12 ms·

Duck Curve

154 points by B1FF_PSUVM 7y ago

deleted 7y ago
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diafygi 7y ago
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
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  - 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.
k__ 7y ago
Could we use space mirrors to illuminate solar farms at night?
- semiotagonal 7y ago
  Wouldn't it be cheaper just to whip a cable over to Australia?
  - lazyguy2 7y ago
    We could bore a series of holes through the center of the planet and then use gigantic orbital crystals to create a array of lazers to focus the sun's light through to the dark side of the planet.
    - jjoonathan 7y ago
      I'm a fan of using magical heat-producing rocks to boil water and spin turbines, but admittedly that has fallen a bit out of fashion.
      - MiroF 7y ago
        This could be nuclear or coal
        jjoonathan 7y ago
        There's an argument to be had that burning coal doesn't count as magic while fission does, but in any case, good catch, let me amend that to: magic heat-producing rocks that don't fill the atmosphere with dinosaur squeezings.
  - thinkloop 7y ago
    It's temperature would have to be maintained around absolute zero to compensate for the transmission loss, for that we would need a continuous source of cheap, clean energy.
  - 7y ago
nxpnsv 7y ago
The Duck picture alone makes this page worth checking out
- deleted 7y ago
  [deleted]
- saghm 7y ago
  I went into the article based on your recommendation, and I was not disappointed
- kkylin 7y ago
  Indeed! Veering (far) off topic, but I cannot resist posting this while we're on the topic of ducks: http://www.scholarpedia.org/article/Canards http://www.scholarpedia.org/article/Canards
- twic 7y ago
  According to the Wikimedia page, the duck is from an article [1] by Jordan Wirfs-Brock. Some quick internet stalking suggests is the daughter of Smalltalk and OOP pioneer Rebecca Wirfs-Brock. Illustrious family! [1] http://insideenergy.org/2014/10/02/ie-questions-why-is-california-trying-to-behead-the-duck/ http://insideenergy.org/2014/10/02/ie-questions-why-is-calif...
ssalka 7y ago
See Also: Bart pattern in crypto trading
- robbya 7y ago
  https://cryptocurrencyfacts.com/2018/04/16/the-bart-crypto-pattern/ https://cryptocurrencyfacts.com/2018/04/16/the-bart-crypto-p...
boulos 7y ago
I’m surprised the mitigation discussion didn’t include “more wind generation”. Especially at the coast [1], you have plenty of wind at and around sunset from the large temperature differential. The chart is load minus solar/wind, but the example graph was a low wind day apparently (and IIRC, we are predominantly solar in California). But even then, this curve doesn’t seem to apply in California in the summer when load demand is highest (look at CAISO demand for say July 24). The amount of built up generation should be looked at in terms of annual peaks and overall efficiency. July has demand up to 45GW range where renewables are only currently able to shave off 10 GW of that (but basically all day long). The forecasted demand for today has a peak of 25 GW. Is it “just” about how quickly net demand spikes? The grid seems to handle 10+ MW or scheduled maintenance (look at October 1). [1] https://www.windfinder.com/forecast/pacifica_dumps_san_francisco https://www.windfinder.com/forecast/pacifica_dumps_san_franc... (ignore the current high winds, go a few days forward).
- danans 7y ago
  > I’m surprised the mitigation discussion didn’t include “more wind generation”. Especially at the coast This is just my conjecture, but I wouldn't be surprised if the very high cost of coastal land, and possible objection by nearby homeowners in CA is part of the reason for lack of wind power on the immediate coast. If you go just a bit inland, however you'll find the massive new Turtle Island wind farm near the Sacramento River delta.
  - Filligree 7y ago
    Coastal land, yes. It's usually unproblematic to build wind farms offshore, and they work even better there.
    - ZeroGravitas 7y ago
      Offshore wind power started off in areas with shallow seas, it's only now getting around to floating wind that would suit California.
      - 7y ago
phyzome 7y ago
Sounds like capacitors would help here, even regular ones, since they'd only need to hold excess solar energy for a few hours in order to smooth out that evening demand.
- mod 7y ago
  In the graph on the page, the solar output isn't even meeting the current demand. No need to store it.
  - bitpow 7y ago
    Storing it would help reduce the peak in the evenings.
  - hn_throwaway_99 7y ago
    The point is that, without storage, no matter how much solar you install you don't lower the required amount of fossil fuel plant capacity at all because the peak occurs when solar is at 0.
    - ZeroGravitas 7y ago
      The yearly peak, in summer, occurs when solar is running. The daily peak, on spring and autumn days, falls outside the solar peak, but also well below the yearly peak. So solar does help displace the least efficient and most expensive part of your gas fleet. But it's not the peak that's the point of the duck curve, it's the solar falling faster than gas can switch on and that difference is very amenable to being fixed by even a small amount of battery storage.
      - cesarb 7y ago
