What is BESS?

A Battery Energy Storage System (BESS) is a large-scale, rechargeable energy storage facility, most commonly using lithium-ion batteries, that stores electricity from the power grid and releases it when demand is high.

For context, a 79-megawatt (MW) utility-scale BESS is typically designed with approximately 316 megawatt-hours (MWh) of energy capacity. This represents a 4-hour duration system, meaning it can deliver 79 MW of power continuously for four hours at full capacity.

These facilities are industrial in scale, often spanning multiple acres and consisting of rows of shipping container-sized battery units, along with inverters, transformers and support equipment. Individual battery containers are typically similar in size to standard freight containers, commonly around 20 to 40 feet long, 8 feet wide and about 8.5 to 9.5 feet tall. Projects of this size typically require substantial site preparation, including perimeter security and earthen berms or barriers for screening, noise mitigation and safety separation.

Battery systems degrade over time, reducing storage capacity and efficiency; and components may require replacement within approximately 5 to 15 years, depending on usage and operating conditions.

These facilities are often unmanned and operated remotely through automated monitoring systems. While designed with safety controls, risks can include thermal runaway events, which may lead to fires that are difficult to extinguish and can burn for days, the release of hazardous gases such as hydrogen fluoride and potential environmental impacts if containment systems fail. Emergency response can be complex and may require specialized training and resources. Such activity risks contaminating nearby soil and water sources, while also contributing to long-term degradation of air quality and causing permanent, irreversible damage to ecosystems, wildlife, marine life and the natural landscape.

Operational noise is generated by cooling systems, inverters and transformers, which can produce a constant low-frequency hum that may be noticeable depending on proximity and site design.