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19 Comments

  1. Rod Adams wrote:
    Aside: Though AWEA’s Goggin denies that this fact of life occurs when operating real equipment, most people who drive automobiles will recognize that their fuel economy varies substantially depending on whether they are driving long and steady highway miles or stop and start city miles. A smaller portion of the population might even recognize that city mileage can drop even more if you have a heavy foot on the accelerator and have to break sharply when the light turns red. Wind generation can have a similar pattern on certain blustery days, requiring other generators to do the stopping and starting to keep the grid output matched with demand. End Aside.
    The owners of wind turbines force increased fuel costs and CO2 emissions from fossil fuel plants, and bear none of the costs. On top of that, these fossil fuel plants are forced to cycle more often, increasing the maintenance costs (especially on plants that were designed for base-load operation), and once again the wind turbine folks skate free.

  2. Consumers can consume electricity intermittently, and still pay the same price as if they had consumed the kWh’s continuously. This has contributed to the illusion of wind power with their claims of competitive prices per kWh

  3. Jerry! you may have hit on the answer – people wishing to buy only wind-based electricity should get cut off when the wind doesn’t blow! Wind’s irregularity of supply matched by imposing it on willing portions of the demand population – and no backup required.
    Bit of a problem when (as here) the local city trains claim to run on wind electricity though.

  4. This article, http://www.quadrant.org.au/magazine/issue/2010/7-8/the-great-renewable-energy-rort from a right leaning Australian political magazine says, combined cycle gas turbines will save more green house gases than wind backed up by open cycle gas turbines – among the usual litany of wind power negatives, written by an accountant it focusses on public costs health etc. I also watched a recent British documentary, BBC-Britains Secret Engineers, that claims that gigawatts of wind farm projects have been put on hold because of blade interference with aircraft ground control radar, military and civilan. Wind power community costs have not been fully recognised.

  5. I get 3-5 MPG better gas mileage just by using cruise control on highway trips over not using it.
    1. The most efficient CCGT’s can NOT be ramped up rapidly, nor cold started.
    2. The least efficient once through gas turbines can do both. Result – more emissions.
    3. Variable generation (wind/solar) creates high reactive currents on the transmission grid. Result – wasted power. Second problem – extra capacitors (big bucks) on the transmission lines to negate the reactive VARs.
    4. Backup and the 10% mandated “excess capacity” units MUST (FERC regulations) be “spinning.” (Hydro, pumped storage and some OTGTs exempted if proven capable.) Result – older, less efficient units running at lower power levels that are even less efficient. FACT: It takes more fuel per kW of power when the generator is at 10-20% capacity than when at 90-100% capacity. For some units this could be 5-10 times as much.

    1. One clarification: Is #3 because wind turbines effectively motor, and therefore effectively act as inductors and “lag” the grid – requiring power factor correction capacitors – when the wind stops blowing?
      Or is it a case of distribution lines to unreliable distributed “resources” (and I use that term loosely) being too small for the generator as unreliable distributed generators aren’t logically located within the distribution system’s topology, leading to I

      1. Yes the turbines will “motor” if making to little power. The protection circuits will have anti-motor trips that prevent them from turning into a big fan, but they will still produce measurable VARs. If you look at a graph of the power generated by wind/solar per hour (or smaller interval) you will note an uneven unpredictable curve. This causes problems with the moving of electricity from one area to another. Just like water goes from the highest pressure to the lowest pressure, electricity goes from the highest voltage to a point of lower voltage. Complicating matters is the fact that the frequency must be maintained (with looser minute-to-minute tolerances than day-today) at 60.000 Hz. When a windmill/solar panel puts out more voltage, unexpectedly, voltage goes up in that area and some other power plant speeds up increasing frequency and creating VARs and wasting power. Conversely when the output of these highly variable sources goes down, voltage drops in this area, electricity moves to this area and away from where they were trying to move it to (some other county or state) and the base-loaded plant now slows down, creating VARs again, wasting power (actually the fuel needed to create this useless “work.”) On most transmission grids a plant that creates “capacitive” VARs is helpful, if created when and where needed, as most of the VARs are reactive and that is the reason for the large capacitor banks. The utility I worked for has sold electricity to areas several states away. This requires the dispatchers in each area along the way to push electricity in that direction. No, I don’t think our electricity ever gets to the place we sent it to, it is more like the volunteer fire departments each moving to the hole left behind when one is needed to cover a big fire, and our electricity is actually used right next door. Variable, erratic power sources will aggravate the problem of moving the electricity, just like another fire would cause the volunteer fire companies problems when covering for another station.
        Solar, wind will “help” if used on a local limited bases, such as, running pumps for water treatment, storage, purification, etc. other locally consumable manufacturing process, or “off-grid.” The big, unrealized, problem is the integration. The core blog is just one aspect of the problem. There are many others. And, to our determent, just like one of my sons could only learn by making the mistake himself, the environmentalists will not accept the facts until we spent several billion dollars and the data shows that it creates more problems than it is worth.

