CARMEL, Ind. — FERC’s extensive energy storage order has handed MISO’s Reliability Subcommittee a new set of to-dos, including devising a storage capacity accreditation process and deciding whether storage will be subject to a must-offer requirement.

The subcommittee will also vet a proposal that will determine whether energy storage owners or MISO will manage the state of charge for resources. The group will additionally consider broader issues around storage, including:

• What information MISO needs about batteries to manage real-time operations;
• The risks of allowing market participation of energy storage at times when it’s not dispatched; and
• Whether MISO should employ reliability improvements to mitigate risks of storage use.

Finally, the group could lay out rules to clarify that energy used for charging is not considered “station power,” which MISO defines as the power a generating facility uses for operating electrical equipment. MISO’s current definition of station power does not include energy used for pumping at a pumped storage facility.

The items were handed down from MISO’s Steering Committee based on recommendations made from the Energy Storage Task Force after discussions on Order 841 and storage’s potential in the RTO.

At a May 3 RSC meeting, MISO Market Design Manager Kevin Vannoy said the RTO will bring storage participation straw proposals to a June 6 joint meeting of the RSC, Resource Adequacy Subcommittee and Market Subcommittee. He said MISO will vet storage proposals throughout summer to prepare for a December compliance filing.

Vannoy said MISO still hopes FERC will allow it to set a limit on the number of storage resources that can participate in its markets. FERC’s order set a 100-kW minimum size requirement for participation, causing RTO staff to worry that small resources will flood markets with finite capabilities.

— Amanda Durish Cook