When the sun sets and the wind fades, the river rolls on. The perpetual nature of hydropower makes it the perfect companion for the Northwest’s newest renewable energy sources, primarily wind and solar, which now total more than 8,000 megawatts.
Just like hydropower, new renewables benefit the region in many ways, from creating jobs to keeping our air clean. But unlike hydropower, these are variable resources – meaning they turn on and off at the whim of Mother Nature, not necessarily when people need them most.

This poses a challenge for transmission operators who must ensure the amount of power produced equals the amount being consumed, second by second. This constant balance is crucial for system reliability – that is, to keep the lights on.

To maintain this balance, operators must have access to back-up energy sources, called balancing reserves, that can ramp up or down instantaneously to offset the changing output of variable resources. In many parts of the country, this back-up is supplied by thermal generators like coal or natural gas.

But in the Northwest, transmission operators can call on the mighty Columbia.

How it works 

The Columbia River acts as a giant battery for the intermittent power generated by wind and solar. On a very windy day, for example, river operators can reduce hydropower output, storing water that can be released later when the wind dies down.

Hydropower is an ideal balancing resource because of its flexibility, meaning it can respond quickly to shifts in wind and solar power output and can easily be turned on and off.

Most Northwest wind generators are located in the Columbia River Gorge, home to some of the best windsurfing in the world, as well as high-voltage transmission lines that have made it relatively easy for wind developers to reach their customers.

Because these wind farms are concentrated in a single area, they often produce power – or fail to produce power – at the same time. This intensifies the magnitude of peaks and valleys of power generation that  must be filled in, meaning operators must not only have access to flexible resources, but plenty of them.

Hydropower, the largest source of energy in the Northwest, is able to meet the lion’s share of the region’s variable energy balancing needs.

Opposites attract

Solar power peaks during the day. Wind in the Gorge tends to peak at night. Meanwhile the water cycle is constant, ensuring that hydropower is available day or night to provide the foundation of Northwest energy and fill in gaps left by variable energy sources.

Thanks to the diverse patterns of these natural fuel sources, the region’s renewable power generators can work harmoniously to deliver more clean energy, more often, to the people of the Northwest.