Quick reaction averted blackouts on the Texas grid last month, but the incident served as a reminder of the possible risks of relying too much on wind energy for electricity.

Officials of the Electric Reliability Council of Texas (ERCOT) say the grid on Feb. 26 experienced a sudden drop in the system frequency, which was caused by a combination of events, including a drop in wind-energy production just as the evening electricity load was increasing. Wind production fell in a few hours before sunset from more than 1,700 MW to 300 MW. Contributing to the difficulty, multiple power providers fell below their scheduled energy production.

The situation prompted the reliability organization to move immediately to the second stage of its emergency plan, which includes dropping customers who have agreed to service interruption in exchange for lower rates.

This was not the first or even the worst such incident in ERCOT’s area, says Dottie Roark, ERCOT spokeswoman. Of 82 alerts in 2007, 27 were “strongly correlated to the drop in wind,” she says. She could not compare the rate for alerts in 2006 because the measurement criteria were changed after rolling blackouts in April of that year. “We don’t have backup generation for specific plants,” she notes. Instead, ERCOT procedures require the system to maintain 3,000 MW of reserves, including the interruptible customers.

With 4,300 MW, Texas has more installed wind-energy capacity than any other state. A state law in 2005 requires utilities to obtain 5,880 MW of their power from renewable energy sources by 2015 and 10,000 MW by 2025. Still, wind energy generates only 3% of the state’s electricity, notes Terry Hadley, spokesman for the Public Utilities Commission of Texas.

With renewable energy looming large on the horizon, ERCOT is conducting workshops and studies to understand the complexity added to grid operation by wind energy. The organization also will improve its forecasting with a service that provides more specific information about availability of wind resources.