The intermittence of some electricity sources is making it harder for them to balance supply and demand, and could result in more shortages: America’s Power Grid Is Increasingly Unreliable

See America’s Power Grid Is Increasingly Unreliable: Behind a rising number of outages are new stresses on the system caused by aging power lines, a changing climate and a power-plant fleet rapidly going green by Katherine Blunt of The WSJ. Excerpts:

 "A decade ago, coal, nuclear and gas-fired power plants—which can produce power around the clock or fire up when needed—supplied the bulk of the nation’s electricity. Since then, renewable energy sources, including wind and solar farms whose output depends on weather and time of day, have become some of the most substantial sources of power in the U.S., second only to natural gas.

Grid operators around the country have recently raised concerns that the intermittence of some electricity sources is making it harder for them to balance supply and demand, and could result in more shortages. When demand threatens to exceed supply, as it has during severe hot and cold spells in Texas and California in recent years, grid operators may call on utilities to initiate rolling blackouts, or brief intentional outages over a region to spread the pain among everyone and prevent the wider grid from a total failure.

Companies around the country are rapidly adding large-scale batteries to store more intermittent power so it can be discharged during peak periods after the sun falls and wind dies. But because such storage technology is somewhat new, and was, until recently, relatively expensive, it remains a small fraction of the electricity market, and grid operators agree much more will be needed to keep the system stable as more conventional power plants retire.

The problem could soon threaten New York City. The New York Independent System Operator, or NYISO, which oversees the state’s power grid, last month warned of possible supply shortages in the coming years as several gas-fired power plants close or operate less frequently in light of stricter state air quality rules. New York, which has set a goal to eliminate emissions from its electricity supplies by 2040 and no longer has any coal-fired power plants, also recently shut down a nuclear plant some 30 miles north of Manhattan after critics for years called it a safety hazard."

"The North American Electric Reliability Corp., a nonprofit overseen by the Federal Energy Regulatory Commission that develops standards for utilities and power producers, warned in a report last month that the Midwest and West also face risks of supply shortages in the coming years as more conventional power plants retire.

Within the footprint of the Midcontinent Independent System Operator, or MISO, which oversees a large regional grid spanning from Louisiana to Manitoba, Canada, coal- and gas-fired power plants supplying more than 13 gigawatts of power are expected to close by 2024 as a result of economic pressures, as well as efforts by some utilities to shift more quickly to renewables to address climate change. Meanwhile, only 8 gigawatts of replacement supplies are under development in the area."

"One of the biggest challenges facing grid operators and utility companies is the need for better technology that can store large amounts of electricity and discharge it over days, to account for longer weather events that affect wind and solar output. Most large-scale batteries currently use lithium-ion technology, and can discharge for about four hours at most."