Battery Energy Storage Systems (BESS) are increasingly recognized as a promising solution for enhancing the flexibility of power systems, especially in managing the variability of renewable energy sources like solar and wind.
Their unique capability to rapidly absorb, store, and discharge electricity makes them highly effective in stabilizing energy supply. BESS has gained significant traction due to its versatility in addressing various challenges within the power grid. Moreover, multiple BESS units can be integrated to function collectively as a Virtual Power Plant (VPP).
The article explores the concept of BESS in depth, covering its benefits, practical applications, advantages, system architecture through block diagrams and layouts, associated challenges, key insights from past projects, relevant international standards, and recommended design methodologies.
Introduction
A Battery Energy Storage System (BESS) is an electrochemical device that charges (or collects energy) from the grid and discharges that energy at a later time to provide electricity or other grid services when needed. Several battery chemistries are available or under investigation for grid-scale applications, including lithium-ion, lead-acid, redox flow, nickel cadmium, and Sodium-sulfur.
BESS has a wide range of applications covering from generation and transmission upto behind-the-meter applications. For generation side application, BESS can be used for spinning reserve, frequency regulations, black start, energy arbitrage and even as an alternative to peaking plants. For transmission and distribution sides, BESS can contribute as an asset deferral or congestion relief to the utility companies.
There are a few types of normally known battery types in the market, namely Lead Acid, Sodium Sulphur, Lithium-ion and Flow Battery. Every type has its own unique characteristics. Lead-acid batteries are considered a pioneer in supplying batteries for the power system. Lithium-ion is attaining popularity due to be competitiveness in pricing.
A Brief History of Batteries
Volta discovered the first battery in 1799.
The lead-acid battery was first reported in 1859.
The alkaline cell was first marketed in the 1960s.
The rechargeable lithium-ion battery was invented in 1972.
Differentiating Characteristics of Different Battery Technologies
As per IEC 62933-1 (Part 1: Vocabulary), Grid-connected installation with defined electrical boundaries, comprising at least one electrical energy storage, which extracts electrical energy from an electric power system, stores this energy internally in some manner and injects electrical energy into an electrical power system and which includes civil engineering works, energy conversion equipment and related ancillary equipment.
Lithium-ions Batteries
Lithium-ion batteries are perhaps the most promising for both small and large-scale electricity storage in power generation. They currently offer superior performance and have dominated the market globally. For Li-ion battery applications, the industry is currently in the process of improving capacity, power, size, reliability and safety for applications involving both electrical vehicles and power generation. Due to technological innovations and improved manufacturing capacity, lithium-ion chemistries have experienced a steep price decline since their inception.
The cost trajectory of Battery Energy Storage systems in future years is projected to decline, as per Bloomberg
NEF projections shown
Battery Energy Storage System (BESS)
The BESS (Battery Energy Storage System) is a modular energy storage system based on Li-ion batteries. It shall provide a solution to mitigate the impact on the grid associated with the unscheduled tripping of a gas turbine. Additionally, it may be tied to a power generation facility while delivering power quality and grid stabilization functionalities. However, the fulfillment of this additional function shall be further evaluated when precise requirements, for example, the result of a grid study, are available.
The BESS will be used to exchange active and reactive power between the energy storage medium and the electrical grid at the defined point of interconnection (POI).
High-Level System Overview
A high-level system overview, showing the main components, is depicted in Fig. below. A number of Li-ion battery modules are mounted in a battery rack. Each battery rack is controlled and monitored by one battery management system (rack BMS or RBMS). Battery racks can be paralleled and are connected to one AC/DC power converter. A sinusoidal filter is used on the AC side of the converter to reduce output distortions. Finally, the output voltage is set to the required value for the transformer.
Several of the below depicted blocks can be used to deliver the total power required.
Components of BESS
Battery Energy Storage System consists of the following major equipment:
Battery Rack/Container (Li-ion batteries)
Power conversion system including Inverters
Transformer
Bay/System Controller
UPS for Auxiliary Power
Energy Management System
Components of a Battery Energy Storage System (BESS)
Advantages of utilizing BESS
Promoting Sustainability: The integration of renewable energy sources such as solar and wind significantly reduces greenhouse gas emissions, contributing to a cleaner and more sustainable energy ecosystem. These technologies are pivotal in transitioning toward low-carbon power generation.
