Battery Energy Storage System Technology Explained

By R.W. Hurst, Editor

Battery Energy Storage System

What is a battery energy storage system (BESS)?

A battery energy storage system is an energy storage solution that cost effectively stores electricity in rechargeable batteries for later use. It is a type of energy storage (ES) system that uses batteries to store and discharge electricity.

BESS stores electricity when it is generated in excess and then releases it back into the grid or uses it when the electricity supply is limited. It can also be used as a backup power supply in case of power outages or to stabilize the grid during periods of high demand.

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A battery energy storage system typically consists of a set of batteries, power conditioning equipment such as inverters, and a control system that manages the charging and discharging of the batteries. The batteries used in BESS can vary from lead acid to lithium-ion and other advanced chemistries, depending on the application's specific requirements.

BESS has become an increasingly important energy storage solution as renewable energy sources such as wind and solar power have become more prevalent, as they can provide a means of storing energy during times of excess generation for use during periods of low age. Additionally, BESS can help to reduce the need for fossil fuel-powered peaker plants, which are used to meet peak demand but can be expensive and environmentally damaging. BESS can store the power generated by solar power systems.

How does a battery energy storage system work?

A BESS works by storing electrical power in batteries for later use. The basic operation of a BESS can be broken down into several steps:

Charging: Electrical power is supplied to the battery to charge the batteries. This can be done from various sources, including renewable energy sources such as solar and wind power or the grid during periods of low demand.

Storage Technologies: Once the batteries are charged, they store the electrical power until needed. The amount of power stored in the batteries depends on the capacity of the system.

Discharging: The batteries release the stored power when electrical power is needed. This can be done by converting the DC power from the batteries to AC power using an inverter. The amount of energy released depends on the demand and the capacity of the system.

Monitoring and Control: The BESS is typically monitored and controlled by a control system that manages the charging and discharging of the batteries. This control system ensures that the batteries are charged and discharged safely and efficiently and operate within their design limits.

Overall, a BESS can provide a means of storing excess power from renewable sources for later use, reducing peak demand on the grid, providing backup power during outages, and improving the stability and reliability of the electrical grid.

What are the benefits of a battery energy storage system​​​​​​​?

There are several benefits of a BESS, including:

Renewable Energy Integration: BESS can store excess power generated by renewable energy sources such as solar and wind power for use when the energy demand is higher than the power generation.

Peak Demand Management: BESS can help reduce the demand during peak times by peak shaving and limit the need for utilities to bring on expensive and environmentally harmful peaker plants to meet high electricity demands.

Grid Stability and Reliability: BESS can provide a stable and reliable supply of power, especially during outages or emergencies. BESS can also provide ancillary services to the grid, such as frequency regulation, voltage support, and ramp rate control.

Cost Savings: BESS can help reduce electricity costs for businesses and homeowners by storing and using cheaper off-peak electricity during peak periods.

Environmental Benefits: BESS can help reduce greenhouse gas emissions by enabling the integration of more renewable power into the grid and reducing the need for fossil fuel-powered peaker plants.

Energy Independence: BESS can provide a backup power supply during power outages or emergencies, providing energy independence and reducing reliance on the grid.

Overall, BESS can help improve the electrical grid's efficiency, reliability, and sustainability while providing businesses and homeowners with cost savings and energy independence.

How efficient is BESS?

The efficiency of a BESS can vary depending on several factors, such as the type of chemistry used, the temperature and operating conditions, and the efficiency of the power electronics and control systems used to manage the batteries.

Generally, the round-trip efficiency of a BESS, which is the ratio of the power output to the power input, can range from around 70% to 95%. This means that if you put 100 units of power into the battery, you may get anywhere from 70 to 95 units of power back out, depending on the system's efficiency.

Lithium-ion batteries, commonly used in BESS applications, have a round-trip efficiency of around 80-90%, while lead-acid batteries have a round-trip efficiency of about 70-80%. Other types of batteries, such as flow batteries, may have higher round-trip efficiencies of up to 95%.

It's important to note that efficiency is not the only factor to consider when evaluating the performance of a BESS. Other factors such as cost, lifespan, safety, and environmental impact are also important considerations.