BESS – Battery Energy Storage Systems in Industry

BESS are systems for storing electrical energy using batteries, most commonly lithium-ion, to store and release energy in a controlled manner. Unlike conventional energy sources, which operate in line with real-time demand or fuel availability, BESS introduce flexibility into the power system by decoupling the moment of energy generation from the moment of consumption.

A battery storage system is not limited to the batteries themselves. A complete setup includes several additional components:

• battery modules – typically lithium-ion, responsible for energy storage,
• BMS (Battery Management System) – monitors temperature, voltage, and state of charge,
• PCS (Power Conversion System) – an AC/DC converter enabling interaction with the grid and on-site installations,
• EMS (Energy Management System) – a supervisory system optimizing operation based on energy prices, consumption profiles, and generation,
• safety systems – including cooling, fire suppression, and monitoring.

In industrial applications, BESS are most often deployed in containerized form, simplifying installation and scalability.

Chemical energy storage systems, primarily based on lithium battery technology, are rapidly gaining market share both at the grid level and in localized installations. Across Europe, including Poland, there is a clear increase in planned investments. The largest Polish project is the Żarnowiec BESS, with a capacity of 262 MW and 981 MWh, developed by PGE. It is expected to become one of the largest energy storage facilities in Europe, with commissioning planned for 2027.

The primary use case for energy storage systems is the ability to store excess energy, for example from photovoltaic installations during peak sunlight hours or from continuously operating cogeneration units. Instead of exporting energy to the grid at unfavorable prices or curtailing production, companies can store it and use it later when its economic value is higher. This increases self-consumption and improves the utilization efficiency of existing generation assets.

Another key application is the use of stored energy during periods of high electricity prices. Given the volatility of energy markets, price spreads between hours can be significant. BESS enables energy arbitrage - charging during low-price periods and discharging during peak-price periods. For industrial facilities, this directly translates into reduced operating costs.

BESS also supports load profile stabilization, often referred to as peak shaving. It can mitigate short-term spikes in power demand that affect contracted capacity charges or create the risk of exceeding agreed limits. Thanks to their extremely fast response times, battery systems can compensate for load increases almost instantaneously, which is particularly important in facilities with variable or impulse-driven processes.

Additionally, BESS can participate in ancillary services markets, such as frequency regulation and voltage control. Due to their millisecond-level response capability, they are especially well suited for services like FCR and aFRR. In practice, this creates opportunities for additional revenue streams through participation in flexibility markets, which in many cases plays a key role in the investment case.

Compared to other energy storage technologies, BESS stand out primarily for their flexibility and response speed. In comparison to:

• mechanical storage (e.g. pumped-storage hydropower) – they are scalable and can be deployed on-site,
• thermal storage – they store electricity directly without conversion to another medium,
• compressed air energy storage (CAES) – they offer higher efficiency (typically 85–95% vs. 40–70%),
• hydrogen systems – they do not require costly conversion and storage infrastructure.

The key advantage of BESS is their extremely fast response time (on the order of milliseconds), which is critical both for stabilizing industrial processes and for participation in system services.

The sizing of an energy storage system is based on two fundamental parameters:

• power (MW) – the maximum instantaneous charge/discharge capability,
• capacity (MWh) – the total amount of energy that can be stored.

The relationship between these two parameters, expressed as discharge duration at full power, determines the role the storage system will play within the facility’s energy system.

Typical industrial installations range from 0.5 MW to several tens of MW in power and from 1 MWh to over 100 MWh in capacity. In most cases, however, systems are designed for discharge durations between 1 and 4 hours. This reflects both industrial load characteristics and market dynamics.

Storage systems with 1–4 hour durations are optimal for applications such as load management (e.g. peak shaving and load shifting) and energy arbitrage. In practice, this means the system can cover peak demand during critical periods of the day - typically morning and evening - when both consumption and energy prices are highest. At the same time, this duration aligns with typical high-price windows in day-ahead markets, enabling effective price optimization without oversizing the installation.

Short-duration systems, operating over several to tens of minutes, are mainly used for power stabilization, short-term peak reduction, and power quality improvement. However, they are insufficient for more advanced optimization strategies that require sustained energy delivery over longer periods.

Moreover, for long-duration storage (e.g. beyond 6–8 hours), other technologies become more competitive, such as pumped-storage hydropower, thermal storage, hydrogen systems, or demand-side management solutions. As a result, battery storage in the 1–4 hour range represents a balance between operational flexibility and investment cost-effectiveness, explaining its dominance in industrial projects.

Battery energy storage systems (BESS) are among the most flexible and versatile tools for energy management in industry. Their ability to respond rapidly to changes in demand, integrate with renewable energy sources, and actively participate in energy markets means they serve both technical and economic functions. In practice, this allows facilities not only to improve energy efficiency but also to actively manage their consumption profile and mitigate the impact of price volatility on operating costs.

A critical aspect of BESS implementation is the proper selection of technical parameters, particularly the relationship between power and capacity. This determines whether the system will effectively deliver its intended functions - from power stabilization and peak reduction to energy arbitrage and participation in ancillary services.

Market experience shows that systems with 1–4 hour durations offer the optimal balance between operational flexibility and economic viability in most industrial applications. At the same time, it should be emphasized that although BESS provide high efficiency and extremely fast response times, they are not a universal solution for all energy storage scenarios. For long-term storage needs, alternative technologies may be more appropriate. Therefore, BESS should be treated as part of a broader energy strategy, where their role is to optimize short-term system operation, enhance flexibility, and improve the overall energy security of the facility.