    2. There is actually a chart showing this to be true, Rich. It is a long URL:
      http://books.google.com/books?id=9PSBHgqBpFYC&pg=PA252&lpg=PA252&dq=combined+cycle+heat+rate+
      Kehlhofer&source=bl&ots=5pTlhHRYch&sig=BgPvy2COetgKOcoKka-j2kDAV4&hl=en&ei=TRQBTYKSIIWCsQ
      PSp-yvCw&sa=X&oi=book_result&ct=result&resnum=5&sqi=2&ved=OCCwQ6AEwBA%23v=onepage&q&f=fals
      e#V=onepage&q&f=false
      Combined-Cycle Gas and Steam Turbine Power Plants
      by Rolf Kehlhofer, See Page 211
      Given the rule of thumb that CC is 50% more efficient than CT, the CC curve gets a 50% boost – or the CT maximum efficiency is 67% – take your pick. What I need is to understand the maximum ramping slopes of the most efficient CC units, and the (incremental) heat rate penalties at various slopes. With this info, we can improve Kent Hawkins model as well as make some high level statements proving the net fuel and emissions savings of wind energy. Ofcourse the empirical way is to convince PUCs and ISO/RTOs to make uniform dispatchability rules for all generator types in order to get interconnection approval. That rule would force a gas plant (or storage or hydro facility) to be located behind the main transformer at each wind facility. Now you have a competitive scenario – capacity resource vs. capacity resource. All in cost can be compared, and emissions can be measured. Checkmate.

  6. As an electrical power systems engineer, I feel the need to clarify some points:
    Wind turbines do not operate in the motoring regime. The control systems are structured such that they are always injecting positive real power into the system. Motoring, by definition, requires drawing real power from the grid. Wind turbines will never operate like this.
    Fixed speed wind turbines, which are generally old models that are no longer being installed, did have problems requiring reactive power support. These older wind farms typically had capacitors installed nearby to provide this reactive power. New wind turbines have extensive power electronics that mostly avoid reactive power problems. Specifically, the doubly fed induction generators (DFIGs) that are installed on the majority of new turbines can control their reactive power over wide ranges of injections, both lagging and leading. Many plans for the next generation of wind generators call for converting all the power from the turbine thorough power electronic systems. Both DFIGs and these generators make wind turbines an asset to reactive power support from the grid operator’s perspective.
    There are many reasons to question the grid impacts of wind power, but reactive power problems are not a major concern for modern wind turbines.
    Rich, I think you need to brush up on your knowledge of power systems behavior. In an AC system, real power does not necessarily flow from higher voltage to lower voltage magnitude. Rather, real power flows from buses with higher voltage angles to lower voltage angles. Voltage magnitude is much more closely associated with reactive power injections.
    For a better discussion on reactive power, I would recommend the Wikipedia page: http://en.wikipedia.org/wiki/Reactive_power or a power systems text, such as Power system Analysis and Design by Glover, Sarma and Overbye (chapter 6).

