Peak Demand Tomorrow Morning: Is the Grid Ready?

ERCOT is forecasting peak demand of over 73,000 megawatts. The grid should — should — be fine.

I often point to four factors that spur grid outages: demand, thermal power plant outages, natural gas supply, and renewable energy production. Any one or two of these can be problematic and there won’t be rolling outages — but if three or four become challenges, look out.

Texas’ recent experiences with severe heat and cold show we should add a fifth factor: batteries. They have so fundamentally changed the grid that you really can’t talk about grid reliability, or the probability of outages, without talking about batteries.

Cutting to the chase: If the current weather forecast holds, the grid should keep running without any trouble, largely because it’s just not that cold. But it’s also because batteries are significantly improving grid reliability.

Here’s how all of these things are shaping up:

Demand

ERCOT is currently forecasting over 73 gigawatts of demand tomorrow morning. Last MLK weekend, during Winter Storm Heather, we exceeded 78 gigawatts of demand, the second highest demand ever. Winter Storm Uri was likely somewhere between 82-92 gigawatts of demand (no one knows for sure because it couldn’t be served). So 74 gigawatts shouldn’t be a problem, assuming ERCOT’s projections aren’t off — and despite the agency’s (unfortunately well-earned) reputation for forecast errors, weather forecasts support this one. We’ll see.

(Side note: very low temperatures — around 10-15 degrees or less — exacerbate ERCOT’s demand forecasting problems, since the agency still doesn’t adequately factor Texans’ dependence on resistance heat into its projections; more on resistance heat here and here.)

Note that each winter day usually has two peaks, as shown below: one in the morning (as electric hot water heaters, coffee makers, hair dryers and other morning staples around the state switch on), and another less severe peak in the evening.

Batteries are helping ERCOT manage peak demand humps that come before solar generation ramps up or after sunset. More on that below.

Thermal Power Plants

On Jan. 4, ERCOT issued an extreme cold advisory. That same day, thermal power plant operators brought a lot of power plants online: in the space of four hours, thermal power plant outages dropped by nearly 30%

Unfortunately, as shown above (h/t Grid Status), thermal power plant outages are back up to around 7,000 megawatts today. Hopefully, that’s because the wind was strong last night, it was very sunny today, and thermal operators are making repairs and doing maintenance that will allow the plants to come back online when they’re needed more than today. But again, every winter grid emergency and most near-grid emergencies in Texas — especially Winter Storm Uri in 2021 — has been marked by widespread gas and coal plant outages.

Gas Supply

The last three cold snaps have seen precipitous drops in gas production and output: 30% in Heather and Elliott, and 40% (before the power went out) in Uri. Natural gas supply remains the Achilles heel of reliability

This cold snap is far less severe than any of those. Temperatures in the Permian Basin are not expected to drop below 25 degrees this week. As such, I’d be surprised to see more than a 10-15% drop in gas production.

Still, it remains vitally important that stronger winterization standards be put in place and enforced to ensure the availability of gas during strong winter cold snaps.

Renewable Energy Output

Today (Monday, January 6), the grid came within 600 megawatts of setting an all-time solar record, eclipsing 21,000 megawatts for only the 9th time in ERCOT history. It was the coldest day of the winter so far. Cloud cover will diminish solar output later this week but temperatures are not expected to be near low enough to cause problems.

Wind, meanwhile, is expected to add at least 4,000 megawatts during both the morning and evening peaks and more low-cost energy during the night, especially starting Tuesday night. ERCOT has usually defined “low wind” as about 3,000 megawatts, so this level clearly tracks the expectations for wind power on the grid and its role in the state’s energy portfolio. The new batteries on the system make renewable variability even less of a concern.

Batteries

And now the headliner: Batteries are playing a key role with both the morning and evening peaks, and that role will only grow.

During Winter Storm Uri four years ago, there were only 200 megawatts of storage in ERCOT. We now have fifty times that amount — 10,000 megawatts. That’s also double the amount we had only one year ago. This is a major factor in the favor of Texans and our grid during any kind of extreme heat or cold.

It will be interesting to see tomorrow morning how much of an impact storage makes, but it’ll probably be significant. I wouldn’t be surprised to see a new all-time peak record for storage over the next couple of days.

This isn’t the big one

KPRC in Houston put it pretty well over the weekend: while a severe Uri-like freeze is inevitable at some point, this isn’t it. There are no significant concerns this week of rolling outages in ERCOT caused by lack of supply and excessive demand.

However, the risk remains elevated for this winter. The state’s lack of action on energy efficiency means the grid will remain vulnerable to demand spikes when it gets very cold.

So Texas policymakers can’t get complacent. No matter what happens this week, policymakers must work to boost weatherization and efficiency — by helping homeowners upgrade inefficient heating systems, for example — to better manage demand spikes and lower the odds of outages.

The Legislature kicks off next week for their third chance to address the demand side and reduce energy waste. If they don’t, Texans will remain at unnecessarily high risk — 50-80% chance according to ERCOT — of outages next time a truly severe winter storm blows through. This one, though, isn’t that kind of storm.

Thank you for reading. Please share this post widely. Please also consider becoming a paid subscriber if you aren’t already. And if you are, thank you!