems like there are mountains everywhere you look in some parts, surely some of them are suitable for hiding a pumped storage facility?

NeedMoreTea 7y ago
There were two or three backup sites within 15 miles of Dinorwig that were being evaluated prior to it being built. There in case the main site proved impractical or too expensive for some reason. I'd posit there are ample disused quarry sites that could serve a similar purpose scattered around the UK, US and much of the developed world.
diafygi 7y ago
Hmmmm, yes, probably. However the reasons for deploying millions of lithium batteries instead of a few dozen pumped hydro stations are likely more political and business reasons than technical reasons. First, it's way easier and faster to just park containers full of batteries wherever you need to shift the energy than to find and build new pumped hydro location then build/upgrade the transmission to the locations where the load shifting is needed. And when you need the load shifting ASAP, you're probably going to opt for the solution that can deployed now, especially when the regulatory reaction to this problem is to adjust prices ("time of use" rates) to discourage people from using power during the slope. Second, battery installers are able to sell directly to consumers, which means they can bypass utility bureaucracy. Many utilities are very slow to adopt "non-wires alternatives" because their business model doesn't incentivize them to building out a distributed, flexible grid, and they are increasingly becoming worried about their generation assets being financially stranded. This means that it's often easier to sell thousands of energy storage units to thousands of homes and businesses, than it is to sell that same thousand units directly to the utility. With pumped hydro, there's no distributed option, so you end up being at the mercy of the utility wanting your product. So yes, you're probably right that pumped hydro is on paper cheaper for addressing the Duck Curve "neck" problem, but this is a case where the difference between theory and reality is substantial for non-technical reasons.
deleted 7y ago
[deleted]
lazyguy2 7y ago
> Couldn't you do other types of storage rather than batteries? Sure. But they all have their own downsides. Pump air into vast underground tunnels. Pump water into towers. Spin up massive drums as flywheels (this one is my favorite. Spinning weights are incredibly power dense). Lift massive weights. It's all been done. There are companies working on making these things more practical. Meanwhile the power companies have instituted new standards in grid-tied inverters for solar panels that have effectively solved the problem for them. It's based on the frequency of the grid. As the grid becomes over powered it's frequency tends to shift a bit higher. As the grid becomes over loaded the frequency tends to shift a bit lower. By responding to these frequency shifts the grid-tied inverters will either allow electricity to be generated when the frequency falls back slightly, throttle electrical generation when the frequency rises slightly, and then shut off completely when the grid goes down. So the effect is that those expensive solar panel arrays in places were they are already popular... are effectively shut off during the peak solar power generation hours. And are turned off completely when the grid itself is shutdown. Lithium batteries represent a unique opportunity for truly distributed power generation. They are just reaching the point, price-wise, were they can be used as a practical way to store energy on a individual small business or household manner. This way individuals themselves can take charge of their own power needs and no longer has to rely on centralized bureaucracies to save the world for them. Unfortunately due to the way grid-tied systems are now required to work it has effectively nullified most of the benefits of having private solar arrays. IF you want to be your own power generator you have to be off-grid to do it. And this the reason this is unfortunate is because almost nobody is building private solar arrays this way. There is a semi-religious belief that grid-tied systems allow a ROI in the form of selling power back to the grid. Also they are built with the assumption that battery backups for the house is too expensive and impractical. All these things are true if you are looking at low-voltage SLA battery arrays and grid-tied standards from 5-10 years ago, but with high voltage lithium power (it's a lot cheaper to convert 300v DC to 240v AC then it is to convert 48v DC to 240v AC), how accounting for energy usage has changed, and how grid-tied systems are being remote controlled by the power company this is not necessarily the truth anymore.
- rory096 7y ago
  Can you link a cite for those standards for grid-tied inverters? I've never heard of grid-commanded curtailment for home solar — generally those frequency signals are created by the inverter to tell the (AC-coupled) PV to turn off when a house is off-grid and the battery is full.
rory096 7y ago
The Bath County Pumped Storage Station in Virginia stores 24GWh. It was built between 1977 and 1985 at a nominal cost of $1.6 billion.[0] If we conservatively take those as 1985 dollars, that's equivalent to $3.9 billion in 2019 dollars, or $162.5/kWh. That's comparable to today's price for lithium ion battery storage (~$176/kWh[1]), even before taking into account the massive real increase in cost of large infrastructure projects over the last 35 years. That said, Dominion Energy recently selected a site for a planned second pumped storage facility, conceptually entering operation in 2030.[2] It's a long way off from construction, but they claim that the current budget is $2 billion.[3][4] [0] https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station https://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Sta... [1] https://about.bnef.com/blog/behind-scenes-take-lithium-ion-battery-prices/ https://about.bnef.com/blog/behind-scenes-take-lithium-ion-b... [2] https://www.roanoke.com/news/local/dominion-narrows-to-tazewell-county-site-for-possible-hydroelectric-facility/article_f8376628-cea2-5cdb-8d4a-7e9b225041da.html https://www.roanoke.com/news/local/dominion-narrows-to-tazew... [3] https://www.dominionenergy.com/company/making-energy/renewable-generation/water/powering-southwest-virginia https://www.dominionenergy.com/company/making-energy/renewab... [4] https://www.nrdc.org/experts/walton-shepherd/dominions-greenwashed-pumped-storage-pipedream-wont-fly https://www.nrdc.org/experts/walton-shepherd/dominions-green...
phyzome 7y ago
Pumped hydro needs a pretty specific geographic profile. It's pretty great where it works, but good luck finding good candidate spots. Some people have been working on an approach pulling railcars full of rock up a slope, which should have more location options, but I don't know how the math and economics works out.
- fluffything 7y ago
  > Some people have been working on an approach pulling railcars full of rock up a slope, which should have more location options, but I don't know how the math and economics works out. Have a link?
  - detaro 7y ago
    https://www.aresnorthamerica.com/article/8736-america%E2%80%99s-first-commercial-scale-rail-energy-storage-project-receives-blm-approval https://www.aresnorthamerica.com/article/8736-america%E2%80%...
  - NeedMoreTea 7y ago
    There's a similar approach that seems promising - dropping a huge weight down disused mine shafts, and winching it back up at times of low demand. It looks to be a lot simpler than the railway wagon approach. The UK has loads of potential sites, I imagine the US does too. A fairly detailed look: http://euanmearns.com/short-term-energy-storage-with-gravitricity-iron-versus-ion/ http://euanmearns.com/short-term-energy-storage-with-gravitr...
- imtringued 7y ago
  It doesn't. The only gravity based storage mechanisms that work out take their materials from the immediate environment like hydraulic hydro storage which scales up to 2 TWh for a large storage plant.

