Via The Arizona Capitol Times: 

Thanks to helpful geography, Arizona is enjoying something of an energy breakthrough. In 2017, Arizona’s electricity generation from solar power exceeded its hydroelectric output for the first time. And the state now ranks second in the nation in solar generation.

Overall, nuclear power, coal, and natural gas still carry the major load, though, contributing a combined 88 percent of Arizona’s utility-scale electricity generation. And anchoring it all is the Palo Verde Nuclear Station, the largest nuclear power plant in the nation and the largest net generator of electricity. Solar isn’t insignificant, though. Thanks to clear Southwestern skies, Arizona’s solar sector produced roughly 6 percent of the state’s net electricity in 2017.

Such a diverse energy mix has benefited Arizona residents. In January 2019, residential electricity prices amounted to 12.22 cents per kilowatt-hour, lower than the national average of 12.47 cents. Much of this can be attributed to the sturdy coal and nuclear power plants that have ensured the state’s baseload generation for decades.

But what about a trend emerging in some states — to scrap coal and nuclear in favor of natural gas and renewables? Would such a shift have significant repercussions for Arizona?

While Arizona has plentiful sun exposure, there are still limitations for renewables. Both wind and solar perennially require robust back-up systems for when the weather doesn’t cooperate. The Department of Energy estimates that even the most advanced wind turbines reach their full capacity only 42.5 percent of the time. And the highest-performing solar panels — like the ones in Arizona that feature sun-tracking motors — reach their full capacity an even lower 30 percent of the time. Filling these gaps often requires on-demand energy from “spinning reserves” of natural gas and coal-fired power generation.

Unfortunately, battery storage has yet to prove an all-purpose solution for such shortfalls. The best grid-scale battery technologies currently available can only provide hours of backup. That’s simply not enough to compensate during days — and even weeks — of low wind or solar output.

America’s energy profile is already changing, though. Since 2010, roughly 40 percent of America’s coal fleet has been shut down or designated for closure. And six nuclear plants have closed since 2013, with more closures planned by 2025.

These coal and nuclear plants possess one clear advantage, though. They store fuel on-site, and can run non-stop for months at a time. In contrast, wind and solar are dependent on optimum weather conditions. And natural gas is similarly challenged, since it relies on continuous fueling from a vast nationwide pipeline system. Arizona already understands the volatility of such a complicated pipeline arrangement – in December 2018, residential natural gas prices in Arizona rose to 27 percent above the national average.

Industry experts are now growing concerned about the weather and delivery challenges faced by renewables and natural gas. The North American Electric Reliability Corporation recently cautioned that a rapid shift to clean energy and natural gas “could leave the bulk power system vulnerable to fuel delivery risks in areas where firm pipeline service is not procured.” And in January, the heads of four major U.S. utility providers expressed concern that a lack of “fuel security and fuel diversity” could limit overall electricity production.

Undoubtedly, natural gas and renewables are gaining prominence in Arizona and the nation. But it makes sense to keep all options on the table. In Arizona, coal and nuclear power have proven reliable for decades. They should continue to be part of an all-of-the-above energy mix alongside natural gas and solar for years to come.

See the article here.