Energy Recycling and Conservation: Battery Energy Storage Systems (BESS) enable the capture and reuse of surplus energy that would otherwise be lost. This stored energy can be deployed during periods of high demand or low generation, enhancing overall system efficiency and resource utilization.
Improved Reliability and Resilience: Energy storage solutions ensure continuity of power supply by compensating for grid outages or fluctuations in renewable generation. By storing energy during periods of abundance and releasing it during shortages, BESS supports grid stability and reliability.
Economic Efficiency: Over time, the combination of renewable energy and storage technologies proves to be more cost-effective than conventional fossil fuel-based power. This not only reduces operational costs but also lowers electricity bills for consumers and businesses, offering long-term financial and environmental benefits.
Operational Flexibility: Renewable energy systems, when paired with storage, provide greater flexibility in energy management. Businesses can optimize their operations by reducing dependency on grid electricity, mitigating exposure to price volatility and supply disruptions.
Enhancing Grid Performance: BESS contributes to grid efficiency by absorbing excess energy during low-demand periods and supplying it during peak loads. This dynamic balancing reduces energy waste, prevents grid overloads, and supports a more reliable and cost-effective power infrastructure.
Application Class:
Following could be various purposes of storage applications categorized as per IEC std. 62933-2-1.
Class A – Short-duration power-focused application: BESS is designed to repeatedly inject or absorb up to the specific amount of power for a short period of time (BESS can charge and discharge at rated output power for not more than 1 hour).
Class B – Long-duration energy-focused application: BESS is designed to routinely provide or take power from the power system over a long duration period (BESS can charge and discharge at rated output power for more than 1 hour).
Class C – Emergency ancillary services: BESS is designed to supply AC power in electric power grids or microgrids over a fixed duration. BESS can therefore reduce the risk of major blackouts.
Applications of Battery Energy Storage System (BESS)
Battery Energy Storage System (BESS) Key Benefits
Key Characteristics of Battery Storage Systems
Rated power capacity discharge capability
Energy capacity
Storage duration
Cycle life/lifetime
Self-discharge
Round-trip efficiency
Project Basis of Design
Designing a battery energy storage system involves careful consideration of several factors to ensure optimal performance, longevity, and safety. Here are some crucial design considerations:
Define the Project Requirements: Start by outlining the project’s scope, budget, and timeline. Determine the specific energy storage capacity, power rating, and application (e.g., grid support, peak shaving, renewable integration, etc.) of the BESS.
Select the Battery Technology: Choosing the right battery technology is critical as it directly impacts the system’s performance, efficiency, and overall cost.
Design the Container Layout: Design the container layout to accommodate the battery modules, inverters, transformers, HVAC systems, fire suppression systems, and other necessary equipment. Plan the layout to optimize space utilization, thermal management, and safety.
Integration with Renewable Energy Sources: In many cases, BESS is integrated with renewable energy sources like solar or wind power. Coordinating the battery storage system with the intermittent nature of renewable energy generation is essential to ensure a stable and reliable power supply.
Environmental Conditions and Site Considerations: Location and environmental conditions can significantly affect the performance and lifespan of a battery energy storage system. Factors such as temperature, humidity, ventilation, and physical space availability must be evaluated during the design process
Safety Protocols and Regulatory Compliance: Designing a BESS involves implementing proper safety protocols and adhering to regulatory requirements.
