Application Consultation

Energy Storage System

Legacy ESS

Homes Powered
Hectares of Land


We are proposing a 400 megawatt (MW) ESS to be located on land north of Bronwylfa road, Rhostyllen, Wrexham. The development site covers approximately 5.5 hectares, and is located in fields to the east of the Legacy National Grid substation and west of the A483.

We used feedback received during Pre Application Consultation to finalise the planning application, which has now been submitted to Wrexham County Borough Council. The application can be viewed on the council website with the planning reference number P/2024/0155.

We held a community consultation event at The Rhostyllen Parish Hall, Wrexham, LL14 4AR on Thursday 11th May 2023. The information boards shown at the event are available in the Project Resources section at the end of this page. The site design has been amended following public consultation and the development area reduced by 64%. 

Why do we want to develop here?

The UK has a legally binding target to achieve Net Zero by 2050 and has committed to fully decarbonising the electricity network by 2035. As a result, many low carbon and renewable energy generation is needed across the UK. Renewable energy generation is however intermittent, and Energy Storage Systems are therefore required to provide a balancing service to the National Grid, facilitating the transition to renewable energy sources. These projects are therefore a crucial component of achieving Net Zero.

The site has been carefully selected and designed through a detailed assessment process considering heritage, landscape, ecological and environmental designations, access, flooding, transport and agricultural land quality. We have engaged a team of expert consultants to provide advice on the project.

We sought pre-application advice from Wrexham County Borough Council and have completed statutory Pre Application Consultation, with both consultations having informed the site design and planning application.

Environmental Benefits

The UK has a legally binding target to achieve Net Zero by 2050 and has committed to fully decarbonising the electricity network by 2035.

The Welsh Government has already set an ambitious target for Wales to meet 70% of it’s electricity demand from Welsh renewable sources by 2030 and are consulting to push further o meet 100% of its electricity needs from renewable sources by 2035.

As a result, many low carbon and renewable developments are needed across the UK. Renewable energy generation is intermittent and Energy Storage Systems help to balance this by storing electricity at times of low demand and releasing this at peak demand. This allows us to make better use of our existing electricity supplies and for electricity generated from renewable energy sources to be fully utilised.

There will be a significant increase in demand for electricity in the coming years as more sectors (such as cars, heating, road fleet and trains) rely more extensively on electricity as a fuel source.

The Future Energy Scenarios 2022 report (written by National Grid ESO) indicates that the UK will need more than 250GW of energy storage by 2050 and this proposal would add a significant amount of energy storage to this pipeline.

In April 2022, Renewable UK reported that, nationwide, there was around 1.5GW of energy storage in operation, 1.5GW under construction, and 10GW that had consent, but had not yet been built. A significant increase is required in order to meet the projected requirements.


Current planning process status



Community Consultation Event

We held a community consultation event at The Rhostyllen Parish Hall, Wrexham, LL14 4AR on Thursday 11th May 2023.



Pre Application Consultation

We sought pre-application advice from Wrexham County Borough Council and have completed statutory Pre Application Consultation,



Application Submission

The planning application has now been submitted to Wrexham County Borough Council. The application can be viewed on the council website with the planning reference number P/2024/0155.



Decision on Application

Information regarding the decision on our planning application will be shared here in due course.


Site Design

The site has been carefully selected and the design is informed through the ongoing detailed assessment process.

We undertook a Site Selection Assessment which sought to identify an optimum site of the requisite size within a 2.5km study area from the Legacy National Grid substation. A total of 29 locations were initially identified and, when these sites were assessed against a set of key criteria. The site now identified for development was classified as the most suitable to locate the development.

The proposal will be connected to the nearby Legacy National Grid substation via an underground cable.

It is proposed that access to the development will be from an existing field access on Bronwylfa Road and a new access created from the lane on the sites western boundary. Internal access tracks will be created within the development site around the ESS containers and to the substation.

The storage containers are distributed through the site in pairs with an associated cabin, containing power conversion equipment (MV Skid). Groups of ESS units will be connected together into a transformer bay that ultimately feed back to the overall site substation.

The existing public right of way crossing the site has been retained, with new planting and bunding to the west.

Following community consultation the development area has been reduced by 64%. Feedback received from the event has been taken into consideration with additional screening provided along the western and southern boundaries by way of woodland tree planting and bunding. A permissive footpath has been incorporated into the scheme to enhance the pedestrian connectivity between Rhostyllen and Bersham Cricket Club.

If approved, the development would have an operational period of 50 years, needing only occasional maintenance. At the end of this period the development would be decommissioned, all equipment removed, and the land restored to its current use.

Site Access

It is proposed that construction access will be from the B5097 and Cadwgan Lane on the sites western boundary.

We have undertaken an assessment to confirm that the necessary abnormal load construction vehicles can safely access and egress the site.  There will be minimal abnormal load movements to the site throughout the construction period.

We have forecast the number of construction vehicles that will be required. These are detailed in the Construction Traffic Management Plan which has been submitted as part of the planning application.

