7 ms·

Worked on a project to address the problem of predicting wind power production over the short term (as in the next couple of hours). It is a very hard problem,

Worked on a project to address the problem of predicting wind power production over the short term (as in the next couple of hours). It is a very hard problem, and when I left it we had declared it successful because we were something like 10% better than the current method, which is just to assume that current production will continue. Wind power is a strange beast. A 300MW wind farm can go from 250MW to 0MW to 100MW over a 1-2 hour period. Trying to properly plan for that or ramping up/down your coal/gas plants to cover the changes is very difficult and expensive.

curtis 11y ago
I'm inclined to think that wind will only work at bigger scales if we can find industrial processes that are dominated by energy costs rather than capital costs and which can scale up and down in energy consumption fast enough to track the wind output. I can think of a couple of possibilities. Water desalination is an obvious candidate. It might be economical to massively overbuild desalination plants and then only run them at peak capacity when wind is at peak as well. If the cost of electricity is much greater than the capital cost of the desalination plants, then it might be a net win when amortized over the lifetime of the plants. Generating hydrogen by electrolysis and then immediately converting it to ammonia by the Haber process might be another. The production of ammonia for use in fertilizer using methane as the hydrogen source is a major green house gas contributor. There would be a significant advantage if we could move to carbon-free production.
- daurnimator 11y ago
  The usual candidate for this is aluminium smelters. They are extremely energy intensive: usually operators will only turn them on full when electricity is below e.g. $50 a MW. The have the added bonus that they can act as a temporary battery: you can smelt extra aluminium to use up the negative energy rates, but then let it convert back again.
  - phire 11y ago
    I thought aluminum smelters couldn't really shutdown production. I remember it was big news in New Zealand when Tiwai Point (which uses 15% of the power nation wide) shut down some of it's production during the 2008-2009 power shortage (caused by a drought in the hydro power lakes. Graph: https://upload.wikimedia.org/wikipedia/commons/e/e2/Electricity.NZ.TiwaiPoint.png https://upload.wikimedia.org/wikipedia/commons/e/e2/Electric... You can also see the other major drought in 1993.
    - NickNameNick 11y ago
      An unplanned, no warning shutdown of a smelter would be bad - it ruins the rather large and expensive carbon electrodes used to melt the aluminium. Probably not so good for the crucibles and other equipment that might get frozen up. Planned shutdowns are another matter entirely. In terms of instantaneous interruptible load, wood pulping mills are king. There are some enormous wood chippers in NZ's north island that can be remotely turned on and off by one of the generating companies. some marketing speak here. http://energyforindustry.co.nz/experience/interruptible-load-partnership/ http://energyforindustry.co.nz/experience/interruptible-load...
      - phire 11y ago
        Also, just about everyone's hot water cylinder in New Zealand is remote controlled by the power company (and has been since the 50's) Allows instant shedding of quite a lot of load in the short term without any visible impact to customers.
    - daurnimator 11y ago
      They can't just turn the whole plant off; but we were taught they can just be left with a trickle charge to keep them in liquid state. The large energy cost is in driving the reaction forward.
      - phire 11y ago
        Oh right, you can adjust the speed of the reaction throughout the day to adjust to market fluctuations.
- nl 11y ago
  Decentralised energy storage (home battery packs) is coming, and quicker than people think. It'll change the economics of this again.
  - ZeroGravitas 11y ago
