Long Duration Energy Storage (LDES) systems work by capturing heat during times of excess energy production—typically midday when solar generation peaks—and storing this energy for later use. This stored energy can be converted back to electricity or used directly for heating purposes during the evening or on cloudy days when solar output is low. The beauty of LDES lies in its simplicity and efficiency.

The case for LDES in California and Texas is particularly strong due to the unique utility grid electricity profile for both states. Solar energy production peaks around midday, but the highest demand for electricity occurs in the early evening. This misalignment leads to what is known as the "Duck Curve", a phenomenon whereby there is a rapid increase in the demand for electricity just as solar production is waning. LDES can flatten the belly of the curve by shifting the solar energy collected during the day to the evening, thus smoothing out the supply-demand mismatch.

Moreover, LDES can enhance grid stability and reliability. By providing a steady, dispatchable source of energy, LDES helps mitigate the intermittency issues associated with solar power. This capability is crucial as California and Texas aim to increase their renewable energy share and reduce reliance on fossil fuel-powered peaker plants, which are often called upon during times of high demand but are costly and emit large amounts of greenhouse gases.

The Texas grid (ERCOT) and California’s grid (CAISO) rely heavily on solar and wind energy, which are intermittent and pose challenges for balancing supply and demand. Surplus solar and wind power, especially during certain times of the day or year, can lead to inefficiencies. Consequently, ERCOT’s demand for energy storage is expected to grow from 6.3 GW to 17.7 GW by mid-2025 and CAISO with over10 GW of battery storage currently in operation is planning to add 12.1GW this year.

Phase Change Materials (PCMs) further enhance LDES systems by significantly improving their thermal management capabilities. PCMs absorb and release latent heat during phase transitions, which allows for the efficient storage and release of energy over extended periods. This property is particularly valuable in stabilizing temperatures within LDES systems, minimizing thermal losses, and maintaining a consistent energy output.