Application Number: 22/503315/SUB

Address: Cleve Hill Solar Park Cleve Hill Graveney Kent ME13 9EE

Proposal: Submission of Details to Discharge Requirement 9 Surface and Foul Water Drainage

Case Officer: Terry Hardwick

Response from the Faversham Society that Requirement 9 should not be discharged

Author: Professor Sir David Melville CBE BSc PhD HonDSc CPhys FInstP

The proposed Surface and Foul Water Drainage system for the CHSP fails to take account of the water run-off and well established hazards associated with a potential fire and/or explosive incident in the proposed Battery Energy Storage System (BESS). We strongly assert that it is inappropriate and premature to discharge Requirement 9 before the details and design of the BESS are defined and the Battery Safety Management Plan is agreed.

As we see more BESS being built throughout the world, so too we have regular reports of major incidents of associated fires and explosions. A number of these incidents including one in 2021 in Liverpool have been the subject of detailed official reports, providing a better understanding of the mechanisms involved and the requirements to extinguish BESS fires and to avoid explosions. The drainage plan must take account of this experience.

The Li-ion cells of a BESS are susceptible to “thermal runaway” - the condition when an individual battery cell increases its temperature through self-heating in an uncontrollable fashion and progresses to neighbouring cells leading to off-gassing, fire, or explosion.

From the 2022 Merseyside Fire and Rescue Service (MFRS) investigation of the Carnegie Road, Liverpool incident and reports of similar incidents in Arizona, Belgium and Beijing the common feature is the difficulty of extinguishing these ‘fires’ since they do not require oxygen to burn and can only be dealt with by deploying prodigious amounts of cooling water. The reason is that they can and do continue to reignite for days whenever local temperatures in the battery stack rise above 150C and there is still electrical energy stored. The conventional ‘’clean-agent’’ fire suppression systems were entirely ineffective and even increased the likelihood of explosions by blanketing the fire.

Reports of 70 ft flames from a container in Arizona and debris scattered over a range of 23m from an explosion in Liverpool indicate that fire propagation between containers and therefore across the whole BESS is possible.

There is also experience of the large volumes of water used by first responders to cool and  extinguish these conflagrations:

25,000 gallons of water were required to contain the single Tesla car fire in Texas April, 2020 (storage capacity 0.1MWh). A simple scaling to a typical 5 MWh container implies a need for 1.25 million gallons and as much as 175 million gallons if the whole 700 MWh BESS were to be involved.

In April 2021 an explosion occurred as firefighters were dealing with a fire in a 25MWh BESS in central Beijing. Although the volume of water involved was not reported, we know that 47 fire trucks and 235 firefighters were deployed for a BESS fire 4% of the size of the CHSP BESS.

In Liverpool, the MFRS report that once water was applied, analysis showed that the resulting run-off water contained Hydrofluoric Acid (HF) – a highly toxic acid which can dissolve concrete and whose fumes can be fatal to life.

The consequences if contaminated water were released into the environment could be catastrophic.  To be clear, “the environment” in this case includes the ground beneath the electrical compound as well as the rest of the surrounding CHSP site.  Given that the developers cannot credibly contend that there is no possibility of a thermal runaway event occurring if a BESS is installed at the Cleve Hill site, the drainage plan and infrastructure must provide for that eventuality.  It is imperative that run-off water from any ‘fire’ be fully contained, stored and treated before discharge into the adjacent Swale SSSI / Special Protection Area / Ramsar site / Marine Conservation Zone.

Given the unprecedented number of solar PV panels, of further concern is that several research studies have shown that some potentially harmful elements, including lead, selenium, strontium, lithium, nickel, and barium have been detected in the leachate from PV systems.  Leaching from cracked or broken PV cells is likely to be higher than for intact ones leading to the recommendation that broken/cracked cells are replaced immediately. The Society is concerned that accumulated leaching from the solar panels might ‘poison’ the land beneath them which could preclude the planned reversion of the area of the CHSP to salt marsh at the end of its life, leaving the public purse with a costly clean-up task to obviate marine and terrestrial pollution. 

The Faversham Society therefore:

1. Objects to the discharge of Requirement 9 on the basis that the proposal takes no account of the risk of extensive contaminated water run-off resulting from dealing with thermal runaway fires in the BESS.
2. Asserts as a consequence of 1. That the plan is premature and cannot be revised, agreed and discharged until the BESS design and the Battery Safety Management Plan are specified.
3. Recommends that the developers accept that facilities for the containment, storage and treatment of large volumes of contaminated run-off water will need to be allowed for in the site layout plan.
4. Recommends that while the levels of leached metals from PV arrays detected so far are considered safe, the long-term environmental risks remain unknown. Insufficient toxicity and environmental risk information currently exists.  Soil and groundwater samples should therefore be collected regularly (at least annually) by a third party from multiple locations within the CHSP and analysed to ensure a) that concentrations of leached metals do not reach unsafe levels; b) that they are not carried by water into the adjacent Swale SSSI / Special Protection Area / Ramsar site / Marine Conservation Zone and c)that there is not a long term build-up which could preclude the current plan for managed reversion to salt marsh at the end of CHSP’s lifespan.