        > it's the solar falling faster than gas can switch on Is "switch on" really the problem? As Germany showed during the solar eclipse (https://www.dw.com/en/german-power-net-survives-solar-eclipse/a-18331190 https://www.dw.com/en/german-power-net-survives-solar-eclips...), as long as it's a predictable event, you can have the necessary generation already "switched on" and running at a low power, and the limit becomes only how fast you can ramp up their power. Which is still an issue, but not as much as it would be if they had to turn on all the gas generators with zero notice.
dimitar 7y ago
This applies to Photovoltaics only, not to wind or concentrated solar, and looks like something that is pretty specific to California's energy mix and policies. If we replace fossil fuels during the day and turn on hydro and other during the night, I still think the duck curve is not an argument against adding much more PV capacity.
z-cam 7y ago
We think that leveraging electric vehicles as a storage device will help solve the duck curve problem. Utilities are reluctant to invest billions of dollars in energy storage to smooth out their demand curve. But consumers are already making this investment by switching en masse to EVs. We're building software that will one day help utilities transact with individual or fleet vehicle owners to leverage their vehicles as energy storage.
- hn_throwaway_99 7y ago
  Yeah, I'm curious if the number of "batteries" already connected to the grid could mitigate this quite a bit. For example, large industrial freezers (or perhaps even "smart" home freezers) could take their temp extra low during the day so they wouldn't need to use power during the evening. Also, with the current discrepancy in electricity costs between the day and evening, seems like this could make something like Tesla's Powerwall much more price competitive if it meant you only had to use the grid during the cheapest times.
  - VyperCard 7y ago
    Yes they can. The company I work for does that using a few halls with industrial freezers.
- dimitar 7y ago
  Wouldn't EV increase electricity demand in the evenings when people get home and plug in their cars?
  - jcrben 7y ago
    California has time of use rates (relatively new and uncommon). And we're beginning to see deep discounts in the middle of the day consistent with the solar. So people may strategically charge during the day. If it's a commuter car on a reasonable commute and you've got 300 miles of range, it's feasible to wait till midday. You can see the power supply / consumption at http://www.caiso.com/TodaysOutlook/Pages/supply.aspx http://www.caiso.com/TodaysOutlook/Pages/supply.aspx
baybal2 7y ago
This problem is blown out of proportion. The energy storage is not a "do or die" issue for the industry by any extent. Technical solutions for short term energy storage are known, and been used for decades. Were it economically sound, it would've been adopted already. In fact, it is being done when the need is genuine, just without much publicity. People who spin this topic feel to me to be in the business of selling tech companies.
- acidburnNSA 7y ago
  The problem today is solved, almost universally, with high-carbon fracked natural gas plants. This is cheap in current markets and incredibly effective from a technological standpoint. As we recognize climate change as a problem, this solution loses credibility, but yet, there it is. I don't think people are recognizing how hard it is to deeply decarbonize with intermittent energy sources, and so I have to disagree. I think this problem is too often brushed aside as a non-issue by renewable energy optimists.
  - diafygi 7y ago
    Hmmm, so I work in the distributed energy resources sector, and I disagree that people in this space aren't recognizing how hard it will be to deeply decarbonize using intermittent generation. You're completely correct that as we add more and more intermittent generation to the grid, keeping the grid always online becomes crazy difficult. However, everyone I know in the space looks at that challenge as opportunity rather than discouragement. It's not like we're going to hit high penetrations of intermittent renewables overnight. It's going to be a gradual ramp over years that allows us to also deploy complimentary systems to deal with the ever increasing intermittency. Piece-by-piece we will deploy flexibility technologies (DR, DERMS, storage, etc.) and move to new regulatory incentives and utility business models (performance-based ratemaking, etc.) that allow us to reach our 100% goals. There's a ton of super smart people already working on the intermittency problem, and entire businesses are being built to solve it (disclosure: many of them use our platform). So I guess while I agree with your assessment of the level of difficulty, I don't agree with your level of despair. There's way too many smart engineers working in the space now for intermittency to be in impossible problem to solve.
OliverJones 7y ago
