Meanwhile, in Texas, a Brief Lull in the Wind

Michael Giberson

On Tuesday this week, while Florida transmission operators were getting everyone back online after a sub-station fire lead to cascading outages around the state, in Texas grid operators were responding to an emergency of their own. A sudden drop off in the West Texas wind produced an almost as sudden drop in wind power generation, from about 1700 MW to 300 MW. The Fort Worth Star-Telegram reported:

Operators of the Texas power grid scrambled Tuesday night to keep the lights on after a sudden drop in wind power threatened to cause rolling blackouts, officials confirmed Wednesday.

At about 6:41 p.m., power grid operators ordered a shutoff of power to so-called interruptible customers, which are industrial electric users who have agreed previously to forego power in times of crisis. The move ensured continued stability of the grid after power dropped to alarmingly low levels.

Dottie Roark, a spokeswoman for the power grid, said a sudden uptick in electricity use coupled with a sudden drop in wind power caused the unexpected dip. As a result, grid officials immediately went to the second stage of its emergency blackout prevention plan.

“This situation means that there is a heightened risk of … regular customers being dropped through rotating outages, but that would occur only if further contingencies occur, and only as a last resort to avoid the risk of a complete blackout,” the State Operations Center stated in an e-mail notice to municipalities.

The episode may embolden wind power critics — the Star-Telegram quotes an attorney as saying, “This is a warning to all those who think that renewable energy is the sole answer” — but I’d rather call it a reminder rather than a warning.

After all, other than some industrial customers who voluntarily shut down, and who are compensated for standing ready to shut down on short notice, no one in the restructured Texas power market lost power on Tuesday night. A rare event happened and from public reports it appears that existing, standard reliability measures at ERCOT, the state’s integrated power market and transmission system operator, were sufficient to keep the system running.

If wind is more susceptible to such swings in output than other generators — and it is — efficient coordination of the power system simply requires ensuring that such generators pay the right price for the additional reserves or other measures needed to maintain system reliability.

And, by the way, as a follow-up story notes, in addition to the sudden drop off in wind generation the ERCOT system was also faced with “a failure of several [other] energy providers to reach scheduled production.” It isn’t just wind that shows some variability in output.

6 thoughts on “Meanwhile, in Texas, a Brief Lull in the Wind

  1. Let’s review:

    Total ERCOT capacity: ~70,000 MW
    Total ERCOT wind capacity: ~ 4,356 MW (~6% of total capacity)

    Wind output before drop: 1,700 MW (~39% of installed wind capacity)
    Wind output after drop: 300 MW (~7% of installed wind capacity)

    Fortunately, this event and the California wind event of 2006 occurred before state RPS were fully implemented. Interruption was sufficient to control the problem. Would it have been sufficient with 20% wind capacity; or, with 20% of consumption from wind? Hopefully the utilities and their regulators will deal with that issue before it arises.

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  3. Thanks for the balanced story. It’s also important to note that when the wind stops blowing and wind farm electricity generation drops, the process usually takes hours. By contrast, other power plants may go out of service instantaneously when a problem occurs. Wind forecasting, which could have helped address the ERCOT situation, can and is being used by utility system operators to manage wind on their systems, and will become standard practice as the use of this clean, renewable energy source continues to grow.

    Thomas O. Gray
    American Wind Energy Association

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