November 5, 2021: GS Yuasa’s presentation at today’s ABC showed how the advantages of a dual chemistry energy storage system could offer the lead battery industry a new path forward by combining the virtues of lead batteries with the strengths of lithium ones.

Effectively, the hybrid system is designed to fit the energy storage requirements of the grid — from immediate demands such as frequency response to longer term needs such as are found with UPS systems.

“We looked for the lowest cost solution and showed how lead and lithium with different operational characteristics can obtain an overall improved storage performance by combining the best points of both,” said Peter Stevenson, senior technical co-ordinator at GS Yuasa, who pioneered the project.

He said lithium-ion battery strengths — cycle life, high discharge rate, high charging rate, partial SOC operation, high efficiency and high energy density — fitted well with lead-acid strengths, which are its price, simple control mechanisms, the fact it is abuse tolerant, its abundant raw materials and low embodied energy.

The first live demonstration of the project called ADEPT went live at the end of 2018.  Since then, Stevenson said they had been working on three projects — two in Wales and one in Portsmouth in southern England.

ADEPT is a 100kW grid-connected hybrid connected directly to the DC bus. The general operational pattern has been charging the system overnight at around 20kW and discharging it at 100kW, maximum inverter power, during evening peak hours.

The second half of the presentation, given by Southampton University PhD candidate Andrei Dascalu, described how the testing — such as pulse discharge and constant current charge/discharge, at different C rates — was used to extract the parameter of equivalent circuit models for both battery cell types and hence validate the model.