Transmission lines are chasing the rapid growth of wind generation across the nation, but it may be a while before they catch up.
Billions of dollars in transmission lines will have to be built before the nation's wind resources, which are concentrated in the center of the country, can be fully exploited by large population centers to the east and west.
In the meantime, regulators, generators and utilities have to deal with transmission congestion and wind curtailments, the temporary shutting down of generation to maintain system balance and reliability. Those hurdles increase the costs of renewable energy and decrease its environmental benefits.
Steve Gaw, a transmission policy specialist with The Wind Coalition, a trade group in Austin, Texas, said investment in transmission across the nation has been lagging for several decades. That changed only in the last five years as wind generation began coming online in a major way.
A combination of favorable tax treatment for wind generation and state mandates for renewable energy pushed the nation's wind capacity to more than 60,000 megawatts in 2012, according to the federal Energy Department. That's enough to power 15 million homes.
Oklahoma ranked sixth among states for wind capacity last year, up from eighth place in 2011. New power purchase agreements for wind generation in the state are increasingly being signed with out-of-state utilities. Meanwhile, the Southwest Power Pool, a regional transmission organization covering 15 million people in Oklahoma and parts of eight other states, has more almost 27,000 megawatts of wind generation in service or ready to come online in the next few years.
“The best wind resources tend to be at the western side of the (SPP) footprint,” Gaw said. “Those were areas that generally didn't have much (customer) load, so the transmission wasn't as developed. That has been changing in a significant way.”
Developers can build wind farms much faster than new transmission. The typical wind farm needs thousands of acres, but the parcels of land are easier to combine for a wind project than the rights of way for transmission lines.
“It may be economically and environmentally efficient to build excess capacity into certain transmission projects given the scarcity of rights of way and the challenges of developing location-constrained renewable energy resources without existing transmission,” the Washington-based Bipartisan Policy Center said earlier this year in a report on grid modernization.
Some grid projects are bypassing regional transmission organizations altogether. Clean Line Energy Partners LLC has five high-voltage, direct-current transmission lines planned for renewable energy in various parts of the country, including the Plains and Eastern Clean Line. It will take power from planned wind farms in the Oklahoma and Texas panhandles and western Kansas and transmit it directly to the western Tennessee for utilities in the southeastern United States. The company also may deliver electricity to customers in Arkansas using an “off-ramp” from the line.
Clean Line said in August a survey of wind companies showed they could develop up to 16,000 megawatts of capacity for the Plains and Eastern Clean Line. That represents more than four times the 3,500 megawatts planned for the 700-mile transmission line, which is still in the environmental impact and siting stage. The $2 billion line could be operational by 2017 or 2018, the company said.