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This article was originally published on Aug. 18, 2020. It has been updated to remove outdated material and edited to clarify the difference between Public Safety Power Shutdown and rolling blackouts due to electricity shortages.
Think of it as the kind of line you don’t want to be in the front of.
Heat waves can send demand for air conditioning soaring across California, and wildfires can damage transmission lines. Sometimes, that leads the operator of California’s electrical grid, the California Independent System Operator, or Cal ISO, to ask residents and businesses reduce electricity consumption or even order rolling blackouts, or PG&E to implement Public Safety Power Shutoffs.
So how can you tell if your power will go out? It depends on which of the two types of shutdowns is happening.
When high winds create conditions where downed powerlines may start wildfires, PG&E will implement Public Safety Power Shutdown (PSPS) blackouts. The utility tries to provide advance warning a day or so ahead of an actual shutdown. You can check whether your property is on the list by checking this PG&E Outage Watch updates page. These shutdowns can also happen without warning.
The second type of blackout can happen when electric demand exceeds supply. If that occurs, the grid managers at the Cal ISO in Folsom order big utilities like PG&E, Southern California Edison and San Diego Gas & Electric to institute “rolling blackouts” to reduce demand enough to stabilize the grid. Otherwise, there could be large-scale failures of the power grid across the West.
The utilities decide whom to turn off. PG&E has set up a website where customers can enter their addresses and find out their “rotating outage block” number.
That website is here.
The page looks like this.
After you look up your address, you can compare the outage block number to PG&E’s list of which block numbers will have power shut off and at what time.
Most outages are 1 to 2 hours, PG&E says. If you have recently had your power shut off as part of a rolling blackout, you are unlikely to be shut down in back-to-back events under PG&E’s system. Hence the name “rotating” blackouts. The idea is for everybody to share the pain, although there are exceptions for critical infrastructure like hospitals and police stations.
You can compare your outage block number to PG&E’s list showing which blocks are turned off at what time.
That page looked like this for Tuesday, Aug. 18, 2020.
For example, if your Outage Block is 4 and your Sub Outage Block is R, then your number is 4R, placing you in line to have power cut at 8 p.m.
If outages are pushed back because enough people conserved, the group order will remain consistent even though the times may change.
Anyone with an outage number of 50 is exempt from shutoffs. Those include hospitals, police and fire stations, along with areas that were blacked out in the last round of rolling blackouts.
The biggest crunch on the grid usually comes between 6 p.m. and 8 p.m. because it’s still hot in many places, air conditioning is running high, and electricity generation from large solar farms falls as the sun goes down. Usually, grid operators can make up that gap by importing power from other states. But during record heat waves, there’s less to go around.
The ISO has said that the problem can be solved several ways. First by expanding battery storage projects, which store electricity from solar farms so it can be used after the sun sets. Second, the ISO says that another state agency, the California Public Utilities Commission, needs to require large utilities like PG&E to sign more contracts to secure electricity from power plants during the most severe demand periods, even though they may not occur often, so they aren’t left short at crunch time. In short, the ISO and many independent power experts say that the problem is one of growing pains, as California generates an increasing amount of its electricity from renewable energy like solar and wind — now 34% of all the state’s power — to reduce smog and greenhouse gases that are driving climate change, and it needs to transition the way the power grid works.
Finally, rolling blackouts are not the decision of PG&E and other utilities, and are unrelated to PG&E’s problems in recent years causing wildfires or blowing up gas lines.
The utilities are ordered to shut off power by the California ISO to stabilize the power grid. Another type of power outage, called a Public Safety Power Shutoff, or PSPS, is something that utilities like PG&E choose to impose during very dry, windy days in some areas, to reduce the risk of trees blowing into power lines and causing big wildfires.
Finally, to look at who has power on or off in PG&E’s service area at any given time, go to PG&E’s outage map.
It looks like this.
