Golden Valley Electric Association is considering upgrading or replacing its Battery Electric Storage System, or BESS. Golden Valley uses the big battery mainly to prevent blackouts. But the BESS is nearing the end of its useful life.
When the BESS went online in 2003, it was the largest battery in the world. And the utility industry hailed the co-op for investing in what was then state-of-the-art technology.
“Golden Valley has been a pioneer in this area,” says Jan Ahlen, director of energy solutions for the National Rural Electric Cooperative Association. “Not many co-ops had energy-storage systems back in the early 2000s.”
That was before Golden Valley Senior Engineer Nathan Minnema began working for the co-op, but he says BESS’s reputation is well-known.
“That was kind of the cutting edge, at the time,” he said.
Minnema says the BESS has so far reliably been doing what it was designed to do. That is, to dump up to 40 megawatts into the co-op’s system when a problem occurs, like a power plant going offline, to keep electricity flowing until crews can fire up one of the backup generators. It’s done that nearly 900 times over the past 18 years, saving the co-op’s members more than $15 million.
“We’ve been very happy with it,” he said. “It’s just that, like anything, you need to review it, as far as ongoing performance.”
Minnema says Golden Valley did that recently, as part of the co-op’s ongoing review of its power systems. And also because the battery was approaching 20 years of service, and he says its useful lifespan ranges from 20 to 30 years. He says all those years of discharging energy to avoid blackouts, and then recharging to be ready for the next one, has taken a toll.
“Batteries, obviously, degrade. So we’ve seen the performance drop off,” he said in an interview last month.
Minnema says the BESS still meets Golden Valley’s needs. But he says the recent checkup revealed some problems with its control system, which among other things handles the battery’s discharging and recharging cycle. He says that got him and others wondering whether it would be more cost-effective in the long run to upgrade the control system or consider investing in a newer battery.
“Instead of just kind of diving into a control-system upgrade,” he said, “we thought it was prudent to look at not only that, but also other technologies.”
That’s why Golden Valley has begun soliciting proposals on replacing the BESS. It’s an ongoing process, but Minnema says the co-op’s already received a number of proposals, most of which employ lithium-ion technology, to replace the BESS’s nickel-cadmium, or Ni-Cad, -based system.
“Obviously, lithium-ion is where things are going for battery storage right now, so as expected we got some lithium-ion interests from bidders, as well as, I think, some other options.”
Minnema can’t talk about the estimated costs of the proposals, because the co-op is still soliciting them. But he says the range in cost between the least expensive to most expensive is about $100 million. The BESS, by comparison, cost about $35 million.
“You know, we’re a member-owned cooperative,” he said, “We want to make sure that we make these dollars the most beneficial for our members.”
Minnema says Golden Valley also is considering what energy-storage system would work best with Golden Valley’s mix of power sources, most of which are fueled by coal and oil. There’s also some renewable energy, like the 25-megawatt Eva Creek wind farm and the half-megawatt solar farm, located next door to the BESS in the industrial area on Fairbanks’s south side.
“We’re kind of currently in the evaluation phase of looking at the proposals received … and how best systems of various sizes would interact with the generation fleet.”
Minnema says that evaluation should be wrapping up later this year, in time to present a recommendation to the co-op’s Board of Directors to consider for next year’s budget.
Editor's note: Click here to view a YouTube video about the BESS.