By Hudson Sangree

SAN FRANCISCO — The explosive growth of solar power in California will require a huge amount of new electricity storage to allow the state to meet its ambitious green energy goals, panelists said Tuesday at this year’s Infocast Storage Week conference.

“What’s my vision for storage? Very quickly. We’re going to have to have a lot of it,” said Monterey Bay Community Power CEO Tom Habashi, who was part of a panel on storage and community choice aggregators (CCAs). “We are not even at a fraction of 1% of what we need to be at. I don’t see any other way of reaching decarbonization unless we have a lot of solar and a lot of storage to go with it so we can cover all the hours when the sun doesn’t shine.”

Last year’s SB 100 established a timeline for the state’s utilities and CCAs to get all their electricity from zero-carbon sources by 2045. But the state’s ample solar production peaks at a time when it’s least needed — during the lowest point of the so-called “duck curve” in the middle of the day. (See Can Calif. Go All Green Without a Western RTO?)

Larger batteries are just beginning to store a tiny portion of the electricity needed during the evening ramp, when the sun goes down and electricity demand soars as people arrive home on the West Coast. Doing away with natural gas peaker plants, as the state envisions, will require solar projects to be coupled with storage, speakers said.

The Monterey Bay CCA, for example, has 265 MW of solar energy plus 85 MW of storage. “We’re way, way ahead of what we are required to do,” Habashi said.

John Zahurancik, CEO of Fluence Energy and a 20-year veteran of large-scale storage projects, said larger and longer-duration battery projects are coming online all the time, but that it’s likely just the beginning.

“We’re in the early days of when this starts to scale,” Zahurancik said during a panel on standalone storage. “It’s just starting to pick up speed.”

Fluence is building a 100-MW standalone storage project, among the largest in the U.S., he said. More utilities are looking to lithium-ion batteries, in “increasingly large types of systems,” as a solution to the challenges of intermittent solar and wind power.

Asked whether any technologies would emerge to compete with lithium-ion batteries, Zhurancik said the batteries are a proven technology being built at volume with backing from deep-pocket investors. He said he expects to see improvements and changes but probably not a “wholly new” storage solution in the next five years.

Rooftop Solar ‘Underestimated’

In a panel on ISOs and storage moderated by RTO Insider Deputy Editor Robert Mullin, Clyde Loutan, CAISO’s principal planner for renewable energy integration, said the ISO hadn’t anticipated how fast rooftop solar would proliferate and create challenges for it.

“We completely underestimated the speed at which rooftop PV was going to come onto the grid,” Loutan said. There are 7,000 MW of rooftop solar in California, and planners expect to see as much as 13,000 MW by next year, he said.

Utility-scale solar projects supply another 12,000 MW of electricity in CAISO, he said.

With a variable resource like solar, output can suddenly drop by 1,000 MW, requiring battery storage that can come online quickly and make up for the shortfall, he said, and solar falls away each night.

“During the evening you got to meet that huge ramp when the solar drops off,” Loutan said.

On the other hand, there’s far too much solar power available on weekends. Oversupply and undersupply create challenges controlling the grid and maintaining the frequency at 60 Hz, Loutan said.

“You need a lot of stability,” he said. “You need a lot of fast-injecting capability. Storage can provide that.”

‘Best, Highest Use’

Mullin cited an RTO Insider story in which MISO CEO John Bear said RTO staff are working to determine the “best, highest use” for storage projects.

“We’ve almost internally forced ourselves as a company to calling them batteries, as opposed to storage, just because we don’t want to presuppose what the best use of them might be,” Bear said at the Gulf Coast Power Association’s MISO South Regional Conference in February. (See Overheard at GCPA MISO South Regional Conference.)

Batteries might be most valuable as quick-response resources to help balance the grid, he said.

Asked to elaborate, Kevin Vannoy, MISO’s director of market design, said, “What I think John was getting at there was it’s not about just storing energy for later injection.”

“I think we don’t want to limit ourselves to just a single product when it comes to storage or a single use or a single application because of the flexibility and the different products it can provide and the problems that it can solve.

“We don’t want to get stuck into just thinking of these as we have our traditional pumped hydro units,” Vannoy said. “We want to make sure we’re getting the full value … [and] capabilities that batteries and storage can bring.”

Loutan said the highest and best use for storage right now is to provide reliability and frequency response.

“We still need to explore the capabilities of storage,” he said. “How can we utilize the capabilities of storage to develop new products and help operate the grid differently?”

Challenges and Opportunities

Connecting storage to the grid isn’t as simple as plugging in a battery, panelists said. Challenges exist, with more to come, but batteries also present potential solutions to pressing needs, they said.

“One thing I would recommend is … making sure that the battery’s sized accordingly,” said Eric Hsia, liaison to the CEO at PJM. Oversizing or undersizing can cause trouble.

“If they do that and they do it wrong, it could potentially pose operational issues, which we did experience in the regulation market,” he said.

Kenneth Ragsdale, market design principal with ERCOT, said “I don’t want to sound like a Texan, but I think our challenges are a little harder than theirs.”

The Texas Interconnection is smaller than the Western or Eastern interconnections, “so the loss of our two largest units in the ERCOT system is a big hit in terms of trying to maintain the frequency. We’re very careful about making sure we have enough rotating mass, enough inertia, on the system.”

ERCOT adopted a “fast frequency response” protocol, he said. “Basically, you need a resource that can respond to a frequency deviation within 15 cycles,” he said. “We see a lot of hope for some batteries coming in and doing that.”

Batteries could also help alleviate five- to 15-minute price spikes and deal with the daily four-hour peak in the hot Texas summers, Ragsdale said.

In New York, “there’s tremendous opportunity for storage,” said Mike DeSocio, senior manager of market design with NYISO. The state mandated storage and has about 2,000 MW queued up, from 1.5- to 300-MW storage projects. “Storage is coming,” he said.

The state is looking to develop large quantities of offshore and onshore wind power along with rooftop solar. Batteries could help balance those variable resources with low-carbon electricity, he said.

Batteries could also buffer the state’s ample nuclear output (which is set to get financial support from zero-emission credits) — the same way pumped hydro did when the nuclear plants were first built, he said.

“I kinda feel like we’re going back to the future here a little bit,” DeSocio said.