Battery storage for several hours

However, there is growing interest in the deployment of energy storage with greater than 4 hours of capacity, which has been identified as potentially playing an important role in helping integrate larger amounts of renewable energy and achieving heavily decarbonized grids.1,2,3

We highlighted including Li-Sulfur, solid-state, and flow batteries as important for the future of battery storage. We found flow batteries as especially relevant for ulta-long duration storage, noting their potential for: 1. Separation of power and energy, allowing for flexible and cost-optimized storage capacity.

value for a fifth hour of storage (using historical market data) is less than most estimates for the annualized cost of adding Li-ion battery capacity, at least at current costs.25 As a result, moving beyond 4-hour Li-ion will likely require a change in both the value proposition and storage costs, discussed in the following sections.

A battery with less than the duration requirement can receive partial capacity value, as shown in Figure 2, representing a linear derate, so a 2-hour battery would receive half the credit of a 4-hour battery, but a 6-hour battery receives no more value or revenue (for providing capacity) than a 4-hour battery in this example.

61 Cole, Wesley, Akash Karmakar. (2023). Cost Projections for Utility-Scale Battery Storage: 2023 Update. NREL/TP-6A40-85332. 8. lasts 30 years or more. Flow batteries do not suffer from the same degradation mechanisms as Li-ion batteries, and have the potential for relatively low-cost electrolyte replacement.

Our white paper, Utility-scale energy storage at an inflection point, underscored the importance of alternative storage technologies to lithium-ion. We highlighted including Li-Sulfur, solid-state, and flow batteries as important for the future of battery storage.