Lead-acid technology is 150-year-old technology, but an Australian company has put a new spin on it to give batteries a longer life and higher efficiency.
UltraBattery is a hybrid, long-life lead-acid energy storage device that was developed by CSIRO in Australia, and manufactured by East Penn Manufacturing in the United States and the Furukawa Battery Company in Japan.
The technology works by combining ordinary lead-acid battery chemistry and ultracapacitor chemistry in a single cell.
One of the product’s main features is its partial state of charge – it’s neither completely full or completely empty of charge.
This means the battery can continually service power variability needs and run longer between refreshes, so it has less downtime.
“You can consider it like a time buffer to optimise the operation of the system. For instance, on simple diesel generator-powered sites, what we’re doing is allowing the diesel generator to run in the most efficient zone, and then turning it off and running off battery for a while and then charging the battery again from the diesel,” said John Wood, CEO of Ecoult.
If the system is operating in a microgrid that has contributions from wind, solar and potential fossil fuel generation as well, the battery operates as a buffer to ensure the load and generation are matched.
“As well as the large MW UltraBattery systems, there are also a lot of small applications where we have the Ultrabattery being applied into small microgrids, resort microgrids, domestic-type use and diesel efficiency – any number of applications are possible,” Wood said.
The UltraBattery has also overcome one of the problems with standard lead-acid batteries – decreasing power and efficiency due to sulphation when used in partial state of charge applications.
Ecoult says the ultracapacitor integrated in the UltraBattery inhibits the sulphation process and allows it to continuously operate at a high efficiency.
The company also says the UltraBattery has benefits in terms of lower rates of secondary degradation factors because it operates in a partial state of charge where the internal voltage is lower.
The UltraBattery can be used in two types of applications – Ecoult is focused on the stationary energy storage market, while its parent company East Penn concentrates on automotive applications.
One example of a large stationary application is the King Island Renewable Energy Integration Project.
“Hyrdo Tasmania has developed some very sophisticated microgrid technology and the battery, in that case, works as a part of their overall system by contributing to the capabilities they have developed to sustain very long periods of operation running zero diesel on King Island,” Wood said.
UltraBattery has also been used to provide frequency regulation in the PJM Interconnection project, the largest of 10 independent system operators in the United States, with Ecoult implementing a grid scale energy storage system that provides 3 MW of regulation services.
There were two main areas that were challenging in the product’s development.
One was the maturation of the fundamental battery chemistry itself, which had contributions from East Penn Manufacturing, Furukawa Battery and CSIRO, which invented the fundamental chemistry.
The other challenge was the monitoring and management of the battery so it could provide reliable and robust behaviour in diverse applications.
“[We have] gained tremendous experience in operating long strings of batteries in a partial state of charge. Ecoult has established Ultrabattery as a really well-behaved chemistry for large systems,” Wood said.
Predicting the growth of the emerging industry of energy storage was also a challenge in the development process.
“In doing the development, we were both learning about the technology and learning about the way the technology needed to be applied to the best productive advantage of our customers,” Wood said.
“So then you’ve got to understand the full range of capabilities of the technology and how to best utilise it.”
Wood said after the Department of Energy in the United States released grants for large scale energy storage, the industry became aggressive about promotion and released the first systems, which showed how the different technologies performed.
But he said the industry is still evolving and maturing.
“The industry started with a lot of grants. What we’ve been trying to do is to make sure we apply ourselves to developing applications with UltraBattery where there are the most compelling standalone economics,” Wood said.
“To that end, one thing we all need to remember when we do energy storage is ghat it’s not just the cost of battery, but also that you need to have a connection to the grid, the power conversion systems and switchgear, etc.”