Saturday, April 4, 2020
April 4, 2020

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Energy Adviser: Here’s how ‘the grid’ powers homes


If someone asked you where your electricity comes from, maybe you’d answer, “from the grid?” But what do we know about “the grid” or how it delivers the electricity you use?

The U.S. power grid is the largest machine in the world. It’s made up of three sections that interconnect thousands of power plants run largely by hydropower, fossil fuels and atomic energy, along with wind and solar. From these extend millions of miles of transmission lines that start out as big around as your arm and shrink to the diameter of a little finger when they enter your home. On the way there, transformers boost the power up for transmission over long distances and scale it back for use at your home or business.

In Southwest Washington, much of the power for our homes starts in the Pacific Northwest hydropower system, that consists of both federal and nonfederal projects. The federal projects are managed by the Bonneville Power Administration, with the closest generator being Bonneville Dam. Finished by the Army Corps of Engineers in 1938, the Corps added a second powerhouse to the dam in 1981. Turbines at this dam alone generate about 5 billion kilowatt hours of electricity a year — roughly enough to heat, cool, and light 443,000 average-sized homes for a year.

Hydropower uses the water cycle, so it’s a renewable resource, and the system of dams keeps our region livable by limiting the impacts of floods and droughts, providing recreation, irrigation to our farmlands and facilitating navigation of the rivers.

The federal hydrosystem, starting with the Columbia River basin that extends into Canada and ends in the Pacific Ocean, captures and contains our region’s rainfall, so water is there for us to drink, irrigate crops and turn generators that power the economy and light, warm and cool our homes. The dams help keep water table levels high and reduce our region’s chance of droughts and floods. The storage capacity behind the hydroelectric plants makes them flexible and allows for electric generators to increase and decrease output to balance intermittent power sources such as wind and solar.

The raw hydropower the turbines generate at the power station can’t go right into your home. Power lines go to “step up” substations that raise the power to 500,000 volts (or more) and then transmit it through cables on overhead lines to towns where it’s needed. Stepping up the voltage allows for the electricity to flow much more efficiently over long distances. Along the way, “step down” substations and transformers closer to the destination lower the voltage to usable and safer levels and deliver it overhead or underground.

To increase reliability and enable broader balancing of resources, electric utilities and larger balancing authorities like BPA have connected all their power stations into a vast network we generally call “the grid.” Alternative power generators — wind and solar — also feed into this network. (Driving up the Columbia Gorge you can view wind power generators and commuting past 117th and Padden Parkway you can see Clark Public Utilities’ Community Solar array.) Automated and manual systems work around the clock to match demand and output for every second of every day. This means more stations will run at close to full capacity during the mornings and evenings when most people are home from work running hot water, using lights, cooking and operating appliances.

As energy consumers, we want safe, reliable and affordable electricity. We want power generation that meets our peak needs, quickly recovers from an outage and keeps the power on at our homes and businesses. With a backbone of hydroelectric power, the Northwest is fortunate to enjoy clean, renewable energy and here in Clark County, nonprofit public power means that energy is delivered at cost, always with the customer’s interest at the core.

For more on power supply and how electricity is made and moved, visit

Energy Adviser is written by Clark Public Utilities. Send questions to or to Energy Adviser, c/o Clark Public Utilities, P.O. Box 8900, Vancouver, WA 98668.