As we strive to scale clean energy and decarbonize grids worldwide, long-duration energy storage (LDES) is emerging as a crucial solution. The demand for reliable, carbon-free energy (CFE) is growing as companies big and small aim to decarbonize and reach ambitious net-zero targets. Utilities and energy suppliers are at the forefront of the energy transition, tasked with meeting the increasing needs of their customers, including large commercial and industrial (C&I) customers with increasing load demands, while adhering to stringent decarbonization goals and adapting to rapidly evolving technologies. LDES has the potential to bridge the gap between intermittent renewable energy generation and the consistent, reliable power supply that consumers expect. This blog post explores the evolution of LDES, its various forms, and its transformative potential for energy supply.
The Evolution of Long-Duration Energy Storage
Energy storage has a long history, with technologies like pumped hydro storage providing reliable energy solutions for decades. However, the rise of variable renewable energy sources, such as wind and solar, has exposed the limitations of existing storage technologies. The variability of these energy sources necessitates storage solutions that can provide energy dispatchability over extended periods—sometimes for days or even weeks.
Emerging trends highlight the increasing need for LDES to support the proliferation of renewable energy. According to the International Energy Agency (IEA), additional annual renewable capacity grew by 50% globally in 2023, reaching a record 510 GW of annual capacity, with solar leading the charge. This growth in variable renewable energy underscores the urgent need for LDES to ensure a stable and continuous energy supply. Key innovations, such as advanced battery technologies and thermal storage, are driving the LDES market forward, offering promising solutions that can store energy for longer durations.
Market Context
The growth of the clean energy market is driven by a few factors, including increased demand for energy solutions that support decarbonization goals and skyrocketing load growth from data centers, cloud computing, and artificial intelligence (AI), and the electrification of transportation and buildings. The pressure on grids to manage these demands is intensifying. The market for 24/7 CFE is also gaining momentum as companies and governments aim to meet ambitious decarbonization targets, including powering their operations with green electrons every hour of the day.
Contractual instruments like power purchase agreements (PPAs) are becoming more critical in this landscape and securing sufficient green electrons to meet goals has never been more challenging and simultaneously critical path for corporate offtakers. Scaling LDES to support energy suppliers in offering clean energy projects that meet their customers’ goals requires overcoming significant challenges, particularly in reducing costs and improving market viability. As the clean energy market matures, LDES is positioned as a key enabler, providing the necessary infrastructure to store and dispatch energy as needed, thereby optimizing the use of variable renewable sources.
How is LDES Defined?
Long-duration energy storage refers to energy storage systems that can discharge electricity for extended periods, though the definition can vary significantly ranging from 4+ to 10+ to 100+ hours or more (see Table 1 of the recent Sustainable Energy for All report for additional LDES definition details). Unlike short-duration storage, which is designed to handle brief fluctuations in supply and demand, LDES is intended to bridge longer gaps, such as those caused by prolonged periods of low renewable generation or unexpected spikes in demand. LDES technologies are essential for balancing the grid, ensuring energy reliability, and enabling the integration of higher levels of renewable energy into the energy mix.
Types of Long-Duration Energy Storage
LDES technologies come in various forms, each with unique advantages and disadvantages:
- Pumped Hydro Storage: A mature technology that stores energy by pumping water uphill to a reservoir during low-demand periods. It is highly efficient but is geographically limited and requires significant upfront investment.
- Compressed Air Energy Storage (CAES): CAES stores energy by compressing air and storing it in underground caverns. While scalable, it faces challenges in efficiency, cost, and geographical constraints.
- Flow Batteries: These batteries store energy in liquid electrolytes, offering scalability and long-duration storage potential. Although still in the early stages of market penetration, flow batteries show promise due to their flexibility and potential for cost reduction.
- Thermal Energy Storage: This technology stores energy in the form of heat, which can later be converted back into electricity. Thermal storage is adaptable and can be integrated with existing energy systems, but it requires significant infrastructure and is currently less mature than other LDES technologies.
- Innovative and Emerging Technologies: Emerging solutions, such as hydrogen storage and gravity-based systems, are on the horizon. These technologies are in the research and development phase, with ongoing efforts to improve their market readiness and cost-effectiveness.
Looking Ahead
Long-duration energy storage is emerging as a game-changer, addressing the pressing need for grid resilience as renewable energy generation grows. The technologies discussed in this post provide a glimpse into how LDES can stabilize grids and ensure a reliable power supply, even in the face of fluctuating renewable generation. As energy suppliers and utilities navigate this complex landscape, choosing the right storage solutions, in tandem with further innovation, will be critical.
