An energy storage system (ESS) is a device or a group of devices used to store energy and provide it for later use. Battery, chemical, electrochemical, mechanical and thermal are some of the commonly used energy storage systems that meet daily source needs.
Energy storage systems make it easier to store and deliver energy where and when it is needed, creating a more resilient energy infrastructure and generating cost savings for consumers and utilities. Additionally, these secure systems by responding quickly to power fluctuations. reliability and stability.
In addition to rising energy costs, changes in renewable energy supply and surges in electricity demand are creating challenges for the global grid, requiring greater flexibility in our original structures to make them accessible and affordable for all Afford clean energy.
With current and emerging energy storage technologies, energy can be reliably delivered at the flip of a switch.
Even when the sun is not shining or the wind is not blowing, grid-based energy storage can solve the intermittency problem of solar or wind power and provide a continuous supply of clean energy for residential, commercial and industrial applications.
Components of Energy Storage Systems (ESS)
A typical energy storage system consists of two main components:
A power conversion system (PCS) handles the conversion of AC to DC and DC to AC (AC and DC are types of electricity) that flows into the battery for charging or is converted into electrical energy from the battery. The batteries store alternating current and feed it into the grid.
The battery management system (BMS) is responsible for battery charging, balancing and health monitoring, as well as the microcontroller that provides system control and communications.
Drivers of Energy Storage Systems
In the rapidly growing power industry, more and more companies are choosing renewable energy to meet different needs, such as:
- Off-grid power generation
- Improve sustainability
- Improve energy efficiency
- Manage risk
- Reduce emissions
- Reduce energy consumption
However, renewable energy sources such as solar and wind are affected by weather changes, and ESS systems can supplement and mitigate the intermittency of solar or wind energy by storing energy for later use.
For example, when solar panels are affected by cloud cover or rain, ESS technology helps maintain reliable power and utilize stored energy when needed.
Additionally, energy storage helps power grids, including microgrids, run more cost-effectively because the system operates at average load rather than peak load. ESS technology also provides significant annual cost savings.
Benefits of Energy Storage Systems
Energy storage systems offer clear benefits —- ranging from proactively managing the mismatch between electricity supply and demand to enhancing the resilience of the grid.
The benefits of ESS include, but are not limited to, the following:
- Ensuring reliability of critical services
- Increasing facility flexibility
- Increasing the resilience of interdependent networks
- Meeting loads during peak demand
- Prepare the grid for EV charging (fast)
- Serving Remote Communities
In recent years, there has been an increased focus on energy storage solutions. Such as fixed storage, to improve grid reliability, resilience, and demand management.
Risks of Energy Storage Systems
Energy storage systems do pose some risks, such as.
- Electrical fires
- Overheating
- Short circuits
- Thermal runaway
For example, ion batteries, which combine easy-to-make electrolytes with energetic materials, can lead to fire hazards if the diaphragm is damaged, making it imperative to have an integrated fire protection system for early and reliable fire detection in silver ion battery energy storage systems.
In addition, the widespread adoption of grid-based potassium batteries does present certain challenges related to cost, limited lifetime, and safety.
And economic and technical factors make the commercial viability of ESS deployment challenging. As a result, ESS technology is in various stages of adoption globally.
Types of ESS Technology
Based on the form of energy storage (storage principle), the Energy storage technologies are usually categorized into five types, including：
1. Chemical energy storage
- Ammonia
- Hydrogen
- Methanol
- Synthetic natural gas
- Synthetic fuels
Chemical energy storage uses electricity to produce chemicals that can be used as fuels for power generation, transportation, or heat load support.
Chemical energy storage includes hydrogen and other hydrogen-rich chemical energy carriers produced from a variety of domestic energy sources (e.g., fossil, nuclear, and renewable) for use in a variety of energy storage applications, including
- Heavy-duty vehicles
- Electricity to gas
- Electricity to liquid
- Steel manufacturing
Hydrogen can be stored as a gas in pressurized tanks or large underground caverns (compressed gaseous H2), as a liquid in cryogenic preferably low-temperature liquid H2), or as liquid or solid hydrides (e.g. hydrogen and magnesium).
2. Electrical Energy Storage
Capacitor
Super capacitor
Superconducting Magnetic Energy Storage (SMES)
Supercapacitors, also known as “electrochemical double layer capacitors” or “supercapacitors,” are high-power, low-energy devices that use an electrochemical double layer of charge to store energy.
Supercapacitors are scalable and can withstand a large number of cycles (up to 100.000) due to the absence of chemical reactions.
SMES systems store electric current as a field generated by current flowing through a superconducting coil (cooled below a critical temperature point) and release the energy by discharging the coil. The storage system discharges in a timely manner and has the added advantage of easy maintenance of the electromagnetic field.
