Battery energy storage systems are often quoted in terms of their power (measured in megawatts or kilowatts). However this is not helpful unless there is an indication of how much electrical capacity is offered by the system. It is a common mistake is to use the term capacity when referring to the power rating of the battery system.
A Battery Energy Storage System rated at 400MW cannot be compared with a 400 MW Power station. A power station can produce 400 MW of power continuously, apart from short periods of shut down from time to time for servicing. As long as there is energy to drive the drive the turbines which themselves drive the electricity generator, 400MW will be available to distribute into the national grid.
A Battery Energy Storage System will have a limit to the power it can supply to the electrical grid. The energy rating, or battery capacity, of the battery system measured in Megawatt-hours MWh indicates the amount of electrical energy that can be stored and delivered into the National Grid. But it provides this power for a limited amount of time. Statera Energy have now stated that their proposed BESS can deliver 400 MW for 6 hours, that is to say that the planned capacity of the BESS is 2400 MWh. The product of MW output and time in hours cannot exceed 2400 MWh.
A summary of the top Battery Energy Storage Systems which are in use or under construction are listed on the website referenced here.
The 2400 MWh BESS proposed by Statera would be housed in 600 12m shipping containers, each weighing 44 tonnes. They would be delivered to the site via Glennie Way through Chickerell to Coldharbour.
The map shows the proposed site of the BESS and the projected route to deliver the containers is shown in dark blue.
Such large containers would require articulated lorries to transport them.
Currently, Europe's largest Battery Energy Storage System is at Pillswood, Cottingham East Yorkshire. This is 196MW and was developed by Harmony Energy. There is also a 320MW Battery Energy Storage System being developed at London Gateway.
As shown in the table above, the largest Battery Energy Storage System so far is at Moss Landing California. If the project at Chickerell were to get the green light, residents of Chickerell and Southhill would have the doubtful distinction of being next door to one of the World's largest Battery Energy Storage Systems.
The site proposed by Statera Energy for their monster Battery energy Storage System is in the middle of a residential area.
Yet in comparison the Battery Energy Storage System at Moss landing is well isolated.
The nearest conurbation to Moss Landing is San Jose, about 55 miles to the North, while San Francisco is a further 43 miles to the North.
As can be seen from the map, the Moss Landing Battery Energy Storage System is situated in a region surrounded by Wildlife area and Marine Reserves.
There are some tourist attractions along the beaches but there no hotels and very few (if any) residential properties
The Lithium ion Cell is the heart of the modern technology of many items used extensively today. The battery in a mobile phone is a lithium ion cell and that in the Apple iPad also. A typical cell is made up of
The separator besides keeping the two electrodes apart (thus preventing a short circuit), also allows Lithium ions to pass freely back and forth during the charging and discharging process.
The lithium compounds include iron, nickel and/or cobalt whose electrons are only loosely bound to their central atomic nucleus. Applying a positive voltage to the cathode can move electrons through the outside circuit to the anode while the lithium ions move through the electrolyte from cathode to anode.
In the diagram the lithium ion cell is connected to a DC power supply. As the voltage is applied, positively charged lithium ions move from the cathode through the electrolyte to the graphite anode and nestle between the graphite crystal structure. Meanwhile electrons from the cathode travel twoards the positive teminal of the power supply and then towards the anode. They then meet the lithium ions . The charging process removes electrons from the cathode and unites them with the lithium ions at the anode
The result is that the cathode has lost electrons which have been deposited at the anode. The cathode is now negatively charged and if the DC power source is replaced by a load such as an electric light bulb or electric motor, the opposite journey takes place. The Lithium ions move back through the electrolyte while the electrons that were at the anode travel through the outside circuit back to the cathode. In doing so the electric current provides useful power.
So it would seem that the lithium ion cell is a providential opportunity to solve all our net zero problems. But unfortunately life is not so simple. These lithium cells are fairly fragile, susceptible to vibration and when fully charged can burst into flame or explode if abused.
The paper by Dr Edmund Fordham, Professor Wade Allison and Professor Sir David Melville cited earlier describes how lithium battery cells, in certain circumstances, can get overheated and if they reach a certain temperature, they will catch fire and emit noxious gases. If a single cell bursts into flame, it will heat up adjacent cells which will also burst into flame. If the cells are not immediately cooled down a chain reaction will set in and there will be what is called thermal runaway.
A recent paper https://www.cetjournal.it/cet/22/90/108.pdf by Guy Marlair, Amandine Lecocq, Arnaud Bordes, Paul Christensen, and Benjamin Truchot sets out their Key Learnings from Recent Lithium-ion Battery Incidents. They conclude that "No chemistry, not even less reactive LFP lithium-ion chemistry, is exempt from thermal runaway"
They recommend that a fail-safe approach with multi-layer protection barriers should be the future strategy, not just relying on the use of safer materials in the hope of negating the Thermal Runaway hazard.
It follows therefore that any design claiming a fail-safe approach needs to be exhaustively analysed and tested and demonstrated before any decision is made whether or not to give the go ahead.