    I consider home battery packs a much greater sign of market dysfunction than negative spot prices. Notably Tesla are targeting Hawaii and Australia as early markets. The grid should be distributing that energy at a fair market price, if it makes economic sense for an individual to avoid the grid for that service then there's probably an issue somewhere.
    - nl 11y ago
      What's the difference between market dysfunction and market disruption? It seems to me that home battery packs make things like wind power much more attractive because of their ability to smooth out the difference between supply and demand. I'm not sure why that is dysfunctional. It seems to me like it is compensating for a technical issue?
      - ZeroGravitas 11y ago
        It's dysfunctional because the balancing of supply and demand can be done cheaper and more effectively as part of the grid. But the grid operators often have poorly aligned incentives and so don't bother to do this. When looked at from a holistic view, the grid should pay much more for distributed solar production. If it was valued correctly then consumer battery storage would rarely, if ever, make economic sense. Hawaii have been refusing to allow more solar to be added to the grid, instead of investing on the network upgrades to make it work. Australia are charging high electricity prices for overbuilding the network and not properly valueing the contribution of solar. Various other places are trying to introduce punitive charges for domestic solar. It's good that consumer storage exists as it puts market pressure on these dysfunctional organisations, but decent regulation would have sorted this out properly with far greater efficiency.
    - skywhopper 11y ago
- IkmoIkmo 11y ago
  In Europe I feel most talk is still on connecting Norway to say Germany with new electricity lines to utilise Norway's natural pumped storage potential. Another interesting development recently was the creation of electric diesel. The economics don't seem to make a lot of sense yet but I don't think they've hit the efficiency limits of what is possible yet. The interesting thing is that it's carbon neutral (assuming the energy going into the process is carbon neutral, e.g. when excess renewable energy drives energy prices negative at moments of the day) probably works on a massive scale, and immediately allows existing fleets of combustion engines to become more sustainable. I'm not sure how fast these factories can turn on and off production but I'm assuming it's pretty good. The efficiency is pretty low, electricity to diesel I've heard of efficiencies of 13%. And then a diesel engine itself is only about 30% efficient, compared to electric engines of > 90%. It makes more sense to invest in storage solutions and an electric car fleet, but if we do get significant excess renewable energy that is difficult to store, combined with ediesel becoming more efficient, then it becomes an interesting idea. Particularly for all the transport that is hard to electrify (airplanes, trucks), carbon neutral synthetic fuel made with renewable electricity could make sense one day. I'm mostly optimistic about electrifying cars though. The next-gen top electric cars are getting close to ~100 kwh storage (today it's more like 80-90). Cars per capita in OECD countries is probably around 0.6 - 0.7 or so. That's a lot of storage if fully electrified, about 60-70 kwh per capita. Daily residential electricity usage is probably about 10 kwh in OECD countries. Of course that's when you electrify the entire car fleet which is a ridiculously big task (today's new car sales tend to be sub 1% electric), but if you can do 5% within a few decades, you can create multiple hours of storage which would be a huge impact on the ability to balance intermittent energy sources, without having to invest in storage for the sake of storage.
- twic 11y ago
  We do this in the UK: https://en.m.wikipedia.org/wiki/Dynamic_demand_(electric_power) https://en.m.wikipedia.org/wiki/Dynamic_demand_(electric_pow...
venomsnake 11y ago
While this is true, I have a feeling that wind averaged over a big land mass like US, Canada and Alaska will be a very close to constant. What we need is a better buffer system - here is where the supercaps, once developed could play a huge role. Or hydrogen/ fuel cells.
