The actual operation of an electric grid is a delicate balancing act between supply and demand.
-- the grid needs to respond in real-time to changes in supply/demand (weather induced outages, Germany using your grid as an energy sink)
-- the grid needs to respond to daily fluctuations (day/night cycles, cold day, warm day, etc)
-- the grid needs to respond to medium-term fluctions (scheduled maintenance on plants and infrastructure, seasonal variations, price of coal, natural-gas, oil, etc)
-- the grid needs to respond to long-term fluctuations (new infrastructure, recessions, regional economic growth or decline, technological changes, etc.)
On top of all this, governments can change the regulatory environment on a whim thus invalidating many decisions made with previous assumptions.
Back to the original article, wind energy is particularlly problematic for the grid because its output is highly variable, not predictable in the short-term, can not be economically stored except in specialized cases, and is rife with government-induced market distortions that are also not all that predictable in the medium and long term.
The real problem here is that the Europe's and specifically Germany's grid is not designed to handle the huge variations imposed my plants using renewable energy. It was designed with nuclear, coal and gas power plants in mind that create relatively constant and easily predictable amounts of energy.
This hasn't really been a problem before but with real interest and focus on that problem it will surely be solved and will eventually be small footnote as a short term problem we once had on the way to a future in which we will produce energy solely from renewable sources.
The fact that Germany is producing more energy than it knows what to do with is actually good news as it shows that the Energiewende is working.
Right on: this is an exciting opportunity for grid management. A number of transitions will have to occur: movement toward more peaky-capable baseload generation, probably through natural gas turbines, movement toward storage etc.
At the very least it's surprising they aren't pumping water uphill, or just shutting down hydro throughput, in these time periods. Or perhaps Europe's system of hydro electric dams isn't large enough.
Northern Germany like the Netherlands consists entirely of flat land, so there are no hills to pump water up. Further more such solutions require a river relatively close to the hill that runs with enough water that the pumps have enough work to do and that can easily handle the water when you drain it.
Even so such plants are used in the Middle and South of Germany where hills and mountains exists but you have to get the energy there and Poland is closer.
Germany has a unified grid, I'm sure. We need to remember how small Germany is: smaller than California, for example and California relies on everything hydro from the Pacific Northwest all the way down to mountain western state coal. In anticipation of hot days the Pacific Northwest actually stops water flow on river dams to allow them to peak at high price points.
There is probably a middle point here tho: Europe may have proportionally less hydro available. In fact it looks like Germany now has more wind capacity than hydro (something no where near achieved in California) so you're right: they might not be able to make it up that way.
The article seemed to indicate that this is not the case, and that until the south and north parts of the grid are well-connected domestically, excess power from the north gets routed south via Poland and the Czech Republic.
one more problem is that mainland Denmark is well connected to Germany and not to Jylland, which is connected to Scandinavia. Scandinavia has mountains and operates th Nordpool market.
A HVDC network going from north african deserts to norwegian n mountains could solve some problems.
Also, about the German grid: http://lehre.umweltpruefung.tu-berlin.de/mw/index.php?title=.... Germany has less need to distribute power east-west because, if there is wind in the Northwest, there will likely be wind in the northeast, too, but there, statistically, will be less sun in the south. Similarly, having sun in the south correlates with less wind in the north.
Southern Germany gets part of it peak loads from Austrian pumped water reservoirs. But this does not solve the problem, as the energy trade between Austria and Germany is hampered by insufficient transmission capacity between the two countries, causing the neigbouring countries networks to take the load.
In other words, it exacerbates the problem rather than fix it.
(another reply explained why this isn't easily done within Germany: Lack of suitable potential reservoirs)
It's like the writer doesn't know that windmills can be stopped. In fact, they have builtin brakes which autoengage and stops the mill when the wind becomes too powerful.
Reading on, the problem seems to be not really specific to the windmills themselves, but to the fact that Germany is transmitting a lot of power from the North (where the windmills are) to the South (where the industry is). There is also a lot of transfer between Austria and Germany going on (with Austria's hydroelectric pumped-storage power stations essentially serving as batteries), and the Czech's are unhappy that their grid is used for this transmission for free.
