What is BESS?
A battery energy storage system (BESS) is used for short-term peak power services, which would store electricity from the grid to be used when there is a shortage of power. They provide balancing services to the electricity network and help replace the function of fossil fuel powered peaking plants.
How does it work?
Our batteries are designed to fill gaps in the UK’s electricity supply by charging up when energy is abundant, such as when renewable energy is being produced (for example on windy or sunny days) and discharging energy back into the grid when needed (e.g. when the wind isn’t blowing, the sun isn’t shining, or we aren’t able to import energy from elsewhere).
BESS facilities also allow us to rely more on renewable energy sources and less on expensive fossil fuels to provide electricity to thousands of homes and businesses.
How else does BESS support the Network?
The National Grid has a responsibility to ensure that the system operates at 50Hz (+/- 1%). As such, it must ensure sufficient generation and demand is held in automatic readiness to manage frequency variations.
As an example, in 2019, there was a substantial blackout as two key energy sites were struck by lightning (one gas installation and one windfarm). The National Grid reported that the inability to restore power quickly was due to the lack of back-up. Today, BESS are more prevalent across the network and would step-in during an event like this[1].
When operational, the proposed BESS can be mobilised instantly to help maintain relevant frequency. Fossil-fuel fired peaking plants were typically deployed to manage the peaks and toughs, BESS systems allow the National Grid to balance the network without the need to resort to fossil fuel powered solutions.
How big is the site?
The total size of the site is approximately 2.5 hectares. Sections of the site are currently being used as a construction compound for neighbouring works on the sewage treatment works.
Why this location?
There are many considerations to be taken into account when selecting an appropriate site for a BESS, including grid availability, planning constraints, land, access, and services.
How much energy will it store?
It is proposed that this site would have a capacity of 100MW.
Will it cause noise?
Once constructed, BESS sites produce noise when they are charging or discharging. This tends to be limited to a couple of hours per day.
Background noise levels will be monitored and analysed as part of a noise impact assessment. If required, mitigation measures will be put in place, such as an acoustic fence, to ensure that noise impacts are acceptable at nearby sensitive locations.
Will there be lighting on site?
There will be motion-detected lighting on site which faces into the development and not onto any roads or neighbouring properties. Lighting will be sensitively designed to minimise any impacts on sensitive ecological receptors and nearby residents.
Will there be impacts on the surrounding environment?
We are working with a team of specialist consultants to develop a robust landscaping strategy to help screen the site from surrounding visual receptors such as homes and nearby footpaths. We have designed the site to ensure all sensitive ecological receptors are assessed and considered in our design and mitigation strategies. We have devised a landscaping scheme that will contribute to an overall biodiversity net gain for the local environment.
The proposed construction activities will bring more vehicle movements to the area. All construction vehicle movements and deliveries will be carefully modelled and timed to reduce impacts as far as possible. The condition of the roads will also be monitored throughout the construction phase to control and repair any damage, dirt, or dust.
Once operational, the BESS will generate very little traffic, typically there are just one or two maintenance visits in a transit van or similar per month.
How will the site be monitored?
The batteries are monitored by a Battery Monitoring System (BMS). Each cabinet has a hard wire cable connection to the control room which transmits data to allow for 24/7 monitoring of the site.
If there were to be an emergency incident, the relevant emergency services would be immediately alerted. We carry out site visits with the local fire service prior to the site becoming operational.
What safety measures will be included?
In terms of operational safety, the proposed BESS will be compliant with UK and internationally recognised good practice guidance.
The thermal instability of lithium-ion batteries is mainly defined by the thermal runaway temperature. This temperature is a threshold above which uncontrolled self-heating of cells starts and is difficult to stop. Therefore, it is essential to ensure that the battery cells operate below the thermal runaway threshold. The most commonly deployed battery chemistries for BESS are lithium nickel manganese cobalt (NMC) and lithium iron phosphate (LFP). The LFP chemistry is preferred from a safety perspective because it has a higher thermal runaway temperature threshold compared to NMC.
