New source of power

With the Lake Dorothy project online, Juneau will have enough renewable electricity to fill needs

Posted: Sunday, September 06, 2009

BART LAKE - The powerhouse at the Lake Dorothy Hydroelectric Project hums as it converts water from Bart Lake, 1,000 feet above in the rugged terrain of Southeast Alaska, into electricity to run Juneau.

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Michael Penn / Juneau Empire
Michael Penn / Juneau Empire

Another 1,000 feet above that, Lake Dorothy has been tapped to bring a continuous flow of water to the power plant.

Test operations for the project 14 years in the making began providing power to Juneau last Monday.

The Lake Dorothy Hydroelectric Project on the south side of Taku Inlet southeast of Juneau is an engineering marvel that surmounted numerous challenges, engineering and otherwise, said Corry Hildenbrand, project manager for Alaska Electric Light & Power.

"This was a tough one; it's definitely a world-class project, he said.

The challenges were many. Steep terrain, wildlife concerns and bad weather combined with a location so remote that much of the equipment, workers and supplies had to be flown in by helicopter.

Instead of building massive dams to hold back water for power generation, electricity companies in Southeast Alaska often tap into existing lakes, drilling tunnels deep into the base to turn the lake itself into a reservoir.

That technology was pioneered in Norway, which has similar landscape of fjords and high mountain lakes, and brought to Alaska, Hildenbrand said.

Lake tap projects don't flood new ground or have the same environmental impact that has devastated salmon runs in the Pacific Northwest and elsewhere.

Just the road from tidewater on the inlet to Bart Lake itself was a challenge. Only four miles long, it required flying drill rigs and other equipment up to the lake so construction crews could work from both ends.

Hugging the side of the gorge, avoiding the creek that flows out of Bart Lake, workers blasted through rock and built up the roadbed, meeting in the middle.

It was expensive, Hildenbrand acknowledged. "You do what you have to do," he said, and the road had to be done.

Eggs in different baskets

As Lake Dorothy was switched on, it made Juneau one of the nation's greenest cities, able to provide for all of its own needs and more with renewable power, said Scott Willis, power generation manager for the utility.

"Lake Dorothy is a diesel avoider or diesel preventer. Without Dorothy, our only alternative would be to run diesel to meet the town's needs," he said.

The Lake Dorothy project has been expensive, costing $70 million to provide an additional 15 megawatts of power to meet Juneau's growing demand, but it also provides more security for the community. Lake Dorothy's power transmission lines avoid the avalanche-prone area near the Snettisham Power Project, Juneau's largest source of power.

Twice in the past two years, avalanches have taken out transmission towers, forcing Juneau to get most of its power from backup diesel generators in town.

"If we were to have another avalanche, we'd still have to run some diesel, but much less than we needed earlier this year or last winter," Willis said.

"The security of having Lake Dorothy online is just an incredible relief," said Cathie Roemmich, CEO of the Juneau Chamber of Commerce.

"We learned the hard way what it means to lose your power, and nobody was spared from the economic effects," she said.

The security Lake Dorothy provides will come at some cost. Power rates in Juneau, now set at a base rate of about 10 cents per kilowatt hour by the Regulatory Commission of Alaska, will likely have to be raised about 2 cents to pay for the new plant, said Tim McLeod, president and general manager of Alaska Electric Light & Power.

While rates will go up, McLeod said they'll be able to stop burning diesel except for during emergencies. When the city has been forced to burn diesel to meet demand, the RCA allows it to increase rates with what's known as a "cost-of-power adjustment" to cover added fuel costs.

McLeod said AEL&P expects to file for new rates next spring, after it has run awhile with the new power source online.

Juneau has long had some of the lowest power rates in Alaska, and sometimes the lowest. It and other hydro-powered Southeast communities usually compete for the lowest rates, each being forced to bump them up as they add new capacity.

A financial marvel, as well

What really made Lake Dorothy able to happen is an electric transmission line connecting Juneau with the Greens Creek Mine on Admiralty Island, McLeod said.

Funded in part with $15 million from the federal government, that line allows AEL&P to sell Juneau's surplus power to the mine and replace self-generated diesel power. Some surplus power also goes to Princess Cruise Lines ships.

"The Greens Creek connection was almost a miracle to Juneau; it's something that utilities don't usually enjoy, having that kind of load to help with the projects," Willis said.

The conundrum for most of Alaska's isolated communities is that they start to run short on power, but if they build a big new project they'll have more than they need - with no way to sell it to finance the construction.

"We're really glad the mine is here and able to use the power that we can't use," McLeod said.

The ability to run its mine on hydroelectric power makes it more competitive in world markets, especially with wildly fluctuating diesel prices, the company said.

The Lake Dorothy Project that's now complete is really just the first of a two-phase project, Willis said. A tunnel will eventually lead all the way from Dorothy Lake to the powerhouse, doubling the amount of power it can produce.

That's more than Juneau needs now, even with the mine and the cruise ships, McLeod said.

When that second phase will be built depends on how quickly the demand for electricity in Juneau grows.

New homes, more electric appliances or more use of electric heat could all combine to use up Juneau's surplus power, and McLeod is in no hurry to use up the hard-won surplus.

"We'd prefer that people don't use electric heat; there's better ways to use electricity," he said.

When Juneau begins running out of power again, interruptible customers such as the mine and cruise ship docks will again get switched off, he said.

"Lake Dorothy is for the families and people of Juneau, it is only the surpluses that go to Greens Creek and Princess," McLeod said.

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