It’s time to expand the generating capacity at the Tyee Lake hydroelectric station to handle growing demand — particularly from heat pumps — the plant’s operator said of its plans to line up $20 million in funding and a federal permit to add a third turbine to the facility.
The Tyee Lake station started supplying Wrangell and Petersburg in 1984. It was built with two turbines rated at 10 megawatts each, with an empty bay at the Bradfield Canal facility to add a third turbine when needed.
That time is now, said Robert Siedman, chief executive officer of the Southeast Alaska Power Agency, or SEAPA, which owns and operates Tyee Lake. It also operates the Swan Lake hydroelectric station to power Ketchikan, with an intertie connecting both plants.
“It really has to do with load growth,” Siedman said. Most new residential and commercial construction includes electric heat, either baseboard units or heat pumps, he said. In addition, it’s increasingly common for people to convert existing homes and businesses from oil to electric heat.
A consultant’s study for the Southeast Conference in 2016 reported that oil fueled almost three-quarters of space heating demand in the region. That number was down to 50% by 2023, Siedman said.
A $38 million federal grant to the Southeast Conference and a second Alaska nonprofit last year will help pay for an estimated 6,100 new heat pump installations in coastal communities from Ketchikan to Kodiak. Those additional units will accelerate the need for more electricity.
SEAPA anticipates receiving authorization for the additional generator at Tyee this year from the Federal Energy Regulatory Commission. “We have submitted our final application to FERC,” Siedman said.
Design work for the project is 90% complete, he added, with bids due later this month for the equipment to boost the plant’s capacity.
‘The transformers will be the longest lead time,” he said, and could take two years to arrive after contract award. The generating turbine could take about a year.
If all goes as planned, the third turbine could be generating power by December 2027.
“There’s no question” of enough water flowing out of Tyee Lake to spin the third turbine, the power agency head said.
The project is estimated at about $20 million, with SEAPA aiming to put together the finances without a rate increase, Siedman said.
The agency has a $5 million federal grant lined up and has requested $4 million through the Alaska Energy Authority, a state agency. It also is pursuing additional federal funding under an investment tax credit program and could pull from its reserves if it needs to fill a small gap at the end, he said.
The need to move ahead with adding a third turbine was evident in 2022 when strong demand for electricity during a cold period pushed up against the agency’s limits to supply power to Wrangell and Petersburg.
“We were running flat out at 100%,” Siedman said, needing the communities to run their diesel-fueled generators to help carry the load.
A 2023 report confirmed what the agency knew: They needed to add more capacity at Tyee.
The Tyee lake tap and power station and power line into Wrangell and Petersburg were built at a cost of more than $130 million in state funds more than four decades ago. The station is on the mainland at the head of Bradfield Canal, about 40 miles southeast of Wrangell.
The transmission line measures 69 miles across land and 12 miles under water to reach Wrangell Island and then skip over to Vank, Woronkofski and Mitkof islands to serve Petersburg.
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