Soil-Based Thermal Storage Emerges as Promising Solution for Energy Efficiency and Grid Relief

As the heating season concludes, scientists are turning their attention to innovative methods of energy storage. A recent study by Kaunas University of Technology (KTU) in Lithuania suggests that soil can serve as an effective medium for thermal energy storage, allowing excess energy to be retained and released during periods of high demand.

The core of the research centers on a ground-based thermal accumulator capable of storing surplus heat underground and discharging it when needed. In the initial phase of the study, the research team explored generating heat directly from wind energy rather than converting it into electricity. By replacing traditional generators with hydraulic systems, they unexpectedly discovered that hydraulic losses could produce usable heat. However, some thermal energy is lost during transmission, making it crucial to reduce heat loss and enable long-term storage.

To test their hypothesis, researchers placed artificial heat sources in surface-level soil and observed the diffusion and retention of heat over time. They found that heating the soil to the point of water evaporation triggered a phase change, which significantly improved heat storage capacity. The resulting steam dispersed heat more broadly throughout the soil, and temperature changes remained controllable. This system could help stabilize district heating networks, alleviate grid pressure during peak loads, or power standalone thermal storage units for buildings and streets.

The study also found that underground thermal storage was more efficient than expected. The same principles could be applied to cooling systems as well. Through laboratory testing and year-round monitoring, the team discovered that soil beneath buildings could passively store heat, reducing thermal losses and improving energy efficiency. Numerical simulations showed that isolating soil layers could lower heating energy consumption. When combined with heat sources from fossil fuels or biomass, this method could also contribute to reducing carbon emissions.

The researchers are currently developing a small-scale prototype and refining heat distribution techniques. Future plans include integrating underground heat exchange technologies such as boreholes and pile foundations to enable large-scale applications in both industrial and residential settings. This emerging technology offers a promising path toward more efficient energy storage and meaningful emissions reduction.