This three-part series assesses utility-scale wind’s ability to provide reliable power, a necessary qualification for its use in electricity systems. After Part I’s introduction, Part II dealt with power density, where wind fails to meet today’s standards. This final part will look at the extension to power density, that is, capacity (power) value, which takes into account wind’s randomness and intermittency of supply. Again wind fails to qualify as industrial energy.
Electricity capacity is measured in power terms, for example MW. In this connection it is important to note the importance of the distinction that must be made between capacity factor, capacity credit and capacity value. Compared to capacity value, capacity credit and capacity factor are of small importance. Jon Boone has long called attention to this as follows:
“Modern society exists on a foundation built upon productivity that comes from reliable, controllable, interdependent high-powered machine systems. All conventional units that provide electricity must pass rigorous tests of reliability and performance; they must produce their rated capacities, or a desired fraction, as expected whenever asked–or be removed from the grid. Some are like refrigerators, doing heavy-duty long-term work; others are like our toasters or irons, not working all the time but responsive when called upon to do so. This ability to perform as expected on demand is known as a machine’s capacity value. Conventional power generators have a capacity value of 99.999%. Using them for 97% of our electricity, the country achieves high reliability and security at affordable cost. Wind provides no capacity value and can pass no test for reliability; one can never be sure how much energy it will produce for any future time. Generating units that don’t provide capacity value cannot be reasonably compared with those that do.
This is a practical way to think about this concept: You don’t drive your car all the time, with the result that its capacity factor—the percentage of your car’s potential that you actually use–is probably 15-20%, if that. But when you do wish to drive it, the car works virtually all of the time, getting you from pillar to post in line with your own schedule. This is its capacity value. Ditto with your chain saw–or television, or any modern appliance we all take for granted because it works when we want it to work. Appliances that don’t do this are quickly discarded, although this wasn’t the case for much of our history (look at the early days of television or radio or even the automobile). Only in the last hundred years or so have we in the West come to rely on machines with this standard. In fact, it’s the basis of our modernity and it underlies contemporary systems of economic growth and wealth creation.”
In other words, for electrical energy to be useful, we must be able to switch it on and off at the level needed and rely on it being available during the period of use. To accomplish this, capacity (in this context capacity and power are interchangeable terms) must be reliably available on a continuous basis. This is as opposed to wind “activity” as described in Part I, which is available only randomly and in continuously varying amounts over time.
Statistical expectations of this are not meaningful. This cannot be over-emphasized, as electricity is a vital resource for many of our activities and continued well-being. Further, unlike most resources, electricity cannot be stored, and in most applications, in its absence, substitution of some non-electrical power source is not feasible.
For utility-scale wind plants to have value, they must provide renewable power, not just renewable energy. This means wind capacity must be reliably available on demand and throughout the period of use, and it is not. This is why it was separated from conventional generation sources in Table 1 of my USAEE article, and is characterized as having no capacity value. Even at the disadvantageous increased costs shown, it cannot be compared to the high capacity value conventional generation sources as inclusion in the same table implies.
In summary, reliable capacity is the means by which useful electrical energy is provided. In its absence, the availability of energy, regardless of the reliability of the energy source, is of very little, if any, value.
Wind proponents acknowledge wind’s capacity inadequacies and make the seductive argument, based on the erroneous assumption that it is “clean” or “green”, that it must be used if, as and when it becomes available. As such, they maintain that wind makes an energy contribution that is, in itself, useful. But it is not and does not bear close examination in any analysis of the claimed benefits of fossil fuel or CO2 emissions reductions, costs, and job creation.
An analogy might provide a further insight on capacity value.
Medical Care Analogy
A good analogy for an electricity system is medical (not health) care. In both systems the delivered service cannot be stored, or, in general be replaced with some other resource. In both cases, the consequence of insufficient capacity is curtailment of services. In the electricity sector, “The lights go out”, and in medical care, treatment is delayed, perhaps too late to deal properly with the medical problem, or, in the worst case, save the patient.
