A divided Public Utility Commission gave preliminary approval today to construct $5 billion in transmission lines to bring wind power from West Texas to urban areas.

The project is expected to cost average household consumers about $4 a month.

It should boost the state's wind farm business, already the largest in the nation, to even greater levels. It would increase capacity for wind generation to 18,456 megawatts.

The plan, which is expected to be finalized later this month, is a middle ground between five scenarios ranging from $3 billion to $6.4 billion.

Chairman Barry Smitherman and Commissioner Paul Hudson supported the transmission proposal, but Commissioner Julie Parsley said she is concerned about putting too much wind into the state's power system.

Wind doesn't blow all the time and sometimes will increase or drop off dramatically, potentially putting stress on the grid, known as the Electric Reliability Council of Texas.

"I worry about the reliability of the system," said Parsley.

Tom "Smitty" Smith, Texas director of Public Citizen, said Texans will ultimately benefit from higher levels of renewable energy.

"What this will net is significant long-term savings because we will not be burning nearly as much natural gas, and it will reduce the overall cost of electricity," Smith said. "It also will create significant new jobs and reduce pollution in our urban areas."

A limited government group said the plan is too expensive, and will have to be backed up with even more natural gas power plants.

"The costs of building those new transmission lines should be borne by the companies who develop the wind and solar farms, as well as the consumers who purchase that energy. They should not be socialized across every ratepayer on the ERCOT grid," said Drew Thornley, a policy analyst with the Texas Public Policy Foundation.

janet.elliott@chron.com