fulafel 11y ago
Though this evens out a lot when you have many farms with some distance between them. Many coal and nuclear plants are actually quite good at load following (at least in France and Germany it's common to run nukes in this mode). The units are quite big so they don't have to do that many % per hour in order to keep up with a wind park.
- Animats 11y ago
  "Though this evens out a lot when you have many farms with some distance between them." Unfortunately, it doesn't. The big grids such as CAISO (all of California, with wind farms over a range of 500 miles) and PJM (Ohio to the Atlantic Ocean) still routinely see 4:1 variations over the course of a day. Here's today's CAISO data: Max wind generation: 1350 MW, at 1 AM. Min wind generation: 186MW, at 5 PM.[1] This sucks. At least with solar, you get max output and max air conditioning load at the same time. Getting max wind generation at 1 AM is not too helpful. However, the California Water Project, which is a big power buyer for pumping water uphill, profitably buys late-night cheap power for pumping, then lets water back down through turbines during high-load periods. So some of the big reservoirs double as pumped storage. Batteries would help. It will take a lot of them. At least 300,000 Tesla Powerwall battery packs would be required to load balance that variation in wind. That's about a billion dollars, which is not unreasonable. When we see wind farms starting to buy batteries in bulk, it will be clear this is working. But the amount of battery required for reliability is higher than the amount required for improved profitability. Something has to be able to provide power when the wind is calm for a few days, which happens. [1] http://content.caiso.com/green/renewrpt/20150918_DailyRenewablesWatch.txt http://content.caiso.com/green/renewrpt/20150918_DailyRenewa...
  - ZeroGravitas 11y ago
    Variation and unpredictability are two different things. It varies by geography, but often wind is stronger at night and in the winter but that is different from minute by minute variation, which is what can be reduced by building lots of distributed wind farms. Solar, for example, could be said to have infinite variability since its not available at night, but its actually fairly predicatble if it is spread around geographically.
WalterBright 11y ago
This should change with electric cars. I'd love to have an electric car set up to recharge when the rates were low. This could really even out the power consumption. Heck, I can think of a lot of uses of power that become practical if the rates are really low. The hot water heater could be heated up a bit extra hot. Ice could be made to supplement the air conditioner during high electric cost times, etc. All that's needed is variable pricing to the consumer.
- kalleboo 11y ago
  Tesla also has its Powerwall which is practically begging for this use case http://www.teslamotors.com/powerwall http://www.teslamotors.com/powerwall
  - WalterBright 11y ago
    Yup. I seriously do not understand why electric utilities do not do variable pricing to consumers. Do it, and the 'problem' of electric surpluses will go away.
    - raverbashing 11y ago
      For home customers? There's usually some cost differences for night/day time (or winter/summer) depending on your contract Now, to have variable pricing for home customers I think the complexity outweighs the advantages (as in, limited capacity to enjoy momentarily cheaper prices)
      - ZeroGravitas 11y ago
        Usually how this is done is that you get a cheaper tariff and give up some level of control, e.g your air-con might be shut off for 5 mintues (along with 100 of your neighbours) to respond to a demand spike elsewhere.
        AnthonyMouse 11y ago
danbruc 11y ago
I have watched and read about this topic before and got the impression that it is essentially a solved problem with a prediction accuracy of better than 5 % and a time resolution of 15 minutes one day into the future. Is this not good enough? Are the prediction not actually that good?

