Water vapor rose above St. Anthony Falls on the Mississippi River in Minneapolis on Tuesday. Temperatures that fell to more than 25 degrees below zero hit the area this week. (The Minnesota Star Tribune)

This week's bitter cold had the potential to be deadly. But thanks to reliable forms of energy like coal, natural gas and nuclear power, it wasn't.

Lawmakers considering doubling Minnesota's renewable energy mandate to 50 percent by 2030 should use this week's weather as a moment to reconsider their plans to lean so heavily on wind and solar.

On Wednesday, when the morning temperature in the Twin Cities was negative 24 degrees, wind energy provided just 4 percent of the electricity and utilized just 24 percent of its installed capacity in a region monitored by the Midcontinent Independent Systems Operator (MISO), a not-for-profit organization that ensures reliable, least-cost delivery of electricity across all or parts of 15 U.S. states, including Minnesota.

Meanwhile, coal-fired power plants provided 45 percent of MISO's power and nuclear provided 13 percent — most of this from Minnesota's Prairie Island and Monticello nuclear plants (which we should keep open, by the way). Natural gas provided 26 percent of our electricity use at that time, and the remainder was imported from Canada and other U.S. states.

Natural gas also heated the homes of approximately 66 percent of Minnesotans this week, by far the most for any home heating fuel, but there wasn't enough gas to combat the frigid temperatures.

Because of the extreme cold, Xcel Energy urged its natural gas customers in Becker, Big Lake, Chisago City, Lindstrom, Princeton and Isanti to reduce the settings on their thermostats, first down to 60 degrees, then to 63, through Thursday morning to conserve enough natural gas to prevent a widespread shortage as temperatures remained 14 below zero. Some Xcel customers in the Princeton area lost gas service, and Xcel reserved rooms for them in nearby hotels.

Enacting a 50 percent renewable energy mandate will not replace coal-fired power plants with wind and solar. It will replace coal-fired power plants with wind, solar and natural gas — enough natural gas power plants to potentially generate up to 100 percent of our electricity needs in the very possible eventuality that wind or solar are generating zero electricity at a given moment. Or, on a day like Wednesday, 96 percent of electricity might have to be generated by natural gas, with wind contributing 4 percent.

This week's urgent notice from Xcel to conserve natural gas shows there is real danger in putting all of our eggs into the renewables-plus-natural gas basket. At minimum, pursuing a grid powered entirely by solar, wind and natural gas would require more natural gas pipeline capacity, which is likely to be opposed by the factions that are currently challenging the replacement of the Line 3 pipeline.

Lest I be accused of unfairness, it's true that any number of unforeseen circumstances could prevent a coal, nuclear or natural gas plant from being able to run during a cold snap like this. But the key word is "unforeseen." The intermittency of wind and solar is a feature, not a bug, which is why Minnesota lawmakers should reconsider the wisdom of enacting a mandate requiring 50 percent of our electricity to come from intermittent renewable sources.

If Minnesota lawmakers are sincere in their belief that we must reduce carbon dioxide emissions as soon as possible, they must lift Minnesota's ban on new nuclear power plants, which has been in place since 1994.

Not only would nuclear power plants be essentially guaranteed to run in minus-24-degree weather, but a forthcoming study by American Experiment has found that new nuclear power plants could not only achieve a lower emissions rate by 2030, but also save Minnesota $22.3 billion through 2050.

Minnesota can show true leadership, and provide reliable, affordable and safe electricity by legalizing new nuclear power, not by doubling Minnesota's reliance on intermittent renewable power (and natural gas).

Isaac Orr is a policy fellow at Center of the American Experiment.