The study, however, noted that the far-less-expensive Chakachamna project faces uncertainties and gathering data on Susitna should not be abandoned until its feasibility is resolved. The study has been eagerly anticipated, and the governor and Legislature will use it in weighing policies and spending on Railbelt energy projects.
"If we had to pick a winner today Chakachamna looks better," said Joe Balash, an energy aide to Gov. Sean Parnell, discussing the results of the study Friday.
But Balash said far more is known about the Susitna project, including regarding costs, and it could be a mistake to stop working on it and have Chakachamna not pan out.
The long-held dream of a huge hydro project on the Susitna River had been rapidly regaining momentum in recent years. Some legislators have pushed it as the solution to Alaska's power needs and spoke of state financing for the project. The goal of Alaska achieving 50 percent of its electricity from renewable sources by 2025 also helped push it to the forefront of the energy debate.
But the study released Friday from consultant Black and Veatch, an international engineering and construction firm, found the designs for the Susitna dam drawn up in the 1980s would provide more power than the Railbelt is projected to need. A scaled back Susitna project would better fit the need, according to the consultants, but still would not be as cost-effective as the proposed Chakachamna project.
The Black and Veatch report found, though, "significant uncertainty" with the Chakachamna project, and said it could fail because of licensing or technical issues. The consultants call for continuing to study Susitna until development potential of Chakachamna and a small Glacier Fork hydro project on the Knik River is clear.
"Glacier Fork, Chakachamna and Susitna should be pursued further to the point that the uncertainties regarding the environmental, geotechnical and capital cost issues become adequately resolved to determine if any of the projects could actually be built," their report said.
The state has a goal of 50 percent renewable electricity by 2025, first laid out by then-Gov. Sarah Palin a year ago, that would likely need Susitna hydropower if the Chakachamna project doesn't happen, the report said.
The Legislature appropriated $2.5 million for the Black and Veatch study, which resulted in the highly technical report released Friday that's hundreds of pages long.
Fairbanks Democratic Sen. Joe Thomas, who sponsored the money for the report in the Senate, is one of the biggest boosters of Susitna power in the Legislature.
Thomas said Friday he has doubts about the report's conclusions but needs to finish going through it to fully understand the reasoning. Thomas said he is afraid the report might bury Susitna support in favor of a Chakachamna project that could never happen.
"I don't think anything actually compares to (Susitna) for the generating capacity and the price per kilowatt hour," said Thomas, who is a member of the Senate special committee on energy.
The report found a Susitna dam project could cost between $4 billion and $10 billion to build, depending on its location and configuration.
The developer of the Chakachamna project pegs its construction cost at $1.6 billion.
That project would be about 85 miles west of Anchorage. Engineers would drill into the bottom of Chakachamna Lake and funnel water down a 10-mile long tunnel. The idea is that the water would descend nearly 1,000 vertical feet to a huge underground powerhouse where it would jet past turbines and produce 1,600 gigawatt hours of electricity for the Railbelt grid each year. A 42-mile transmission line would run from the site to Chugach Electric's Beluga substation.
The developer is Pribilof-based TDX Power, a Native-owned firm that's backed other renewable energy projects in Alaska.
The Black and Veatch report took a broad look at power generation in the Railbelt, far beyond just the potential of hydro projects. One conclusion drawing notice is its recommendation that the Healy Clean Coal plant remain mothballed "for the foreseeable future" until it becomes clear if new carbon dioxide regulations will be enacted and how they would impact the economics of it.
The $300 million plant was built with state and federal funds in the late 1990s as an experimental "clean coal" technology effort. It has not operated since 2000 after mixed results from startup tests and a dispute between the state's Alaska Industrial Development Export Authority and Golden Valley Electric Association of Fairbanks.
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