Once smart-grid tech starts to emerge, many possibilities to muffle the quacking of the duck curve present themselves. The most obvious, and applicable in any climate and weather, is domestic hot water heating. Temporarily suspending power to electric hot water heaters at times of high demand can save tons of short-term load. And, it's potentially responsive enough to support frequency control ancillary services (the very expensive task of keeping the power grid running at exactly 60Hz or 50Hz when power demand is changing fast). Another is electric vehicle charging time-shifting, either mandatory or voluntary. A third, more complex, opportunity is HVAC. If heating / airconditioning systems can get ahead of their needs during late afternoons, then temporary power suspension in early evenings is feasible. This kind of application may be easiest to deploy in commercial locations like big-box stores, office buildings, and data centers. A mindset change required is this: demand time-shifting IS energy storage. A bigger mindset change: grid operators are in the information business, whether they know it or not. All this proposed timeshifting is based on information.
- kbutler 7y ago
  Each of those has major problems. Water heating is usually natural gas. Electric vehicle charging during the day prevents charging at home. So employers would need to come on board paying for charging stations with employee parking. And shopping malls, schools, etc. Heating is also usually natural gas, and while cooling is almost universally electric, it doesn't take very long minutes to a very few hours) in hot weather to consume any reasonable pre-cooling.
  - Gibbon1 7y ago
    Elimination of natural gas water heaters is necessary. Workplace charging stations isn't so much an employer thing, as a commercial real estate thing. So it's not so much an inconvenience since borrowing money to pay for upgrades of real estate is what those guys are about. And of course natural gas heating needs to die as well.
  - function_seven 7y ago
    I imagine the electric vehicle charging could be time-shifted to overnight. Between 10pm and 6am Also, energy for water heaters and home heating vary a bit across the country. Electricity is more common in some parts than in others. Even in places that are overwhelmingly gas or propane fueled, the 10% of systems that are electrically powered represent a small but significant opportunity to time-shift demand. A/C is definitely the largest culprit here, though. And precooling does work if you lower the temperature of the interior thermal mass of the house. I used to do it when I was subject to random 4-hour A/C shutoffs as part of my discount plan. If I got the house down to 66˚F before the shutoff occurred, the house would remain comfortable for a couple hours. I may have used an overall larger amount of power to do this, but it was the "right" power: drawn from neighbors' solar rather than generating plants.
anonu 7y ago
It is because of effects like the "duck curve" that make me wish I was an electricity trader. Being able match these patterns and events and correlate them to different geographies would probably be quite profitable. I briefly looked into trading on some of the popular ISOs (NYISO for example) - but it quickly became clear to me that my hobbyist approach to these markets was not going to cut it as they are way more technical and require a bit more capital than your typical equity markets. EDIT: https://www.nyiso.com/ https://www.nyiso.com/ << if you want to learn more about the US de-regulated and open electrical grid, this site has 100s of technical pages and material. They seem to want and encourage people to be part of the market.
ZeroGravitas 7y ago
The duck curve is a non-problem, just like all the predictions from the same era that 5, 10, 15, 20, 25% was the absolute limit that renewables could provide without totally overhauling the grid. That number has continually risen as grids just did it and blew past the imagined limits. California now has a mandate for 100% clean energy which makes "we can't turn our gas plants on fast enough a few days a year to avoid curtailing some renewables" seem ridiculously parochial. On those high renewable, low demand days in the future there will be plenty of responsive demand to soak it up. Free car charging for anyone plugged into a socket for example.
Tempest1981 7y ago
With PG&E shutting off power in California, I think we'll see a growth in battery packs (like Tesla Powerwall) -- at least among the ~1 million impacted customers. There is now a much stronger incentive to get off the grid, with the shut-offs expected to continue for 10 years.
sandworm101 7y ago
So there is no wind in california?
iddqd 7y ago
I drew a duck graph on a whiteboard the other day. Wish I had known it had a name, could’ve gotten an easy chuckle from the room.
carapace 7y ago
http://www.geni.org/globalenergy/library/newsletters/1995/buckminster-fuller-on-the-global-energy-grid.shtml#GlobalEnergyGrid http://www.geni.org/globalenergy/library/newsletters/1995/bu... > "This now feasible, intercontinental network would integrate America, Asia and Europe, and integrate the night-and-day, spherically shadow-and-light zones of Planet Earth. And this would occasion the 24-hour use of the now only fifty per cent of the time used world-around standby generator capacity, whose fifty per cent unused capacities heretofore were mandatorily required only for peakload servicing of local non-interconnected energy users. Such intercontinental network integration would overnight double the already-installed and in-use, electric power generating capacity of our Planet." > Telegram to Senator Edmund Muskie, Earth, Inc., 1973, Fuller.

