Montana hydro storage project could buffer wind, solar surges

...The innovation of pumped storage uses water and gravity to generate electricity much like dams do. Two reservoirs are built, and when water flows from the higher-elevation reservoir to the lower, electricity is produced. But what happens if the upper reservoir empties? From there, pump storage relies on the peaks and valleys of electrical supply produced by variable renewable energy sources like wind. The wind blows -- or the sun shines in the case of solar – mostly during the day and produces excess electricity. That electricity can be used to pump the water back to the upper reservoir, storing the energy until it’s needed to turn the turbines again. One reservoir on top of the 1,200-foot-high butte of the Gordon Butte Project will feed the lower reservoir, allowing for storage and generation of 400 megawatts, more than either Colstrip plants 1 or 2. The project has a water right that Carl Borgquist, president of Absaroka Energy, said would not deplete the watershed, taking water only during the month of high runoff. The project will generate a lot of energy, but the real benefit is that it would buffer the highs and lows of renewable energy production, absorbing the surges and then compensating for the drop-offs. Utility companies have opposed adding a large number of renewable energy projects to their mix because of the headache of constantly having to balance the electrical load. If the Gordon Butte Project comes online, it can balance the load...more