The Federal Energy Regulatory Commission on Aug. 15 accepted proposals by the Midcontinent Independent System Operator Inc. to clarify that energy storage batteries are eligible to provide up and down ramping service, if technically capable. The measure is part of a broader push to open up markets to the emerging technology. FERC also affirmed MISO’s proposal to apply its must-offer rules to energy storage that provides capacity. FERC said that the grid operator must demonstrate how its market rules provide a means for batteries to provide capacity in a way that acknowledges the energy limitations of the technology. The grid operator proposed the energy storage category, called “Stored Energy Resource-Type II”, last April after Indianapolis Power & Light complained that current regulations improperly exclude the resource from selling services into the market. Indianapolis Power & Light is a unit of AES Corporation.