154 points by B1FF_PSUVM 7y ago

deleted 7y ago

[deleted]

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.

k__ 7y ago

Could we use space mirrors to illuminate solar farms at night?

semiotagonal 7y ago
Wouldn't it be cheaper just to whip a cable over to Australia?
- lazyguy2 7y ago
  We could bore a series of holes through the center of the planet and then use gigantic orbital crystals to create a array of lazers to focus the sun's light through to the dark side of the planet.
  - jjoonathan 7y ago
    I'm a fan of using magical heat-producing rocks to boil water and spin turbines, but admittedly that has fallen a bit out of fashion.
    - MiroF 7y ago
      This could be nuclear or coal
      - jjoonathan 7y ago
        There's an argument to be had that burning coal doesn't count as magic while fission does, but in any case, good catch, let me amend that to: magic heat-producing rocks that don't fill the atmosphere with dinosaur squeezings.
- thinkloop 7y ago
  It's temperature would have to be maintained around absolute zero to compensate for the transmission loss, for that we would need a continuous source of cheap, clean energy.
- 7y ago

nxpnsv 7y ago

The Duck picture alone makes this page worth checking out

deleted 7y ago
[deleted]
saghm 7y ago
I went into the article based on your recommendation, and I was not disappointed
kkylin 7y ago
Indeed! Veering (far) off topic, but I cannot resist posting this while we're on the topic of ducks: http://www.scholarpedia.org/article/Canards http://www.scholarpedia.org/article/Canards
twic 7y ago
According to the Wikimedia page, the duck is from an article [1] by Jordan Wirfs-Brock. Some quick internet stalking suggests is the daughter of Smalltalk and OOP pioneer Rebecca Wirfs-Brock. Illustrious family! [1] http://insideenergy.org/2014/10/02/ie-questions-why-is-california-trying-to-behead-the-duck/ http://insideenergy.org/2014/10/02/ie-questions-why-is-calif...