3. Electrochemical Energy Storage/Battery Energy Storage System (BESS)
Since Alessandro Vota invented the first battery in 1800, batteries have evolved into many forms, with a variety of rechargeable cells available to meet specific power and duration requirements.
Rechargeable battery：
Flow batteries (variants include vanadium redox batteries, ZnBr (zinc))
Lead-acid batteries and advanced lead-acid batteries (bipolar lead-acid, lead-carbon)
Lon batteries (including LCO, LFP, LMO, LTO, NCA and NMC)
Sodium ion battery
Sodium sulfur battery
Solid state battery
The concept of ESS batteries is to store energy through reversible electrochemical reactions in one or more electrochemical cells and convert the stored energy into electrical energy.
A battery unit is a single device, while a battery module refers to battery cells connected in parallel or in series. A battery pack consists of a series of individual modules and a protection system organized together.
Traditional battery systems consist of deep-cycle lead-acid batteries. However, lightweight, efficient, and scalable lithium-ion batteries have come to dominate in recent years and are becoming widely used in a variety of applications, including mobile phones, electric vehicles, and smart grids, stationary energy storage.
Additionally, lithium-ion batteries are suitable for smaller, larger systems that can store several megawatt hours (MWh) and can support the entire grid. For example, a utility-scale 100 MWh system can be installed on less than 0.5 acres of land.
Flow battery technology is based on the circulation of liquid electrolytes, charging or discharging electrons and generating electricity through redox (reduction and oxidation) reactions. Flow batteries are designed with recyclable components, have a longer service life, and provide cost-effective, reliable power.
4. Mechanical Energy Storage
Mechanical energy storage systems store energy generated by movement. Examples include:
Adiabatic Compressed Air Energy Storage (ACAES)
Compressed Air Energy Storage (CAES)
Fireless locomotive
Flywheel Energy Storage (FES)
Pumped Hydro Energy Storage (PHES)/Pumped Hydro Energy Storage (PHS)
Compressed air energy storage draws in air and creates a high-pressure system in a series of large underground chambers/caves. Where compressed air, usually mixed with some natural gas, is released into a generator or power turbine when the demand for electricity spikes or wind speeds slow down.
The flywheel stores grid energy in a rapidly rotating machine rotor, absorbing and often releasing high power for a short period of time. The magnetic field keeps the wheel in a friction-free vacuum to prevent energy loss. In addition, when electricity is needed to generate electricity , the rotation speed will slow down.
Flywheel energy storage systems balance fluctuations in power supply and demand, recover braking energy from electric trains, or provide short-term power during power outages. These systems have low environmental impact, low maintenance costs and long service life compared to other energy storage systems.
Pumped hydro facilities are based on a gravity concept and involve turbines using excess electricity to pump water (during off-peak hours) to an elevated reservoir.
During peak periods of electricity demand, water stored in the upper reservoir can flow to the lower reservoir and run through turbines to generate electricity.
Large-scale energy storage projects use pumped hydro to generate electricity and account for about 95% of storage on the U.S. grid, according to the U.S. Department of Energy.
However, building new pumped storage plants is challenging due to factors such as long development times and permitting implications for large water-based infrastructure.
5. Thermal Energy Storage
- Brick Storage Heater
- Ice storage Air Conditioning
- Liquid Air Energy Storage (LAES)
- Molten Salt Energy Storage (MSES)
- Phase Change Materials
- Solar Pond
- Steam Accumulator
Thermal energy storage systems use excess energy to capture heat and coldand then release the energy as needed.
For example, molten salt stores heat generated by the sun so that it can be used when the sun is not shining. Another example is ice storage in buildings, which can reduce the need for compressors while providing air conditioning for longer periods of time.
LAES uses excess grid electricity to cool ambient air and convert it into liquid gas. The liquid is then converted back into gas gas through exposure to ambient air or by utilizing waste heat, and the expanded gas is used to drive turbines to generate electricity.
Phase change materials are used in thermal batteries that store excess electricity or heat. Phase change materials (PCM) absorb or release enough energy to provide cooling or heat when they change phase.
For example, a material stores heat when it changes from solid to liquid, and changes to solid again and releases heat to provide hot water, etc.
Battery Energy Storage System Applications
Battery storage systems can be recharged with electricity generated from renewable energy sources such as solar or wind.
Solar storage batteries can help businesses and homes become more energy independent while ensuring a reliable supply of electricity during long-term power interruptions.
BESS is versatile and flexible in terms of energy capacity. Energy security, self-sufficiency and battery backup power in emergencies are key drivers for home battery storage systems/battery storage solutions.
Home energy storage systems store generated heat or electricity to use the energy when needed and reduce dependence on the grid.