From the American Institute of Physics
Using fluctuating wind power
Incorporating wind power into existing power grids is challenging because fluctuating wind speed and direction means turbines generate power inconsistently. Coupled with customers’ varying power demand, many wind-farm managers end up wasting power-generation capacity and limiting the service life of turbines through active control – including fully stopping turbines – in order to avoid any possible damage to the power grid from spikes in supply. In a paper published in the American Institute of Physics’ Journal of Renewable and Sustainable Energy, researchers propose a new strategy to optimize power-generation efficiency and so better control wind farms.
The new strategy is based on continuous predictions of how fluctuating winds affect each turbine’s maximum generation capacity. It also incorporates factors missing in other wind-farm control strategies, including differing power generation between turbines, actual fluctuations in power generation capacity, errors in prediction, communication disruptions preventing active control, and even turbines without the capacity for continuous active control. To demonstrate the feasibility of the new strategy, the researchers compared their predictions to raw data from a single wind turbine. The team then further refined their calculations and simulated a control operation with data from a wind farm of 33 turbines.
The results suggest that wind-farm managers can improve their power-generation efficiency with the new strategy. However, the researchers caution that before implementing the strategy, each wind-farm manager should adjust the underlying parameters – such as how often to adjust each turbine’s speed – based on local conditions.
Article: “An Active Power Control Strategy for Wind Farm Based on Predictions of Wind Turbine’s Maximum Generation Capacity,” is published in the Journal of Renewable and Sustainable Energy.
Link: http://jrse.aip.org/resource/1/jrsebh/v5/i1/p013121_s1
Authors: Dewei Liu (1), Jianbo Guo (1), Yuehui Huang (1), Weisheng Wang (1)
(1) China Electric Power Research Institute
Related articles
- Rethinking wind power – Harvard study shows it to be overestimated (wattsupwiththat.com)
- Research suggests scientists have overestimated capacity of wind farms to generate power (eurekalert.org)
- Protesters say turbines will disrupt migratory patterns of swans near Grand Bend (lfpress.com)
Greg said:
The other thing, as in my earlier comments, it that solar is generally inverse of wind.
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That may be true in some places, but it is utterly false for many others. As a previous poster said, blocking highs in winter in Europe can last for weeks, while the sky remains cloudy. In Australia, where I live, summer heatwaves and blasting westerly winds go together.
When I read the head post, my first thought was “You mean they don’t do this already? How primitive are these operators, and why are they allowed anywhere near our precious power grids?” Imagine the outcry if a conventional power station was fired up and then everyone went home and just let it rip, irrespective of real demand and fluctuating outputs if something went wrong. That is pretty much what wind power does.
Friends:
I would appreciate an explanation of why anybody would want windfarms in the absence of subsidies.
Wind farms exist to farm subsidies. They have no other purpose.
They are expensive, polluting environmentally damaging bird swatters that cover the countryside in concrete for their foundations and roads to access them. And they produce no useful electricity at any time: they merely displace thermal power stations onto reduced output – which increases their fuel requirements and emissions – when the wind is sufficiently strong but not too strong for the windfarms to operate.
(There may be some who fail to understand why producing less power increases fuel consumption by power stations. This is because a power station has an optimum efficiency. Reducing its output a little reduces its efficiency a lot, so it uses more fuel to generate less power. The effect is similar to driving a car at 5 mph in fifth gear: it can be done but it uses a lot of fuel.)
Indeed, as the above article says, the electricity from windfarms is worse than useless because it disrupts the grid when it forces thermal power stations to operate less efficiently by reducing their output.
In this thread, several people have suggested energy storage to reduce the problems of the intermittent supply from windfarms. There is no such storage system and if it existed then it would be used whether or not there were windfarms because it would reduce the need for power stations by about a third.
Demand for electricity varies from hour to hour, day to day, and month to month. Power stations take days to start-up from cold so they all operate continuously but vary their output to match demand. Pumped storage is inefficient and expensive but is cost effective because it removes the need to operate some power stations solely to meet the few hours of peak demand each day. Adequate energy storage would enable almost all power stations to continuously operate at optimum efficiency and so fewer power stations would be needed. But no such system exists.
There are several problems of large energy storage. Fuels are stores of energy and they are useful because they concentrate much energy in small volume and release it in a controllable manner and at a relatively safe rate. For example, gelignite stores less chemical energy than coal, but burning a kilo of each of them has different effect because gelignite burns much faster than coal.
Flywheels store mechanical energy. If flywheels were used to smooth the output from power stations then I would not want to risk getting within 10 miles of them for fear of one coming loose.