You cannot just build more pumped-storage hydroelectric power plants, you need mountains or at least hills, that fit certain parameters and in the places you can build them you will already find them.
Northern Germany probably doesn't have a single such plant but Northern Germany also doesn't have a single mountain, hill or anything higher than a tree as far as the eye can see.
You will find those plants in Southern Germany and Austria but then again they do actually have places to put them.
Besides stopping the windmills or installing plants is not the problem. The problem is that the German grid can't deal with the energy produced in Germany and uses neighboring grids that are not designed to handle that much load.
If the power companies stop running the windmills, they don't get any money.
>Wind farms in West Texas earlier this year were paying utilities to use their electricity on particularly gusty days because they can still earn $22 a megawatt-hour in federal tax credits
Starting next year there will be an extra management bonus in Germany if the wind park is remote controllable. (There are two ways to sell wind energy in Germany, just sell it as it is produced (fixed feed-in-tariffs, EEG) or trade it. In the latter case it makes sense to stop your wind park as prices become negative.)
The issue is not that they can't be stopped, but that it is not in Germanys interest to stop them. They need the energy, just not in the North where it is produced. They just don't have the North-South transmission capacity, and so the energy flows through neighbouring countries and put their neighbours networks at risk.
As long as their neighbours let them, it's vastly cheaper for Germany to keep this going than to speed up the upgrades of their own transmission capacity.
You are correct, but the problem is tuning the production from wind farms to match demand exactly, in real time, which is what is required to operate the grid. When it comes to renewable energy wind is the hardest in this regard, because production can fluctuate rapidly in very short time scales, especially when there's gusting.
all modern wind turbines have variable incidence blades meaning power regulation can happen on a second timescale.
I'm not exactly sure about the electrical machinery, but if that is sophisticated enough, it can be used in high accuracy fashion to control the generation so that the electeicity is produced in high quality.
You can think of the wind plant working as a giant flywheel. If there is a sudden gust, the spin speed increases and the extra speed is gradually harvested as energy. No sudden spikes. In theory the plants could be used to improve the frequency quality even more by also acting as motors.
If there is a real wind powef power electrical engineer around, feel free to chime in.
i'm sure you're correct. i actually don't know the nitty-gritty technical details. i only know wind from a policy perspective. any power source imposes costs on the grid (transmission congestion, ramp rates, supply/demand mismatches, active/reactive power, etc.) and wind is considered almost pathological in every dimension - but i'm sure it's all solvable.
Did you even read the article? It is about failures in grid construction and of failures to construct proper trading areas (resulting in chokepoints in the grid).
One thing that everybody forget is that with agreement with the main power producers in Germany, the government of Gerhard Schröder (10 years ago) started the plan to built the network to link North Germany to the South for renewable energy production together with the agreed shutdown of the nuclear powerplants in 2020. Once the left/green government was replaced with the current one, the big power producers did a nice lobbying not to shutdown the powerplants and thus delayed the building of the network. But the laws to develop renewable energies (and the subsidies going with) were not changed. Thus, we ended up with a lot of individuals, small and medium companies building small "power plants" with wind and solar energy. A lot was done in the North because of good winds combined with cheap land. End result, power imbalance.
Also, the power network is still very "former East - former West" built, which is not helping. We had 3 years ago a blackout of the West while the East (which includes the part with most of the windmills) was still up.
At the end, the problem is mainly because of the delayed investment from the network operators and they are now affected by their own unwillingness to build the network. From a financial point of view, it is easy to understand because they are mainly coal/gas/nuclear producers and they would have had to build a network which would then be used by their competitors...
> Also, the power network is still very "former East - former West" built, which is not helping. We had 3 years ago a blackout of the West while the East (which includes the part with most of the windmills) was still up.
You're right that the former east has its "own" grid operator [1], but there is much more installed wind power in the north west[2].
Bitcoin mining perhaps? If I recall, after the initial hardware investment, electricity cost is the main variable to a successful mining operation. Reduce that cost to $0 and it suddenly becomes significantly more appealing...