curtis 11y ago

I'm inclined to think that wind will only work at bigger scales if we can find industrial processes that are dominated by energy costs rather than capital costs and which can scale up and down in energy consumption fast enough to track the wind output. I can think of a couple of possibilities. Water desalination is an obvious candidate. It might be economical to massively overbuild desalination plants and then only run them at peak capacity when wind is at peak as well. If the cost of electricity is much greater than the capital cost of the desalination plants, then it might be a net win when amortized over the lifetime of the plants. Generating hydrogen by electrolysis and then immediately converting it to ammonia by the Haber process might be another. The production of ammonia for use in fertilizer using methane as the hydrogen source is a major green house gas contributor. There would be a significant advantage if we could move to carbon-free production.

daurnimator 11y ago
The usual candidate for this is aluminium smelters. They are extremely energy intensive: usually operators will only turn them on full when electricity is below e.g. $50 a MW. The have the added bonus that they can act as a temporary battery: you can smelt extra aluminium to use up the negative energy rates, but then let it convert back again.
- phire 11y ago
  I thought aluminum smelters couldn't really shutdown production. I remember it was big news in New Zealand when Tiwai Point (which uses 15% of the power nation wide) shut down some of it's production during the 2008-2009 power shortage (caused by a drought in the hydro power lakes. Graph: https://upload.wikimedia.org/wikipedia/commons/e/e2/Electricity.NZ.TiwaiPoint.png https://upload.wikimedia.org/wikipedia/commons/e/e2/Electric... You can also see the other major drought in 1993.
  - NickNameNick 11y ago
    An unplanned, no warning shutdown of a smelter would be bad - it ruins the rather large and expensive carbon electrodes used to melt the aluminium. Probably not so good for the crucibles and other equipment that might get frozen up. Planned shutdowns are another matter entirely. In terms of instantaneous interruptible load, wood pulping mills are king. There are some enormous wood chippers in NZ's north island that can be remotely turned on and off by one of the generating companies. some marketing speak here. http://energyforindustry.co.nz/experience/interruptible-load-partnership/ http://energyforindustry.co.nz/experience/interruptible-load...
    - phire 11y ago
      Also, just about everyone's hot water cylinder in New Zealand is remote controlled by the power company (and has been since the 50's) Allows instant shedding of quite a lot of load in the short term without any visible impact to customers.
  - daurnimator 11y ago
    They can't just turn the whole plant off; but we were taught they can just be left with a trickle charge to keep them in liquid state. The large energy cost is in driving the reaction forward.
    - phire 11y ago
      Oh right, you can adjust the speed of the reaction throughout the day to adjust to market fluctuations.
nl 11y ago
Decentralised energy storage (home battery packs) is coming, and quicker than people think. It'll change the economics of this again.
- ZeroGravitas 11y ago
  I consider home battery packs a much greater sign of market dysfunction than negative spot prices. Notably Tesla are targeting Hawaii and Australia as early markets. The grid should be distributing that energy at a fair market price, if it makes economic sense for an individual to avoid the grid for that service then there's probably an issue somewhere.
  - nl 11y ago
    What's the difference between market dysfunction and market disruption? It seems to me that home battery packs make things like wind power much more attractive because of their ability to smooth out the difference between supply and demand. I'm not sure why that is dysfunctional. It seems to me like it is compensating for a technical issue?
    - ZeroGravitas 11y ago
      It's dysfunctional because the balancing of supply and demand can be done cheaper and more effectively as part of the grid. But the grid operators often have poorly aligned incentives and so don't bother to do this. When looked at from a holistic view, the grid should pay much more for distributed solar production. If it was valued correctly then consumer battery storage would rarely, if ever, make economic sense. Hawaii have been refusing to allow more solar to be added to the grid, instead of investing on the network upgrades to make it work. Australia are charging high electricity prices for overbuilding the network and not properly valueing the contribution of solar. Various other places are trying to introduce punitive charges for domestic solar. It's good that consumer storage exists as it puts market pressure on these dysfunctional organisations, but decent regulation would have sorted this out properly with far greater efficiency.
  - skywhopper 11y ago
IkmoIkmo 11y ago
In Europe I feel most talk is still on connecting Norway to say Germany with new electricity lines to utilise Norway's natural pumped storage potential. Another interesting development recently was the creation of electric diesel. The economics don't seem to make a lot of sense yet but I don't think they've hit the efficiency limits of what is possible yet. The interesting thing is that it's carbon neutral (assuming the energy going into the process is carbon neutral, e.g. when excess renewable energy drives energy prices negative at moments of the day) probably works on a massive scale, and immediately allows existing fleets of combustion engines to become more sustainable. I'm not sure how fast these factories can turn on and off production but I'm assuming it's pretty good. The efficiency is pretty low, electricity to diesel I've heard of efficiencies of 13%. And then a diesel engine itself is only about 30% efficient, compared to electric engines of > 90%. It makes more sense to invest in storage solutions and an electric car fleet, but if we do get significant excess renewable energy that is difficult to store, combined with ediesel becoming more efficient, then it becomes an interesting idea. Particularly for all the transport that is hard to electrify (airplanes, trucks), carbon neutral synthetic fuel made with renewable electricity could make sense one day. I'm mostly optimistic about electrifying cars though. The next-gen top electric cars are getting close to ~100 kwh storage (today it's more like 80-90). Cars per capita in OECD countries is probably around 0.6 - 0.7 or so. That's a lot of storage if fully electrified, about 60-70 kwh per capita. Daily residential electricity usage is probably about 10 kwh in OECD countries. Of course that's when you electrify the entire car fleet which is a ridiculously big task (today's new car sales tend to be sub 1% electric), but if you can do 5% within a few decades, you can create multiple hours of storage which would be a huge impact on the ability to balance intermittent energy sources, without having to invest in storage for the sake of storage.
twic 11y ago
We do this in the UK: https://en.m.wikipedia.org/wiki/Dynamic_demand_(electric_power) https://en.m.wikipedia.org/wiki/Dynamic_demand_(electric_pow...

