
There are several types of STES technology, covering a range of applications from single small buildings to community district heating networks. Generally, efficiency increases and the specific construction cost decreases with size. UTES (underground thermal energy storage), in which the storage medium may be geological strata ranging from earth or sand to solid bedrock, or aquifers. UTES technologies include: [pdf]
Image showing heat loss from a house. New research on thermal energy storage could lead to summer heat being stored for use in winter. Credit: Active Building Centre, Swansea University Funding to research thermal energy storage that could cut bills and boost renewables.
A group of Swiss researchers claim to have come up with a process that stores heat captured during summer for easy, flick-of-a-switch use in winter, with the added benefit that the captured energy can be physically transported anywhere it may be needed.
Funding to research thermal energy storage that could cut bills and boost renewables. New technology that could store heat for days or even months, helping the shift towards net zero, is the focus of a new project involving the Active Building Centre Research Programme, led by Swansea University, which has just been awarded funding of £146,000.
Seasonal thermal energy storage (STES), also known as inter-seasonal thermal energy storage, is the storage of heat or cold for periods of up to several months. The thermal energy can be collected whenever it is available and be used whenever needed, such as in the opposing season.
Warm-temperature seasonal heat stores can be created using borehole fields to store surplus heat captured in summer to actively raise the temperature of large thermal banks of soil so that heat can be extracted more easily (and more cheaply) in winter.
Alternative descriptions include: Heat Bank, Heat Battery, Heat Store, Heat Vault, Underground Energy Storage, Seasonal Heat Storage, Interseasonal Heat Store, Seasonal Thermal Store, Interseasonal Thermal store, Underground Thermal Energy Storage ("UTES"), seasonal soil heat accumulator.

The different kinds of thermal energy storage can be divided into three separate categories: sensible heat, latent heat, and thermo-chemical heat storage. Each of these has different advantages and disadvantages that determine their applications. storage (SHS) is the most straightforward method. It simply means the temperature of some medium is either increased or decreased. This type of storage is the most commerciall. [pdf]
The different kinds of thermal energy storage can be divided into three separate categories: sensible heat, latent heat, and thermo-chemical heat storage. Each of these has different advantages and disadvantages that determine their applications. Sensible heat storage (SHS) is the most straightforward method.
Thermal energy (i.e. heat and cold) can be stored as sensible heat in heat stor-age media, as latent heat associated with phase change materials (PCMs) or as thermo-chemical energy associated with chemical reactions (i.e. thermo-chemical storage) at operation temperatures ranging from -40°C to above 400°C.
Thermochemical heat storage works on the notion that all chemical reactions either absorb or release heat; hence, a reversible process that absorbs heat while running in one way would release heat when running in the other direction. Thermochemical energy storage stores energy by using a high-energy chemical process.
If the products of the endothermic reaction are stored, the chemical heat pipe can also be operated as a thermochemical heat storage system, thereby combining both a distribution possibility for thermal energy that is in principle free of losses as well as a thermochemical energy storage.
Summarizes a wide temperature range of Cold Thermal Energy Storage materials. Phase change material thermal properties deteriorate significantly with temperature. Simulation methods and experimental results analyzed with details. Future studies need to focus on heat transfer enhancement and mechanical design.
Sensible heat thermal storage is achieved by heating the storage medium (liquid sodium, molten salt or pressurised water) and increasing its energy content but not changing state during accumulation. Energy is released and absorbed by the medium as its temperature reduces and increases respectively.

The Iron Redox Flow Battery (IRFB), also known as Iron Salt Battery (ISB), stores and releases energy through the electrochemical reaction of iron salt. This type of battery belongs to the class of (RFB), which are alternative solutions to (LIB) for stationary applications. The IRFB can achieve up to 70% round trip . In comparison, other long duration storage technologies such as pumped hydro energy storage pr. [pdf]
Iron-air batteries have a “reversible rust” cycle that could store and discharge energy for far longer and at less cost than lithium-ion technology A U.S. company is designing a large battery that it says could help decarbonize the nation’s power sector more cheaply than lithium-ion storage systems—and with domestic materials.
The low cost and high availability of iron could allow iron-air batteries to store electricity for several days during periods of low solar and wind power generation. One such iron-air battery is being designed by Form Energy, a company based in Massachusetts that’s co-run by a former Tesla Inc. official.
A battery energy storage system (BESS) is an electrochemical device that charges (or collects energy) from the grid or a power plant and then discharges that energy at a later time to provide electricity or other grid services when needed.
A more abundant and less expensive material is necessary. All-iron chemistry presents a transformative opportunity for stationary energy storage: it is simple, cheap, abundant, and safe. All-iron batteries can store energy by reducing iron (II) to metallic iron at the anode and oxidizing iron (II) to iron (III) at the cathode.
Pure iron and iron compounds are used as active materials in iron batteries to enhance electrical and ionic conductivity and cycle life . Recently, there have been research reports on iron-air batteries in liquid electrolyte or all-solid-state battery systems .
Capabilities and limitations Our iron battery has sufficient capabilities for practical use in low power devices and projects. The cell’s internal resistance is high, and so the discharge rate is limited.
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