Battery Energy Storage Systems: planning guidance

2 BESS Development Context

Role of BESS in the Energy System

2.1 BESS have an important role to play in the development of a flexible, resilient, and decarbonised energy system for Scotland.

2.2 As Scotland’s energy generation is increasingly drawn from renewable sources there is an ongoing need for the wider energy system to adapt and meet new operational requirements, including through having a flexible and responsive electricity grid. Renewable sources such as wind and solar are intermittent and do not necessarily generate energy at the time it is needed. BESS technology enables this energy to be imported and stored when demand is low, and to be released back into the grid when demand is high, supporting the efficient operation of the energy market and deployment of renewable energy technologies across Scotland.

2.3 This process also supports wider frequency balancing services of the grid, minimising imbalances between generation and demand within the system which can arise from fluctuating supply. Where there is a dip in generation and insufficient power, batteries can be discharged to balance frequency and prevent power cuts. More information on balancing the National Grid can be found at: How do we balance the Grid? | National Energy Systems Operator.

2.4 The power ratings and energy capacity of a BESS influences how it operates. The power rating is the maximum rate at which a BESS can charge or discharge electricity. For example, a 40MW BESS has the ability to charge/discharge 40MW of power. The energy capacity indicates how much energy a BESS can store and deliver over time. For example, a BESS with an energy capacity of 80MWh could provide 80MW of power continuously for 1 hour or 40MW of power continuously for 2 hours.

2.5 National Planning Framework 4 (NPF4) designates Strategic Renewable Electricity Generation and Transmission Infrastructure (including ‘on and offshore electricity generation, including electricity storage, from renewables exceeding 50 megawatts capacity’) as a National Development. Specifically, it states that “A large and rapid increase in electricity generation from renewable sources will be essential for Scotland to meet its net zero emissions targets. Certain types of renewable electricity generation will also be required, which will include energy storage technology and capacity, to provide the vital services, including flexible response, that a zero carbon network will require.”

BESS Projects: Locational and Physical Characteristics

2.6 BESS is a modular technology capable of being deployed at a range of scales, configurations, and in different geographic settings across Scotland.

2.7 The specific mix of plant, technology, and supporting infrastructure will vary by site, but core components typically include:

• Battery Storage Units – containerised units arranged in cells, modules, and racks, housing battery technology to store and discharge electrical energy as needed^[2].
• Power Conversion Systems – consisting of inverters to convert direct current (DC) produced by batteries into alternating current (AC) required in UK grid, and transformers which step up or step down voltage to allow safe operation of equipment or reduce electricity losses in energy transfer. Elements of electrical infrastructure may be housed within dedicated compound/switch room/substation building(s).
• Grid Connections – cable connections from the BESS site to the wider electricity network infrastructure (substations and overhead lines), and/or to energy generation sources.
• Battery Management Systems (BMS) – integrated systems and equipment to control battery performance and safety, including monitoring of cell voltages, temperatures, state of charge, fault detection, and instigate safe shutdown if protective thresholds are breached.
• Cooling Systems – Heating, Ventilation, and Air Conditioning (HVAC) units that may be linked to BMS to maintain optimal operating temperatures and reduce risk of overheating or thermal incidents.
• Fire Safety Systems – Specialist fire, gas and/or smoke detection and water and/or gas suppression equipment integrated within battery storage units, and related plant and facilities (e.g. water tanks) to ensure fire safety within and around the site.
• Site Accesses and circulation – Access junctions, internal roads, parking and hardstanding areas to provide safe and reliable access, for operational vehicles and emergency response vehicles, including fire appliances, under both normal and incident conditions.
• Drainage Infrastructure – Surface water management features to manage rain and surface water, reduce the risk of surface water flooding, and to capture, contain and manage fire-fighting water and contaminated runoff to prevent off-site impacts in the event of a fire.
• Soft Landscaping – Landscape features including tree and hedgerow planting, landscaped bunds, grassland or wildflower meadows, ponds and basins (as part of Sustainable Drainage Systems (SuDS), and other ecological and biodiversity enhancement features.
• Security Infrastructure – Perimeter fencing, CCTV and other features to prevent unauthorised access and ensure the safety and security of equipment.
• Welfare Facilities – Ancillary buildings for staff welfare, operational control / monitoring, and storage of equipment for site maintenance.

2.8 The location of BESS developments is influenced by several factors specific to the operational requirements of BESS technology and its role within the wider energy system. This may result in it being near other energy generation such as onshore wind or solar, grid infrastructure such as substations, or development with high energy demands, such as data centres.

2.9 The availability of grid capacity and the ability to import and export power cost-efficiently can be a strong influencing factor, as well as minimising distance from the point of connection due to the complexities of securing physical cable connection over long distances, and the extent of ‘transmission loss’ which can occur.

2.10 Other factors typically influencing the location and siting of BESS development may include:

• Available land area suitable for BESS development, of necessary size and without significant environmental or technical constraints such as steep topography, risk of flooding, or ground conditions unsuitable for construction.
• Accessibility and ease of connection to the road network, for purposes of construction, operational management, and in the event of emergency responses.
• Avoiding sites subject to environmental, cultural heritage, or other planning designations and protections, and/or sites which have high landscape, cultural heritage, biodiversity or other value.
• Health and Safety and local amenity considerations, including surrounding land uses.

2.11 Further detail and guidance on site selection for BESS development is provided in Section 4.