diafygi 7y ago

Replying to my own comment with a more meta comment: I'd also like to point out that the Duck Curve is a good example of the class of problem in the energy transition that seem like a major blocker at first and is often pointed to by detractors to using solar energy, but isn't really. Since these types of problems take years to manifest, it can be being broken down into smaller prioritized problems (such as addressing the slope problem of the "neck") that we, the cleantech sector, can individually figure out and deploy solutions to without stopping progress decarboninzing the grid. If you just keep solving thousands of these smaller problems over time, eventually you'll end up solving the overall problem. In a time where it's politically infeasible to do big things (e.g. building hundreds of nuclear generators), the cleantech sector has for the most part been making progress through incremental solutions that over time will get us where we need to go. I have no doubt that we'll solve the Duck Curve problem, but it will likely be one step at a time, not large strategic changes, which to outsiders make it seems like the problem is still a "blocker". Anyway, this is what fighting climate change looks like, and as an engineer, it's tons of fun to know that if you just keep solving problems, you'll wake up one day in a 100% clean energy world that you helped create.

saagarjha 7y ago

> Base load natural gas Sorry, what? Natural gas spins up quickly and is frequently used in “peaking” power plants, while coal and nuclear provide the actual base load.

NeedMoreTea 7y ago
Not if you look at how it is becoming more common to use in Europe, as renewables are increasingly adopted. In the UK, with around 20% of capacity possible from nuclear, 20% from wind, gas is the largest source that makes up any shortfall from renewables and nuclear. Coal is generator of last resort kicking in after using the international interconnects. Both of those non-traditional uses are down to simple economics - it's not economic to use coal unless there is literally nothing else available. It's reached a point where the couple of remaining UK coal plants are paid a small subsidy to stay idling, ready for spin up rather than cold start, for days or weeks on end without actually providing power to the grid. Coal will be entirely gone before 2025. Gas is getting to that point, but for now, it's the bulk of UK generation. Peaking is mostly Dinorwig and the other pumped storage scattered around the UK, along with the secondary ability to disconnect the highest industrial users - around 10% of supply I think - they get a discount on rate for accepting an interruptible supply to help manage the grid.
jonas21 7y ago
Yeah, I think the bigger issue with natural gas peaking plants is that it's not an efficient use of capital to build and maintain a plant that only gets used for a few hours a day.

boulos 7y ago

Thanks for this pointer! I asked this in my comment about wind, but wanted to ask you: why is a renewal dip (and generation response) so different from several GW of planned maintenance? The renewal dips are actually quite predictable as well.

diafygi 7y ago
Hmmmm, I think the difference is that the dip will be ever-increasing to the point where it completely eliminates the need for fossil-based generation. California (and many other places) have 100% carbon-free energy mandates over the next few decades, so this isn't a once-in-a-while situation where you can just ramp up a bit more at other facilities to get by for the maintenance window.

scythe 7y ago

Japan has forty years of experience with energy storage actually: https://en.wikipedia.org/wiki/Sodium%E2%80%93sulfur_battery#Japan https://en.wikipedia.org/wiki/Sodium%E2%80%93sulfur_battery#... >one of four battery types selected [...] as part of the "Moonlight Project" in 1980. They have 2600 MWh of installed grid energy storage capacity as NaS batteries: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7804322 https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=7804322 >According to NGK, the company has delivered NAS battery systems with a total output of 530 MW and storage capacity The power generation shortfall on the Duck curve is about 10000 MW. So Na-S capacity has reached 5% of that. But it's a start, and it's cheap, and it's been shown to work. Plus, growth in these kinds of industries can be supralinear.