Jim Conca: America’s electrical grid readies for solar eclipse

The solar eclipse on Monday will have an interesting side effect of shutting off lots of electricity generation in America as the moon’s 70-mile-wide shadow rolls across our ever-increasing number of solar arrays.

As the eclipse races from Oregon to South Carolina, it will cut solar power production by about 9,000 megawatts, about as much electricity as produced by 10 nuclear plants the size of our own Columbia Generating Station in Richland.

Then the solar power will come roaring back.

How do you keep the lights on when the sun suddenly goes out? The loss and rebound of generation is much larger than our electric grid usually faces, but with advance preparation, the grid will make it through the event just fine, largely because of the diversity of energy sources that we still have.

Nuclear plants will continue to provide the backbone of the system, and generators running on natural gas will power up quickly as the sun is blocked, and then power down even faster as the sun reappears, a costly but easy fix.

This energy diversity is critical because our energy system has to function through more and more frequent challenges, like extreme cold and polar vortices, water droughts and low mountain snowpack, heat waves with wind doldrums and other problems. Those who think we should only have one type of energy, either just fossil fuel or just renewables, rarely consider the problems encountered by the lack of diversity.

Parts of 12 states will be totally darkened; many others will see the sun partly or mostly obscured. Washington state will see over 90 percent occultation, and most of our rooftop solar, like the array on Judith’s and my roof, the Pasco community solar project, and others here in the Tri-Cities, will lose about 90 percent of our generation at the time it is most needed. The smoke we were experiencing in the Pasco Basin already dropped solar production about 20 percent.

The eclipse will occur over a two-hour period at each spot, with totality only lasting about three minutes along the primary path. Power grids are not set up for eclipses, which happen much faster than a sunrise or a sunset, and over a broader area than typical cloud cover.

At peak sunshine, California gets 40 percent of its energy from solar panels, and it will lose nearly three-quarters of that during this eclipse. Power output will drop by 70 megawatts a minute and then come thundering back at 90 megawatts a minute. State officials are urging citizens to conserve power for two hours during the eclipse by turning off lights and appliances in an effort to save the 3,500 megawatts that will be lost.

North Carolina will be hardest hit with its 3,000 megawatts of solar capacity. The moon will block more than 90 percent of the state’s sunshine at exactly the time when these solar farms are operating at maximum capacity. The utilities are planning to unplug the solar arrays beforehand, and ramp natural gas up and down to handle this rapid change in sunshine.

The obvious long-term solution to these natural problems, as well as those that are human-made, is to maintain a diverse energy mix that limits the threat to the system from interruptions of any single source. A mixture of renewables, nuclear and gas is the best mix to handle any situation.

This will be the first coast-to-coast solar eclipse in the United States since 1918, when America had no solar arrays. The next total solar eclipse in North America will occur on April 8, 2024, when we will have even more solar power.

Hopefully, we will be smart enough to maintain our power diversity, especially nuclear and hydro.

This story was originally published August 18, 2017 at 11:46 AM with the headline "Jim Conca: America’s electrical grid readies for solar eclipse."