Battery Storage Infrastructure and Flood Risk

Over the last decade, the mix of generation providing electricity to the National Grid has undergone a significant change. In addition to the familiar wind turbines and solar farms are a new breed of battery storage facilities. Like electricity substations, their location must be balanced between good access and acute sensitivity to key environmental risks, such as flooding.

As Government encourages more generation of electricity from renewable sources, the National Grid is looking to increase the number of facilities that can provide short-term supplies and support overall demand growth.

The anticipated expansion of electric vehicle usage, charging points and greater draw on the grid by the population, means battery storage infrastructure is likely to be expanded within our rural and urban communities.

These can be purpose-built ‘barns’, as well as backup generation equipment, with supporting fuel-storage facilities.

A fast and simple way to connect such facilities to the National Grid is to construct them in a rural setting and claim that they are needed locally to support the grid, thus avoiding the complications and costs of using an existing “brownfield” site in an industrial location.

Energy storage projects are becoming increasingly common in the UK. Planning permission applications for such facilities have quadrupled since 2016.

Location of facilities and flood risk

There are no hard and fast rules about how suitable areas for battery storage and backup generation developments should be identified. However, in considering locations, local planning authorities (LPAs) should ensure they take into account the requirements of the technology and, critically, the potential cumulative impacts on the local environment.

Electricity substations and solar arrays are already highly vulnerable to risks of flooding – whether fluvial (rivers or sea), pluvial (surface water) or from groundwater. In 2014, the National Grid admitted that 7 of its biggest substations could fail due to flooding, affecting 1.1 million people.

In its flood risk review of national infrastructure assets, the Government identified 7000 locations or 14% of all substations were at risk in England.

This risk is directly transferable to battery storage, which may be highly susceptible to very localised flash flood and groundwater risks.

Leighton Buzzard Battery Storage Case Study

A proposal for a development site in Leighton Buzzard by UK Power Networks in 2013 shows how flood risk significantly affected the choice of materials and scheme.

The 6MW/10MWh battery facility is famed for being the UK’s first grid-scale battery storage facility and came to fruition under the Low Carbon Network Fund, helping to prove the technical and commercial viability of battery storage technologies.

A variety of sites were looked at using the sequential testing methodology. Once the site was agreed, it was then about how to mitigate the residual flood risk.

The proximity to Clipstone Brook, a small stream close to the proposed site meant some of this land was in a high-risk flood area, as designated by the Environment Agency

This would have had implications for safety hazards connected with the proposed technology.  For UK Power Networks, this meant a move away from battery solutions based on liquid electrolytes, where there was some risk of hazardous liquids being released in a flood. Instead, Lithium Ion batteries have become increasingly preferred.

In order to mitigate flood risk, the following factors were required in the design:

• No raising of the site ground level;
• A clear void under the building to allow for flood water to pass freely and occasional access for maintenance purposes;
• No amendments to the cross-sectional alignment of the bank of Clipstone Brook;
• No tree-planting close to the watercourse edge;
• No bunding of any kind is included in the design to prevent displacement of potential flood waters; and
• An easement between the perimeter fence, along level ground, to the edge of the watercourse to allow access for maintenance.

Due to the flood risk at site, the design specified that the storage building was raised on stilts to ensure that any potential flood waters were not displaced, increasing the risk of flooding elsewhere.

The 100-year worst-case predicted flood levels were estimated at around 0.66m above the ground level of the development. However, health and safety policies within UK Power Networks meant that any void under the building less than 2m would be classed as a confined space. So the building was raised by 2m at the lowest ground level point. This mitigates against a predicted 1000-year flooding event.

A flood maintenance plan ensures that the clearance and removal of any debris happens after flood events. An alarm is also installed on site, which alerts UK Power Networks control engineers in the event of a flood.

The raised building design was balanced with the need to minimise the visual impact of the building and keep it below the levels of existing housing.

A sustainable drainage system (SuDS) was implemented to ensure flood risk is not increased to other areas surrounding the battery storage site. This included using shingle drainage around the building. Other measures to manage drainage include soakaways, swales, infiltration basins, permeable paving or retention ponds.

Get a Clearer Picture

Farmers and other rural landowners, faced with uncertainty over Brexit are also looking at battery storage facilities and the potential to accommodate them via the planning regime for income generation. So it is anticipated that the need to verify site suitability, especially to identify flood risk and how this impacts on the development opportunity, will be a key planning consideration.

GeoSmart understands how river, surface and groundwater flooding can affect infrastructure development sites.  We work with utilities to map and alert asset managers on groundwater flood risk as well as identifying optimum locations and maintenance priorities.

Our expert flood risk consultants will advise on flood zones and constraints, as well as potential vulnerabilities that could impact on proposed energy infrastructure applications.

For more information about our desktop flood risk assessments call us on 01743 298 100 or email enquiries@geosmartinfo.co.uk