Elliot Mainzer knew years ago that things needed to change. As president and CEO of the California Independent System Operator, he saw demand for power increasing right as the interconnection queue became increasingly clogged — especially with projects that the state didn’t have the transmission capacity to get online.
In 2024, new operating projects in CAISO spent an average of 9.2 years in the interconnection queue, the longest of all the ISOs evaluated by an outlook published in May by the research group Enverus. Meanwhile, one early 2024 study from the grid industry association Advanced Energy United found that CAISO’s queue got particularly congested following the COVID-19 pandemic, when there was a fast uptick in new generation applications for interconnection.
“There was some inevitable change that was going to have to happen,” Mainzer told Latitude Media about those post-COVID years. “Everybody understood. FERC understood it; the utilities understood it; we all understood that that paradigm was just not working.”
From its perch outside of Sacramento, CAISO runs the transmission grid: overseeing infrastructure planning and interconnection queues, and managing the resulting flow of electricity to local utilities. And as the state’s energy needs shift, CAISO has had to shift as well.
For instance, the grid operator is now a year into the implementation of a new process for managing the interconnection queue, with an eye toward speeding things along and getting more generation hooked up sooner. “We talk about this in terms of trying to take friction out of the system,” Mainzer said. “There’s still some work to be done, but I think we’ve made some real progress in the fact that we’ve brought so much new generation on board.”
But the moment has also called for better coordination with the various other organizations responsible for energy in the state.
“Running grids anywhere in the country really takes a village,” Mainzer said. For the state of California, he added, simultaneously making sure the state can stay on track for its climate goals, improving power reliability, getting transmission built, and managing interconnection queues has required clearly laying out who does what.
In 2022, CAISO, and the California Public Utilities Commission and Energy Commission signed a memorandum of understanding to codify those roles. And in its wake, Mainzer said the three organizations have a “really good set of working relationships…particularly with respect to power transmission planning and interconnection key reform, all of which have to be totally synchronized and coordinated in order to work efficiently.”
The state has brought on 25 gigawatts of new generation since that MOU was signed; a 2024 Berkeley analysis estimated that the state will need roughly $45 billion to $60 billion in transmission investment over the next two decades to support additional new generation.
Reforming the interconnection queue
It’s not as though CAISO was starting from zero. The 2024 Advanced Energy United study actually found that CAISO had one of the most successful interconnection processes in the United States — just one plagued by long waits. But by last year, ramping demand made it clear that the queue wasn’t going to unclog itself.
In 2024, CAISO went to the Federal Energy Regulatory Commission in search of interconnection reform. The first shift they made was to plan transmission around the load forecasts and power resource planning from the state PUC and Energy Commission. From there, they took on the interconnection queuing process; rather than rely on a first-come-first-served approach, CAISO looks at the projects in the queue that are near to places where there is either existing capacity or new transmission being built.
In practice, this means that the projects with “the least incremental impact on the grid” and the projects in which load-serving entities have expressed interest are first in line for CAISO to study, Mainzer explained. “We put that into production in the fall of 2024 and we immediately cleared, like 65% of the requests out of the queue.”
A year after the reforms got FERC’s approval, though, Mainzer sees that the changes are already bettering the queue. As an example, Mainzer pointed out that the state hasn’t had a single flex alert since 2022. “That said, no rest for the weary,” he added. “We’ve got to turn around and do that every single year again, and continue taking friction out of the system.”
That said, the response to CAISO’s interconnection reforms was not universally glowing. “There were obviously some concerns among some folks in the independent power community,” Mainzer acknowledged, including whether the new system would advantage new generation from load-serving entities over independent projects that had been sitting in the queue for longer.
In Mainzer’s view, things are so far working as intended. “We’re going to watch it really carefully,” he said. “It was a complex set of reforms; we need to make sure we don’t see any untoward behavior…and we’re going to continue fine tuning our interconnection processes in the years ahead.”
As for whether wait times are coming down? Well, it may be too soon to tell, especially because the reform comes alongside a continued influx of projects; Mainzer acknowledged that “there’s still work to be done.”
For instance, CAISO is exploring whether artificial intelligence and other tools can get study timelines down even more. (The grid operator is already embracing AI more than its counterparts elsewhere in the country; this summer, CAISO began piloting a generative AI platform designed to enable it to streamline outage coordination, making California the first state to actively manage power outages with AI.)
“I don’t think we’re done yet,” Mainzer said. “But in terms of being able to significantly shrink down the size of the study pool to a set of projects that still have a really healthy supply curve — but projects that are relevant and projects that have a good chance of commercial success — we think that’s been a big improvement.”
Streamlining the load side
Meanwhile, shifts are also coming on the load side. California is especially focused on reliably determining how much load growth it can expect from data centers, Mainzer said.
“With respect to the data centers, there is a ton of work going on right now at the California Energy Commission, with the utilities themselves, to try to get the best estimates possible about just how significant the demand is going to be in California,” Mainzer said, adding that CAISO is already reinforcing the transmission system in Silicon Valley in anticipation of growth there.
They’re also, however, beginning to figure out whether data centers can also provide flexibility for the grid — which could be highly relevant to how and where projects get interconnected. Earlier this year, a team of researchers at Duke University found that if large loads, and especially data centers, could be flexible with their energy use, it could unlock more than 100 gigawatts of extra capacity on the grid.
“We’re going to need these resources to come on the system and provide some level of flexibility during extreme grid events, so that they don’t just create big resource adequacy issues for the system,” Mainzer said. “So I think in the next year, we’re going to have a much clearer understanding of what the data center load growth looks like.”
But for now, while Mainzer’s counterparts at the PUC and the Energy Commission are beginning to explore load flexibility and DERs and how they can play a role in reliability, CAISO’s bread and butter is still on the transmission and generation side, especially in the next year.
“To me, that focus on resource adequacy, on transmission planning, interconnection queue reform, and efficiently onboarding new resources, that’s the central preoccupation and focus of our California responsibilities,” Mainzer said.
“But right now — and I would say, in the next year — our focus will be continued interconnection queue reform, supporting the state in constructing and energizing new transmission, and at the end of the day, really taking this next step where to bring that next level of benefits around the regional energy market to the electricity consumers.”
