Aaron Thorup, Duke-American Transmission Co.

SALT LAKE CITY — A massive $8 billion project that would produce more than double the amount of energy generated by Hoover Dam taps some of the most unique and deep salt caverns found in the world — just outside of Delta in Millard County.

The salt domes for compressed air energy storage are the biggest structures of their kind west of the Mississippi and figure as central components of a four-company green-energy project detailed in a Tuesday teleconference by company executives.

Construction of one of the nation's largest wind farms is planned for 40 miles outside of Cheyenne, Wyoming, to ultimately deliver enough electricity to power 1.2 million homes in Southern California.

The green-energy initiative involves Pathfinder Renewable Wind Energy, Magnum Energy, Dresser-Rand and Duke-American Transmission, which plan to submit their proposal to the Southern California Public Power Authority by early 2015 in response to the agency's request for proposals to supply the Los Angeles area with renewable energy and electricity storage.

"This project would be the 21st century's Hoover Dam — a landmark of the clean-energy revolution," said Jeff Meyer, managing partner of Pathfinder Renewable Wind Energy.

A 525-mile direct-current transmission line would take 2,100 megawatts of electricity produced at the wind farm for storage in the salt caverns in Millard County built by Salt Lake City-based Magnum Energy.

The energy would be converted to compressed air and stored in four caverns a quarter-mile deep during periods of low demand. At peak, the facility would use the stored, high-pressure compressed air, combined with a small amount of natural gas, to power eight generators to produce electricity.

The caverns have already gone through federal, state and local regulatory hurdles for the appropriate permits and await the permitting process to play out for the transmission line, which is expected to take about four years.

Chris Jones, managing director of business development with Duke-American Transmission, said a preliminary route for the high-voltage transmission line has been identified after the conclusion of a large right-of-way study, outreach and meetings involving multiple federal agencies, impacted counties and state officials.

"In this federal permit application, we have taken a bit of a different approach because we wanted to have a well-informed route with an opportunity for feedback from agencies and others before we make our applications," Jones said.

Jim Heid, senior vice president of Dresser-Rand, said the project represents an "alignment of the planets" by being able to tap into the incredible wind resources of Wyoming for storage of electricity in a fantastically unique geologic feature in Utah.

"It is a unique formation of dome salt, very deep, very thick and very rich in salt, which lends itself to be mined out to form these great caverns," Heid said. "If it was located anywhere in the world, we would be looking at it for its ability to handle the pressures and the volume and its long-term ability to store that amount of air."

The project, which has a target completion date of 2023, would generate more than twice the amount of electricity produced by the 1930s-era hydroelectric dam in Nevada — 9.2 million megawatt-hours per year versus 3.9 million megawatt-hours.

Proponents say the storage caverns outside of Delta would allow the renewable energy project to overcome the intermittent nature of wind and solar power because the Millard County facility could be cranked up on demand to meet customer needs in Southern California.

The electricity would then be delivered to California via the existing 490-mile-long transmission line at the Intermountain Power Plant.

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