The Home Heating Debate Heats Up As Temperatures Plunge In Texas

The Texas grid recently hit a new winter peak record of about 65,731 megawatts (MW). If Texas' residential heating were 100% electrified, as many climate change mitigation strategies call for, that peak might have been closer to 80,000-90,000 MW, up to about 10,000 more megawatts than we have.

Texas recently joined the rest of the country in experiencing some frigid winter weather. On Tuesday, the high temperatures throughout most of the state didn’t break freezing, setting up Wednesday morning to be one of the coldest daybreaks this decade. Clear skies drove temps down into the teens across most of the state and even sent the Mexican border towns into freezing territory, a rare occurrence indeed.

This doesn’t happen often, but when it does, the result is pretty much the same. Electricity prices within the Texas grid, known as the Electric Reliability Council of Texas, or ERCOT, rise as people try to keep their homes warm when they wake up and get ready for work. In some parts of Texas, wholesale electricity market prices spiked to over $5,000/MW. Quite a jump when you consider average prices are usually in the mid-$20/MWh range.

High prices in South Texas.

So why the spike? Most of Texas (and in the South generally) uses electricity for heating. In fact, it’s our preferred heating "fuel." We use electricity to heat our homes and some businesses because these heating systems typically have the lowest upfront costs and we don’t use them that much (we’re a summer peaking state).

Some of these heating systems are direct electric resistance heaters, big coils of wires that heat up when turned on — think of a big toaster in your attic that you blow air through and the air heats up. Some systems are heat pumps, which are basically an air-conditioners running backwards. Heat pumps also use electricity to heat, but are much more efficient than big toasters. However, when the outdoor temperature gets around the low 20s, these systems can’t operate anymore, and therein lies the problem.

    Heating fuel choice trends by region, 2005-2013. Can't wait for refreshed data! https://t.co/XoBBubfKJ1 via @EIAgov pic.twitter.com/5RqIsZbU8Q
So when that rare cold weather strikes and the heat pumps are no longer able to provide heat, their “auxiliary” or “emergency” heat kicks in, and the system reverts to being a big toaster. And if you want to heat a whole house with a toaster, you need a really, really big toaster.

A few numbers.

During the summer, because of Texas’ many air conditioners, residential demand increases about 400% from off peak (~9,000 MW) in the spring to summer peak (~35,000 MW).

While commercial and industrial load only fluctuates about 35% from low to high, ERCOT is built to service all those residential air-conditioners that keep us sane. ERCOT’s all-time peak demand is 71,110 MW, set on Aug. 11, 2016. Most summers see new peaks, but during the Jan. 16-17, 2018, freeze, EROCT hit a new winter peak record of 65,731 MW and blew past the previous winter peak by over 2,800 MW.

A quick back-of-the-envelope thought experiment.

There has recently been a considerable amount of interest in electrifying everything in the U.S. economy. Doing so can make the economy more energy efficient, as well help fight climate change. With that in mind, the National Renewable Energy Lab recently announced the Electrification Futures Study to look at the consequences of a highly electrified US energy sector.

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