BEXAR COUNTY (Dennis Foley / KTSA News) — Lights on, lights off.
For thousands of homes in the greater San Antonio area and even across the state, it’s been more often off than on.
The response from San Antonio’s gas and power provider?
“CPS Energy is absolutely sorry that this is happening and the impact to members of our community that are experiencing outages,” CPS Energy President and CEO Paula Gold-Williams told reporters Monday afternoon.
How long will it continue? It will likely last through Tuesday, but Gold-Williams said it could be in place for several more days.
“We are asking our customers to put on layers, to get blankets, to do what they can do to be safe,” CPS Energy Chief Customer Engagement Officer Rudy Garza told reporters.
Despite the region seeing several days of freezing rain and then nearly a half-foot of snow, which had forecasters more concerned about ice bringing down power lines, the most likely reason you are without power and are a CPS Energy customer is because your power has been turned off by the utility.
“It started late last week, a movement toward cloudy [conditions], colder temperatures, wet temperatures and just low sustaining temperatures that reached near freezing,” Gold-Williams explained. “When we have sustained cold, cold temperatures, what really happens is there is more demand for energy and there is only so much capacity from the system.”
Solar appears to be a clear issue for CPS Energy in this storm. With the high amounts of cloud cover and limited battery capacity, it meant that solar power production dropped substantially from the storm.
The head of CPS Energy said there has been a trend in recent years of increasing power demand in the winter. She noted that historically, there had only been one peak in power usage: summer. This meant that the utility could use spring, fall, and winter to take some generating units offline to do some maintenance to prepare for summer.
Gold-Williams said in the winter, the San Antonio region only needs 50 percent of its capacity to meet the winter demand. When a stretch like the past week or so happens, that creates a problem.
With the management of the demand, Gold-Williams said the region avoided what could have been a peak of power usage that would have been greater than seen in the summer.
Some numbers: Gold-Williams said CPS Energy has a electrical capacity of 7,000 megawatts. In the summer, the peak demand is usually around 5,000 megawatts. In a typical winter, the demand is in the 2,500 to 3,000 megawatt range. This multi-day stretch demand would have been at around 5,000 to 5,400 megawatts.
Again, the CPS Energy system has a capacity of 7,000 megawatts, but that is currently down for multiple reasons: maintenance and solar.
“It is an unprecedented weather event that we actually had thought that the cold weather was behind us,” Gold-Williams explained. It is inferred that it means CPS Energy was already getting to work on its spring maintenance plans, which is done when demand is even lower than in winter.
ERCOT declared its third level of its energy emergency alert at 1:25 a.m. Monday when its reserve energy was too low to supply the demand.
As noted from the ERCOT chart, the actions by electric providers did cut down on demand. But also dropping throughout the day was ERCOT’s power capacity, meaning less electricity was being made available throughout the day for a variety of reasons.
How The Rotating Outages Work
CPS Energy said their goal is to have customers who are in a rotating outage setup to be without power for 15 minutes and with power for 45 minutes each out. As many people have noticed, what has actually been happening is that ratio has been inverted: 45 minutes without power and 15 minutes with power. This is because of the demand on the system.
But this is not affecting all power users.
Gold-Williams said that the process is done through software controlling about 250 circuits across the service area. About two-thirds of those circuits are in this plan, while one-third are not because they are connected to critical infrastructure like hospitals, police stations, etc.
Planning For The Future
When asked by KTSA News about how the utility plans to address capacity issues in the future — more in light of the annual threat from ERCOT each summer that it is projecting record use — Gold-Williams said there isn’t a quick fix just because of the lifecycles of generating units.
In terms of fixing what went wrong, Gold-Williams lays it out like this:
“Every single technology has a benefit and a challenge. As clean and non-emitting solar is, we got very little solar over the last several days. [Monday] is the best day that we’ve had solar and we haven’t been able to recharge the batteries. Natural gas has certain challenges with it. It has more emissions, not as much as coal, but it does stay consistently up. The challenge we had this time is we had an electric stress on the system, but we also had a stress on the natural gas system across the state. We had issues where supply could not be delivered. There is a ton of natural gas in Texas, it’s not all extracted.”
The utility president said the plan for the future will have to be balanced by ensuring the system is resilient, environmentally friendly, safe, and, importantly, affordable.
Gold-Williams said that while having a quick fix to prevent these rotating outages from happening in the future, the lessons learned from this experience is going to certainly to be looked at for deciding how CPS Energy moves ahead.