So, my question is, why would anybody want windfarms in the absence of subsidies?
Richard
Please help stop the slaughter of birds and bats!
Peter says: March 25, 2013 at 3:12 pm
Put a baby thorium reactor at each site. Cant thorium can be ramped up and down or turned off quickly unlike plutonium?
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There are no Thorium reactors except for a few research units, and conventional reactors burn mostly Uranium. Plutonium is bred in Uranium reactors, then burned to produce about 20% of the power. Plutonium is also sometimes added to the fuel mix to use up Cold War bomb materials. As for the throttleability, conventional reactors can drop to 1% power in a few minutes, but why would the operator do that? Operating them is cheap, with fuel costs at about $.015 per KWHr. The costs are mostly in building them and the administration paperwork is the same regardless of how much power is generated.
What happened in Fukushima was that they dropped the power to 1% before the tsunami hit, but that 1% was still enough to destroy the core without pumped coolant. The grid was washed away and they needed backup diesel power to run the pumps. But the diesels were drowned too. They designed for a 5m tsunami (the hundred year maximum) and got a 12m one (the thousand year maximum). New plants will get at least some of the diesels on high ground.
I have way to make all large wind turbines 20 to 50% more efficient and produce power all the time at a consistent rate.. Hint, turbines would never need brakes again and all extra energy is stored to turn gen motor when wind is calm, no batteries. I have been testing it for 3 years and it works. Patent time . I am on twitter
We’re not to the point yet where we can determine within minutes where a thunderstorm outflow boundary will form … we’re not that good yet. Still reactive (rolling with the punches), not proactive (anticipating the punches), at that point.
Heck, NOAA’s SPC (Storm Prediction Center) missed (completely blew) a ‘call’ regarding storm initiation made in a Mesoscale Discussion just this last weekend … nothing formed-up as anticipated. And there is the uncertainty as to WHEN T-storms initiate along the West Texas dryline in the spring even; grasp this fact – forecasting is an inexact ‘science’.
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Rob Potter and DirkH both challenge the viability of pumped storage to even out wind’s variability based on the total volume of pumped water that would be necessary. Thank you. That is the kind of informed criticism that I have come to appreciate on this site. That said, I suspect that you may be underestimating the volume already in place. Wikipedia has a fairly extensive “List of pumped-storage hydroelectric power stations” with greater than 1 GW.capacity. Many are newly constructed or still in construction, suggesting that at least some bond holders consider it a good investment.
The MacKay article is illuminating (withouthotair.com). He does calculate that the needed pumped storage capacity for the UK is “a lot” (1200 GW-hours to be precise) but he does not assume that any one solution (like pumped storage) must be the only solution.
But maybe it is infeasible for an island like the UK. MacKay does, after all, assume that the worst reasonable case is a UK-scale blocking system that shuts down all wind generation for a five-day lull. That does not necessarily make it an infeasible solution for the US with its larger, interconnected electrical grid, unlikely to be simultaneously blocked by any one weather pattern. I don’t know that it’s the right answer but it is an intriguing thought.
China Datang Corp. Renewable Power Co. (1798), a state-owned wind-energy developer, said 2012 profit declined 85 percent as slower first-quarter wind speeds and “grid curtailment” in some regions reduced power generated
Net income fell to 112.1 million yuan ($18 million) from 729.8 million yuan in 2011. China’s electricity grids are unable to absorb the influx of wind power, forcing the government to tighten approvals on new projects and slow the development of the industry. Installations of wind turbines in China fell 18 percent to 15.9 gigawatts last year from 2011, according to data compiled by Bloomberg New Energy Finance.
http://www.businessweek.com/news/2013-03-22/datang-renewables-profit-falls-on-intensified-grid-congestion
I went by a windmill farm near Blackwell, OK last week. It wasn’t producing enough electricity to light the red warning beacons on the tops of the windmills. This in windy Oklahoma in March.
A question I’ve never seen addressed. How are we going to rid the landscape of the huge concrete bases when these windmills are removed? I think the installers of these windmills ought to have to set up an escrow fund for their ultimate removal.
http://canadafreepress.com/index.php/article/53864
The bird mortality disaster must no longer be hidden
Not only has the wind industry never solved its environmental problem. It has been hiding at least 90% of this slaughter for decades. In fact, the universal problem of hiding bird (and bat) mortality goes from bad to intolerable beyond the Altamont Pass boundaries, because studies in other areas across North America are far less rigorous, or even nonexistent, and many new turbines are sited in prime bird and bat habitats.
