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Texas teamwork solving bottlenecks -- Transmission congestion

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Transmission bottlenecks in West Texas are causing curtailments of as much as half of the wind generation in the region, but that could soon change as the state's utilities and its grid operator combine forces to clear the path for more development. About 950 MW of wind is now online in Texas, with an additional 800 MW to be added in 2003.

The congestion is the result of a huge and rapid response to the state's renewable portfolio standard (RPS), combined with a transmission grid designed to deliver far fewer megawatts to East Texas population centres. The RPS requires 2000 MW of renewables in the state by 2009, with 1000 MW online by the end of 2003. In 2001 alone, developers built wind projects exceeding 900 MW.

The projects are located in remote areas of Texas and were built much faster than transmission providers can build lines, says Bill Bojorquez at the Electric Reliability Council of Texas (ERCOT), the regional transmission organisation that oversees 85% of the state's grid. "We compensate the wind generators for the curtailment and allocate the costs to all other grid users," says Bojorquez, a solution it sees as temporary.

ERCOT, he says, would prefer to build transmission upgrades to fix the bottlenecks. Texas utilities have already begun the process, methodically shoring up transmission routes to reduce the likelihood of more curtailments and to build capacity for more wind development.

Improved lines

Utility TXU, which has five million customers and 13,000 miles of transmission lines, is the largest single buyer of wind energy in Texas. It buys 384 MW from Texas wind farms, and will buy another 240 MW from Cielo Wind Power's Noelke Hill Wind Ranch by September 2003. TXU's transmission unit, Oncor, is working with American Electric Power (AEP) and the Lower Colorado River Authority (LCRA) to improve four 345 kV lines that will help move power from the Cielo project, and others, in the west of the state. In fact, the upgrades will add enough transmission to nearly meet the state's 2009 RPS goals, if all wind continues to be located in West Texas.

Oncor has completed its 115 mile section of the line ahead of schedule, while the 70 mile section being built by AEP and LCRA is in progress. AEP is the largest owner of wind projects with about 390 MW, all located in West Texas. LCRA, a state agency that provides power and water in central Texas, buys nearly 130 MW of wind energy.

AEP's Stephen Williams says his company and LCRA are also building smaller transmission lines from McCamey, the centre of Texas wind development, to Odessa and San Angelo, part of a hub and spoke system which he says will give more immediate and local relief from curtailments. A later project that will not be completed until after 2007 is the $200 million San Angelo and McCamey line, which could clear the way for up to 2000 MW more wind. So far there are no further wind projects with signed interconnection agreements before 2007 once next year's batch is built.

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