Wind chills the bright May morning as we walk the grassy plateau of Gordon Butte, a 2-mile-wide plug of volcanic rock towering above the plains about three miles west of Martinsdale, in Meagher County. The snow-streaked Crazy Mountains pull our gaze south, but we’re heading north, to the butte’s sharp, timbered edge.
My tour guide, Eli Bailey, a project manager with Bozeman-based Absaroka Energy, stops to point out where an 18-foot-diameter water conduit will be drilled deep into the butte and diagonally out its base. This part of the plateau, he says, will become an 80-acre reservoir.
As we proceed to the butte’s edge and peer down at the valley more than 1,000 feet below, this project’s purpose comes into focus. There, Bailey points, will be another reservoir, and a “powerhouse” stacked with hydroelectric turbines and pumps for circulating water between the two reservoirs—generating electricity when it’s needed, and pumping the water back uphill to store energy when it’s not.
It’s called “pumped-storage” hydropower. And this blueprint for Gordon Butte is part of a new wave of projects that represent the rapidly changing nature of the region’s energy mix—and of the electric grid itself.
Demand for the Gordon Butte project, which has an estimated price tag of $850 million, comes from a simple fact: electric utilities must balance the electric grid. At any moment, the amount of electricity being generated must exactly match the amount being used by light bulbs, heaters and factories.
Traditionally, utilities have done this with relatively minor adjustments, tuning the steady hum of hydroelectric dams and coal-fired power plants. But as more power from wind and solar is connected to the grid, the natural cycles of weather and daylight cause major new swings in the amount of power being produced.
“We’re not sure what the wind is going to do, even this hour,” says John Hines, vice president of energy supply for NorthWestern Energy, the utility that serves most of the state.
He shows me a graph depicting the output of NorthWestern’s wind energy resources over a two-day period. The output soars to 250 megawatts—enough to supply roughly 125,000 homes—before plunging to nearly zero in a matter of minutes. NorthWestern copes with these wild swings by using fast-reacting natural gas generators at its Dave Gates power plant, which came online outside Anaconda in 2011 as wind power was growing rapidly. The gas generators rev up when wind power dips, filling in the gaps.
Absaroka Energy President Carl Borgquist thinks pumped-storage hydro is a better way. It doesn’t require burning natural gas—water is simply pumped uphill when there’s extra energy on the grid. This concept has been used for decades by a handful of utilities in the United States, mostly to buffer the output of large power plants. But new technology developed in Europe is fueling a handful of new projects that are geared to quickly respond to swings in the grid. The generators double as pumps, and are very efficient.
“You can do more with less,” Borgquist says.
While critics point to the instability of wind and solar power as justification for sticking with coal, Borgquist sees a challenge.
“It’s a really interesting moment in terms of the grid’s evolution,” he says. “We need to be flexible and adapt,” as states like California and Washington lead the charge toward an electric grid heavy on renewable sources. Increasing concern about the climate-altering effects of carbon dioxide—emitted chiefly by power plants—will most likely expand this shift in coming years.
The demand for the Gordon Butte project may actually come more from those states than from Montana. NorthWestern Energy has no immediate plans to tap this project (because the Dave Gates plant currently meets its needs), but Gordon Butte is only about five miles north of a major transmission line that carries power from the 2,100-megawatt Colstrip power plant to utilities in the Pacific Northwest.
That region’s grid balance is stressed by huge wind farms along the Columbia River Gorge, and those utilities may clamor for a share in the Gordon Butte project, which at maximum capacity could supply 400 megawatts for eight hours.
Back at Gordon Butte, I ask Bailey how this project ended up in the middle of a 55,000-acre cattle ranch in Montana.
“This just happens to be a crossroads for everything you need,” he says. The Colstrip transmission line is a major asset, and the sharp topography of the butte is exceptional, providing a large elevation drop in a short distance and therefore reducing construction costs. An existing road, recently constructed to install six large wind turbines on the butte, also reduces cost.
There’s a ready source of water from nearby Cottonwood Creek, delivered through an existing irrigation canal. Once filled, the project will tap the water only once a year, to replenish losses from evaporation and seepage. And this area is private property, so permitting is much easier than if the project were on federal or state land.
The project could break ground as early as next year if Absaroka Energy receives its license from the Federal Energy Regulatory Commission, which it currently is applying for. If construction goes as planned, with the project going online in three years, it may be the first use of this new type of pump/generator in the United States.
As we head back across the plateau to Bailey’s truck, the wind still bites the morning air. From our perch above the plains, we can see at least five wind farms. Far in the distance, beneath the white crest of the Snowy Mountains, I can barely make out the 90 turbines at Judith Gap, their 126-foot blades spinning away.
I imagine being here in coming years—the wind blowing, and the water on this dry plateau slowly rising.
Marshall Swearingen freelances from Bozeman, where he grew up. He is a regular contributor to High Country News, the nonprofit bi-weekly newsmagazine “for people who care about the West.” Follow him on Twitter @marshallswearin.