Reliable Energy: Balancing supply and demand

tight rope walker's feet on a wire

Just as a tightrope walker must maintain balance to guarantee a successful highwire crossing, power grid operators must maintain a delicate balance, accurately matching supply with demand and carefully preparing for their next move.

Hydropower’s many positive attributes, coupled with careful planning and precise management, make this power source one of the most reliable.

It’s Always On

Renewable resources aren’t often associated with reliability because their generation depends on Mother Nature. But unlike other renewables, Northwest hydropower is dependable and predictable.

The water cycle constantly replenishes the fuel supply of the Columbia River Basin, which receives significant runoff from mountain snowmelt. With such a plentiful fuel source, hydropower serves most of the region’s power needs year-round.

Hydropower is the only renewable resource that produces such a high and continuous electrical output.

It Follows Demand

Hydro is a load-following resource. That is, it can throttle up or down to match the daily peaks and valleys of our energy use—increasing in the morning when people start the day, and decreasing in the evening as people wind down.

Operators control the electrical output by choosing how much water to allow through the water intakes in the dam. Opening and closing the intakes directly controls the amount of water flowing to the  turbines, which determines the amount of electricity the dam  generates.

You Can Save It for Later

One of the greatest challenges of electrical systems is that energy must be consumed as soon as it’s produced—it can’t be stored and saved for later. But hydropower offers the next best thing.

Storage reservoirs behind dams in the Columbia River Basin can store up to 30% of an average year’s runoff. These reservoirs act like batteries by storing energy—or in this case, water—when it’s not needed, and releasing it later when there’s more power demand.

Hydropower operators can also plan ahead for seasonal changes. Generally, operators in the Columbia Basin will fill reservoirs during the wet months in preparation for drier conditions.

It Can Quickly Change Output

Hydropower plants are nimble enough to ramp up and down within minutes, or even seconds. This means they are ideal resources for meeting one of the requirements of electrical systems: The amount of power entering the transmission grid must equal the amount being consumed at all times.

An imbalance can cause generating units to react by increasing or decreasing their rotational speed, or frequency, which should always be at 60 hertz. If not corrected, the generator could fall offline or even trigger a cascading outage.

Hydropower can respond to imbalances from moment to moment, always keeping the system in balance.

It’s a Self-Starter

In the event of a systemwide blackout, utilities need access to black start capability—the ability to start a generator in the absence of an outside power source. Just as a car needs a jump-start when it has a dead battery, most types of generators need an external power supply to return to operation.

Hydropower plants are the only large-scale generators that can dispatch power to the grid immediately when all other sources are inaccessible.

This is how hydropower generates 86% of the electricity distributed by Benton REA.

Courtesy of the Bonneville Power Administration

Recent Posts