Power System Study for BESS Grid Integration
Battery Energy Storage Systems (BESS) play a crucial role in modern power grids by enhancing reliability, stability, and flexibility. Grid integration studies are essential for ensuring that new power generation sources, especially intermittent renewable energy and Battery Energy Storage Systems (BESS), can be reliably and efficiently connected to the existing electrical grid. These studies encompass a range of technical, economic, and regulatory analyses. Here’s an overview of the key studies typically required for grid integration:
Load Flow Analysis
Short Circuit Analysis
Arc-flash study
Harmonic Analysis
Protection Coordination Study
Voltage Stability Analysis
Dynamic and Transient Stability Analysis
LVRT/ HVRT for RE Integration
Grid Code Compliance Study
Key Requirements and Considerations for BESS Grid Interconnection
Compliance with Grid Codes and Standards
Voltage and Frequency Regulation
Power Quality
Protection and Safety
Control and Communication
Interconnection Agreement
Grid Support Functions
Environmental and Site Considerations
Key Performance Guarantees
Energy Capacity Guarantee
Availability Guarantee
Round Trip Efficiency (RTE)
Challenges to Implementing Battery Energy Storage Systems
Cost of Constructing
Limited Durability and Life Cycle
Impacts on the Environment
Key Learnings from Past Projects
The BESS cooling system emits low-frequency noise that is difficult to contain; therefore, undertaking a noise impact assessment is very important, particularly in populated areas.
Fire protection systems associated with BESS is a challenging area to solve.
In the case of a major fire, there is a high risk of ground contamination. Creation of bounded areas associated with a “catchment” may be required.
Toxic fume release rates are not easily available from the OEMs, as the testing does not capture this data (rather, a % of constituents but not totals).
The preferred design of the BESS containers is with external access only (with no access inside the enclosures).
Project schedules are affected by the supply chain; therefore, securing delivery early is important. Delays of up to 6 months have been experienced on some of our projects.
The grid connection process requires modelling of the BESS performance – particularly modelling the inverter performance characteristics.
The energy market is in a state of flux. It is difficult to predict how the cost of BESS services can be approximated in enough detail to build a robust financial case.
Safety Parameters to be Considered in Design
Thermal shock and cycling
External short circuit protection
Overcharge protection
Over-discharge protection
Over-temperature protection, under-temperature protection
Thermal propagation protection
Mechanical damage by external forces
Internal short circuit
Temperature abuse
Key Factors Affecting the Viability of Battery Energy Storage System Projects
Cost of storage
Network reinforcement cost
Commercial services
Policy developments
Battery Energy Storage System in India
India has committed to increasing its share of non-fossil fuel-based generation sources to 40% by 2030, which necessitates a demand for flexibility in power systems. Energy storage will play a crucial role in increasing the system’s overall flexibility by serving multiple grid applications. The recent developments in the Electric Vehicle (EV) sector and its ambitious targets will only increase the demand for energy storage systems.
The Central Electricity Authority estimates that 411.4Gigawatt-hour (GWh) energy storage will be needed by 2031-32 – 236.2GWh from battery energy storage systems (BESS).
As per the National Electricity Plan (NEP) 2023 of the Central Electricity Authority (CEA), the energy storage capacity requirement is projected to be 82.37 GWh (47.65 GWh from PSP and 34.72 GWh from BESS) in the year 2026-27. This requirement is further expected to increase to 411.4 GWh (175.18 GWh from PSP and 236.22 GWh from BESS) in the year 2031-32. Further, CEA has also projected that by the year 2047, the requirement of energy storage is expected to increase to 2380 GWh (540 GWh from PSP and 1840 GWh from BESS), due to the addition of a larger amount of renewable energy, considering the net-zero emissions targets set for 2070.
The Government of India is supporting the growth of energy storage capacities with a combination of policies and incentives.
The government has issued an advisory to co-locate a minimum of two-hour battery storage with solar projects and also stipulated an energy storage obligation, applicable to entities like distribution utilities, that will gradually increase from 1% in 2023-24 to 4% by 2029-30.
Conclusion
The article has discussed different mid- and long-term applications for Battery Energy storage installations in electric power systems. Battery Energy storage technology is found to be useful in maintaining grid stability and reliability by storing excess generation over different time horizons (minutes, days, weeks) and meeting the peak demand. Battery Energy Storage System (BESS) is increasingly recognized as a key enabling technology in the development and realization of future low-carbon networks. Such networks are necessary in order to support the wider low-carbon agenda.
Batteries have already proven to be a commercially viable energy storage technology. BESSs are modular systems that can be deployed in standard shipping containers.The low cost and high efficiency of lithium-ion batteries have been instrumental in a wave of BESS deployments in recent years for both small-scale, behind-the-meter installations and large-scale, grid-level deployments.
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