Energy Storage Can Reduce Variable Energy Generation Up to a 55%: Report

National Renewable Energy Laboratory (NREL), a global research organizaiton recently released a report titled ‘Timescales of Energy Storage Needed for Reducing Renewable Energy Curtailment.’ This report talks the importance of integrating large quantities of variable generation (VG) energy, such as wind and solar energy, into regional power grids while minimizing curtailments. Achieving this integration demands flexible solutions including grid operations and the deployment of technologies accordingly.

The report identifies a growing interest in energy storage technologies that can accommodate the increasing demand for renewable energy. Notably, the costs of storage have witnessed a decline, increasing its feasibility. The report presents an innovative solution by quantifying the energy storage to mitigate VG curtailment and underscores the value it brings to the integration of VG and grid operations.

Key findings from the report reveal that relatively short-duration energy storage solutions hold substantial potential in reducing VG curtailments, particularly up to a 55% penetration rate. It is worth noting that, across diverse combinations of wind and solar resources, a significant portion of the potential curtailment reductions can be achieved with just 8 hours of storage, with the initial 4 hours delivering the most substantial benefits. Additionally, the report emphasizes that VG penetrations of up to 55% exhibit diminishing returns, if used for very long-duration or for seasonal storage deployment.

The report presents scenarios where an increase VG contribution that exceeds 50%, serving as valuable test cases for the role of storage in curtailment mitigation, particularly in remote areas. For instance, using a wind-to-solar ratio of 4:1, a 55% VG penetration scenario can be realized with non-transmission-related curtailment limited to just around 12%, even without additional storage or cross-regional energy sharing.

Different resource mixes, particularly in the context of wind and solar, are evaluated, revealing that a wind-to-solar ratio of approximately 2.2:1 minimizes curtailment, a crucial insight for efficient renewable energy integration. There is an advantage in using shorter-duration energy storage as it become evident when using curtailment mitigation. In scenarios involves the using a mix of wind and solar resources, that provides a 4-hour storage device. Which can prevent approximately 70% of the curtailment that would otherwise occur. Other benefits include increasing to over 85% with 8 hours of storage. Conversely, the report states a Wind Vision scenario which means that, 10% of the nation’s end-use demand served by wind by 2020, 20% by 2030, and 35% by 2050.curtailment is reduced by about 35% at 4 hours, 50% at 8 hours, and remains below 60% at 12 hours.

In conclusion, the report demonstrates that wind, PV, and solar energy sources present a viable pathway for renewable energy integration. Notably, short-duration energy storage, particularly 4 to 8 hours, offers an effective solution for integrating variable generation up to 55% penetration. The report also underscores the economic value of storage solutions, suggesting that cost improvements may make storage with durations of 6 to 8 hours feasible. However, deploying very long-duration or seasonal storage solutions at VG penetrations up to 55% may offer limited value.

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