More on Wind
I was having a back and forth with a reader about wind power and how much fossil fuel capacity must be kept on standby to support grid reliability with wind. Here are some excerpts of what I wrote:
Forget all of the studies for a moment. I used to operate power plants. Any traditional capacity (fossil fuel, nuclear) except perhaps gas turbines takes on the order of a day or more to start up - if you don't take that long, the thermal stresses alone will blow the whole place up. During the whole startup and shutdown, and through any "standby" time, the plant is burning fuel. Since we don't have a good wind energy storage system, some percentage of wind capacity must be backed up with hot standby, because it can disappear in an instant. We are learning now, contrary to earlier assumptions, that wind speeds can be correlated pretty highly over wide geographies, meaning that spreading the wind turbines out does not necessarily do a lot to reduce the standby needs. And since plant startups take time, even gas turbines take some time to get running, the percentage of wind power that required hot backup is pretty high -- I would love to find this percentage.
I found at least one source for such a percentage, which posits that for England, the percentage of hot backup needed is as high as 80%: http://www.ref.org.uk/Files/ref.for.decc.28.10.09.i.pdf
I quote from page 6-7:
On any view, including the square root rule of thumb referred to above, the result, imposed for purposes of maintaining adequate response and reserve requirements, implies that a high degree of conventional (dispatchable) plant capacity is retained in the system to support wind generation. Thus, for 25 GW of installed wind capacity only 5 GW of conventional plant can be replaced leaving 20 GW in the role of standby capacity (also known as "Spare" or "Shadow Capacity").3
So 80% of the expected production from wind has to be backed up with hot spares burning fossil fuels. They go on to say that the percentage of required spare capacity may be lower if the grid area is substantially larger, but not a lot lower. I had not considered hydro power, but apparently that can be used to provide some quick response to wind production changes. The report also talks about diesel generators for standby since they can be started up quickly, but these are seriously inefficient devices. Despite the report's conclusion that the situation might be a bit better on the continent with a larger and more diverse grid, a report of the largest German utility seems to argue that German experience may actually be worse:
As wind power capacity rises, the lower availability of the wind farms determines the reliability of the system as a whole to an ever increasing extent. Consequently the greater reliability of traditional power stations becomes increasingly eclipsed.
As a result, the relative contribution of wind power to the guaranteed capacity of our supply system up to the year 2020 will fall continuously to around 4% (FIGURE 7). In concrete terms, this means that in 2020, with a forecast wind power capacity of over 48,000MW (Source: dena grid study), 2,000MW of traditional power production can be replaced by these wind farms.
It is hard to tell, because 48,000 MW is the nameplate capacity which is virtually meaningless, but my guess is that they are not doing better than 80%.
Colin:
Some problems with wind power also identified in this Thursday NYT article:
http://www.nytimes.com/2010/03/05/business/05solar.html
Spain, which generates more than 12 percent of its electricity from wind, has struggled with wind variability, Mr. Lave said. Similar problems are also cropping up in the United States, especially in states where solar and wind power are on the rise. In 2008, for example, Texas narrowly avoided a blackout when wind power, which supplied 5 percent of demand at the time, experienced an unexpected lull, driving wind electricity generation down to 350 megawatts, from 2,000 megawatts, in less than four hours, according to Mr. Lave.
March 6, 2010, 7:37 ammostly cajun:
As a person who's spent over thirty years getting intimate with electrical power, your assessment is correct.
However, these are inconvenient facts that stand in the way of the utopia our socialist overloards have planned for us.
MC
March 6, 2010, 7:44 amrxc:
It is really even worse that described, because these are only analyses of the instantaneous power supplied/consumed at any one time. In addition, when large amounts of capacity go away quickly, it causes the transmission system to "ring" a bit, as the various spinning reserve resources take up the load. In the worst case, it is possible for the ringing to amplify itself because of the time constants, and certain generators can lose synchronicity with the network. If they lose frequency control, the transmission system will quickly die. This actually happened in the US a few years ago, due to the collapse of an overloaded transmission link.
Furthermore, all of this reactive current madly rushing back and forth heats the lines, and in the summer it can actually cause them to sag too close to the ground/surrounding trees (which no one likes to have cut). This causes those segments to trip, and the failures cascade.
People who talk about distributed power systems have never really operated a large power system, and have no idea what can happen when reactive currents get too high.
March 6, 2010, 8:17 amterry colon:
It would seem wind power should not be directly attached to the grid, but should do something like separate hydrogen from water to power fuel cells which could supply a steady, controlled amount of energy. In such a system, rather than on land perhaps windmills might be better sited offshore where they'd be wind and water for the task.
