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NERC sees growing role for battery storage, calls for further studies

Battery energy storage can provide essential services to ensure the reliability of the bulk power system, but system planners need to conduct more analysis in order to integrate higher levels of storage into the grid, according to a report released by the North American Electric Reliability Corporation (NERC) this week.

Battery energy storage can contribute to the reliable operation of the bulk power system “in a similar fashion as synchronous resources that provide those same necessary characteristics to the grid,” the report said.

“North America currently has less than 2 GW [gigawatts] of battery storage, but that capacity is projected to increase 100 percent to 4 GW by 2023,” Thomas Coleman, NERC’s chief technical advisor of engineering and standards, said in a statement. “It is abundantly clear that battery energy storage systems have a key role” in the “rapid transformation of the transmission grid” to meet goals for the reduction of carbon dioxide emissions while maintaining reliability, security and resilience, he added.

NERC cited Department of Energy projections that by 2050, 35 percent of the United States’ energy will come from wind power (404 GW) and 27 percent will come from solar photovoltaic power (632 GW).

As the amount of renewable generation on the grid has grown, battery energy storage has also expanded. In 2014, utility-scale battery storage capacity in North America was approximately 214 megawatts (MW). By 2019, battery storage increased to 899 MW. “This growth is expected to continue with utility scale storage levels reaching 3,500 MW by 2023,” the NERC report said.

Battery energy storage can play several roles in the transformation of the grid, NERC said, identifying functions such as supplying peaking capacity; minimizing the need for new generation and transmission infrastructure, and providing reliability services such as frequency response, ramping and voltage support.

To keep pace with this transformation, however, NERC said electric system planners “should conduct further analysis to model a system with significant battery storage and hybrid power plants.”

And while existing NERC reliability standards adequately cover existing battery storage installations, the report recommended “NERC should conduct a thorough assessment of existing standards and guidelines to ensure that they adequately consider the projected large increase in battery energy storage systems.”

In addition, the report said that data on battery storage “lacks consistency across reporting entities, necessitating a need for better reporting mechanisms for this type of data.” NERC recommended that entities that compile battery data information enhance both their data and their reporting methods.

NERC also said that the value of battery storage as a complement to variable energy resources, such as wind and solar, should be fully understood by system planners and operators. "System planners must conduct adequate studies to determine the dynamic stability impacts of battery storage interconnection, the capability to provide capacity to meet long-term and contingency reserve margin requirements and the ability to provide essential reliability services."

The report also recommended that NERC’s Reliability and Security Technical Committee form a task force to study the implications of battery energy storage systems and their overall effects on bulk power system reliability and resilience.

“As we continue to assess the implications created by the integration of cutting-edge technologies to the electrical grid and the increasing amount of projected battery storage in the future, industry and regulators must pay more attention to bulk power system-connected battery energy storage systems,” Coleman said.