LDES Technologies


Thermal energy storage (TES) systems can store heat or cold to be used later, under varying conditions in temperature, place or power. TES systems are divided into three types:

  • Sensible heat
  • Latent heat
  • Thermochemical

Thermal energy storage can help to balance energy demand and supply on a daily, weekly and even seasonal basis, presented in thermal systems. It can also reduce peak demand, energy consumption, CO2 emissions and costs while also increasing the overall efficiency of energy systems.

The application of thermal energy storage with renewable energy sources, waste heat, or surplus energy production can replace heat or cold generation from fossil-fuels, reducing greenhouse gas (GHG) emissions and lowering the need for thermal power capacity of the generators. In Europe, the IEA has estimated that around 1.4 million GWh per year could be saved— and 400 million tons of CO2 emissions avoided—in the building and industrial sectors by more extensive use of heat and cold storage.

Thermal energy storage converts electric energy from the grid into thermal energy that is stored in inexpensive materials. TES systems can store energy from hours to weeks before converting it back to electrical energy or discharging the thermal energy directly. TES systems can provide 10s or even 100s of hours of electricity or heat at rated capacity. The energy capacity of the TES system can also be extended by increasing the amount of storage material, which is independent of the power capacity of the system.

TES has improved safety relative to traditional electrochemical and mechanical storage technologies, and—for certain storage materials—can have extremely high energy density. In addition, inexpensive raw materials make TES among the lowest-cost solutions for energy storage.

Read more about thermal energy storage in our report here.

Long Duration Energy Storage 101: All About Thermal Energy Storage Technologies Part 1

Long Duration Energy Storage 101: All About Thermal Energy Storage Technologies Part 2

Latent heat (solid-liquid)
Sensible heat (solids / liquids)
Sensible heat (solids)
Thermochemical (salt)


Long duration energy storage includes electrochemical energy storage such as static batteries, flow batteries, metal (iron) air batteries, and other battery chemistries.

These types of batteries have a number of advantages, such as longer duration (over 4 hours), increased safety, less concern with ambient temperatures, easy scalability, no detrimental effects of a deep discharge, very low self-discharge, lower levelized cost of storage, and long cycle life.

Long Duration Energy Storage 101: All About Electrochemical Energy Storage Technologies

Flow Battery
Metal Anode
Non-Metal Chemical Storage


Mechanical energy storage works in complex systems that use heat, water or air with compressors, turbines, and other machinery. Currently, the most widely deployed large-scale mechanical energy storage technology is pumped hydro-storage (PHS). Other well-known mechanical energy storage technologies include flywheels, gravity-based, compressed air energy storage (CAES), and liquid air energy storage (LAES).

PHS has been deployed since 1907, and CAES since 1978. We are seeing the next wave of innovation with these technologies that are increasing security, reliability, flexibility, and the duration of today's energy storage solutions.

Long Duration Energy Storage 101: All About Mechanical Energy Storage Technologies

Closed loop PHS and run of river
Gravity-based PS
Liquid Air Energy Storage
Liquid C02


Hydrogen and other energy-carrying chemicals can be produced from a variety of energy sources, such as renewable energy, nuclear power, and fossil fuels. Converting energy from these sources into chemical forms creates high energy density fuels. Hydrogen can be stored as a compressed gas, in liquid form, or bonded in substances. After conversion, chemical storage can feed power into the grid or store excess power from it for later use. The flexibility of being able to feed stored energy back into the grid or sell the produced chemical into industrial or transportation applications provides additional opportunities for revenue and decarbonization.