Fire risk within BESS is managed in several ways (in addition to the base chemistry of the battery cells), including software and hardware fail safes and fire suppression systems in place.
Equipment and technology selection, site design, and the development of robust emergency plans will be considered as part of the detailed site design in order to contribute to mitigating against operational fire risks. Our suppliers will be required to have relevant quality certifications for their equipment before these are considered for operational use.
We will engage with the Fire and Rescue Service and will continue to do so on an ongoing basis to ensure they are aware of our proposals and that we have the opportunity to take their advice into account at early stages of the design process.
Key measures that will be in place to reduce operational fire risk:
- The battery technology type for the Orchard BESS will meet all relevant safety standards and will ensure a high level of performance.
- The battery chemistry selected will be lithium iron phosphate (LFP) which has a higher thermal runaway temperature threshold compared to other commonly used chemistries.
- Battery Management Systems (BMSs) will constantly monitor the battery conditions of each cell in the container, meaning that the system will be shut down if any individual battery is not behaving as expected.
- The battery enclosures will have smoke and heat detectors installed.
- Within the battery enclosures, the safety features include internal electrical protection, separation layers, thermal monitoring, a fire detection and suppression system, and venting valves. These systems are automatically triggered and would suppress any fire immediately.
- The firefighting and emergency strategy will be developed using guidance from the Health and Safety Executive (HSE), which will ensure suitable strategies are in place, safeguarding the battery site itself, the public, and the environment in the unlikely event an incident does occur.
Will there be a community benefit fund and how will that work?
As the project progresses we will look at how we can support the community and will enter those discussions at the appropriate time. If there are any local projects or schemes you wish to make us aware of, please complete the survey.
What are the key components of a BESS site and what do they do?
Battery Energy Storage Containers
The containers will comprise cells of batteries that can store and discharge electrical energy. Cells are the basic unit of a battery comprising a cathode, anode, separator, and electrolyte in a casing. Compared to other battery types, lithium iron phosphate or lithium ferro-phosphate (LFP) is the most suitable material for grid-scale energy storage systems in terms of its stability, lifespan, high energy density, and wider operating temperature range. LFP can remain structurally stable at temperatures as high as 800oC. LFP batteries are also less prone to fires and thermal runaway.
Groups of cells tend to be arranged into packs. Packs comprise multiple battery modules (groups of cells), connectors, protection systems, and battery management system (BMS). They are carefully configured inside bespoke containers. Each container can be configured to include explosion-proof fans, smoke/heat/gas detectors, aerosols (which can be automatically triggered on detector signal), and dry pipe water fire suppression systems.
Transformer Stations
A transformer station is the intermediary device between the battery containers (DC) and the power grid (AC). In order to store electric energy, alternating current (AC) needs to be converted to direct current (DC). The transformer station facilitates the two-way conversion of AC/DC and DC/AC and is therefore a critical component of the energy storage system. It can also regulate voltage and frequency to match the grid requirements, detect faults, initiate system shutdown, and provide real-time data for system diagnostics. Transformer stations typically comprise bidirectional converters, control systems, and switch gear.
132/33kV Switchyard
The proposed 132/33kV switchyard will comprise a set of electrical facilities in which voltage is transformed and electricity flow directed onto distribution network. To put it simply, electricity will flow from the network, through the switchyard, through the PCSs, then into the battery cabinets for storage and released back into the system once generation is required.
The switchyard will be subject to shared ownership which is why it has two points of entry. One side will be owned and maintained by the local Distribution Network Operator (DNO). The other part will be owned and maintained by the customer. There will be a metering breaker between the two parts, which delineates the point of supply from the point of distribution. The DNO portion of the switchyard will require a separate access point which must be available to the DNO twenty-four hours a day, seven days a week.
Other DNO and customer facilities
Other DNO and customer facilities will include car parking for visiting staff and store building(s) to container spare parts necessary to maintain supplies.
[1] https://www.theguardian.com/business/2019/aug/12/what-are-the-questions-are-raised-by-the-uks-recent-blackout