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Energy Storage Could Support Majority Renewable Future: NREL Study

Energy storage, particularly diurnal storage, can play an important role in providing resource adequacy in future scenarios where renewable energy is the dominant form of generation, according to a new report from the National Renewable Energy Laboratory (NREL).

The study, Grid Operational Impacts of Widespread Storage Deployment, is the sixth and latest in NREL’s Storage Futures Study, a series of studies on the role of energy storage in maintaining a resilient and flexible electrical grid through 2050.

Past NREL studies in the series had shown the potential for between 213 gigawatts (GW) and 932 GW of energy storage by 2050 and, even in the most conservative scenario, in excess of 125 GW.

In the new study, NREL used 213 GW as a reference case and the most likely mid-range for energy storage installations. The study also modeled around a scenario in which 74 percent of electric output would be generated by wind and solar power by 2050.

“We really wanted to look at the effects of higher levels of deployment,” Jennie Jorgenson, principal investigator of the study, said.

Starting with its Regional Energy Deployment System (ReEDS) model that shows least-cost scenarios for energy storage under a range of cost and performance assumptions, NREL took the next step by testing that model to see how energy storage would perform under on an hourly basis.

“Overall, we find that the high storage (and often high variable generation) power system scenarios envisioned in ReEDS successfully operate with no unserved energy and low reserve violations, showing no concerns about hourly load balancing through the end of 2050,” the researchers wrote in the study. “Unserved” energy in the report refers to dropped load.

“We once again find that the potential future energy system with large quantities of energy storage could successfully balance load 24/7,” Jorgenson said in a statement. “On top of that,” she said, “we find power systems with high levels of energy storage operate more efficiently by storing otherwise unused renewable energy to displace costly generation from other sources.”

The study found the charging and discharge cycles of energy storage are well aligned with the diurnal cycles of solar power. Wind power, on the other hand, is less well aligned with daily cycles and often experiences periods of overgeneration that can last many hours or days, which is much longer than the storage durations in the study. Energy storage can play a key role in utilizing energy from both solar and wind power, but the synergies with solar power are more consistent, the researchers found.

The study also found that energy storage can increase the efficiency and lower the emissions of a power system by using wind or solar overgeneration to displace coal and natural gas-fired generation.

Energy storage also, more often than not, encourages higher utilization of transmission assets, the researchers found, but cautioned that further study would be needed to understand the interaction of storage and transmission assets.

“Collectively, the results of this and previous Storage Futures Study analysis show the growing opportunity for diurnal storage (that is, storage with up to 12 hours of duration) to play an important role in future power systems,” the researchers wrote.

Greater deployment of diurnal storage can increase efficiency of operations by reducing overgeneration, decreasing generator starts and emissions, and increasing utilization of the transmission system, they said.

Energy storage can also play “an important role in providing capacity during the top net load hours. Future work could examine the role of longer-duration storage resources, especially under highly decarbonized grid conditions, such as those approaching 100% clean energy,” the researchers said.

NREL is planning a free webinar on its new study on Jan. 25. There will also likely be a final synthesis report on NREL’s energy storage series in the next month or so, Jorgenson said.