Just a thought.
March 6, 2010, 9:40 amMal:
Some more problems for Alternative energy
http://chicagoboyz.net/archives/11847.html#more-11847
March 6, 2010, 9:51 amMesa Econoguy:
Lest we forget our friend, Betz’s Law...
March 6, 2010, 11:02 amastonerii:
Costs a fortune to manufacture, costs a fortune to maintain, supplies variable intermittent electricity, uses very rare minerals that only come from unstable regions. What is not to like.
March 6, 2010, 11:05 amIan Random:
The simplest way to point this out to the green morons, is to mandate the lights in state capitals be driven only by intermittent diffuse renewables like wind, solar and wave. Of course, if you live in the boondocks today, sometimes wind and solar make economic sense along with a propane powered refer. In the future, I wonder if you could use intermittent unregulated power sources economically to make CO or H2.
March 6, 2010, 12:47 pmHenry Bowman:
The well-known engineer Henk Tennekes has weighed in with his view of wind power, and it's not pretty at all. It's short and really a must-read.
March 6, 2010, 1:01 pmPat Moffitt:
Wind power is the recycling of the energy world. A feel good idea that costs way more than its worth and does more harm than good
March 6, 2010, 3:35 pmMark:
Wind could be kinda sorta made to work, much like solar can be kinda sorta made to work.
What you would need is some kind of storage to store excess energy during peak production, and allow reuse at a later time. I would guess lithium batteries, or lead acid if you have a lot of space would do the trick, but then these technologies make the system a lot more expensive, and cause environmental damage of their own.
I could see, however, in a few years, using a device like the bloom to create energy from natural gas while the alt energy source is not running. I don't know if the gas companies have issues with pumping more or less fuel as the demand changes. They seem to do a good job when it gets warmer and colder as day transitions to night.
March 6, 2010, 4:29 pmDr. T:
Wind power is fine for pumping water into troughs for animals or irrigation systems for crops, because the pumping doesn't need to be continuous: the systems need only enough wind power to pump X number of gallons per day. But, trying to use wind power for distributed electricity generation is just stupid and wasteful. It's like building a hydroelectric plant on a river that only has adequate currents after heavy rainstorms and cannot drive the turbines at any other times.
March 6, 2010, 4:44 pmDoug:
@ Colin: I get a kick out of the line in the NYT article you cite: "By adding renewable power to existing fossil fuel plants that operate around the clock, the thinking goes, utilities could have readily available power that could be fired up instantly whenever their wind or solar resources dropped off."
I.e., let's add wind and solar generators to the gas plant grid so that when the wind and solar generators can't produce anything, we'll have additional backup sources that aren't there, too. This must be the green weenie equivalent of perpetual motion.
March 6, 2010, 11:42 pmIgotBupkis:
> but apparently that can be used to provide some quick response to wind production changes.
Yeah, you use hydraulics as a storage/leveling mechanism. As with any other, you're going to lose a lot to inefficiency, off an already inefficient and low-energy system.
I've seen a concept for a workable "wind energy" system, but it only looked like it might work by making its own wind. There was a report something like 15-odd years or more ago about it in the WSJ, IIRC. The idea was, take a cooling tower-like design. At the bottom of it, place wind turbines. Now, up at the top, spray a mist of water. The water, with its massive heat absorption capacity, sucks the heat out of the air, cooling it rapidly. This makes it heavy, and it sinks, pushing out the air beneath it, through the turbines. Lather, rinse, repeat.
I have no idea if the energy obtained pays for the cost of pumping the water up to the top of the cooling tower (I'll assume the misting can be done with fine jets, requiring little to no energy). It does, clearly, require a fairly adequate supply of water, though it's been suggested that one could use seawater (the downside is that sea water is pretty corrosive, and there's also a residue of salt that will need to be cleaned up constantly).
I have no idea if the idea is actually workable/functional, but it does sound possibly so. I wonder if any patent on it has expired since, as it was def. over 15 years ago.
March 7, 2010, 1:07 amIgotBupkis:
Heh...Forgot who pointed me to this... Kudos to whomever it was, wherever it was...
Clean Energy FAIL
March 7, 2010, 2:11 amCraigo:
Most people have no idea about the simple truth that electricity is generated to meet immediate demand. There is no magical large scale storage in batteries unlike their solar calculator. The simple concept of daily variation and meeting demand is barely on their radar. The wind does not blow and the sun does not shine to meet peak daily demand. Trying to explain boiler start ups or shut downs is commendable.
