Hydro expansion another step in grid improvement
A small valve opened in a remote mountain valley at the head of Kachamek Bay sending a stream of water downhill that will eventually become low-cost power for places as far away as Fairbanks.
The Alaska Energy Authority started flowing water through its West Fork Upper Battle Creek Diversion Project Aug. 25.
The $47 million project will increase the amount of water in nearby Bradley Lake, in-turn increasing the practical power production capacity of the AEA-owned Bradley Lake Hydro Project by about 10 percent, according to AEA project manager Bryan Carey.
Already the largest hydro plant in the state, Bradley annually produces about 380,000 megawatt-hours of power for the six electric utilities in Alaska’s Railbelt. The reliable supply of glacial-fed “fuel” stored behind the Bradley dam can be used by the utilities to manage the variable portion of their electric load and optimize operation of their gas-fired generators.
“We want our gas turbines to be at the sweet-spot” for maximum efficiency, Homer Electric Association Board of Directors Vice President David Thomas said during a tour of the new facilities.
“You could argue Bradley Lake is the largest battery in the state.”
The Bradley Lake turbines are rated to produce up to 120 megawatts of power at any given time but constraints at both ends of the project have limited its average production to about 44 megawatts. And because Bradley power costs just 4 cents per kilowatt-hour to produce, according to AEA — making it some of the cheapest power in the state — more is better, said Tony Izzo CEO of Matanuska Electric Association.
Izzo also chairs the Bradley Lake Project Management Committee. The hydro project is operated by HEA under a contract with AEA.
Feedstock natural gas for the utility’s other power plants calculates out to a cost of about 8 cents per kWh.
“It’s pretty easy to see the benefit (of Bradley Lake) when you look at the numbers,” Izzo said.
MEA is in the middle of studies to see how much variable renewable power its grid can accept and identify some of the prime areas for renewable energy generation in its service area.
The Battle Creek project will add about 37,300 megawatt-hours of production capacity to Bradley by diverting glacial water from the West Fork of Upper Battle Creek and piping it nearly 2 miles to the manmade lake; enough power to light about 5,000 Railbelt homes, according to AEA.
The 60-inch high-density polyethylene pipe buried largely alongside the project access road installed to carry the water from the lake can handle up to 600 cubic feet of water per second, equivalent to a small river, according to Carey. The diversion stream was flowing at about 60 cubic feet per second, or cfs, on Aug. 27, he said.
Being short and steep glacial drainages Bradley and Battle creeks do not have many salmon — which makes them good candidates for harnessing their water — but they do have some. AEA is required to keep an average minimum flow of 15 cfs in Battle Creek to maintain fish habitat. Carey acknowledged the project will likely change the fish habitat some; the stabilized flow is likely to benefit salmon such as kings that spawn mid-stream, but could challenge others.
He said Battle Creek was finished on time, but slightly over budget — AEA previously pegged it at about $44 million — but Izzo noted it was completed within the parameters of the original financing plan and small overruns are often a fact of life for that type of work.
“On a remote project in the mountains, that’s not exceptional,” Carey said.
At about $16 million, the three miles of new road needed to reach the project accounted for approximately 40 percent of the overall cost of the work, which was led by Anchorage-based Orion Marine Contractors.
AEA and utility officials noted the recent agreement to purchase of the 39-mile Soldotna-to-Quartz Creek segment of transmission line by the authority from HEA is another small step along with the commissioning of the Battle Creek project to spur more efficient power production and distribution Railbelt-wide.
The “S-Q” transmission line was out of service for about four months last year following damage from the Swan Lake fire, which cost ratepayers to the north about $11 million by cutting off access to Bradley Lake and necessitating more gas-fired power.
Even when the 115-kilovolt line is operational, it has “line loss,” or the amount of power lost during transmission, of about 40 percent at maximum capacity, according to AEA Engineering Director Kirk Warren.
The goal is to eventually upgrade the S-Q line under AEA’s ownership with financial support from the utilities that will benefit.
Warren estimated upgrading the S-Q line to 230 kilovolts would cost $800,000 or more per mile based on previous work, but it would also allow the utilities to access more Bradley power without losing nearly as much of it to the ether.
“It’s part of the overall continued effort to reduce rates or keep rates down and increase the use of renewables,” Izzo said.
Elwood Brehmer can be reached at [email protected].