What Causes a “Rolling Blackout”?

By Vernon Trollinger, September 8, 2011, Energy Efficiency, FAQs

Rolling Blackouts happen when generation from Texas Electricity companies can not keep up with electrical demand. In order to prevent a cascading grid failure, the system operator —in this case, Electricity Reliability Council of Texas (ERCOT) —shuts down different sections of the grid until enough generation capability is restored to use.

This prevents overloading generators and transmission lines and damaging them. Texans saw this happen back on February 2, 2010 when cold temps caused 50 power plants to fail. ERCOT was forced to use 8 hours of rolling power blackouts to head-off a cascading system failure like the Great Northeastern Blackout of 2003.

This summer’s hot-hot-hot temperatures drove the use of electricity in Texas into the record books. ERCOT’s capacity to provide reliable electrical service to the Texas grid strained under the load. While much of the demand was air conditioning, part of the problem in supplying electricity lay in the transmission lines themselves. When electricity is passed through a wire, it’s natural electrical resistance causes the wire to get warm. Multiply this by several thousand watts and add to it temperatures over one hundred degrees and even thick transmission lines get hot. In fact, they even expand from the heat and sag towards the ground. If that hot wire hits a tree and shorts-out, a whole neighborhood or town loses power. If the same thing threatens to happen all over the powerline network, ERCOT’s job to get power from a powerplant to your computer gets a whole lot more complicated.

So, what can you do? Cut back on your electrical use as much as you can on days when ERCOT issues a conservation warning. When everyone helps to conserve, they help ensure that there will be no interruption of power or damage to transmission and generation plants (which could take days to repair). Remember, you can stay informed by checking out ERCOT. You can follow Oncor on Facebook or on Twitter. You can also get information from Bounce Energy on our Facebook page or on our Twitter feed.

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