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BW ESS is a global energy storage owner-operator, moving with speed to deliver market-leading projects.
The Elstree development was originally proposed by Penso Power Limited, a leading developer of BESS projects in the UK.
BW ESS merged with Penso Power Limited in October 2024, building on a successful partnership that began in 2021. This merger combines BW ESS' decades of expertise in energy infrastructure investment and operations with Penso Power's innovative approach to energy storage deployment.
Our experience spans the development, delivery, and operation of major energy storage projects, working alongside best-in-class developers, suppliers, contractors, and financial institutions. With nearly 2GW of connection capacity across 10 strategic UK sites, we're actively expanding Britain's energy storage capabilities.
The Minety project in Wiltshire stands as a milestone in our portfolio, becoming Europe's largest battery storage facility upon energisation in early 2021. We're currently advancing several significant projects: the 100MW/331MWh Bramley project in Hampshire, the 400MW Hams Hall facility in North Warwickshire, and our 200MW Berkswell project in Solihull, which begins construction later this year.
As a long-term owner-operator, we maintain direct oversight of our sites throughout their operational lifetime. We use top-tier suppliers, and our fully warranted battery systems meet the latest safety and regulatory standards.
Key benefits of battery storage
Balancing Supply and Demand
Batteries allow for the efficient storage of surplus energy during low-demand periods and release it at peak times, managing grid congestion efficiently. This reduces the need for costly and disruptive network upgrades.
Enhancing Energy Security
Battery storage supports energy security and enables the addition of more renewable generation to our electricity system; thereby supporting lower emissions, lower costs and lower energy prices leaving current and future generations more prosperous.
Supporting Net Zero Ambitions
Battery storage is recognised as essential infrastructure by the Department for Energy Security and Net Zero. Battery storage plays a critical role in creating a cleaner, greener energy future for the UK.
Battery storage is driving the UK's transition to renewable energy, providing the foundation for a sustainable and secure electricity system.
Detailed overview of the proposed site
Location
The site is located 300 meters from the Elstree 400kV National Grid substation, and occupies 6.1 acres (2.5 hectares) of low-grade agricultural land, as classified by DEFRA mapping. This location would enable efficient grid connection with minimal disruption to the surrounding area.
Green Belt Considerations
The site is located within the Green Belt, though it contains no protected national, local landscape designations or conservation areas. Our planning application will include a comprehensive 'Very Special Circumstances' case to justify development in the Green Belt.
Landscaping
The site benefits from natural screening provided by established trees and hedgerows. We would enhance this existing coverage through additional landscaping, including the planting of new native trees. All of these improvements will be detailed when the planning application is submitted.
The site is well contained within the wider landscape. As the battery units are around 3m in height, they would be well shielded by existing and new vegetation surrounding the site.
A preliminary ecological assessment survey has been carried out which identified no requirement for further detailed surveys. The proposals would include mitigation during construction, where needed, to ensure no harm to flora or fauna, as well as Biodiversity Net Gain enhancements.
Accessibility
A new dedicated access track from Hilfield Lane would serve all construction and maintenance needs. Public footpaths adjacent to the site would remain fully accessible throughout both construction and operation.
Construction is expected to take approximately 18 months with, on average, two deliveries per day. Once built the local traffic implications of the site are very low; typically, one van movement per month.
The existing footpath that lies adjacent to the site would not be impacted by the proposal and would remain open both during construction and once the site is operational.
A Planning, Design and Access Statement, a Transport Assessment and a Construction Traffic Management Plan (setting out the avoidance of deliveries at peak times or weekends) will be submitted with any planning application.
Operations
The BESS facility would operate through sophisticated remote monitoring systems, requiring only monthly maintenance visits. This automated approach would ensure efficient operation with minimal local traffic and disruption.
Noise
Battery storage sites create little noise, and they only operate for certain parts of the day. At times of peak output, the noise level experienced is still low. Studies have shown that the level of noise generated by battery storage units is the equivalent of a domestic dishwasher.
Why this site?
Proximity to Substation
The Exeter National Grid substation, a major grid supply point just 300 metres from our site, offers immediate connection capacity for a BESS project of this scale.
Addressing Regional Needs
The South East of England represents a key area of energy demand, requiring robust infrastructure to maintain system resilience and security of supply. Locating energy storage within this high-demand region strengthens the electricity system's ability to meet peak demand periods effectively.
Site Selection
After a comprehensive site selection process of potential locations, this site was chosen for its minimal planning constraints and suitability for ecological preservation and visual impact mitigation.
Integrated Ecological Design
Enhanced Biodiversity Design
A diverse range of new ecological features enriches the site's natural environment, surpassing the 10% biodiversity net gain standard. Specialised habitats include wildlife support structures such as bird and bat boxes, beehives, and dedicated areas of wildflower meadow, creating additional opportunities for local species to thrive.
Natural Site Screening
Mature trees and established hedgerows provide comprehensive natural screening around the site perimeter. The facility's low-profile design, with units approximately three metres in height, works in harmony with this existing vegetation to ensure seamless integration with the surrounding landscape.
Operational Excellence
Sophisticated remote monitoring systems ensure optimal performance through limited physical presence. The facility maintains noise levels comparable to household appliances, while monthly maintenance schedules maximise efficiency with minimal local impact.
Key Benefits of the Scheme
Enable Clean Energy Transition
- Deployment of 170MW/425MWh of energy. The equivalent to powering 1 million homes for 1 hour.
- Contribute towards energy security and the UK Government’s commitment to reach net zero carbon emissions by 2050 and Hertsmere’s commitment to achieve net zero carbon emissions no later than 2050.
Enhance Biodiversity
- Delivers biodiversity net gains onsite with the planting of new native trees and hedgerows. Other ecological enhancements could include bird and bat boxes, beehives, ponds, hibernacula sowing of native wildflowers and grasses.
Strengthen Energy Resilience of the UK
- Will enhance energy security and system resilience, ensuring there is sufficient capacity available to meet periods of peak electricity demand.
- Battery storage helps balance variable electricity demand with intermittent supply to enable the addition of more renewable generation to our energy system, supporting lower emissions, lower costs and lower energy prices.
Contribute to the Local Economy
- Payment of business rates to Hertsmere Council over the lifetime of the project, providing valuable revenue to help the Council deliver vital public services.
- Provide a monetary contribution to a local community fund on a yearly basis (for the duration of the project lifespan).
Share Your Thoughts
We warmly invite your valuable feedback, views and suggestions for our project. BW ESS is a long-term project owner, and we value building good relationships with neighbours in the local communities around the site in Aldenham, Letchmore Heath and Patchetts Green. Please feel free to reach out to us:
- Complete the form below with your comments
- Call the consultation team: 020 7457 2030 or 0749 386 7448
- Email us: hilfieldlanebatteryplans@instinctif.com