The website http://www.bmreports.com/bsp/bsp_home.htm demonstrates the daily fluctuations in demand in UK market. The contribution of wind power is well demonstrated. eg current output at time of comment was 59MW of a metered capacity of 1588MW - less than 4% of wind capacity! Coal and gas carry the load and pumped storage is called on to help the peak demand. For the less familiar, pumped storage is a nett consumer of power and smooths the peaks and troughs of demand by either using surplus (coal, gas or nuclear) power to pump water up hill or releasing it back down hill to generate hydro power. In other words, not the warm and fuzzy lo-co2 hydropower.
Now to put that into context, Britain plans to build more wind plants to meet future demand!! Selling wind turbines sure sounds like the snake oil of the decade.
March 7, 2010, 5:15 amFred Z:
So, once again you lot have proved that "Lefties Are Innumerate".
But we have known that for years.
And yet we still argue with them. They will never understand. They cannot. Their brains are specialized for manipulating people, whereas ours are poor at that and specialized for manipulating the physical universe. We are makers, they are takers and fakers.
I have no idea how to solve this except to be ever more stubborn, more intransigent, to refuse to be manipulated, to try to stop the manipulation of others.
But argue with the silly buggers? Waste of time.
March 7, 2010, 9:54 ammarkm:
"The idea was, take a cooling tower-like design. At the bottom of it, place wind turbines. Now, up at the top, spray a mist of water. The water, with its massive heat absorption capacity, sucks the heat out of the air, cooling it rapidly. This makes it heavy, and it sinks, pushing out the air beneath it, through the turbines. Lather, rinse, repeat."
I have no idea if this is could be a practical energy source. One thing I am sure of: if it is ever proposed to actually build such a plant, the greenies will suddenly realize that water vapor is a greenhouse gas!
I think that the dangers of global warming have been grossly overhyped, but I'd really want to see a good model of the local weather effects before any large scale deployment of such plants. Think of lining the southern California coast with such plants: there'd be more rain, higher humidity over the deserts, and more snowfall in the Sierras. LA would have an easier time finding drinking water. OTOH, more muddy hillsides would slide out from under split level houses. The danger from brush fires would be reduced initially, but the brush would grow faster, so I don't know about the long run.
And somewhere a dry-climate-adapted plant or animal would be endangered by the wetter weather.
As a Michigander, I'm probably downwind from the second-best place to locate these gigantic humidifiers - if they can figure out a way to keep them from freezing up every time the intake air drops below 40 or 50 degrees F. I certainly don't need more rain and snow or higher humidity in August. OTOH, compared to coal plant emissions, what am I worried about!
March 7, 2010, 5:12 pmmorganovich:
the reason wind farms don't work to generate reliable power is simple and immutable issue of the physics.
power generated by wind spinning any sort of blades or apparatus over a given sweep is a function of windspeed raised to the fourth power.
consider what this means:
any given set of blades has an optimum windspeed for peak power output. this is the speed they use for nameplate specification. above that speed, they need to start feathering the blades and dumping power, but that only goes so far at which point they need to shut down the turbine.
but the real issue is what happens it is less windy?
if windspeed is 80% of peak, power output is only 41% of faceplate.
at 50% peak windspeed it's less than 7%.
absent the ability to store large quantities of power cheaply and efficiently, the physics of wind power make it impossible for it to be a reliable part of the grid.
March 7, 2010, 6:49 pmsmurfy:
Yeah it takes some time to fire up your precious coal powered plant. So what? That's why we are installing smart grids, so we can instantly cut your consumption instead!
March 8, 2010, 12:45 pmheresy101:
As a resource planner for a utility that has very competitive rates and is very renewable, these comments presented so far are mostly wrong. Yes, wind is unpredictable and I have the data and charts to prove it. In our area, wind has a 33% capacity factor (CF) but can't be counted on in the short term (less than an hour) as a reliable resource. Over a year's time the energy is very close to the predicted 33% CF.
Hydro power and gas turbine (or reciprocating engines) are a good backup for wind's variability. Hydro can make money doing "spin" and be available to meet the ups and downs of wind generation. This is not without cost because the water that is run through the turbines has a value if held to the peak value of summer. This ranges from $65-125/MWH. While this is not "cheap", this can fill in the variability of wind for an effect cost that is similar, or much less, than the cost's of a natural gas fired unit.
As far as natural gas as a backup, there are reciprocating (giant "diesel engines") that have a heat rate of 8300 (maybe as low as 7300) which is similar to combined cycle systems. These can do "spin" but more often do "non-spin" which allow them to be online in 20 minutes. The accuracy of the wind forecasts allow this matching to occur. Using $5/mmbtu natural gas, the costs of meeting wind variability is around $45-50/MWH which is expensive relative to coal but is very competitive relative to the market in California.
