Operators of the state power grid scrambled Tuesday night to keep the lights on after a sudden drop in West Texas wind threatened to cause rolling blackouts, officials confirmed Wednesday.
At about 6:41 p.m. Tuesday, grid operators ordered a shutoff of power to so-called interruptible customers, which are industrial electric users who have agreed previously to forgo power in times of crisis. The move ensured continued stability of the grid after power dropped unexpectedly.
Dottie Roark, a spokeswoman for the power grid, said a sudden uptick in electricity use coupled with other factors and 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 said in an e-mail notice to municipalities.
Known as the Electric Reliability Council of Texas, the quasi-governmental agency that manages the power grid must ensure that power generation and power use remain constantly in balance. Otherwise, the whole grid can go dark, and the result is a systemwide blackout.
According to ERCOT, those interruptible customers who lost power Tuesday night had it restored by 9:40 p.m.. The interruptible customers are generally industrial businesses that pay less for electricity in exchange for an agreement that they will let ERCOT cut their power during shortages.
Some wholesale energy prices also spiked Tuesday evening – especially in West Texas. ERCOT also reported that the drop in wind power led to constraints on the system between the north part of the state and the west.
Kent Saathoff, vice president for system operations at ERCOT, said Tuesday’s event illustrates the inherent challenges associated with using wind power. Because the wind sometimes stops blowing without a moment’s notice, engineers at ERCOT must remain nimble enough to respond to resulting instability on the grid, he said.
“There is a major workshop going on at our office right now to discuss these very issues,” Saathoff said.
Although he said the emergency event was rare, it is not unprecedented. On April 16, 2006, for instance, a much more serious shortage prompted rolling blackouts across much of Texas. ERCOT officials at that time also ordered power curtailments for the state’s interruptible customers.
That 2006 event was prompted largely by scorching heat coupled with a shutdown of several generators for spring maintenance. This time the shortage was prompted largely by a near-total loss of wind generation, as well as a failure of several energy providers to reach scheduled production and the spike in electricity usage.
ERCOT reported that wind power production plummeted Tuesday evening from about 1,700 megawatts to about 300 megawatts. A single megawatt is enough electricity to power 500 to 700 homes under normal conditions.
The emergency procedures Tuesday night added about 1,100 megawatts to the grid over a 10-minute period, according to ERCOT.
Some critics have said that wind power, although providing a source of clean energy, also brings with it plenty of hidden costs and technical challenges. Besides requiring the construction of expensive transmission lines, the fickle nature of wind also means that the state cannot depend on the turbines to replace other sorts of generators.
“This is a warning to all those who think that renewable energy is the sole answer [to the state's power needs],” said Geoffrey Gay, an attorney representing Fort Worth and other North Texas municipalities in utility issues. “We can’t put all our eggs in one basket when it comes to any form of generation. We need to consider the cost and the reliability issues, in addition to the environmental impact.”
Susan Williams Sloan, a spokeswoman for the American Wind Energy Association, said those technical challenges are not insurmountable. She said part of the solution is to locate turbines in diverse areas of the state. “When the wind is not blowing somewhere, it’s always blowing somewhere else,” she said.
Sloan also said that technological advances will make it easier in the future to forecast wind energy.
About 4,356 megawatts of wind turbines are currently installed in Texas, she said.
By R.A. Dyer
28 February 2008