A Grid Manager’s Nightmare

By Ed Caryl

The California Independent System Operator (ISO) manages the high-voltage wholesale power grid for the state of California. On their web site, they have several links including one to yesterday’s hourly breakdown of power usage and sources. The figures below are for May 25 2011.

Figure 1. The hourly breakdown of renewable power fed to the California grid. Source: California ISO.

In California, most wind power is generated in three high wind locations: Altamont pass east of San Francisco, Tehachapi pass east of Bakersfield, and San Gorgonio pass near Palm Springs. Notice the huge drop in the wind farm output centered on 10 AM local time. The wind power output at all the wind farms dropped from over 1800 Megawatts to less than 200 Megawatts in less than six hours. Solar power picked up about 400 Megawatts of that, but solar had a glitch of it’s own at about 5 PM, when a cloud obscured the sun at the major solar plant in the Mojave Desert. The grid had to replace this power, just when the load was reaching maximum in the middle of the day. Where did the backup power come from? As you can clearly see in figure 1, none of the backup power came from a renewable source.

Figure 2. The hourly breakdown of all electrical power production in California on May 25th 2011. Source: California ISO, same link as above.

California must import up to 33% of its power, most from thermal and nuclear plants in other southwest states, and some from hydroelectric dams in the Pacific Northwest. As you can see from the plot in figure 2, most of the slack when the wind died came from thermal power plants in California and imported power from other states. Nuclear plants are difficult to throttle up and down, so most of that make-up power came from thermal sources (fossil fueled).

To be available on a moments notice, (or even on a few hours notice) thermal power plants are on “standby” status. In most cases this means that they have turbines already turning, feeding minimal power to the grid, so that they can be “throttled up’ quickly. The fastest responding are the natural gas powered plants. Coal powered plants take a bit longer to be fired up.

Planning is a big part of managing a power grid. The load can be predicted with good accuracy. Even fluctuations in temperature affecting load are predicted more than 24 hours in advance. But wind is more difficult, and clouds over solar plants more difficult yet. Today’s wind, for instance, is fluctuating over a scale of minutes, giving power output fluctuations of 200 Megawatts in 30 minutes. This must be giving the operators headaches.

California plans to build renewable power resources to the tune of 33% by 2020. The Pacific Northwest already has grid problems with Oregon and Washington wind farms. California will need three to five thousand Megawatts of reserve fossil fueled or hydroelectric plants to back up the renewable power resources. Given the May 25th 2011 wind power glitch, that may be low.

10 responses to “A Grid Manager’s Nightmare”

  1. R. de Haan

    This is a great example making clear why wind and solar power isn’t really power at all. It doesn’t provide a reliable base load and is in constant need back up.

    Better to use conventional power generation and have a healthy economy instead.

    And mind you, this is California.

    Do you see the disaster if this model is applied in Germany?

    It’s a fata morgana.

  2. T. G. Watkins

    You may be interested in this site which gives UK electricity generation by fuel source in near ‘real’ time.
    Rarely does wind power exceed 30% of installed capacity and not infrequently less than 5%! It is not uncommon for the UK grid to receive more from the interconnector from France (nuclear) than wind.
    It makes one question the sanity of our political leaders and the complete ignorance of the MSM.
    A small protest against windfarms and new powerlines took place outside the Welsh Assembly on Tuesday which was reported in a small way.
    Regards G.

  3. dave ward

    Just go to this one: http://www.bmreports.com/bsp/bsp_home.htm
    And scroll down to “Generation By Fuel Type (table)”

    It is known that these figures only cover about half the UK windpower sites, but still give a good idea of what’s happening at any one time. Currently it is 1128Mw or 2.9%, but I have a screen capture from the Christmas period last year when it was a pathetic 28Mw…

  4. biggreenlie

    World wide instability of electrical supply is the true results of the Green Mantra that is spouted by the U.N. and it’s tentacles that made up by the NGO’s and fake Green supporters like Gore and his ilk!

    End game?…….massive amounts of money to be made from another fake “bubble” called “Green Energy” by “greed mongers” in the investment community!

    1. Create a crisis
    2. Manage the crisis
    3. Put forward a “cure” for the crisis which involves “massive takeover of resources and lands”

    1. DirkH

      The “cure” for the crisis must be designed in such a way that it pretends to solve the problem but in reality exacerbates it. This is the case with photovoltaics. It pretends to produce clean electricity but does so in homeopathic doses while it consumes massive amounts of conventional electricity and other forms of energy to be created in the first place.

      1 W peak production capacity costs you about 3 Euros ATM, half for the modules, half for inverter and installation. This will produce 800 Wh over a year in Germany, equalling electricity worth 4 Eurocent in bulk prizes; giving you a ROI of 1.3 %; less than the inflation. (The owner will be compensated through subsidies, but that is money taken from other peoples pockets, so the economy as a whole gets a ROI of 1.3%.)

      1. DirkH

        …hmm, 1.3% is the interest rate, not the ROI… assuming a lifetime of 20 years the ROI would be 0.26 ignoring inflation… Now THAT’s bad.

  5. John F. Hultquist

    A related issue has happened in the Pacific Northwest’s Bonneville Power Administration’s (BPA) area where spring snow melt and rain have created a surge of hydropower. Many decisions in this region, not just power related things, are drive by salmon recovery imperatives. When water flows over the dams with a long drop, nitrogen gets incorporated into the water. Less so when water goes through the turbines. Dissolved nitrogen is detrimental to fish so the BPA wants to run the water through the dams, which produces power, and not accept inputs to the grid from wind and solar. Now we have issues!

    From Wednesday, May 18:


    This one on Friday, May 27:


    One of my favorite sayings: You can’t do just one thing.

  6. T. G. Watkins

    Sorry, an extra . may be the problem as site still works for me.
    I find the site helpfully recommended by Dave Ward often has ‘no information available’.

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