The question then arises as to the acceptable level of curtailment. In the electricity sector, existing operating standards are that this is effectively zero. This has been achieved by planning to have sufficient capacity available at all times. Where this has failed in practice, the result is brown-outs or black-outs. The presence of sufficient, reliable generation capacity is the insurance against lengthy or frequent curtailment, which as a society we cannot withstand. It is vital to our general societal needs, including the operation of business, industry, government, and institutions. Medical care is also a societal need, but is delivered at the individual level, and there appears not to be the same level of planning standards (zero curtailment). The underlying issue in both cases is the price (in terms of rates, or premiums, and subsidization) that users are willing to pay to avoid curtailment of services. In both systems the level of planning, management and funding provides the resulting competent capacity.
In summary, in the electricity sector we are very risk-averse, and place a high value on reliable power. This excludes wind as a viable source of electricity. As discussed, wind can provide some level of energy averaged over long periods, but this does not meet the requirements of customers, which is reliable electricity supply as needed, just as the medical care customer requires necessary services at the time of injury or illness, not on average over some relatively long period of time.
Now consider the portion of the analogy relating to the unreliable nature of wind power within the medical care example. This would be represented, for example by secondary medical resources rushing in unneeded and causing the primary resource treating the medical problem to step aside, after spending some time describing the medical problem and treatment being conducted, which introduces process “friction”. The displaced medical resource cannot be used for other purposes, because it must be available to step in again when the capricious resource suddenly changes in intensity or effectiveness or fails, which it does frequently. Again a hand-over would have to take place, adding to process “friction”. Now add government mandates for increased levels of this secondary medical resource for which premium rates are paid. Does this result in a better medical care system, and what is the impact on costs?
The degree to which reliable medical care capacity is available determines its value to our society. The availability of capricious, interrupting medical resources does not provide value at all. The same is true for wind power in electricity systems.
Yet another way to view this is a very general look at how pricing is set in electricity markets.
Electricity Markets
There are two components for pricing electricity in wholesale electricity markets: capacity and energy payments. Capacity considerations and payments, for which reliable capacity is a requirement, are a form of insurance against curtailment as described by McMullough.[1]
Capacity payment is intended to provide financial support for the fixed costs of a project, development costs, and the equity return on the project sponsor’s investment. An important underlying proviso is that electricity can be reliably produced at agreed-upon levels. Energy payment is intended to cover the variable operating costs, such as fuel and variable operating and maintenance expenses, and is based on the electricity delivered.[2]
Clearing prices in the spot, or real-time balancing, market vary but tend to reflect variable operating costs and here wind has a major cost advantage over other market participants, for example gas turbine plants, for which operating costs include gas consumption. As the clearing price is paid to all successful bidders below it, which tends to be at the level of gas plants, wind plants can obtain energy prices that also contribute to fixed costs. Separately, they may even be able to receive their full power purchase agreement prices, which can be at a substantial premium above the clearing price.
So, wind plant developers attempt to appear to be electricity market players by focusing on (and publically emphasizing their contribution to) the only aspect available to them, the energy component. As a result, wind project owners will likely chose to participate only in the spot electricity market, in part because of their greater inability to ensure delivery in the larger day-ahead market, in which failure to deliver incurs penalties, except in cases where, unlike other market participants, wind non-delivery is not penalized.
Because of wind’s unreliability, even in the spot market they would not be a player without mandated acceptance of their production by electricity system operators, on an “if, as and when” available basis.
Here are some final insights into the doubtful value of wind-generated electricity:
The major conclusion is clear: Only reliable energy sources can make any valuable contribution to electricity supply. This requires reliable capacity or power capability. Without any capacity value, and with extremely low capacity density as described in Part II, wind generated electricity fails to meet the essential requirement of electricity system user needs and should not be included in the electricity generation portfolio for the foreseeable future.
[1] McCullough, Robert (1998). “Can Utility Markets Work Without Capacity Prices?” Public Utilities Fortnightly. http://www.mresearch.com/pdfs/275.pdfMcCullough is also the source of the medical analogy.
[2] Hoffman, Scott L. (2008). The Law and Business of International Project Finance. Third Edition. Cambridge University Press. Section 19.07
The major point of this post was recognized in the first treatise of energy economics as follows:
“The first great requisite of motive power is, that it shall be wholly at our command, to be exerted when, and where, and in what degree we desire. The wind, for instance, as a direct motive power, is wholly inapplicable to a system of machine labour, for during a calm season the whole business of the country would be thrown out of gear.”