venomsnake 11y ago

While this is true, I have a feeling that wind averaged over a big land mass like US, Canada and Alaska will be a very close to constant. What we need is a better buffer system - here is where the supercaps, once developed could play a huge role. Or hydrogen/ fuel cells.

fulafel 11y ago

Though this evens out a lot when you have many farms with some distance between them. Many coal and nuclear plants are actually quite good at load following (at least in France and Germany it's common to run nukes in this mode). The units are quite big so they don't have to do that many % per hour in order to keep up with a wind park.

Animats 11y ago
"Though this evens out a lot when you have many farms with some distance between them." Unfortunately, it doesn't. The big grids such as CAISO (all of California, with wind farms over a range of 500 miles) and PJM (Ohio to the Atlantic Ocean) still routinely see 4:1 variations over the course of a day. Here's today's CAISO data: Max wind generation: 1350 MW, at 1 AM. Min wind generation: 186MW, at 5 PM.[1] This sucks. At least with solar, you get max output and max air conditioning load at the same time. Getting max wind generation at 1 AM is not too helpful. However, the California Water Project, which is a big power buyer for pumping water uphill, profitably buys late-night cheap power for pumping, then lets water back down through turbines during high-load periods. So some of the big reservoirs double as pumped storage. Batteries would help. It will take a lot of them. At least 300,000 Tesla Powerwall battery packs would be required to load balance that variation in wind. That's about a billion dollars, which is not unreasonable. When we see wind farms starting to buy batteries in bulk, it will be clear this is working. But the amount of battery required for reliability is higher than the amount required for improved profitability. Something has to be able to provide power when the wind is calm for a few days, which happens. [1] http://content.caiso.com/green/renewrpt/20150918_DailyRenewablesWatch.txt http://content.caiso.com/green/renewrpt/20150918_DailyRenewa...
- ZeroGravitas 11y ago
  Variation and unpredictability are two different things. It varies by geography, but often wind is stronger at night and in the winter but that is different from minute by minute variation, which is what can be reduced by building lots of distributed wind farms. Solar, for example, could be said to have infinite variability since its not available at night, but its actually fairly predicatble if it is spread around geographically.

WalterBright 11y ago

This should change with electric cars. I'd love to have an electric car set up to recharge when the rates were low. This could really even out the power consumption. Heck, I can think of a lot of uses of power that become practical if the rates are really low. The hot water heater could be heated up a bit extra hot. Ice could be made to supplement the air conditioner during high electric cost times, etc. All that's needed is variable pricing to the consumer.

kalleboo 11y ago
Tesla also has its Powerwall which is practically begging for this use case http://www.teslamotors.com/powerwall http://www.teslamotors.com/powerwall
- WalterBright 11y ago
  Yup. I seriously do not understand why electric utilities do not do variable pricing to consumers. Do it, and the 'problem' of electric surpluses will go away.
  - raverbashing 11y ago
    For home customers? There's usually some cost differences for night/day time (or winter/summer) depending on your contract Now, to have variable pricing for home customers I think the complexity outweighs the advantages (as in, limited capacity to enjoy momentarily cheaper prices)
    - ZeroGravitas 11y ago
      Usually how this is done is that you get a cheaper tariff and give up some level of control, e.g your air-con might be shut off for 5 mintues (along with 100 of your neighbours) to respond to a demand spike elsewhere.
      - AnthonyMouse 11y ago

danbruc 11y ago

I have watched and read about this topic before and got the impression that it is essentially a solved problem with a prediction accuracy of better than 5 % and a time resolution of 15 minutes one day into the future. Is this not good enough? Are the prediction not actually that good?