Part 1: What’s In the Peak

As extreme weather events drive up peak power demand, and solar power continues to grow rapidly, we are reminded that with electricity, timing is everything. To look at some issues of timing and what they mean for EBCE and its customers, we present a three-part series. This is part 1.

In a precursor of what climate change may bring, California and the West baked under a record heatwave last August. In all, 80 million people across the West were subject to what the National Weather Service called “excessive heat,” including temperatures of 117° F in Phoenix and 112° F in California’s Central Valley.

This pushed the power system to the brink, as demand soared and generators and transmission lines were taxed to their limit. High temperatures cut the efficiency and output from gas power plants, hydropower generation was limited due to drought, and even solar power was reduced by smoke from wildfires.

While California usually relies on imports from neighboring states, utilities across the Southwest struggled to meet their own demand and were unable to spare any exports.

To prevent a total breakdown, California grid operator CAISO twice instituted “rolling blackouts,” cutting power to individual circuits for short periods to relieve stress on the grid. In all, CAISO reported (PDF) that 491,600 customers lost power on August 14 for between 15 and 150 minutes and 320,000 customers lost power on August 15 for 8 to 90 minutes. Power cuts amounted to about 1000 MW on the first day and 500 MW on the second.

While that was bad, it paled in comparison to the Texas blackouts in March of 2021, as extreme cold froze gas pipelines and power plants. At one point, 52,277 MW of power generation capacity -- almost half of the state’s total (PDF) -- was forced out of service due to the impacts of extreme weather conditions, with temperatures as low as -2° F in Dallas. The Texas grid operator, ERCOT, resorted to rolling blackouts, cutting 20,000 MW of power to about 4 million customers for as much as 70 hours.

While Texas officials estimate that over 100 people died from the event, an analysis by the Houston Chronicle suggests it was almost twice as many -- from hypothermia, from carbon monoxide poisoning caused by backup generators, and other causes. No deaths were attributed to the California outages.

WHAT’S IN THE PEAK?

To help solve the problem of extreme power demand, we first have to understand what exactly drives it. While power providers and grid operators are acutely aware of demand by minute and location, what goes on behind the meter has to be modeled.

The National Renewable Energy Lab did that modeling as part of a recent report for the Los Angeles Department of Water and Power (LADWP), looking at how LA could get to 100 percent renewable energy. The detailed 12-chapter study modeled current and future demand (PDF) patterns, including growing levels of building and vehicle electrification.

The study found that space cooling (the dark blue area in Figure 1) currently accounts for fully half of the demand during peak hours, though only about 15 percent of annual electricity consumption.

Figure 1: Components of electricity and peak demand

Looking at the summer day with the highest peak demand, space cooling (shown in purple in Figure 2) rises and falls with the heat of the day, lingering into the evening. Space cooling accounts for about half of the 6000 MW of peak demand in Los Angeles currently.

Figure 2: Hourly electric demand

Figure 2 shows total electricity demand and doesn’t subtract out the generation that happens from customer-owned solar. Since all of that generation happens on sunny days, net demand will be high in the morning and evening, and low at mid-day. Some have dubbed this shape “the duck curve” since it looks like the profile of a swimming duck. It is a critical issue (PDF) for the whole California grid.

Looking ahead to 2045 (Figure 3), EV charging becomes a larger portion of peak demand in the LA region as California pursues vehicle electrification goals. In the extreme “stress” scenario, EV charging becomes a major driver of peak demand, especially in the after-work evening hours. But space cooling still dominates in all three scenarios, as rising temperatures offset the savings from more efficient air conditioners.

Figure 3: growth in peak demand

EBCE’S PEAK

EBCE’s system retail peak in 2020 was roughly 1,150 MW, which happened on August 14, at the peak of the heatwave. This was the highest peak ever recorded by EBCE. “EBCE’s load is very weather-driven, very coincident with CAISO peak, and categorically caused by cooling,” says Taj Ait-Laoussine, EBCE’s VP of Technology and Analytics.

Now that EBCE serves Pleasanton and Tracy, in addition to Livermore and Dublin, all in and near the hotter Central Valley, the heat-driven peak is increasing, compared to the mild climate of the inner Bay Area communities. Valley homes typically have air conditioners, as do commercial buildings everywhere, with HVAC systems that bring in outside air for ventilation. With the inclusion of these new communities, EBCE already appears to have exceeded its previous record during this most recent heatwave in June.

“Our highest days typically fall on the second or third day of a heatwave, especially if that day happens to be on a weekend or a holiday,” Ait-Laoussine says. “For example, we set a record peak for May in 2020 when a heatwave culminated on Memorial Day. By the second or third day of a heatwave, residential customers have a harder time keeping their homes cool.”

Regional temperatures are expected to rise due to climate change, resulting in greater air conditioning demand. And converting buildings to electric space heating may also drive up the use of cooling on hot days -- most Bay Area homes don’t have air conditioners now, but air-source heat pumps, used for heating, can also serve as air conditioners.

Regardless of its own demand, EBCE is connected to the broader California grid, which is heavily reliant on air conditioning and could become more so. If demand exceeds supply, EBCE will be affected as well. To find out what EBCE is doing to better manage peak events, read part 2 in this series, “Getting Ready for the Heat.”