    1. @EE – It may be a fable, but I have been told a story of at least on turbine that does motor quite regularly. It is a large turbine in the parking lot of a major wind turbine supplier factory that happens to be located right next to a major highway. Because of the turbine’s visibility to highway travelers, the company decided it would not be good to show people just how regularly the wind does not blow and the blades do not turn. To prevent their expensive “billboard” from becoming a negative, the marketing arm of the company told the engineers to make sure that the turbine never stopped turning. It is thus a motor more often than it is a generator.
      Also, please correct me if I am wrong, but aren’t there some auxiliary systems in all large turbines that need to be kept operating even if the turbine itself is locked due to either high or low wind conditions? I am thinking of lubrication systems and, in some cases, heating systems to keep the turbine ready in case a breeze develops in the middle of icing conditions.

      1. @Rod:
        I don’t doubt there are some turbines that do operate as motors occasionally for when the bigwigs come to visit, or as advertisements. But clearly the vast majority of the turbines do not motor.
        I know far more about the generators and power electronics on wind turbines (the high power components) than any other pieces of the turbines. There may very well be some auxiliary systems that must run even when the turbine is locked. But again, I don’t think this is an effective criticism of wind turbines. I can’t imagine that the auxiliary systems are more than a negligible portion of the turbine’s output. Other generation plants clearly have similar requirements for auxiliary power. Although I don’t have the numbers easily available, I would imagine that wind power’s auxiliary power requirements are significantly below those of other generation technologies.
        @ Rich
        I realize that my explanation was not geared toward someone without any training in electrical engineering. My apologies for that. Unfortunately, I do not have the time to put together a more accessible explanation, particularly since the normal “water in a system of pipes” analogy doesn’t really hold when dealing with reactive power.
        Here’s my best attempt at answering your questions (again, my apologies that this isn’t more accessible).
        1. No, creating VARs using power electronics does not require additional input power. Reactive power is related to the phase shift between the voltage and current waveforms. Power electronics allow you to inject current at whatever phase angle you like (within the current limitations of your power electronics), and thus control reactive power injection.
        2. Modern power electronics can respond very rapidly (on the order of milliseconds or faster) when compared to the dynamics of wind speed (seconds). The control system can be configured to essentially immediately decrease the reactive power injection to respond to voltage increases, or conversely increase the reactive power injection to respond to voltage sags. Power electronics therefore act to stabilize the voltage magnitude in the grid. More sophisticated control systems are always under development, but these don’t have a large capital cost (control systems are implemented in relatively cheap digital chips). The power electronic devices themselves are made of semiconductors which have had a trend of increasing capability and decreasing costs for the last few decades. In any case, they don’t make up a very large portion of the total cost of a wind turbine.
        3. Clearly, there are challenges to dealing with wind power. I do not want to downplay that at all. There are real costs to integrating large quantities of intermittent resources, and in many (most?) cases these costs are not borne by the wind turbine owners. However, the reactive power concerns you are voicing for wind power are not the main problem facing transmission engineers. The power electronics in modern wind turbines can in fact strengthen the reactive power support in a system. Again, that is not to say that a system with a large proportion of wind power is more stable overall. It probably isn’t. However, the reactive power support of a system with a large penetration of wind generators can be very strong.
        4. No, I am in no way associated with wind power companies of any kind. I am an electrical power systems researcher at a large university. I am not specifically working on wind turbine research, but I do have some level of understanding of the technology they use.
        For the record, I am a strong advocate for nuclear power. I don’t think we will achieve our national goals of moving toward energy independence, decreasing environmental impact, and providing globally competitive electricity prices without a strong and near term commitment to new nuclear plants (both large and small). Rod, I love reading your blog. One of the characteristics I really value is your commitment to engineering precision. Criticizing (modern) wind turbines for supposed reactive power issues is just not factual. There are plenty of reasons to criticize wind power; focus on those that are truly problems.

        1. @EE – thank you for the detailed technical information about the ways that modern power electronics can eliminate the issues of reactor power from wind turbines.
          Are all of the major wind turbine manufacturers using those kinds of controllers in their new machines?
          When did these controllers enter into large scale use in the market?
          (I read about the reactive power control issues in trade publications aimed at grid operators, so I am wondering if they were just whining or if the problem was real but getting fixed. If some of the lower cost turbines are not as sophisticated as others, perhaps that is an issue that needs to be discussed publicly so that wind farm developers are encouraged to take a step up. The situation you describe might be something like anti-lock breaking systems, which 10 years ago were only available on cars at the top of the automotive lines.)