– W. Stanley Jevons, The Coal Question (London: Macmillan and Co., 1865), p. 122.
Terrific exposition of complex issues. The medical analogy is just so. A converse analogy is also apt. Since wind appears as drunken energy staggering its way uncontrollably throughout the grid, imagine the prospect of integrating a substantial portion of drunk drivers on our highways.
Wind technology provides no manipulatable capacity. It’s past behavior cannot predict what it will do at any future time. Although marvels of engineering, the machines that convert wind energy to power needs cannot work miracles: their fuel is are too dilute to sustain the high level work over time required for modern productivity.
What has been miraculous is that the spin of this Enronesque enterprise continuous to reap billions of public dollars–all in support of perhaps the dumbest modern power idea imaginable.
Wind technology can only add sporadic energy to the grid, not modern power quality, much in the way a large rock can add energy to a small stream, in the process interrupting the flow.
Wind power is an oxymoron. Responsible wind power is a double oxymoron.
I agree with many of the points of the post. However, as long as the electricity source is transparent to the user, the user doesn’t care whether the electricity came from hydro, coal, gas, solar or wind (doesn’t care in terms of use and reliability — price and other factors may come into play). As a result, if the utility is able to load balance, wind can be a meaningful contributor (as can solar) to the overall mix. What this requires is a facility that can carry out the load balancing quickly and efficiently. I don’t know whether coal can be brought online and offline easily, but natural gas generators certainly can. Santa Clara, California, has a relatively new natural gas plant that load balances with solar, hydro and wind quite effectively. I should also point out that Santa Clara has the most reliable and nearly, if not definitely, the lowest electricity prices in the Bay Area.
Again, I agree with much of what is said in terms of wind being intermittent, fickle and, often, expensive, but it can definitely be a meaningful contributor to a properly load-balanced energy mix.
I am ignoring for a moment the questions of whether wind is expensive, kills fowl, is an eyesore, is noisy, actually reduces carbon emissions, etc. There are lots of reasons to take large scale wind production with a healthy grain of salt. There are, however, some successful implementations that should be acknowledged in making sure we have the whole picture . . .
Eric Anderson
I disagree on a number of points. First, I don’t agree with your view that the users don’t care about use and reliability as long as price (and other factors – what factors?) don’t come into play. The user needs reliable electricity. One problem is that this is easily taken for granted because it is so well provided today.
Second, although I am at a disadvantage as to your background, it appears that you need a broader understanding of electricity generation and transmission infrastructures, including grid considerations, electricity quality maintenance, load balancing in general and wind balancing in particular (including the consequences of using fossil fuel plants in this role), before drawing the general conclusions that you do. This is the common mistake of wind proponents, who believe that a superficial view of these, and many other considerations, is sufficient to arrive at feasible solutions to providing the necessary electric energy we need.
To say that gas plants can balance wind – end of story – is a strong indication that your understanding is limited. On this point, for starters, I refer you to my posts at:
http://www.masterresource.org/2009/11/wind-integration-incremental-emissions-from-back-up-generation-cycling-part-i-a-framework-and-calculator/
http://www.masterresource.org/2010/02/wind-integration-incremental-emissions-from-back-up-generation-cycling-part-v-calculator-update/
http://www.masterresource.org/2010/06/subsidizing-co2-emissions/
I am unaware of any “successful” utility-scale implementations, except for those that are being “promoted” as such. I hope you are not talking about, such as, Denmark, Germany, Spain, California, Texas, U.S. northwest, Ontario (Canada), Australia and even China.
Returning to Denmark, which has wind penetrations comparable to that projected for the U.S. (about 20% by energy), because its electricity system cannot withstand this much wind, it has to export most of its wind production to Norway and Sweden. These two countries between them have hydro generation of 30 times Denmark’s wind production. Denmark does this at considerable cost disadvantage. Do not rely on the argument that these two countries are storing Danish wind for later use by the Danes. They would be better off without the wind implementations and just importing Nordic hydro when needed.
Further, Denmark is back to off-shore after abandoning it earlier because of the associated problems. Their citizens are opposed to more of the large onshore wind turbines that are being implemented elsewhere. Theirs are mostly considerably smaller. Denmark has to promote offshore because of this, questionable EU energy policies and to support Denmark’s severely threatened wind turbine manufacturing export position.
