There are no viable substitutes for the longest segment of a controversial proposed transmission line through the Hill Country, the state grid operator reported today.

In a filing today with the Public Utility Commission, the Electric Reliability Council of Texas, known as ERCOT, wrote that it found "no effective alternatives" to the big line, which would run for at least 130 miles between a yet-to-be-built substation called McCamey D in Schleicher County to the Kendall substation near Comfort.

The proposed line is part of a $5 billion transmission-line build-out planned by the state to aid the development of wind power, which is generated in West Texas but needed in cities in Central and East Texas. There are so many turbines now that during windy times, some of the machines must shut down because there are not enough wires to transport the power.

However, the grid operator found that another, shorter segment of the same line — which would run about 30 miles run from the Kendall substation to Gillespie County — could be done far more cheaply by upgrading the Kendall substation. That upgrade would cost $8 million, compared with $54 million for the new wires.

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For the longer segment — from McCamey D to Kendall — ERCOT's findings will be a blow to Hill Country residents, many of whom are trying to keep the line out of their scenic patch of Texas. It also appears to be a setback for a major Florida renewables developer, NextEra Energy Resources. Last year, NextEra built its own transmission line, separate from the statewide process, to bring wind energy from a huge wind farm it operates in Taylor and Nolan counties to the Kendall substation. State Sen. Troy Fraser, R-Horseshoe Bay, had pushed for a study of whether the NextEra line could serve as a substitute for the state-planned line. The ERCOT study found that it would not be.

The transmission arm of the Lower Colorado River Authority, or LCRA, aims to build both segments of this line, collectively known as McCamey D to Kendall to Gillespie. ERCOT has previously found that a different LCRA line proposed for Hill Country, running from Gillespie to Lampasas County, could be done more cheaply by upgrading existing infrastructure.

Without the McCamey D to Kendall to Gillespie line, roughly 1,834 gigawatt-hours per year of wind power — enough for about 153,000 households — would be unable to reach the people who need it, according to the study.

The filing should be available soon on the Public Utility Commission website.

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