          1. @ Rod
            The latest data I have, which is according to a Professor here, is from 2008. It shows that DFIG type machines with a significant level of power electronic capability were approximately 65% of new installations in 2008 (I believe this is based on new installed capacity). Machines that convert all power through power electronics are about 15% of new installations that year. Fixed speed turbines, which don’t use power electronics and potentially have issues with reactive power support, are about 20% of new installations. The installation of fixed speed turbines is on a downward trend, so that 20% has probably decreased by now. Unfortunately, I don’t have much data beyond that, or any data on different generations of wind turbine controllers.
            I also talked last night to a friend who works at an ISO out east about this issue. He said that new turbine controllers typically have impressive capabilities, where they can essentially act as static var compensators (SVC) that help support reactive power. The problem they are having with these devices is that apparently some number of the wind turbines are not properly configured to take advantage of these capabilities. With the huge increase in wind installations, I wouldn’t be surprised if some of them were not properly configured. Perhaps this is what the the trade publications are complaining about? If that is the case, it is clearly not a technical problem but a knowledge problem.

    2. @EE
      The majority of the readers here do not have an EE degree, many do not have even have a BS degree, and thus need a simplified explanation. I thought I provided an adequate, yet simplified, explanation, and indicated that the windmill would not actually become a motor and turn into a fan. I am sure that you know that it would take several paragraphs to provide a good explanation of how AC power is actually moved from one area to another without creating even more questions.
      Questions.
      Is it not true that if the wind turbine is controlling VARs it is then using wind energy (fuel) to create these VARs and thus wasting fuel? Doesn’t this decrease the total efficiency (output) of the wind-farm and raise the total cost of wind generated electricity?
      If all of these wind-farms are automatically controlling VARs, what happens when the wind suddenly increases and more power is dumped onto the grid in that area, while the dispatcher is trying to push electricity to a specific area? (Same question but decrease?) Doesn’t this create the need for more sophisticated control systems? How much will this equipment add to the total cost of my electricity?
      Have you ever tried to control a system as complicated as the average electrical distribution system for the typical utility while some other system on the grid, with a mind of it’s own, is also controlling a portion of the system? Especially one that had a slight positive feedback? Have you ever had a system run out of control and cause un-necessary trips?
      Do you sell/build wind-turbines or work in an electric utility dispatchers office?

    3. EE: A few questions about your post, above:
      1) How can WTs always be injecting positive, real power into the system when they are often not spinning?
      2) How are control systems, yaw and pitch motors and blade and nacelle heaters run without a feed?
      3) There are several publications for modern wind turbines that indicate they cannot black start, which, I believe, would be possible if “control systems (were) structured such that they are always injecting positive real power into the system.”
      4) WRT reactive power, isn’t there an empirical, comparative value metric for this that can be used across all generator technologies? From your comments about reactive power, i am unable to put the value of wind turbine reactive power into perspective compared to a) conventional capacity resource reactive power as a percent of rated capacity or point in time output, or b) full time availability of reactive power relative to conventional sources. Is the reactive power portion of generation from WT held constant over the range of wind speeds needed required for generation?

  7. No illusions about developing fission-powered aircraft?
    For shame, Mr. Adams!
    There’s certainly no technical reason why a nuclear-powered aircraft wouldn’t work: There’ve been workable mark-ups for nuclear-powered turbojets, turbofans, and in one particularly insane case, I dimly recall a closed-cycle nuclear turboshaft. I suspect, though, you were referring more to the difficulties of actually operating a nuclear-powered aircraft safely. No one, to my knowledge, has yet come up with a satisfactory answer: Though my favorite try was a Lockheed project from 1968, which proposed a 1.8GW reactor with 20′ of leaden rad-shielding built to endure a crash into a granite mountain at 400 knots without being compromised. I’d have loved to have been a fly on the wall for the trying to actually test such a claim. (The project was for a 1,120′-wingspan “airborne LHA”. We’re all probably better off that it quietly died in Lockheed’s notes, as trying to actually build such a thing would cause heads to explode.)

  8. I clicked on your Brave New Climate link and was blown away by the comments. Mr. Goggin’s article came up against a brick wall of energy expertise, and was found wanting. Good read.

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