Finally, you miss all the points in connection with the power characteristics of wind (and all renewables, but especially wind). Generally speaking (except in the near term in the case of some hydro sources), this factor alone renders them of no value for many decades, notwithstanding current extensive promotion of them. This is the ultimate “whole picture”. All other considerations are arguing around the margins of the matter.
Great response, Kent. What Mr. Anderson evidently fails to appreciate is that, while an electron is an electron, the manner of its delivery makes for a crucial difference. The conversion of energy “fuels” into meaningful and manageable power is the stuff of our electricity system. The fuel for wind technology is not sufficiently dense for this kind of conversion. So it requires a great deal of supplementation. And, “ay, there’s the rub….”
Mr. Anderson, being from and involved in California’s energy system/,arket for ~40 years, I’m well awarea of the Santa Clara plant. I would add that there are several time horizon’s one needs to consider when using the term “load balance.” WRT diurnal cycles, natural gas facilities such as those in Santa Clara are admirable. Not quite as good when called upon for hour to hour swings and terrible for instantaneous-to-5 minute swings. Wind facilities such as those in Altamont can easily swing 20% in less than 15 minutes. Solar is less problematic. Similarly pumped hydro cannot cycle fast enough to account for intermittency of wind; about the only storage technologies that can are batteries and super-capacitors, neither of which are commercially available at scale.
[…] supply stability; it has no capacity value. (Hence the title of Kent Hawkins’ recent series, Wind Has No Value.) What most experts don’t properly account for, even those who understand the data, is the […]
Thank you, Mr. Hawkins, for your detailed response. I was making a very narrow point, more nuanced than the broad brush you painted me with in your reply. As I stated, there are serious questions about whether wind is a good electricity source in terms of noise, emissions, etc., and I believe you have made some excellent points in that regard – perhaps enough so that the whole wind enterprise should be re-examined.
However, your post specifically related to the question of capacity value, and your post might perhaps be summed up with your statement that: “In other words, for electrical energy to be useful, we must be able to switch it on and off at the level needed and rely on it being available during the period of use.”
I couldn’t agree more. My point is simply this: as someone who uses electricity in an area that obtains electricity from a mix of sources, when I turn on a switch I care not a whit whether the electricity originated in the coal plant, in the natural gas plant, in the rush of water through a dam turbine, from PV cells, or from the wind-swept plains. That is what I mean by the electricity being transparent to the user. Of course the user needs reliability on the back end of the process – reliability is key. What I meant by reliability in my parenthetical is reliability on the generation front end.
Your post seemed to shift back and forth between these two forms of reliability: reliability in generation, and reliability of provision to the user, but they are very different issues. Wind power is notoriously fickle on the generation end; that seems self evident. However, and this is the point, it can – and is – being load balanced so that the electricity usage is transparent to the user. I don’t disagree with any of your discussion about the challenges of more wind penetration, what is happening in Denmark, etc. Nevertheless, the fact remains that wind is contributing to the energy mix, at least in Silicon Valley Power’s minor domain, in a way that is transparent to the user. It is understood that Silicon Valley Power’s prices and excellent reliability are part of the reason why huge electricity consumers like Intel, Sun, Applied Materials, nVidia, and others have made Santa Clara home. The inclusion of wind in the mix (about 10-11% in Santa Clara) does not affect the customer one bit in terms of reliability on the user end.
Are there other considerations in looking at wind? Absolutely. I think the jobs creation story is a boondoggle. I understand, including from your helpful research and links, that the emissions reduction is close to non-existent, or potentially even negative (I don’t care too much about reducing CO2 emissions, so this isn’t a particularly salient point for me, but it is a very big issue for the wind PR story). Further, there are legitimate concerns with noise, landscape disruption, and fowl mortality.
Perhaps the whole wind enterprise needs to be abandoned – I’m not sure yet – but the nuance I would raise is simply that the question of reliability – reliability to the end user – is not a particularly strong objection to wind. Other factors you discuss elsewhere are much more important.
Eric Anderson
Thank you for your comments. An important point on reliability at the generation end is that it shifts the power density issue further to the disadvantage of wind.