This is not uncommon with other forms of generation with high capital cost and low production opportunity costs. The Netherlands almost managed to melt the Belgian high power grid importing very cheap French power a few years back. The French nuclear power plants would produce anyway even if they only made a single cent as one cent is better than no cent ;) Windmills owners have the same issue, once build cost of energy production is near zero so sell what you make for what ever the market will pay. Gas, oil and coal stop producing the moment the fuel becomes more expensive than the worth of the produced energy (bound by shut down and start up times).
I expect the same solution. More transmission capability or charging more and fixing the market issue. This really is a market issue in that the east europeans don't charge enough for transmission costs to stop the Germans from doing.
Production variation is a problem but not such a big one as price volatility and consumer (demand) volatility. i.e. power demands at peak times. i.e. when everyone wakes up and turns on their coffee machine etc...
Large (esp. direct drive) windfarms are actually good at dealing with the demand volatility as they can spin up and down in minutes. While weather volatility is in the hours. Same day weather forecast is very good. So inside a grid windfarms are nice. Its when transmitting outside the grid like nuclear they can be mean to other producers.
It is actually very interesting to look at different power plants' startup price thresholds. Nukes and wind are always on, as they cost littleöto keep "on". Hydro depends on time of year, reservoir size etc. Coal is kind of in the middle. If you use the waste heat for district heating in the winter, the logic changes. Natural gas is the last thing turned on. The plants are really cheap to build but gas costs a lot. Depends if you have a deal with Russia. It is an interesting and multifaceted field.
Theres gunna be big money to the company that can figure out how to store huge masses of energy for months, but no doubt thats decades away.
However, is there a more simple solution to this problem, like approaching an industry that already uses masses of energy and seeing if they can encourage them to use the energy when there is overloading? I'm unsure what that industry would be.
Surely using an overabundance of energy is a solvable problem? It seems bizarre to me that it wouldnt be.
There was a successful experiment doing something very similar to this - although I can't find the article - with cold storage facilities in the Netherlands.
Cold storage is apparently a pretty big industry there, and all those buildings are designed to be highly thermally-efficient anyways. There's also a huge segment of the cold storage market where the exact temperature of the storage doesn't matter, it just needs to stay within a specific band.
So what happened? The experiment (which was successful) effectively turned the freezers into batteries. The control systems were set to lower the temperature to two or three degrees lower than usual during the night (which made the cooling plants run longer then), and the plants were scaled back to maintenance power-levels during the day, when demand was higher. The grid was happy, since it moved the load to a low-usage time. The storage owners were happy, since they got a deal on the evening electricity. And the things being stored didn't care, since they were all so far frozen anyways. I wonder if you could do a similar program to get them to cool down further when there's excess power on the grid?
Or to solve this at an earlier point, why not just turn off the windmills when the power's not needed. All the windmills in my community have setting that when the wind is too high, the blades on the windmills pivot to the zero lift axis, and they don't spin.
Or to solve this at an earlier point, why not just turn off the windmills when the power's not needed.
Because the subsidies in Germany are tied to the amount of
electricity sold. That's why they're selling even at negative market price -- to collect the feed-in tariff.
There's a great sci-fi novel, The Windup Girl by Paolo Bacigalupi, set in a post-oil world where tightly wound springs are used to store energy, as we do now with clocks. One of the subplots deals with a character trying to develop a material that can be wound tighter and more compactly without breaking. Or explosively unwinding. I'm not an engineer or physicist, so I've wondered, what is the theoretical limit for storing energy in a spring. Sci-fi stories usually do a bit of handwaving with nano/bio/quantum-tech to make magic materials, but what is the real science? Cars and laptops powered by springs sounds plausible (and awesomely steam punk) to me.
what is the theoretical limit for storing energy in a spring.
I spring is a material (usually a metal, but could be a plastic as well) that is under stress, typically tension, torsion or compression (depending on type of spring). The limit is basically the yield strength of the material, which is the point where the stress vs strain curve goes nonlinear and the material begins to plastically deform. Obviously the fracture limit represents catastrophic failure of the material, but that is higher than the yield limit.
Basically, it's a material strength and elasticity problem.
The Windup Girl was a good novel but its science was poor, at least when it came to energy. The posited system of generating energy by using large animals to wind up springs is completely ridiculous, even in the semi-post-apocalyptic, heavily bio-engineered future it's set in.