The real death toll, as reported by Paul Driessen and others, is thousands of raptors a year – and up to 39 million birds and bats of all species annually in the United States alone, year after year! This is intolerable, and unsustainable. It is leading to the inevitable extinction of many species, at least in many habitats, and perhaps in the entire Lower 48 States.
Henry Clark says:
March 25, 2013 at 12:49 pm
Wind and solar simply don’t scale up very well. Sometimes for non-obvious reasons. Sure, go ahead and use it for your cabin or suburban ranchette. You would have to put thousands of > 1 MW turbines offshore to get the wind speeds and the numbers needed to put a dent in our power needs. That’s not gonna happen.
What the California Energy Commission want is political power. They pretend they are helping people, educating us, and protecting the environment. They are effectively producing just the opposite. What an evil thing Jerry the Gov did to California.
Why are celebrities not speaking out against the windmill slaughter of birds? Write your favorite celeb. A new opportunity for them to get in front of the cameras. An area that so far is wide open.
Greg says:
March 25, 2013 at 1:28 pm
However, stopping to look at the facts posted in that article one can see that the data posted by whatever the power authority down there is called, one finds that the sum of wind and solar was almost constant.
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zero is a constant.
Robert F wrote;
“However, the main problem, economical storage of surplus energy, remains unsolved.”
Well, back in the old days we used to pile up coal outside the power plant, or build lots of oil tanks. Sure seemed like “economical storage of surplus energy”, just put it “over there” until we need it.
Too simple I guess, the hardest part of “optimizing” a coal (or wood) pile is getting the bank angle right so it stays where you put it, must be a computer model around someplace for that.
Cheers, Kevin.
Leo Geiger says March 25, 2013 at 3:35 pm
Weather can be forecast.
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So far, weather forecasting is moderately successful when predicting the past, though there does appear to be a rather large number of adjustments necessary after the fact to make corrections. I believe these corrections are called climate science. It hardly seems possible they can do a good job predicting the future when they need to make so many corrections to the past.
If they were wrong in the past isn’t it more likely they will be wrong in the future? It is almost as if every time the experts say temperatures will go up they go down instead, and every time they same they will go down, the temperatures go up. Almost as if after years of schooling, having facts pounded into their heads, these climate scientists are in fact suffering from the global numbskull effect.
Mike Borgelt says:
March 25, 2013 at 4:09 pm
The historical fact that sails were abandoned for even the very poor early steam engines for marine transport tells you all you need to know about wind power. Works fine on sailboats for fun, nothing serious.
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anyone that says the wind is free hasn’t bought a new sail.
the sails and rig on a sailboat cost about as much as a diesel engine and fuel for 20 years of travel. only the diesel is way more reliable. the only valid technical reason to have sails is that in a small boat you cannot carry enough fuel to cross oceans. (due to the relationship between length and volume).
The solution where ever the government pays a feed in tariff, is to install a diesel genet in the tower base, generate electricity as cheaply as possible and sell it to the grid at the inflated mandated rate.
If your criminal associates can boost a few tankers of fuel you can clean up big and if the utility ever checks, you can be gone in no time.
And the utility company is forced to pay you, until they can prove you are a criminal.
I have to love bureaucratic wisdom.
Hope they’re engineered better that this FAIL one – from today’s Irish Times: http://www.irishtimes.com/news/farmers-badly-hit-by-harsh-weather-in-north-1.1338654
crosspatch says:
March 25, 2013 at 2:44 pm
I have a different idea that actually takes advantage of fluctuating supply.
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I love this idea. It’s actually brilliant. We have a cloud based technology that can do just that. But the system is not in place to take advantage of this idea. In Canada, people have their own generators that the grid is forced to pay a fluctuating price for. When the price differential is profitable based on gas prices, people turn their generators on to the grid and make money.
Our technology can monitor these price deltas and decide when to turn on the generators to supply the grid with profitable (for the small gas generators) energy.
Our controls are about 1/10 the cost of traditional SCADA, so they can make sense easily.
We are using our technology now for small water districts to control local operations. We measure pump energy consumed, water flow and know which pumps are most efficient at moving water. As well, we know the storage and demand capacity in real time. So we can time pumping to avoid peak energy prices (fill the gravity tanks just before rates change) and use the least cost energy and most efficient pumps to move most of the water. We can displace several hundred thousand dollar SCADA systems for $15k to $20k… We also do alarming and all the goodies so we catch leaks and problems before they are costly.