That the user receives reliable power is due to the system operator having to use extraordinary measures to balance wind’s unreliability. The reliability issue transcends considerations at the generation and use points of view of the system.
I don’t recall mentioning noise (and the extensive range of other problems that wind presents) considerations. However, my view on that is that it looks like there is a serious problem that is largely dismissed. Any such problems in this and other areas are needless in light of the inadequacy of wind to deliver on the claims made for it.
Yes,the whole enterprise needs to be abandoned in terms of commercialization at the utility-scale level.
[…] of supply stability; it has no capacity value. (Hence the title of Kent Hawkins’ recent series, Wind Has No Value.) What most experts don’t properly account for, even those who understand the data, is the […]
[…] is Not Power at All (Part III – Capacity Value) http://www.masterresource.org/2010/09/wind-not-power-iii/ “Wind provides no capacity value and can pass no test for reliability; one can never be sure […]
[…] Bryce has identified five myths of green energy–and post after post at MasterResource by Kent Hawkins, Jon Boone, and John Droz Jr. have shown that meaningful CO2 reductions from windpower are highly […]
Mr. Hawkins.
I really enjoyed reading this and gives valuable information for me and others in my community who are concerned of a proposed industrial turbine site (I hate windfarm, sound’s green) that would cover 25% of our small island in Hawai’i.
Here, we have so much to lose if this project goes forward. any more info on inefficiency or where to find case studies that I can print would really help me. I hate to sound like a NIMBY, but this project will permanently disfigure, not only the land that is home to a multitude of ancien hawai’ian historical sites, but also the ocean with errosion, that will choke and kill the reef with sediment. please visit friendsoflanai.org
any info will be appreciated.
-ben
Wind energy is great for grinding corn and pumping water when you can store the results and it does not matter too much when you do it.
It ain’t no good for running a country on electric power where those options don’t exist.
“Conventional power generators have a capacity value of 99.999%”
5 nines? Really? I can’t find where you define capacity value but it appears that you’ve simply defined it as 100% for everything you like and 0% for stuff you don’t like.
“Statistical expectations of this are not meaningful.”
um, everything is a statistical expectation. What is your 99.999% capacity value if not a statistical expectation?
Your comments would be more credible with a better treatment of this core concept. There is no way that a conventional power plants have 5 nines reliability. They simply don’t.
jam
You raise some good conceptual points, and, unfortunately this is what we are talking about. Although conceptual, in electricity supply and use, capacity value is a very important , and has very real impacts on our everyday lives.
What is the value of an unreliable employee who often does not show up for work in the circumstances that his presence is essential on a dependable basis, and when he does show up leaves frequently and unexpectedly? I would argue that in general it is zero, notwithstanding the fact that he does show up from time to time based on a whim. This is outside the issues of time off for valid personal matters (e.g. sickness) and the fact that some work is performed when present (although this person does distract from the effectiveness of other employees).
Similarly, my medical care analogy ended with the following statement, “The availability of capricious, interrupting medical resources does not provide value at all.”
I have defined capacity value as the availability of reliable power, that is, the rate at which energy flux can consistently be provided, at the call of the system operator. In electricity terms it is, again, watt-hours per hour (or watts), representing the amount of useful activity that can reliably be performed in a given period of time (for example, lighting, heating, running computers and machines).
This is different from calculations of reliability/dependability for planning purposes, which allow for scheduled and unscheduled maintenance, and in the case of intermittent sources, for the persistent unreliability of fuel. In the latter case, a statistical expectation can be determined on the contribution to capacity over long time periods for the purposes of capacity planning. This is dependent upon delivering an overall electrical system reliability of greater than 99%. On this basis, the capacity credit for wind in Germany is about 8% of wind capacity. Capacity value addresses wind’s reliability on a short term basis.
So chronically intermittent sources, such as wind and solar, are uniquely different from other sources of electrical energy and a reliable level of power cannot be depended upon. Its capacity value is very low, say approaching zero. In the case of most other generation it is approaching 100%.
Your comment, “…it appears that you’ve simply defined it as 100% for everything you like and 0% for stuff you don’t like” is very questionable.
What Kent said is true. Most turbines can be expected to deliver less than 10% of their nameplate capacity over the lifetime of the unit. The forced integration of such low-capacity technology is economically suspect and, as policy, misguided.
