United States

United States

Texas gets close to transmission wall -- Goal already nearly met

With Texas set to reach its goal of 2000 MW of new renewables three years ahead of time, state lawmakers are considering whether to up the ante. Transmission constraints, however, are likely to play a role in setting any new target.

The original renewables portfolio standard (RPS), passed in 1999, called for 2000 MW of new renewables by 2009. Since then, Texas has added 1190 MW -- an estimated $2 billion investment. Another 486 MW is either under construction or has been announced -- and transmission agreements are final for an additional 720 MW. Wind accounts for approximately 96% of the total and new projects are expected to be fast-tracked to be completed this year to take advantage of wind's production tax credit (PTC), which is set to expire December 31.

Lawmakers are now considering where to go next. Legislation being formulated includes bills for the state to have 8% renewables by 2015, 10% by 2025, and 20% by 2020. The 1190 MW resulting from the RPS so far is equivalent to about 3% of the state's total generating capacity.

The 10% by 2025 goal was proposed by the Texas Energy Planning Council in December and has the support of the Association of Electric Companies of Texas, representing existing utilities. The legislature must act by May 31 or face the prospect of no change to the goal until lawmakers meet again in two years. The stumbling block could lie in transmission capacity.

Many wind projects lie in a 100-mile wide corridor of West Texas stretching from Abilene to Odessa. Two concerns with that location are first, that much of the state's demand is in its more populous east, requiring transmission to get it there, and second, winds in West Texas are light during the summer on-peak hours, undermining the system's reliability.


The Electric Reliability Council of Texas (ERCOT) administers the Texas power grid, which covers about 85% of the state's electricity load. "We're a big supporter of clean energy," says its director of transmission services, Bill Bojorquez, noting that ERCOT worked with lawmakers to set the original 2000 MW target and is involved with legislative discussions to determine a new target.

Bojorquez says the existing transmission grid can accommodate 2000 MW of wind moving from West Texas to the east. Another 30,000 MW of thermal generation also moves on the grid from that region. Any additional generation would likely require transmission upgrades, says Bojorquez, estimating the cost to transmit an additional 5000 MW of wind from West Texas to the urban east could reach $1 billion.

But even with additional transmission capacity, peak demand is a factor. During the hot Texas summer it reaches about 60,000 MW. Winter peak is about 40,000 MW. The West Texas winds, however, tend to die down during the summer, says Bojorquez. "We're concerned that wind has a very low on-peak value as a reserve because we don't historically see it providing much on-peak output on hot summer days. When we have our hot days and highest demand, typically we have low wind."

ERCOT estimates that wind output during the summer peak hours is only about 10% of its full load, but is conducting more rigorous studies to determine whether even that may be too high. "If the on-peak value is small we may need to build even more transmission," says Bojorquez. More transmission allows more projects to be built, so that more generators are available to supply on-peak power.

One piece of good news is that ERCOT studies indicate 300-900 MW of wind could be carried on the existing grid from potential wind generation sites on the state's Gulf of Mexico coastline at Galveston, South Corpus and South Padre Island. Even higher generation levels could be achieved if high voltage transmission systems were upgraded in those locations.

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