Safety of Grid Scale Lithium-ion Battery Energy Storage Systems

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Table 2. “Mega” scale solar plant and/or Li-ion BESS in Australia and the UK*
– 8 – June 5, 2021
The incidents recorded in Table 1 are all in relatively small BESS or a single BEV. Yet “mega- scale” BESS are now planned on a very large scale in many current proposals in the UK, listed in Table 2 and illustrated in the subsequent Figures.
And no engineering standards are currently applied to pre-empt future accidents in grid-scale BESS, the most critical of which would be design features aimed at preventing the phenomenon of “thermal runaway”, the process whereby failure in single cell causes over-heating and then propagates to neighbouring cells so long as a temperature (which can be as low as 150 °C) is maintained.
BEV batteries do now include thermal barriers or liquid cooling channels between all cells to safeguard against this phenomenon, but no such engineering standards exist for grid-scale BESS. A large BESS can pass all existing engineering design and fire safety test codes and still fail in thermal runaway – by now a well-known failure mode. This must be urgently addressed.
The consequences of major BESS accidents could be significant and emergency services need adequate plans in place to handle any such incident.
Project
Hornsdale Power Reserve
Location
S. Australia
Status
Operational
Solar PV Scheme Size Not directly associated
Battery Stores
Single site
Battery type
Li-ion
Battery capacity 193 MWh
Cleve Hill Solar + Battery Store
Kent
Permission granted (2020)
350 MW; land coverage 890 acres
Single site
Li-ion
700 MWh
Sunnica Solar + Battery Store(2)
Cambridgeshire/ Suffolk
Pending submission
500 MW; land coverage approx. 2792 acres
31.5 ha of land over 3 compounds [7] of 5.2, 10.7 and 15.6 ha
Li-ion
Undeclared. Estimate 1500 – 3000 MWh
Longfield Solar + Battery Store
Essex
Pending statutory consultation
500 MW; land coverage approx. 1400 acres
Stated as 3.7 acres: number of sites TBD
Li-ion
Undeclared. Estimate: 150 MWh
* Li-ion technology has been assumed in all these proposals as Li-ion battery electrochemistry is dominant in grid-scale BESS applications (deployment at this scale is unlikely to involve technologies with lesser experience). Estimated values for Battery Capacity for the Sunnica are calculated based on the McMicken facility in Arizona (Appendix 1) and the Cleve Hill DCO. For the Longfield site it is estimated from Energy Institute guidance on energy density [25] at about 100 MWh ha-1. The exact specification for the battery units has not been disclosed by the developers at this present time.