ssalka 7y ago

See Also: Bart pattern in crypto trading

robbya 7y ago
https://cryptocurrencyfacts.com/2018/04/16/the-bart-crypto-pattern/ https://cryptocurrencyfacts.com/2018/04/16/the-bart-crypto-p...

boulos 7y ago

I’m surprised the mitigation discussion didn’t include “more wind generation”. Especially at the coast [1], you have plenty of wind at and around sunset from the large temperature differential. The chart is load minus solar/wind, but the example graph was a low wind day apparently (and IIRC, we are predominantly solar in California). But even then, this curve doesn’t seem to apply in California in the summer when load demand is highest (look at CAISO demand for say July 24). The amount of built up generation should be looked at in terms of annual peaks and overall efficiency. July has demand up to 45GW range where renewables are only currently able to shave off 10 GW of that (but basically all day long). The forecasted demand for today has a peak of 25 GW. Is it “just” about how quickly net demand spikes? The grid seems to handle 10+ MW or scheduled maintenance (look at October 1). [1] https://www.windfinder.com/forecast/pacifica_dumps_san_francisco https://www.windfinder.com/forecast/pacifica_dumps_san_franc... (ignore the current high winds, go a few days forward).

danans 7y ago
> I’m surprised the mitigation discussion didn’t include “more wind generation”. Especially at the coast This is just my conjecture, but I wouldn't be surprised if the very high cost of coastal land, and possible objection by nearby homeowners in CA is part of the reason for lack of wind power on the immediate coast. If you go just a bit inland, however you'll find the massive new Turtle Island wind farm near the Sacramento River delta.
- Filligree 7y ago
  Coastal land, yes. It's usually unproblematic to build wind farms offshore, and they work even better there.
  - ZeroGravitas 7y ago
    Offshore wind power started off in areas with shallow seas, it's only now getting around to floating wind that would suit California.
    - 7y ago

phyzome 7y ago

Sounds like capacitors would help here, even regular ones, since they'd only need to hold excess solar energy for a few hours in order to smooth out that evening demand.

mod 7y ago
In the graph on the page, the solar output isn't even meeting the current demand. No need to store it.
- bitpow 7y ago
  Storing it would help reduce the peak in the evenings.
- hn_throwaway_99 7y ago
  The point is that, without storage, no matter how much solar you install you don't lower the required amount of fossil fuel plant capacity at all because the peak occurs when solar is at 0.
  - ZeroGravitas 7y ago
    The yearly peak, in summer, occurs when solar is running. The daily peak, on spring and autumn days, falls outside the solar peak, but also well below the yearly peak. So solar does help displace the least efficient and most expensive part of your gas fleet. But it's not the peak that's the point of the duck curve, it's the solar falling faster than gas can switch on and that difference is very amenable to being fixed by even a small amount of battery storage.
    - cesarb 7y ago
      > it's the solar falling faster than gas can switch on Is "switch on" really the problem? As Germany showed during the solar eclipse (https://www.dw.com/en/german-power-net-survives-solar-eclipse/a-18331190 https://www.dw.com/en/german-power-net-survives-solar-eclips...), as long as it's a predictable event, you can have the necessary generation already "switched on" and running at a low power, and the limit becomes only how fast you can ramp up their power. Which is still an issue, but not as much as it would be if they had to turn on all the gas generators with zero notice.

dimitar 7y ago

This applies to Photovoltaics only, not to wind or concentrated solar, and looks like something that is pretty specific to California's energy mix and policies. If we replace fossil fuels during the day and turn on hydro and other during the night, I still think the duck curve is not an argument against adding much more PV capacity.

z-cam 7y ago

We think that leveraging electric vehicles as a storage device will help solve the duck curve problem. Utilities are reluctant to invest billions of dollars in energy storage to smooth out their demand curve. But consumers are already making this investment by switching en masse to EVs. We're building software that will one day help utilities transact with individual or fleet vehicle owners to leverage their vehicles as energy storage.

