We are transitioning from fossil fuels to renewable energy sources such as wind and solar, and the use of energy storage is becoming more widespread. And with the popularity of electric vehicles, the grid is under more and more pressure, so the demand for energy storage is growing. So what exactly is energy storage? This article will answer your confusion.

Energy storage the key to a decarbonised future

What is energy storage and how does it work?

Simply put, energy storage is the ability to capture energy at one time for use at a later time. Storage devices can save energy in many forms (e.g., chemical, kinetic, or thermal) and convert them back to useful forms of energy like electricity.

Just like we put food in the refrigerator, we can store it for days or weeks without eating it immediately or discarding it. Energy storage lets individuals and communities access electricity when they need it most—like during outages or when the sun isn’t shining. Storage can reduce the demand for electricity from inefficient, polluting plants often located in low-income and marginalized communities. Storage can also help smooth out demand, avoiding price spikes for electricity customers.

Five types of energy storage technologies

1. Battery storage

Batteries, the oldest, most common and widely accessible form of storage, are an electrochemical technology comprised of one or more cells with a positive terminal named a cathode and negative terminal or anode.

Batteries encompass a range of chemistries. The best known and in widespread use in portable electronic devices and vehicles are lithium-ion and lead acid. Others solid battery types are nickel-cadmium and sodium-sulphur, while zinc-air is emerging.

Another category is flow batteries with liquid electrolyte solutions, including vanadium redox and iron-chromium and zinc-bromine chemistries.

Supercapacitors, although not a battery as such, also can be categorised as an electrochemical technology, with their application particularly for sub-minute level response.

2. Thermal storage

Thermal storage in essence involves the capture and release of heat or cold in a solid, liquid or air and potentially involving changes of state of the storage medium, e.g. from gas to liquid or solid to liquid and vice versa.

Technologies include energy storage with molten salt and liquid air or cryogenic storage. Molten salt has emerged as commercially viable with concentrated solar power but this and other heat storage options may be limited by the need for large underground storage caverns.

3. Mechanical storage

Mechanical storage systems are arguably the simplest, drawing on the kinetic forces of rotation or gravitation to store energy. But feasibility in today’s grid applications requires the application of the latest technologies.

The main options are energy storage with flywheels and compressed air systems, while gravitational energy is an emerging technology with various options under development.

4. Pumped hydro

Energy storage with pumped hydro systems based on large water reservoirs has been widely implemented over much of the past century to become the most common form of utility-scale storage globally.

Such systems require water cycling between two reservoirs at different levels with the ‘energy storage’ in the water in the upper reservoir, which is released when the water is released to the lower reservoir.

5. Hydrogen

Energy storage with hydrogen, which is still emerging, would involve its conversion from electricity via electrolysis for storage in tanks. From there it can later undergo either re-electrification or supply to emerging applications such as transport, industry or residential as a supplement or replacement to gas.

Lithium batteries: the future of storage

In recent years, the renewable energy sector has seen in lithium-ion batteries the solution to its main problem: the storage of generated energy. Being one of the smallest elements in the periodic table, lithium has a high electrochemical potential and can accumulate large amounts of energy. With the desirable low weight and high efficiency, only one obstacle has so far prevented lithium batteries from becoming the standard storage technology for renewable energy: their high cost.

This situation, however, seems to be changing. According to a recent study by Bloomberg NEF (BNEF), the cost of lithium-ion batteries will be significantly reduced in the coming years — beyond even the 85% reduction that occurred from 2010 to 2018. Specifically, BNEF predicts a 50% reduction in the costs of lithium-ion batteries per kW/h by 2030, as demand takes off in two different markets: stationary storage and electric vehicles.

SETEC POWER is keenly aware of market demand and industry changes. It has launched the Emergency mobile EV charging system, which combines battery storage technology with fast charging technology to enable off-grid operation. This is a new attempt at energy storage technology and one of the practical solutions to relieve the pressure on the power grid.

Energy storage technology is currently developing and growing with the support of governments and industry. The demand for energy storage is also here to stay because of its unique role in energy resilience and its ability to help store an increasing amount of clean and variable renewable energy. It will undoubtedly benefit all of humanity.