Frequently Asked Questions Exeter BESS

Based on the current layout, the BESS will comprise a maximum of 60 battery containers and 15 Power Conversion System (PCS) units. The battery containers are where the electrical capacity will be stored, and the PCS is responsible for converting the direct current (DC) stored in the batteries into an alternating current (AC) which allows the electricity to be fed back into the grid (and vice versa when the battery is being charged – the battery will charge by taking electricity from the National Grid).  

The battery systems, which will be housed in storage containers, will have a maximum height of 3.4 m.  

The associated infrastructure required to support the batteries will include: 

• Switchgear which is a combination of electrical disconnect switches, fuses or circuit breakers used to manage, safeguard and isolate equipment; 

• Power control and communication units; 

• Metal water containers/tanks and infrastructure for fire safety purposes; and 

• Storage containers, welfare facilities, internal access tracks, security gates, and perimeter fencing.

A battery energy storage system uses its batteries to store and distribute energy in the form of electricity. These batteries may be charged using excess electricity generated by a connected wind or solar farm, or via a grid connection which will supply energy during periods of low demand. This project is not connected to a wind or solar site, therefore it will be charged by electricity already on the grid network. Once the battery is full, it stores the electricity until it is needed and at this point the electricity is discharged back onto the network.

To see some examples of battery containers please follow these links to articles about other battery sites.

Sungrow battery article - https://renewablesnow.com/news/sungrow-wins-30mw30mwh-battery-deal-in-germany-659488/

Sungrow equipment deal - https://solarindustrymag.com/broad-reach-power-and-sungrow-sign-battery-storage-equipment-deal

Key messages on the energy storage market - https://en.sungrowpower.com/newsDetail/2569/editorial-q-amp-a-key-messages-for-energy-storage-market

Please note: These are examples of other built schemes and there will be differences compared to Exeter Main Battery. Visualisations will be shared as soon as they have been produced.

Battery energy storage systems (BESS) are playing an important role in progressing the decarbonisation of our energy infrastructure.  When there is excess energy and demand is low, it can be stored in a BESS. Later, when demand is higher, this stored energy can be released back into the National Grid. This ensures a steady supply of domestically generated electricity. Although the electricity is not exclusively supplied by renewables sources, BESS units help to manage the key weakness of renewables - their intermittency. This security of supply is especially important in these times of energy uncertainties linked to reliance on foreign supply.

No. This is a temporary proposal with both the lease and any planning approval requiring the site to be fully decommissioned and returned to the site's current use and condition at the end of the project’s life.

One of the key drivers for siting battery energy storage systems is the proximity to a suitable connection point to import and export power to and from the National Grid. Exeter Main Substation offers a viable connection point, and a grid connection agreement has been secured with National Grid.   

A site search for suitably sized brownfield and agricultural sites within a 5 km radius of Exeter Main substation was conducted and identified the proposed site as the preferred option for development. Other sites within the set radius of the substation were discounted for a variety of reasons such as very low background noise levels, having ecological or environmental constraints, or lack of landowner interest.

Construction is planned to start in early 2025, and we expect it to be completed by January 2026. This will allow for operations to start in summer 2026.

The site will connect into the UK’s National Grid System at the Exeter Main Substation, located approximately 5 km east of the site. We are currently undertaking studies to identify the best connection route and design. An underground cable or overhead lines may be utilised depending on constraints and technical issues. This will be analysed in a separate planning application which will cover the cable route.

Typically, at 3.4 m high, the BESS containers are relatively low lying in relation to features in the landscape. Although the proposal will be occasionally visible as you move through the local area, the proposed development will be screened from most residential areas by topography and/or intervening vegetation. Enhancing the hedgerows throughout the site will also improve screening from local roads and villages, and further planting of hedgerows and trees will be provided. Visualisations including the planned hedgerow enhancements will be shared as soon as they have been produced.

A well-designed BESS site provides many opportunities for local ecological and biodiversity improvement, particularly on land that has previously been depleted through farming practices. Potential biodiversity enhancements include the reinforcement of existing hedgerows, planting new hedgerows, trees, native grasses and native shrubs within and around the proposal. Once construction is complete, the site will not discharge any emissions or smells. The batteries and associated electrical equipment are all housed in secure metal containers. The operation of the site is then managed and monitored remotely, with the only activity being the flow of electricity through the cabling to charge and discharge the batteries.  

Any specific ecological habitats or environments identified in the reports will provide further enhancement measures.

Firstly, the battery containers include a range of safety measures aimed at preventing the start of and subsequent spread of a fire. These include internal monitoring systems designed to detect any signs of a fire, which are programmed to swiftly disconnect the affected battery from the rest of the facility. Should the fire persist, internal gas suppression systems would kick in to smother the fire. 

Furthermore, detailed engineering decisions informed by guidance from the National Fire Chiefs Council, and through consultation with the local fire service have been implemented to further reduce the likelihood of fire spread. These measures include:   

• Increased spacing between battery containers;  

• Provision of on-site water storage; 

• Identification of the nearest fire hydrants; and 

• Multiple access points to ensure seamless and easy access by the emergency services. 

In the unlikely event that a fire persists despite the containment measures, then it will be tackled from the outside. The local fire service would use the water stored on site to regulate the temperatures of the surrounding battery containers to prevent the fire’s progression. The sites drainage system has been designed to allow for the retention of any water used in firefighting, so that it is not flowing into local water courses. Additionally, we are in the process of commissioning a plume study to understand how a fire and associated plume might affect the area.  

