Essential reporting in volatile times.

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Sometimes it’s not only what the numbers are, but how you interpret them. We’re experiencing that now with competing memes during the coronavirus outbreak, and it can be done again if you think about where your electricity comes from.

Coal’s share of producing electricity for this region’s needs is declining, true. But in heat waves like this one, it’s still very much needed.

July 20 provided a good day to track coal’s use in generating power for the PJM Interconnection region. PJM is the electric grid management organization that stretches from the Atlantic Coast of New Jersey westward into central Kentucky. It includes all of Pennsylvania, Ohio, West Virginia, New Jersey and Virginia and parts of Kentucky and several other states. PJM ensures that power grid in this region of many millions of people stays online.

July 20 showed how electricity demand in the region changes during the day and how various fuels supply it. The first thing to remember is that nuclear power plants cannot be turned on or off easily, so they’re constantly producing power. Otherwise, power is dispatched by calling on the lowest-cost producers first and then moving up the ladder to the more expensive sources.

Monday’s power demand was at its lowest from about 4 a.m. to 5 a.m., when the PJM grid needed only about 89 gigawatts of electricity. The demand curve looks like a sine wave or one of those up-and-down curvy lines you hear about in math class. The slope increased sharply until about 2 p.m., when it hit 141 gigawatts and more or less leveled off.

At 2 p.m., natural gas supplied about 45% of the electricity being used, coal 26% and nuclear plants about 22%. About 7% of electricity came from renewables, but hydroelectric power was almost two-thirds of that, meaning solar and wind supplied relatively little.

That kind of follows what happened during the polar vortex during the winter of 2019, but with coal supplying more power at that time than natural gas.

So back to the original question: Do we look at coal’s share as an indication the fuel is on its way out, or do we look at it as an indication the fuel is still needed during times of extreme weather and will be needed in some form until other sources can take its place?

If it’s the second question, what are those other sources? The PJM region doesn’t get much of its electricity from renewables. Most of the good locations for hydroelectric power are taken, we don’t have the terrain for large-scale deployment of wind power, and solar power waits for the technology to make it feasible in a highly populated and often cloudy region.

So while coal’s future looks dim, it’s still necessary in this part of the nation unless we can import large amounts of clean energy from elsewhere or build enough generating capacity from other sources to replace it. The third possibility is reducing our electricity use by about 25% during heat waves and cold snaps.

Love it or hate it, for now we need coal unless we can find an adequate replacement or we stop using so much electricity.

Jim Ross is development and opinion editor of The Herald-Dispatch. His email is jross@hdmediallc.com.