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Pre Application Consultation

Legacy ESS

Pre Application Consultation
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Ha of Land

Current planning process status

  • Public Consultation
  • Revise Proposals
  • Application Submitted
  • Application Consultation
  • Decision on Application

Pre Application Consultation

Welcome to the Legacy Energy Storage System ‘ESS’ project website. We are currently undertaking our Pre Application Consultation. The documents below comprise all information that would be required to be submitted as part of the formal planning application and are available to be viewed in full for comment.

In accordance with the requirements of article 2E of the Town and Country Planning (Development Management Procedure) (Wales) Order 2012, a consultation response must be sent to   or using our free postal address FREEPOST Innova’ by 2 January 2024.

All the feedback we receive is important. It will be formally logged and considered as we work to finalise our plans ahead of submitting an application to Wrexham County Borough Council in early 2024.


Agricultural Land Classification

Construction Traffic Management Plan

Transport Statement

Landscape and Visual Impact Assessment

Settings Assessment

Heritage Impact Assessment

Archaeology Desk Based Assessment

Geophysical Survey Report

Archaeology Evaluation Report

Tree Report

Flood Risk Statement

Outline Drainage Strategy

Noise Impact Assessment

Cut and Fill Assessment

Outline Battery Safety Management Plan

Site Layout Plan

Equipment Elevations

Site Location Plan

Preliminary Ecology Appraisal – Cable Routes

Ecology Report

Green Infrastructure Statement

Planning Design and Access Statement

Site Selection Report

About the Project

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 located in fields to the east of the Legacy National Grid substation and west of the A483.

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 our Downloadable Content area. The site design has been amended following public consultation and the development area reduced by 64%. 

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 the feedback from this has been considered in the evolving site design. We will shortly be commencing pre-application consultation with the Council.



Benefits for the Local Community

Our Community Promise

We believe it is important that local communities share in the benefit our project brings. For all our energy storage projects we offer a community benefit fund, which can be used to support local projects and priorities. We will work with our host communities to agree the best way to provide and administer that fund.

Every year the 400MW Legacy Energy Storage System will contribute £50 per MW of import capacity to the community benefit fund. A further £20 per MW of import capacity charitable donation annually for the entire 50-year lifetime. For the 400MW project this totals:

  • £20,000 Community Benefit Fund Per Year
  • £8,000 Charitable Fund Per Year

Need for Energy Storage Developments

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. This results in many low carbon and renewable developments being 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.

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.

The Equipment

Energy Storage 

The development would primarily consist of liquid cooled batteries, the size of a shipping container. 

Medium Voltage (MV) Skid 

The MV Skid is required to convert the Direct Current (DC) to Alternating Current (AC) via an inverter.


The purpose of these transformers is to raise and lower the voltage for export and import between the site and the National Grid.


The main substation contains the largest items of plant, consisting of a Gas Insulated Switchgear (GIS) hall, transformers and filters. It has a footprint of approximately two acres.

Access Tracks 

Access tracks would be established across the site. During the construction phase a construction compound would be established for storage of materials and plant, for parking and site offices and welfare. A new access road will be created for abnormal load deliveries.


A fence would be installed around the perimeter of the development at a height of approximately two metres. The site would be monitored by inward facing CCTV cameras.

Site Access

It is proposed that construction access will be from the B5097 and unnamed 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 are currently assessing the number of construction vehicles which will be required for the proposal. These will be detailed within the Construction Traffic Management Plan which will be 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 are currently undertaking surveys to inform our design process, and for the upcoming planning application.

Landscape & Visual

We are currently completing a full Landscape and Visual Impact Assessment (LVIA) which will accompany the planning application. Key viewpoints from the surrounding area will be assessed and provided with 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. The site also lies approximately 1.8km to the west of the Clwydian Range and Dee Valley Area Outstanding Natural Beauty (AONB). We have contacted the AONB Board for comment.

The initial Landscape Appraisal concluded that any notable effects on landscape character and visual amenity as a result of the proposed development would be localised and could be reduced by mitigation planting, which would provide increased filtering and screening of the proposed development 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 will be submitted as part of 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.


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 will from part of the planning application. We will shortly be submitting a pre-application advise request to the Sustainable Drainage System Approving Body (SAB) at Wrexham County Borough Council.

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 will be 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 will be included in the design and which will ensure that the proposed development will give rise to rating sound levels that do not exceed the measured background sound levels in the area.