We are keeping up with the latest information and advice on battery fires, and any new content and guidance will be reviewed and added as needed.

Yes, the project will produce low level noise due to the operation of cooling fans, which are needed to maintain a safe operating temperature within the battery containers. The battery system could charge/discharge at any time of the day or night, and to assess this a Noise Impact Assessment (NIA) has been conducted by qualified industry experts to evaluate the potential noise from the cooling fans. The results of these studies show that noise will be within acceptable limits for both daytime and nighttime periods, resulting in no local impacts.  

The assessment’s findings indicate that during daytime hours, noise levels are expected to be lower than the average background sound level. During nighttime, noise levels are projected to be at most, equivalent to the typical background sound level.  

The noise output from the system is anticipated to be acceptably low and would not impact local residents. We therefore consider that noise would not pose a significant obstacle to obtaining planning permission for the proposed development. If planning consent is achieved and the BESS is built, we must conduct further noise testing of the actual system to confirm the real noise output meets the levels set out in the Noise Impact Assessment – this must be signed off by the local planning authority before we can begin operations.

Typically, one charge (taking electricity from the grid) and one discharge (supplying electricity into the grid) per day, but depending on electricity prices and other considerations it may not operate for several days at a time. Once charged, the battery can hold the electricity for periods of days or weeks if necessary with minimal losses. It takes approximately 4.5 hours to fully charge the system, and the BESS is designed to be able to discharge at full rate for up to 4 hours, though this could be shorter.

Yes, the cells will degrade over time, just like the battery in your mobile phone. The life of a cell depends on how often it is charged/discharged and other operational parameters, but we anticipate at present that cells may need to be replaced once every 6-8 years. The replacement process is simple – the cells are arranged in trays within the battery container, these are pulled out by hand by an operative and replaced with new ones. No heavy plant or machinery is required, and the steel container housing the battery cells will remain in place throughout.

We will arrange for the batteries to be recycled or reused elsewhere - once the batteries are no longer suitable for the high specification of utility scale energy storage, they can still be useable for electric vehicles and other applications. Recycling plants recover more than 95% of the input material, such as cobalt, nickel, lithium, steel, plastic and other valuable elements through a zero-wastewater, zero-emissions process. At present, the UK and global industry is developing recycling and reusing initiatives and we expect a full battery recycling eco-system to be developed in the coming years.

The application for the proposal will be submitted to East Devon District Council, the Local Planning Authority (LPA). The application will be submitted in late 2023 and a link to the planning portal will be added to the website when the project has been validated. All documents and stakeholder comments will be publicly available. We expect a decision in summer 2024.

As part of the application, we are assessing drainage and flood risk. Those studies are currently underway and initial results indicate there is no risk of flooding on the site. This is due to designing the site to sit outside the areas of flood zone, as well as including a Sustainable Drainage System (SuDS pond). A full report will be included as part of the planning application, detailing any necessary flooding or drainage mitigation.

The associated construction traffic is being assessed by our transport consultant, and the finalised details will be included in our Construction and Transport Management Plan (CTMP). This will be submitted with the planning application, but we anticipate construction traffic to last 6-12 months with the initial 2-3 months being the busiest with deliveries of the battery units, cabling, plant machinery and equipment, and stone for access roads. Once delivered to site, much of the plant and machinery will be safely stored onsite, and therefore traffic to the site will reduce significantly for the remainder of the construction period. 

Construction deliveries will be arranged out with busy hours and an appropriate delivery route will be selected in consultation with residents and the local highways authority. Once construction has been completed, traffic to the site will typically be one maintenance vehicle every few days, as the site is remotely monitored and operated from centralised operations centres.

Exeter Main Battery Limited is committed to helping the local community and enhancing local environments. Proposed local benefits include: 

• Local jobs and investment - we are committed to offering tendering opportunities for local suppliers for various factors of the lifespan of the project.  

• Potential biodiversity enhancements including reinforcement of existing hedgerows and the planting of new hedgerows, and native grasses within and surrounding the proposal. Due to an upcoming change in planning regulations all sites will have to deliver a 10% 'Biodiversity Net Gain' (BNG), we have already committed to this and will deliver it through new planting and enhancements to existing vegetation at the site.

• Community Benefit Fund to be established. 

We have volunteered to set up a community benefit fund and want to know what residents would enjoy and benefit from the most. Any feedback or ideas are greatly appreciated to ensure the fund will benefit the community as much as possible. Please contact us directly through infostorage(at)baywa-re.co.uk or via the Parish Council to share ideas or find out more.

This scheme also represents an important contribution to meeting the UK's legally binding target under the Climate Change Act 2008 to achieve a 'net zero' carbon account by 2050.  By storing energy for times when it is needed most, BESS projects help in the wider utilisation of renewable energy sources, and renewable energy developments deliver both the local community and wider population a clean, secure source of electricity that is generated in the UK.

Exeter Main Battery Limited is a project company wholly owned by BayWa r.e. UK Limited. BayWa r.e. is a leading global renewable energy developer, service provider, distributor and energy solutions provider. Our UK and Ireland offices are based in Milton Keynes, Edinburgh, Glasgow and Cork, actively shaping the future of energy through all project stages: from site identification to commissioning.