Here’s how to get power from wind turbines when there’s no wind. Equip each one with a winch and a heavy weight on a cable. When the wind blows, wind up the cable then lock the winch, storing potential energy in the weight. Once the weight is up, the blades turn the generator.
When the wind stops, loose (not lose) the winch so as the weight drops it turns the generator. Apply gearing as needed to make the drop last a while. The whole works could be inside those big, hollow towers.
Makes as much sense as attempting to rely on inconstant wind for an energy source.
In Norway, an experiment on the island of Utsira involved the mating of a modest wind turbine with a hydrogen generator in order to smooth the relationship between supply and demand.
http://www.iphe.net/docs/Meetings/Brazil_3-05/Norway_Utsira_Wind_H2.pdf
http://www.statoil.com/en/NewsAndMedia/Multimedia/features/Pages/HydrogenSociety.aspx
Started in 2004, this was something of a poster child for clean, green rainbow power, but the fact that the trial has quietly slipped into obscurity and not been repeated or scaled up probably speaks volumes on the practical and economic success of the project (despite the technical success claimed of the project)
Interestingly, one of the challenges was the inefficiency of the H2 fuel cell generator and despite the modelling indicating that the island should be self sufficient, protracted periods without wind still required the provision of connection with the national grid or diesel generator for the ten households that participated.
Still, a more proactive attempt at practically smoothing out the intermittent supply of wind energy than a ‘…strategy based on continuous predictions of how fluctuating winds affect each turbine’s maximum generation capacity…’ which just sounds like more of the usual hot air we’ve all come to expect from the champions and benefactors of the cause.
Ira Glickstein said “The solution is to erect electrically-powered fans at all wind farms such that they can be turned on when there is not sufficient natural wind…. Power those fans by connecting them to the output of remote wind farms that do have sufficient wind”.
I assume – hope – you were joking. The increased energy obtained from the windmills (resulting from the remotely driven fans) can’t be greater than the energy supplied to the fans – otherwise you would just be postulating a large scale perpetual motion machine in breach of the first law. So, the combined output of (a) the farm with insufficient natural wind plus (b) the remote farm supplying energy to the fan would be less overall, resulting from transmission losses in “connecting them to the output of remote wind farms”.
And most of the world doesn’t yet have wide-area grids – or (come to that) any reliable electricity supply at all.
I observe that nobody has offered any answer to the question I posed (with explanation) at March 25, 2013 at 4:45 pm .
I remind that it is
“why would anybody want windfarms in the absence of subsidies?”
I think the lack of any attempt at an answer is informative.
Richard
It is being installed in California. The so-called “smart meters” are directly wired to the utility via a private internet connection and are capable of doing fine resolution billing. All that is required is to make the charging controller aware of the current cost of electricity from the grid. The idea is rather than having a bunch of regulations, you simply use free market solutions so that you price the product according to current supply and allow the market to take up excess capacity when it is available through purchasing more of it when it is cheap. Software managing the charging controller could allow the rate payer a lot of options including keeping electricity cost below a certain amount, aggressively attempting the cheapest power cost possible, etc. And the home storage system could be expanded as needed through rather easy to install storage modules. If the system knows, for example, that power generated by natural gas would be cheaper than grid power at the moment and the system is getting low on power (hot day, need the air conditioning, grid is stressed, there is no wind, grid price is jacked up to conserve power) it could automatically run the natural gas generator to provide power to the system, if available. The system could also be tied in to the local on-site solar or wind or any other source of generation if any is available, too.
The notion is to basically take the opposite approach than what most bureaucrats generally think of first. Rather than attempt to manage individual behavior through various decrees, you minimize waste and maximize efficiency by making the “hooks” available for people to purchase power on demand-based pricing and allow the market to respond to that.
As for buffering you would do well to build a thousand mile pipeline from the Dakotas to Texas to accomodate hydrogen from the electrolysis of water. The pipeline would be fed hydrogen from all adjacent wind farms along the route. Utilities would consume the hydrogen by supplying fuel cell electricity to the grid on a nearly constant rate matched closely to the total hydrogen production rate.
In this way the huge buffering capacity of 1500 psi of compressed hydrogen nearly makes up for the entire massive instability of the windfarm output. The initial cost is high, but the running cost is very low though the running cost of the electricity produced would probably be about 2x higher than the average cost today. The advantage of hydrogen is that consumers of hydrogen could tap the line for fertilizer production, etc.
The obvious, and much simpler alternative, would just be to use the pipeline to store compressed air and bleed it off through cold turbines to produce constant power.
Either way the highly intermittent power of a windfarm is reduced to almost a non-variable to the grid.