By Amanda Durish Cook

MISO could have a limited set of market rules for energy storage as early as 2017, RTO officials told the Market Subcommittee last week.

MISO External Affairs Policy Advisor Jennifer Richardson said storage provisions could be a “combination of using established definitions” and creating new market rules.

In the near term, MISO said it will work with stakeholders on minor revisions to the Tariff and business practice manuals that would open the market to short-term and medium-term storage. By summer, MISO hopes to have a clear idea if storage should be treated as a generation resource or a transmission asset and whether it can participate in MISO’s capacity or ancillary service markets. For that, MISO needs to consider how behind-the-meter storage can function as load-modifying resources or demand response.

AES Project Nears Completion

The storage conversation comes as AES’ Indianapolis Power & Light edges closer to finishing the 20-MW Advancion Energy Storage Array in Indianapolis. The project, slated to be put into operation sometime in June, will be the first utility-level battery energy storage facility in the footprint.

Stakeholders have submitted a first round of comments on the issue in response to MISO’s call for input in January. (See MISO Preparing a Place for Energy Storage in Tariff.)

“A lot of stakeholder comments focused on developing new software,” said Yonghong Chen, MISO’s principal advisor of market development and analysis, during a presentation to the subcommittee. “In the next few months, probably from April to July, we’re going to work with stakeholders to determine what we can do [with existing software]. By next year, we hope to have implementation rules on how storage can participate with our current market software and market rules. … We have some existing language in the Tariff and BPMs that could apply, but some language needs clarification to apply to storage.”

From mid-2017 onward, MISO plans to tackle how storage will fit into five-minute settlement schedules, voltage and local reliability commitments, minimum megawatt participation limits and automatic generation control enhancement, software that deploys fast ramping resources more quickly.

“We want to remain as technology-neutral as possible, but FERC may have to step in at some point,” Richardson said.

Long-Term Plans

MISO said its longer-term storage considerations would run into 2019 and include make-whole payments, cost allocation and impacts to the annual Transmission Expansion Plan.

“We need more time to figure out how to make these work well together,” Chen said.

Jeff Bladen, MISO’s executive director of market design, said storage should work “holistically” with MISO’s market.

“This is very much a topic on stakeholders’ minds, as they’re thinking of developing projects and bringing them to market,” he said. “We have to be careful not to put energy storage into its own silo. It needs to fit into the larger Market Roadmap.”

Stakeholder Comments

Ameren told MISO that it believes energy storage could be categorized as “generation, transmission or other, depending upon its characteristics.” The company proposed that MISO classify storage as a use-limited resource, then perform an “initial asset evaluation” to determine if it should be treated as a generator or transmission asset. Use-limited resources are those “unable to operate continuously on a daily basis, but … able to operate for a minimum set of consecutive operating hours.”

Madison Gas and Electric said storage could fit into a generation or transmission definition. The company went a step further, suggesting that MISO remove prescriptive resource definitions from the Tariff altogether. “To be agnostic or ‘neutral’ when it comes to technology, then we need to be neutral as to what type of resource provides services. The Tariff lists the products and services permitted by each resource type. To become neutral, we should remove prescriptive/descriptive limitations and allow resources to provide any product or service for which it can satisfactorily deliver. We can test and measure performance of resources, eliminating the need to limit products/services by resource type,” Madison’s Megan Wisersky wrote MISO.

ITC Holdings advocated leaving storage unclassified, saying it was “premature” to categorize the technology when it hadn’t yet been integrated into the grid.

Amber Motley, manager of market operations for Xcel Energy, said market participants should be given the option of choosing to categorize storage as either generation or transmission, a position supported by MidAmerican Energy.

Chen said work on energy storage rules would play out in MISO’s Planning Subcommittee and Resource Adequacy Subcommittee, as well as other committees, if needed.

“We’re very mindful that stakeholders don’t want to chase these issues in a hundred different committees. Believe me, we don’t want that either. We’ll try our best to iron out those hard questions internally before we bring them to stakeholders,” Richardson said.

Chen asked for another round of stakeholder input before March 18.