hn_throwaway_99 7y ago
Yeah, I'm curious if the number of "batteries" already connected to the grid could mitigate this quite a bit. For example, large industrial freezers (or perhaps even "smart" home freezers) could take their temp extra low during the day so they wouldn't need to use power during the evening. Also, with the current discrepancy in electricity costs between the day and evening, seems like this could make something like Tesla's Powerwall much more price competitive if it meant you only had to use the grid during the cheapest times.
- VyperCard 7y ago
  Yes they can. The company I work for does that using a few halls with industrial freezers.
dimitar 7y ago
Wouldn't EV increase electricity demand in the evenings when people get home and plug in their cars?
- jcrben 7y ago
  California has time of use rates (relatively new and uncommon). And we're beginning to see deep discounts in the middle of the day consistent with the solar. So people may strategically charge during the day. If it's a commuter car on a reasonable commute and you've got 300 miles of range, it's feasible to wait till midday. You can see the power supply / consumption at http://www.caiso.com/TodaysOutlook/Pages/supply.aspx http://www.caiso.com/TodaysOutlook/Pages/supply.aspx

baybal2 7y ago

This problem is blown out of proportion. The energy storage is not a "do or die" issue for the industry by any extent. Technical solutions for short term energy storage are known, and been used for decades. Were it economically sound, it would've been adopted already. In fact, it is being done when the need is genuine, just without much publicity. People who spin this topic feel to me to be in the business of selling tech companies.

acidburnNSA 7y ago
The problem today is solved, almost universally, with high-carbon fracked natural gas plants. This is cheap in current markets and incredibly effective from a technological standpoint. As we recognize climate change as a problem, this solution loses credibility, but yet, there it is. I don't think people are recognizing how hard it is to deeply decarbonize with intermittent energy sources, and so I have to disagree. I think this problem is too often brushed aside as a non-issue by renewable energy optimists.
- diafygi 7y ago
  Hmmm, so I work in the distributed energy resources sector, and I disagree that people in this space aren't recognizing how hard it will be to deeply decarbonize using intermittent generation. You're completely correct that as we add more and more intermittent generation to the grid, keeping the grid always online becomes crazy difficult. However, everyone I know in the space looks at that challenge as opportunity rather than discouragement. It's not like we're going to hit high penetrations of intermittent renewables overnight. It's going to be a gradual ramp over years that allows us to also deploy complimentary systems to deal with the ever increasing intermittency. Piece-by-piece we will deploy flexibility technologies (DR, DERMS, storage, etc.) and move to new regulatory incentives and utility business models (performance-based ratemaking, etc.) that allow us to reach our 100% goals. There's a ton of super smart people already working on the intermittency problem, and entire businesses are being built to solve it (disclosure: many of them use our platform). So I guess while I agree with your assessment of the level of difficulty, I don't agree with your level of despair. There's way too many smart engineers working in the space now for intermittency to be in impossible problem to solve.

OliverJones 7y ago

Once smart-grid tech starts to emerge, many possibilities to muffle the quacking of the duck curve present themselves. The most obvious, and applicable in any climate and weather, is domestic hot water heating. Temporarily suspending power to electric hot water heaters at times of high demand can save tons of short-term load. And, it's potentially responsive enough to support frequency control ancillary services (the very expensive task of keeping the power grid running at exactly 60Hz or 50Hz when power demand is changing fast). Another is electric vehicle charging time-shifting, either mandatory or voluntary. A third, more complex, opportunity is HVAC. If heating / airconditioning systems can get ahead of their needs during late afternoons, then temporary power suspension in early evenings is feasible. This kind of application may be easiest to deploy in commercial locations like big-box stores, office buildings, and data centers. A mindset change required is this: demand time-shifting IS energy storage. A bigger mindset change: grid operators are in the information business, whether they know it or not. All this proposed timeshifting is based on information.