Mechanical storage has safety issues when it's used for transport. Unlike gasoline (in real life, not movies) mechanical storage does tend to release all its energy at once in a crash.
This is also one of the main environmental premises behind electric vehicles. They charge themselves overnight, soaking up excess baseload power that is producing emissions but is not really going to productive uses. That is, the power they consume is not "additional", or just marginally so. Then during the day many of them will also be plugged in and they could serve as a distributed "soak or supply" asset for the grid.
Producing electricity from heat is a high loss operation. Storing heat is only logical when the source energy is heat. This is what wikipedia means by 1% loss per year. Meanwhile kinetic storage has no loss over time. As a bonus converting kinetic energy to electricity is rather efficient. So far Pumped-storage hydroelectricity is our best method for large scale electricity-to-electricity storage.
Yes, the problem is solvable - improve the grid so that too much energy in one place can be distributed around to where it is needed.
The simplest way to achieve that is probably reasonably sized energy trading areas - that will make the cost for transporting the energy baked into the price in a much better way that how it works in big unified trading area.
American Superconductors has a rig to help solve these problems, it is expensive (probably more expensive than off-loading the excess to unwilling neighbours) but it works.
From a description I once read (but can't seem to locate right now) these devices store excess power for short periods in superconducting coils to release the power again when the consumption side needs it. That way both the grid and the windfarms are matched better to each others needs and capabilities.
That's your problem? Too much energy? Why not create some buffers of sorts - wind energy CAN be stored, you can use it to charge battery banks, extract hydrogen, or even compress air or gas for later use. Obviously, it's not that easy, but it's doable.
By the way, all the wind turbines I've seen can rotate their blades 90deg, so they come to an almost full stop if/when necessary.
The actual "problem" is that Germany has pushed things to the breaking point by waiting too long by upgrading their transmission capacity as their generation ability in the North has increased, because they've so far been able to get away with relying on excess transmission capacity from their neighbours.
It's easily fixable in any number of ways. It's a matter of political will (and cost - both investments and potentially in buying their way out of short term obligations to prevent problems this winter), mostly.
They just haven't got large scale systems designed and installed for storing power.
Its not impossible. It just wasn't a requirement before so there hasn't been a lot of focus. There are technologies out there right now that would probably work ok. If not, energy storage just needs more focus.
I wrote an essay about the requirement for energy storage last month (https://46bit.com/blog/2012/09/23/why-we-use-fossil-fuels/). It's interesting to see how interconnected countries struggle without it now, although that's not quite the story here.
I wouldn't call that a good thing. You generally can't turn off/on a coal plant in a hurry. What they're probably doing is just braking the turbines and still burning some fuel.
(Edited, realised it sounded confrontational to begin with.)
This is correct. In addition there are a number of other ways that grid operators can displace power. This has happened a few times before in Western Europe, and prices have even gone below zero, incentivizing industrial facilities to do things like turn up their refrigerators to soak power
You generally leave the baseload (coal + nuclear) on, and shut down "peaking" capacity, which is, at least in the US, mainly natural gas. Coal is more expensive to build, more expensive to turn on, and cheaper to operate. Nat Gas is cheaper to build, cheaper to turn on, and more expensive to operate
I know you're speaking from the power plant's perspective, but factoring in externalities, natural gas is cheaper to operate than coal. Nuclear is really cheaper. Wind is about the same as coal.
Not really. There are debates about his much, but with regard to coal specifically, it's so bad you can ignore things like global warming entirely and it still comes out more expensive.
It'd be cool to combine wind turbines and pumped storage. Have the windmills simply lift water into a tank at the top. Drain the water out of the tank to produce the power. This would act as a nice buffer, producing constant power whatever the wind.
this seems more like a political problem than a tevhnocal one. Make transmission costs visoble and let the checks, slovaks and poles trade in the austro-german market.
The actual operation of an electric grid is a delicate balancing act between supply and demand.
On top of all this, governments can change the regulatory environment on a whim thus invalidating many decisions made with previous assumptions.Back to the original article, wind energy is particularlly problematic for the grid because its output is highly variable, not predictable in the short-term, can not be economically stored except in specialized cases, and is rife with government-induced market distortions that are also not all that predictable in the medium and long term.