By Amanda Durish Cook

CARMEL, Ind. — While a MISO workshop last week fell short of defining potential market rules for energy storage devices, it did provide stakeholders an opportunity to hash out their thoughts on a technology that straddles the boundaries between generation and transmission.

During the RTO’s first energy storage workshop last month, stakeholders advised it to consider all the capabilities and types of battery storage before drafting market rules and creating definitions. (See MISO Rules Must Bend for Storage, Stakeholders Say.)

At the second — and likely final — workshop Aug. 24, MISO took a stab at providing structure for addressing the complex issue by suggesting which committees should field various storage proposals.

MISO assigned Chief Compliance Officer Joseph Gardner to serve as its liaison to the newly created Energy Storage Task Force, which will gather ideas that could eventually become proposals at the Resource Adequacy Subcommittee, Market Subcommittee, Reliability Subcommittee and Planning Advisory Committee.

The RTO suggested that the PAC could handle storage interconnection methods and possible transmission cost recovery, while the MSC would tackle compensation rules. Either the MSC or RSC could work on the creation of no-harm tests, operating traits and market participation models, while the RASC could undertake capacity accreditation rules, said MISO Executive Director of External Affairs Kari Bennett.

But discussion at the workshop focused on the beguiling and intriguing issues around storage — and how to accommodate the increased adoption of a resource that defies MISO’s current market categories. The RTO currently has about 140 MW of battery storage requests in its interconnection queue.

‘A Giant Lego Set’

Lin Franks stressed the future importance of storage resources in MISO, saying she’s become a battery convert since volunteering to head the energy storage division at Indianapolis Power and Light.

“I feel like I learn something new about these things every day,” Franks said. “Like I said, I’m a born-again Christian when it comes to batteries. They can solve problems, and solve them quickly.”

IPL’s Harding Street Station was MISO’s first battery storage facility, commencing operation in May 2016. The facility can continuously deliver 5 MW for more than four hours, as well as move from a neutral state to full injection or withdrawal of energy in under one second. It serves only primary frequency response, reacting to unanticipated deviations.

“The faster you can solve the [frequency] degradation, the fewer megawatts you need,” Franks said.

IPL last year mounted an unsuccessful campaign to have FERC order MISO to compensate resources for providing automatic frequency control. (See MISO Ordered to Change Storage Rules Following IPL Complaint.)

Like all grids, MISO’s system was designed with control in mind, Franks said. Recent additions of rooftop solar and wind generation can erode that control, but autonomous storage resources can mitigate those risks and provide more resilience.

“We like to talk about storage as one kind of animal, but it’s not. It’s a whole zoo of animals,” Franks said. “When I talk about my lithium ion battery, that’s not what all lithium ion batteries are like. They morph with the industry. They’re like a giant Lego set.”

Franks urged stakeholders to educate themselves on stored energy resources.

“Real-time operators don’t like change. They know what works and they’re comfortable with it. … Just like you, I see some arms crossed out there,” Franks said, teasing the audience.

Franks noted that MISO and state and federal agencies are still working out policy details around storage, including capacity accreditation, facilities agreements, state-of-charge management, interconnection conditions, removal of Tariff barriers and clarification of state versus FERC jurisdiction. She also recommended that MISO lay out an “expedited path” in its annual Transmission Expansion Plan for storage resources.

Franks recounted the confusion Harding Street caused upon entering MISO’s interconnection queue in 2014.

“None of us knew how to model these at the time,” she said, adding that the RTO eventually settled on modeling the battery at its maximum injection and withdrawal.

Each of the storage array’s eight 2.5-MW cores contain more than 20,000 data points captured every two seconds and used to manage the state of charge, which IPL currently handles. But state-of-charge management could be passed to MISO.

“There is the perception among some at FERC that having the RTO manage the state of charge creates a conflict of interest,” she added.

‘Slicker than Snot’

Stakeholders asked MISO officials how its markets could permit storage to serve two masters ― generation and transmission services.

RSC Chair Tony Jankowski, manager of electric system operations at We Energies, wondered how MISO could possibly allow a storage resource to switch between participating as a generating asset or a transmission asset using the RTO’s existing “clunky” market process.

“These things are slicker than snot and can do a lot of things in a very short period of time,” Jankowski said, adding that MISO might accommodate the chameleon-like nature of storage with an “either/or” asset registration.

Indiana Utility Regulatory Commission staffer David Johnston said asset registration raises a question of whether storage resources must enter the RTO’s generation interconnection or the MTEP process.

“I think these are all good questions,” said MISO Director of Planning Jeff Webb, who added that he could not yet venture a guess as to the solutions. One of his concerns is keeping enough available capacity on hand if storage can register as both capacity and transmission assets.

“But none of these [questions] are showstoppers. It’s just how to manage them,” Webb said.

“Whatever the process, I don’t want to halt the progress of these Lego blocks, as Lin called it,” said DTE Energy’s Nick Griffin.

Multiple stakeholders said MISO’s storage models must account for every kind of storage, from the more common battery storage to flywheel to compressed air to pumped storage.

Griffin pointed out that MISO is years away from modeling storage as both a transmission and generation resource. However, Jankowski pointed out that storage modeling could be simplified by distinguishing between synchronous and inverter connections.

Some stakeholders said collection of storage information is the key to creating participation models, but Customized Energy Solutions’ David Sapper said he would play the “contrarian” and caution about information overload. Sapper pointed to the risk of micromanagement through extensive communications and controls, an issue raised by University of Wisconsin engineering professor Bob Lasseter at the Organization of MISO States’ distributed energy resources workshop earlier this month. (See Stakeholders Hash out Future of DER at OMS Workshop.)

While Franks agreed, she countered that a lot of information may be necessary at the onset of market storage participation.

“This is new to [MISO operators], and until they get comfortable, they’re going to want to see more than less — and that may not take very long,” she said.

American Transmission Co.’s Bob McKee said it would be helpful for MISO to create a price menu showing the current compensation provided for possible storage-sourced services like energy arbitrage and frequency response.

“I think it’s fair to say if we did that now, we’d have a lot of question marks in there,” Bennett said.

“That’s fine. This [menu] would tee that up,” McKee said, and other stakeholders agreed.