By the way, I have come to the conclusion that AGW is a crock but we need to do everything possible (except nuclear - too expensive!!) to make the US energy independent!
March 8, 2010, 10:29 pmRathtyen:
Wind generation lends itself best to perform in concert with hydro generation, given hydro has the fastest start-up and close-down times. But that is a limited opportunity, and also depends on the nature of the hydro plant: if it is run-of-river (most hydro is), it may only have limited opportunity to turn off in favour of wind. Still synergies are possible, and wind can be used to extend a hydro generator’s capacity. Hydro has the speed to ramp up and down with wind, but will often only have limited capacity.
The biggest problem is that wind plant is very expensive. The company I work for has extensive hydro operations, and wind for us is not a viable option: too expensive and too unreliable, and too dependant on government support to work economically. Government support at the moment seems sound, but the sentiment is changing, and once it becomes a political negative, government support will get dropped like a hot potato. Then wind generators will be stuck with high cost, high maintenance and low reliability plant. Best of luck to them, but we’ll stick to viable investments.
Wind generation is a fringe technology, and trying to use it for baseload generation is insane. And for longer term planning it is a disaster. Where appropriate back-up capacity is being built, it just insanely expensive, literally more than doubling the cost. But where just additional wind capacity is being built, a generation shortage is looming in the near future. It is worth noting that many wind farms are built on the basis of overall wind, but of course, matching generation to demand, and especially peak demand, is what grids need to deliver. Wind can only do that by accident, and is therefore unreliable.
March 8, 2010, 10:40 pmLink:
"do everything possible (except nuclear – too expensive!!) "
If we standardized nuclear designs, and removed the legal and regulatory delay risk, shouldn't nuclear be cost competitive. It seemed to work for the French a generation ago.
March 9, 2010, 5:56 amNobrainer:
@ Henry Bowman: The commentary from Henk Tennekes would be laughable if it wasn't so sad. He, an apparent engineer, argues against wind energy because it's an engineering challenge, then argues for nuclear power as though operating a nuclear plant is the easiest thing in the world.
He also pulls a sleight of hand by ignoring total emissions and instead focusing on emissions/kWh from thermal plants, which he admits are backed way down.
March 9, 2010, 6:48 amRathtyen:
This sums the issue up very nicely:
http://blogs.news.com.au/heraldsun/andrewbolt/index.php/heraldsun/comments/danish_patsies/
Andrew Bolt
Thursday, March 11, 2010 at 09:20am
Michael J. Trebilcock, professor of economics at Toronto University, says Denmark’s wind power is a con:
There is no evidence that industrial wind power is likely to have a significant impact on carbon emissions… Denmark, the world’s most wind-intensive nation, with more than 6,000 turbines generating 19% of its electricity, has yet to close a single fossil-fuel plant. It requires 50% more coal-generated electricity to cover wind power’s unpredictability, and pollution and carbon dioxide emissions have risen (by 36% in 2006 alone).
Flemming Nissen, the head of development at West Danish generating company ELSAM (one of Denmark’s largest energy utilities) tells us that “wind turbines do not reduce carbon dioxide emissions.†The German experience is no different. Der Spiegel reports that “Germany’s CO2 emissions haven’t been reduced by even a single gram,†and additional coal- and gas-fired plants have been constructed to ensure reliable delivery…
Industrial wind power is not a viable economic alternative to other energy conservation options. Again, the Danish experience is instructive. Its electricity generation costs are the highest in Europe (15¢/kwh compared to Ontario’s current rate of about 6¢). Niels Gram of the Danish Federation of Industries says, “windmills are a mistake and economically make no sense.†Aase Madsen , the Chair of Energy Policy in the Danish Parliament, calls it “a terribly expensive disaster.â€
March 10, 2010, 4:06 pmraj:
You mention that "The report also talks about diesel generators for standby since they can be started up quickly, but these are seriously inefficient devices.". This is completely incorrect. Giant reciprocating engines, as a commenter has mentioned, have heat rates comparable to that of combined cycle gas turbines, especially in hot, dry conditions and at high elevation. And they are far better in efficiency terms (45%)than simple cycle gas turbines ( <35%) that are used for quick-start applications ( in combined cycle systems, the steam turbines may take a long time to start up and hence they are no good for peaking applications). A 120 MW based on a configuration of 8 x 15 MW gas engines, for example, can come on to full load in less than 20 minutes and maintain high efficiency at all plant loads.
March 11, 2010, 9:10 am