Thermal energy storage in the context of "Krems an der Donau"

Grid energy storage, also known as large-scale energy storage, is a set of technologies connected to the electrical power grid that store energy for later use. These systems help balance supply and demand by storing excess electricity from variable renewables such as solar and inflexible sources like nuclear power, releasing it when needed. They further provide essential grid services, such as helping to restart the grid after a power outage.

As of 2023, the largest form of grid storage is pumped-storage hydroelectricity, with utility-scale batteries and behind-the-meter batteries coming second and third. Lithium-ion batteries are well suited for short-duration storage (under 8 hours), due to their lower cost and sensitivity to degradation at high states of charge. Flow batteries and compressed air energy storage may provide storage for medium-duration. Two forms of storage are suited for long-duration storage: green hydrogen, produced via electrolysis and thermal energy storage.

An accumulator is an energy storage device: a device which accepts energy, stores energy, and releases energy as needed. Some accumulators accept energy at a low rate (low power) over a long time interval and deliver the energy at a high rate (high power) over a short time interval. Some accumulators accept energy at a high rate over a short time interval and deliver the energy at a low rate over a longer time interval. Some accumulators typically accept and release energy at comparable rates. Various devices can store thermal energy, mechanical energy, and electrical energy. Energy is usually accepted and delivered in the same form. Some devices store a different form of energy than what they receive and deliver performing energy conversion on the way in and on the way out.

Examples of accumulators include steam accumulators, mainsprings, flywheel energy storage, hydraulic accumulators, rechargeable batteries, capacitors, inductors, compensated pulsed alternators (compulsators), and pumped-storage hydroelectric plants.

The Crescent Dunes Solar Energy Project is a solar thermal power project with an installed capacity of 110 megawatt (MW) and 1.1 gigawatt-hours of energy storage located near Tonopah, about 190 miles (310 km) northwest of Las Vegas. Crescent Dunes is the first commercial concentrated solar power (CSP) plant with a central receiver tower and advanced molten salt energy storage technology at full scale (110 MW), following the experimental Solar Two and Gemasolar in Spain at 50 MW. As of 2023, it is operated by its new owner, Vinci SA, and in a new contract with NV Energy, it now supplies solar energy at night only, drawing on thermal energy stored each day.

Startup energy venture company SolarReserve (created via seed funding), US Renewables Group, and United Technologies were the original owners of Tonopah Solar Energy LLC, the owner and operator of the Crescent Dunes plant. The Crescent Dunes project was subsequently backed by a $737 million in U.S. government loan guarantees and by Tonopah partnering with Cobra Thermosolar Plants, Inc. The overall venture had a projected cost of less than $1 billion. The plant suffered several design, construction and technical problems and, having not produced power since April 2019, its sole customer, NV Energy, subsequently terminated its contract. Bloomberg reported that NV Energy was not allowed to sever its agreement with the plant until after the DoE took over the shuttered plant in August 2019.

Energy recovery includes any technique or method of minimizing the input of energy to an overall system by the exchange of energy from one sub-system of the overall system with another. The energy can be in any form in either subsystem, but most energy recovery systems exchange thermal energy in either sensible or latent form.

In some circumstances the use of an enabling technology, either daily thermal energy storage or seasonal thermal energy storage (STES, which allows heat or cold storage between opposing seasons), is necessary to make energy recovery practicable. One example is waste heat from air conditioning machinery stored in a buffer tank to aid in night time heating.