kbutler 7y ago
Each of those has major problems. Water heating is usually natural gas. Electric vehicle charging during the day prevents charging at home. So employers would need to come on board paying for charging stations with employee parking. And shopping malls, schools, etc. Heating is also usually natural gas, and while cooling is almost universally electric, it doesn't take very long minutes to a very few hours) in hot weather to consume any reasonable pre-cooling.
- Gibbon1 7y ago
  Elimination of natural gas water heaters is necessary. Workplace charging stations isn't so much an employer thing, as a commercial real estate thing. So it's not so much an inconvenience since borrowing money to pay for upgrades of real estate is what those guys are about. And of course natural gas heating needs to die as well.
- function_seven 7y ago
  I imagine the electric vehicle charging could be time-shifted to overnight. Between 10pm and 6am Also, energy for water heaters and home heating vary a bit across the country. Electricity is more common in some parts than in others. Even in places that are overwhelmingly gas or propane fueled, the 10% of systems that are electrically powered represent a small but significant opportunity to time-shift demand. A/C is definitely the largest culprit here, though. And precooling does work if you lower the temperature of the interior thermal mass of the house. I used to do it when I was subject to random 4-hour A/C shutoffs as part of my discount plan. If I got the house down to 66˚F before the shutoff occurred, the house would remain comfortable for a couple hours. I may have used an overall larger amount of power to do this, but it was the "right" power: drawn from neighbors' solar rather than generating plants.

anonu 7y ago

It is because of effects like the "duck curve" that make me wish I was an electricity trader. Being able match these patterns and events and correlate them to different geographies would probably be quite profitable. I briefly looked into trading on some of the popular ISOs (NYISO for example) - but it quickly became clear to me that my hobbyist approach to these markets was not going to cut it as they are way more technical and require a bit more capital than your typical equity markets. EDIT: https://www.nyiso.com/ https://www.nyiso.com/ << if you want to learn more about the US de-regulated and open electrical grid, this site has 100s of technical pages and material. They seem to want and encourage people to be part of the market.

ZeroGravitas 7y ago

The duck curve is a non-problem, just like all the predictions from the same era that 5, 10, 15, 20, 25% was the absolute limit that renewables could provide without totally overhauling the grid. That number has continually risen as grids just did it and blew past the imagined limits. California now has a mandate for 100% clean energy which makes "we can't turn our gas plants on fast enough a few days a year to avoid curtailing some renewables" seem ridiculously parochial. On those high renewable, low demand days in the future there will be plenty of responsive demand to soak it up. Free car charging for anyone plugged into a socket for example.

Tempest1981 7y ago

With PG&E shutting off power in California, I think we'll see a growth in battery packs (like Tesla Powerwall) -- at least among the ~1 million impacted customers. There is now a much stronger incentive to get off the grid, with the shut-offs expected to continue for 10 years.

sandworm101 7y ago

So there is no wind in california?

iddqd 7y ago

I drew a duck graph on a whiteboard the other day. Wish I had known it had a name, could’ve gotten an easy chuckle from the room.

carapace 7y ago

http://www.geni.org/globalenergy/library/newsletters/1995/buckminster-fuller-on-the-global-energy-grid.shtml#GlobalEnergyGrid http://www.geni.org/globalenergy/library/newsletters/1995/bu... > "This now feasible, intercontinental network would integrate America, Asia and Europe, and integrate the night-and-day, spherically shadow-and-light zones of Planet Earth. And this would occasion the 24-hour use of the now only fifty per cent of the time used world-around standby generator capacity, whose fifty per cent unused capacities heretofore were mandatorily required only for peakload servicing of local non-interconnected energy users. Such intercontinental network integration would overnight double the already-installed and in-use, electric power generating capacity of our Planet." > Telegram to Senator Edmund Muskie, Earth, Inc., 1973, Fuller.