Over the past year and a half, the U.S. energy storage industry has been getting into arguments with grid operators over their plans to implement Federal Energy Regulatory Commission Order 841, the mandate to integrate energy storage assets into the country’s wholesale energy markets.
The biggest argument to date has been over PJM’s insistence on a 10-hour duration requirement for batteries to play in its capacity market.
Storage advocates and clean energy groups say the proposal violates FERC Order 841’s call for open and equal access for energy storage assets, by effectively making it impossible for lithium-ion batteries to economically compete against fossil-fuel-fired plants in the country’s biggest capacity market.
They’ve also complained that PJM hasn’t provided an analysis to justify such a long duration requirement, which is actually based on an old rule for pumped-storage hydro projects. But the groups challenging the data behind PJM’s proposed rule haven’t had their own analysis to counter it — until now.
Last week, the Energy Storage Association and Natural Resources Defense Council unveiled an analysis by Astrapé Consulting, using PJM data and industry-standard modeling, that indicates gigawatts’ worth of energy storage in 2-hour, 4-hour and 6-hour durations could provide the same capacity value as power plants that run 24 hours a day.
There’s a relatively simple explanation for this finding. While PJM may see its daily demand on peak days rise, peak and fall over the course of 10 hours or more, the true “peaks” at the very top of that demand curve “can presently be met by efficient dispatch of shorter-duration storage, given the current mix of supply resources,” ESA writes.
Specifically, “The results of our analysis demonstrate that with energy storage deployments up to 4,000 MW, 4 hours of duration allows those resources to provide full capacity value relative to a resource without duration limits,” Astrapé states.
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