Susitna Dam mega project: building new energy for Alaska.

• Author: West, Gail
• Position: BUILDING ALASKA SPECIAL SECTION

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Not often does the opportunity for a mega project present itself--one such as the trans-Alaska oil Pipeline--and even less frequently does the State have control of its fate. The proposed Susitna Dam, however, is such a project. If Susitna becomes reality, and is followed by the proposed natural gas pipeline, the two would bring new energy to the state and its residents and new life to Alaska's builders. Damming the Susitna River to produce hydroelectric energy has been on the table since the 1950s. In the 1970s and early 1980s, the project was proposed as a four-dam system, then scaled back to two dams--one at Devil's Canyon and one at Watana. In 1985, the Federal Energy Regulatory Commission issued a license for the Bradley Lake Dam, and construction began two years later. In 1991 Bradley Lake went online and began producing energy for Railbelt utilities. Its total capital cost was approximately $357 million. Bradley Lake, however, was a much smaller project than the proposed Susitna dam.

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SUPER STRUCTURE

At a projected cost of $4.5 billion, Susitna (at the Watana site) dwarfs Bradley Lake. Compared to Bradley's 125-foot-high structure, Susitna is expected to be 700 feet high. Susitna is also anticipated to be 2,700 feet long at its crest, and would hold back a 39-milelong reservoir that could be up to two miles wide at its widest point, according to Karsten Rodvik, external affairs manager for the Alaska Energy Authority.

"The Railbelt currently uses about 5,300 to 5,400 gigawatt (1 gigawatt is equal to 1 billion watts) hours of electrical energy annually," Rodvik said. "This dam would have an installed capacity of 600 megawatts, its annual energy production would be 2,600 gigawatt hours, which means it would supply about half the Railbelt's electricity needs."

Underlying the new momentum for the Susitna dam is the Railbelt Regional Integrated Resource Plan, which was released in 2010, Rodvik said. The plan looked at long-term power needs for the Railbelt as well as the uncertain gas supplies in Cook Inlet and calculated what that could mean for today's and the future's energy needs.

"Last year, too," Rodvik added, "the Legislature established a new goal for the state to achieve 50 percent of its electrical production from renewable resources by 2025. The only way to reach that goal is with a large hydro project on Alaska's Railbelt. With that in mind, AEA examined both the Chakachamna and the...