Smart load limits could help to keep the lights on through California’s wildfire season.
Today’s post was co-authored with Duncan Callaway.
California’s 2020 wildfire season is off to a blazing start. The burning ring of fire around the Bay Area is now mostly contained thanks to the super-human efforts of our firefighters. But we’re not out of the woods. Not even close.
Although the current mega-fires were started by lightning, the most destructive fires in recent years have been caused by power lines or other electrical equipment.
One way to mitigate this kind of wildfire risk? Cut the power supply when the red flags go up. As we write this blog, the flags are up.
California’s largest utility is now warning of potential Public Safety Power Shutoffs (PSPS) to reduce the possibility that power lines and other equipment could spark new fires. Back in 2018, PG&E was sharply criticized for not de-energizing power lines prior to the devastating Camp Fire. Since then, utilities have been much quicker to call PSPS events:
These PSPS events have been controversial because power outages can impose high costs on homes and businesses. Last year’s outage costs were estimated at $10 billion. That’s a big number! But over time, these costs should come down as we adapt and adjust.
There’s been plenty of discussion about adaptation via investments in back-up generators, micro-grids, battery storage. But what about re-thinking the PSPS events themselves? So far, PSPS events have been implemented using a blunt tool: planned outages.
This all-or-nothing approach leaves much to be desired. Last year, we were frothing our lattes and using our clothes drier while our neighbors a few blocks away went days without power. Ever since we’ve been wondering whether there’s a better way.
Utilities in other parts of the world with frequent outages have been experimenting with better ways. One intriguing example can be found in South Africa. When there’s not enough supply available, this utility sends SMS messages to inform customers that they will be limiting load. Smart meters are used to detect which households are consuming below the prescribed limit. Households that comply remain connected. Non-compliers get remotely switched off (presumably with a chance to get back on when they reduce their demand).
Some California customers might balk at a request to limit load for days on end. But a “please limit-your-load” alert should be much preferred to this alert on your phone:
Could load limits help California keep more essential loads connected through PSPS events? This depends on (1) whether there’s any power available to ration during PSPS events and (2) whether California’s smart metering infrastructure is up to the task. To get to the bottom of these questions, we’ll offer our spitball take. And then we’ll invite you, brilliant blog readers, to tell us if we’re on the wrong (or right) track.
1. Is there power to ration during PSPS events?
Let’s start with a cartoon illustration of how the grid is configured: Customers connect to distribution lines that connect to substations. On the other side of those substations sit transmission lines that criss-cross long distances to bring in power from remote sources.
In distribution systems, there is typically only one path between a customer and their substation. If a distribution line is de-energized due to wildfire risk, there will be no power to ration. Everyone on that line is just 100% out of power.
On the other hand, in transmission systems, there are usually multiple paths from point A to point B (i.e., the system is “meshed”). If one transmission line needs to be taken out of service, but there is an alternative path for power to flow, we can still keep substations powered, along with the distribution systems they serve. If that alternative path can’t support all the power people are demanding, rationing could help to keep the proverbial lights on.
So our question is…are PSPS events sometimes/often caused by de-energizing transmission lines?
We think that transmission is definitely at play, though we don’t know how much of it is in meshed parts of the grid. Back in January, PG&E wrote that about 138,000 accounts in Northern California could have kept their lights on if they had installed backup generation at their substations. This means PG&E considered the distribution systems serving those customers to be safe. Furthermore, PG&E has reserved about 450 MW of temporary backup generation to keep customers powered in the 2020 fire season. Again, any distribution systems they power with those MW must not pose a risk if PG&E intends to power them. It must be risky transmission lines that are putting those customers in PSPS territory.
2. How smart are California smart meters?
Even if there is potential for using load limits to keep essential loads afloat through PSPS events, this idea is not worth pursuing if the implementation costs are prohibitive. So this brings us to the next question. Could we leverage investments we’ve already made in smart meters and customer notification systems to implement load limits at relatively low cost?
We know that California utilities can remotely turn smart meters on and off. We also know that utilities can alert customers when a power outage is imminent. One of us is so excited about AMI that he’s read the Landis and Gyr manual for our PG&E meter cover-to-cover. This manual suggests our smart meter could have a “soft fuse” function. This would allow PG&E to program the meter to cut us off if our demand exceeds an amount that can be remotely adjusted. The meter could also restore power periodically to detect whether we’ve turned off enough things to keep us below the prescribed limit.
The upshot? With some software development, existing AMI infrastructure could be up to the emergency load limiting task.
What are we waiting for?
Load limits are not the most elegant approach to allocating limited power supply. Compared to real-time pricing, load limiting is a blunt instrument. But it could offer a relatively low-cost improvement over the on-off switch we currently flip when PSPS events are called. Load limiting could complement some of the other investments utilities are already pursuing under the banner of wildfire adaptation, such as microgrids and grid sectionalization. It could also come in handy when electricity demand exceeds supply for other reasons, at least until we’ve made more progress on incorporating demand response.
We are part of a larger research team that is working to understand how power system investments and operations should respond to mounting wildfire risk in California. Load limits seem like potentially low hanging fruit in this respect. If you disagree, tell us why! And if you share our nascent enthusiasm, let us know! If this idea has potential, our team is game to help figure out how to implement it.
Keep up with Energy Institute blogs, research, and events on Twitter @energyathaas.
Suggested citation: Fowlie, Meredith. “Smart Meters, Dumb Blackouts?” Energy Institute Blog, UC Berkeley, September 8, 2020, https://energyathaas.wordpress.com/2020/09/08/smart-meters-dumb-blackouts/