The town of Martinsdale in central Montana is a sleepy enclave of unpaved streets lined with a handful of homes and businesses. Once a stop on a busy Chicago-to-Seattle railroad, the place fell quiet when the line went out of business decades ago. But don’t count it out yet. Over the next four years, Montana’s Absaroka Energy is set to turn Martinsdale into a showpiece for renewable energy management in America.
That’s because Absaroka is building a large pumped storage hydro power plant on a nearby butte. It will feed 400 megawatts to a grid linked to cities as far away as Seattle and Portland, Oregon.
The plant is essentially a large water-based battery. It will store water — and its energy — by pumping it through a giant man-made tunnel from a low-lying lake holding more than 1.3 billion gallons of water to an equally sized reservoir built some 1,000 feet above, on top of Gordon Butte. Reversing the flow will quickly generate electricity when it is needed, like when demand grows and the prices are high or when weather-dependent sources of renewable energy such as solar or wind farms suddenly stop supplying power to the grid.
The Montana project will use giant turbines built by GE Renewable Energy. Each machine can behave both as a pump and as a generator. “To be sure, pumped hydro storage has been around for a while,” says Matt Pevarnik, managing director for U.S. Hydro at GE Renewable Energy. “But the technology keeps getting better. The Gordon Butte site will become one of the most advanced pumped storage installations in the U.S.” Pevarnik says that the facility’s overall cycle efficiency — the average difference between energy from the electric grid used for pumping water to the upper reservoir and electricity generated by “turbining” it when the water runs downhill — is as high as 80 percent.
Modern utility-scale pumped storage hydro is a new spin on an older version of the technology, which supported the nuclear and coal-fired power plants in the ‘70s and ‘80s. (Back then, the hydro plants soaked up excess electricity at night when demand dropped by powering pumps that filled up the upper lakes.)
In the U.S., the technology is already in use in hilly places like the mountains of California. A large pumped storage plant in the Sierra Nevada, for example, captures the excess power from solar farms to pump the water uphill. At night, the water flows back downhill and powers customers in nearby Fresno with consistent renewable energy. Gordon Butte will use a newer version of the technology. It will be able to move very quickly from pumping to generating and back again, which provides additional flexibility and reduces the response time to changes in the grid.
There are other benefits. Traditional hydro projects can take a decade or more to get licensed. But closed-loop projects like Gordon Butte that are built “off-stream” — they don’t use natural waterways — are easier to get approved. The Montana project was licensed in just three and a half years.
In the absence of grid-scale batteries, installations like Gordon Butte will be required to resolve the integration and reliability issues that go along with using more intermittent renewable power like wind and solar. The U.S. Department of Energy estimates that planned projects could almost triple pumped storage capacity from 22 gigawatts to 62 gigawatts when they are finished in the coming years but that the U.S. will need 100 gigawatts of stored power by 2050, when renewables could generate as much as 80 percent of our electricity.
With Gordon Butte, Montana will be at the forefront of that change. The site is already home to six GE wind turbines on the back of the butte, where wind speeds average an incredibly strong 20 miles per hour, producing 9.6 MW of electricity. Once the new pumped storage plant comes online, it can store some of that power and provide enough steady electricity to feed the ever-growing demand for green energy on the West Coast. Renewables could also stimulate rural Montana’s economy.
When that happens, sleepy Martinsdale will be writing the future of American energy.