Operational Traffic

Once operational the site would be visited for occasional routine maintenance. Typically, this would involve a light goods vehicle with one or two site operatives, who would access the site and carry out routine maintenance checks on the installed equipment. In the first five years post construction, there would also be regular visits by landscape contractors to monitor and manage completed landscape works like newly planted trees, during the initial establishment phase. There would also be occasional visits from our ecologists to monitor and manage new habitat creation.

Specialist Environmental Surveys

We have instructed a range of specialist consultants who have completed surveys and assessments to inform the site design and planning application.

Landscape and Visual

We have completed a full Landscape and Visual Impact Assessment (LVIA) which will accompany the planning application. Key viewpoints from the surrounding area have been assessed within this LVIA.

The site is not included in any national designations. However, the site is within a Special Landscape Area, a local landscape designation defined by Wrexham County Borough Council. However, the site lies approximately 1.8km to the west of the Clwydian Range and Dee Valley Area Outstanding Natural Beauty (AONB). We have liaised with the AONB board regarding the proposals.

The LVIA concludes that any notable effects on landscape character and visual amenity as a result of the proposed development would be localised and would be reduced by proposed mounding and woodland planting, which would provide increased filtering and screening of the proposed development overtime as planting matures.

Agricultural Land Quality

An agricultural land classification survey has been completed which confirms the development site comprises Grade 2 agricultural land. In planning policy terms, ‘Best and Most Versatile’ agricultural land (which is afforded the highest level of protection) comprises Grades 1, 2 and 3a. Lower grade agricultural land comprises land that falls in Grade 3b, 4 and 5. Previous surveys of this general area of Wrexham have shown higher grade land is common.

Cultural Heritage and Archaeology

Our archaeology consultants have liaised with Clywd-Powys Archaeological Trust (CPAT), who are the archaeological consultees to Wrexham County Borough Council and Cadw, the statutory heritage consultee for Wales. An Archaeological Desk Based Assessment has been completed which considers the proposal and the cable route options in the context of designate heritage assets, such as nearby Offa’s Dyke, as well as the potential for sub-surface non-designated assets.

Following the desk-based assessment and upon recommendation of CPAT, a geophysical survey of the site has been completed. This has indicated potential areas of archaeological interest and we have now completed trial trenching.

A Settings Assessment has been completed to determine the potential for any effects on heritage assets within 3km of the site, along with a Heritage Impact Assessment. These have been included within the planning application. It is anticipated that, with appropriate mitigation, such as screening, sensitive site design and considered planning of the cable route, the potential impact of the development on nearby above ground heritage assets will be minor to moderate.

We have also liaised with Cadw regarding the potential cable route crossing of Offa’s Dyke and will continue to do so throughout the application determination.


An ecological assessment comprising of an Extended Phase 1 Habitat survey, breeding bird surveys, badger survey, bat detector surveys, an assessment of the likely impacts on the ecological features of the site and recommendations for further survey and/or mitigation measures to be implemented has been completed.

The ecology assessment concluded that the application site has been found to comprise low value habitats of low ecological value. The site supports foraging bats and an assemblage of breeding birds of value at the local scale. The scheme will result in the loss of 4.5ha of improved grassland but will retain and enhance the more valuable habitats on site and will deliver a 4.5ha area of ecological enhancement land for long-term biodiversity gains. Therefore a positive change in the ecological value of the site is expected.

Biodiversity Net Gain (BNG)

The UK is one of the most nature depleted countries in the world, caused by the move to intensive agriculture and new infrastructure. Biodiversity Net Gain (BNG) is targeted in England through the development of a Defra Metric, that calculates change based on habitat type and area. However, this metric system is not applicable in Wales. The net-benefits for biodiversity approach by Welsh Government
has the same intent as the BNG approach – to deliver an overall improvement in biodiversity. 

it is anticipated that the scheme will deliver a significant Net Benefit for Biodiversity. This will be achieved through the enhancement of 11ac of land to the west of the site to benefit roosting/foraging/commuting bats, nesting/foraging birds, invertebrates, grassland habitat and riparian habitat. The land will be brought into long-term conservation management which will ensure a sustainable future for this area and the flora/fauna that it supports. Invertebrates and pollinators will benefit from the creation of a greater diversity in vegetation structure and habitat types, as well as specific features such as grass heaps, refugia, south-facing banks and topographical variation. 

The long-term management and monitoring of the biodiversity enhancements will be detailed within a Habitat Management Plan which will be secured by way of a planning condition.


The entirety of the proposed development site is located within  Flood Zone 1, which represents areas which have less  than 1 in 1000 (0.1%) chance of flooding in a given year, including climate change.

The majority of the site is located within Flood Zone 1, meaning it is not constrained by flood risk. We have completed a Flood Risk Statement and an Outline Drainage Strategy, which is included in the planning application. We have also completed a pre-application advice request with the Sustainable Drainage System Approving Body.

The outline drainage strategy has been designed to ensure ensure the proposed development does not increase flood risk on or off site.


The planning application is supported by a Full Noise Impact Assessment which has identified the closest noise receptors and considers the potential noise generation from the plant associated with the proposed development, with respect to existing sound levels in the area. Several mitigation measures have been included in the design to ensure the proposed development will not give rise to sound levels that exceed the measured background sound levels in the area.