You can heat your home with several different energy sources, including natural gas, heating oil or wood. But unless you’re living off-the-grid, the lights in your abode burn brightly because of electricity from the grid. 

Yes, I have a couple of candles, a flashlight and two kerosene lamps in my household. But I don’t use them. Instead, like more than 99 percent of us, I just flip up a switch to turn on electric lights. 

Of course people use electricity for many other purposes. We run all the equipment in emergency rooms on electricity — and when I’m trying to wake up in the morning I sometimes think it’s almost equally important that we run our coffee makers on electricity, too. 

The landscape of energy is changing, but it’s hard to agree on where we should get our electricity. People disagree about that, and for some good reasons. But no matter what you feel about our various energy options, some basic facts about solar energy are worth review.

Most of the energy we use is ultimately solar in origin. Fossil fuels, after all, represent solar energy that Mother Nature stored deep in the Earth over whole geological eras. One down side about fossil fuels is that once we use them, they’re gone. 

Engineer Bob Olsen of Washington State University recently explained his view that we have quite a wonderful system of “renewable solar” energy in place, especially in the western parts of the United States and around the region of the Tennessee Valley Authority. 

“That’s the case not because of solar electric panels, but because of the world’s largest solar collector — seawater,” Olsen said. 

Because we live on land, we don’t often think too clearly about the seas. But the oceans cover about two thirds of the planet. They absorb a lot of heat energy when light shines on them. Each day they soak up enormous quantities of energy from the sun, warming and evaporating as they do so. It’s evaporation from the seas that fills the sky with clouds. Water in the clouds comes down as rain or snow. 

Olsen sees precipitation as the linchpin of renewable solar energy. That’s because the rains flow into major rivers across which we’ve built hydroelectric dams. By running the water behind the dam through turbines, we generate electricity.

Dams have several good features. They cheaply store a great deal of energy. The reservoirs behind each dam are natural storage devices. Solar electric panels on a roof don’t have this feature unless linked to expensive batteries that degrade over time. Dams can easily produce electricity when the sun isn’t shining, a clear advantage in having them power the grid.

If we ever get a large slice of our electricity from windmills and solar panels, I think there will still be room for dams. Like fossil fuel and nuclear plants, dams are able to produce juice at night when the wind isn’t blowing and the sun isn’t shining. Because we want large amounts of electricity at our fingertips 24-7, windmills and solar panels cannot be our sole source of electricity. 

Dams make a lot of electricity without producing any greenhouse gases. And once the basic investment of constructing the dams is finished, they are economical to run because their “fuel” is freely supplied by Mother Nature. 

From where I sit, hydroelectric dams are gifts that keep on giving — every time we switch on the lights. 

Dr. E. Kirsten Peters, a former geology professor, is the director of communications for sciences at Washington State University in Pullman.

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