Obviously, some people are still mentally locked in the old paradigm of electricity (an unflexible demand must be met at all time by a single isolated grid). As it is said : “good is the enemy of better”. Things change. The first people who believed in makings automotive cars were laughed at by those who used horses.
I recommend you have a look at the study “Systemkonflikt in der Transformation der Stromversorgung” from the Fraunhofer IWES for the German SRU (Sachverständigenrat für Umweltfragen), or at the studies of the NREL : “Renewable Electricity
Futures Study”, or “Determining the Capacity
Value of Wind: A Survey of Methods and Implementation” (already 7 years old).
A mammoth, who feels like he is talking to dinosaurs.
Mammoth
I almost don’t know where to start. Your comments reflect an incomplete knowledge of energy and electric energy in particular. I have read something approaching a thousand documents on the subject, including NREL reports, which I do not recommend to serious readers. Quoting a few studies is not a substitute for thinking (… und Ich verstehe Deutsch – somewhat). So I will keep my response at the same level as your comment.
First of all, mammoths would have a difficult time talking to dinosaurs, as they did not co-exist on this planet, let alone they do not speak the same “language”. You appear very rooted in the past. Although knowledge of history is important, it is not sufficient in itself. For example cause and effect in the past are much more difficult to determine than most people think. I know “experts” seem to connect the dots well, but be careful.
I suggest you have the horse/car metaphor wrongly used in this case. It does provide the correct basis for another look at today’s situation. At this point in time people who use cars would laugh at those proposing horses. This is the same as proposing wind, a relic from the past, to replace reliable, economic, and scalable (but not requiring increasingly large amounts of the surface of the planet) energy sources, without which modern societies could not exist. You simply need to better understand our energy needs and feasible energy sources and conversion processes. Power density is but one aspect, albeit it one of the most important ones, of the folly of grid-feeding wind and solar power today.
Of course our electricity infrastructure has to change, but electricity is so imbedded in everything that we do that radical change is not advisable. If you would argue that we do not have he luxury of time, I would respond that the only approach that deals with your associated concerns is aggressive conservation.
As you say, things do change, but all change is not necessarily good. We must be careful not to put into place massive change which will not meet the tests of modern society and in fact endanger what we have and which provides the best support for meeting the challenges that face our species.
I will finish with a quote spoken breathlessly by one lemming to another: “I know times are good but we’re going for change. Stop thinking about it you old dinosaur and just follow everyone else.”
[…] a per kWh basis, wind receives 80 times the public subsidies received by fossil fuels, but produces no reliable electricity capacity and very few American jobs. In fact, for every green job that wind supposedly creates, it destroys […]
[…] one of the five planners who were there knew what “Capacity Value“ was, nor that wind provided virtually NONE. I told him that wind is not the future and that in […]
[…] one of the five planners who were there knew what “Capacity Value“ was, nor that wind provided virtually NONE. I told him that wind is not the future, and in all […]
[…] one of the five planners who were there knew what “Capacity Value” was, nor that wind provided virtually NONE. I told him that wind is NOT the future, and in all […]
[…] to the unreliable, erratic, and volatile nature of wind, industrial wind turbines provide virtually NO Capacity Value, or firm capacity (specified amounts of power on demand). Therefore, wind needs constant […]
[…] wind provides no capacity value, or firm capacity (specified amounts of power on demand), wind cannot replace our reliable, […]
[…] wind provides NO capacity value, or firm capacity (specified amounts of power on demand), wind requires constant “shadow […]
[…] Because wind provides NO capacity value, or firm capacity (specified amounts of power on demand), wind requires constant “shadow […]
[…] wind provides NO capacity value, or firm capacity (specified amounts of power on demand), wind requires constant “shadow […]
[…] wind provides NO capacity value, or firm capacity (specified amounts of power on demand), wind requires constant “shadow […]
[…] a per kWh basis, wind receives 80 times the public subsidies received by fossil fuels, but produces no reliable electricity capacity and very few American jobs. In fact, for every green job that wind supposedly creates, it destroys […]
[…] http://www.masterresource.org/general-problems/wind-not-power-iii/ […]
[…] one of the five planners who were there knew what “Capacity Value” was, nor that wind provided virtually NONE. I told him that wind is not the future, and in all […]