Novel battery storage with solar power could be low-cost clean energy solution

The costs of a type of battery storage suited to supporting the decarbonization of emerging economies have been predicted by Sheffield researchers.

Energy storage is key to decarbonizing energy supply, as it means excess energy generated by renewables (i.e., wind and solar) can be stored and then used at a time when there's less wind blowing or sun shining. Batteries are a convenient form of energy storage as they can be "plug and play" modular systems that don't require much infrastructure.

Researchers from the Brown group in the Department of Chemical and Biological Engineering have predicted the costs of a battery storage system called soluble lead flow batteries (SLFB), which are promising for use in emerging economies due to how robust they are and their expected lifetime.

The researchers looked specifically at a 24 volt system for a solar charging hub in Sierra Leone (developed by Sheffield company Mobile Power), which can provide clean energy for homes, businesses and electric vehicle charging. The paper is titled "Predicting the cost of a 24 V soluble lead flow battery optimised for PV applications" and was published in the Journal of Power Sources.

The researchers used a techno-economic model to define and optimize the cost/performance of the system—the first such analysis of the SLFB. They determined that a four hour duration—how long the battery can discharge its stored electricity before needing to recharge—was best, and in an optimistic scenario a total component cost of <£50/kWh would be achieved.

This is due to the low raw materials cost of the components of such a system, and is half the cost of the current most common battery type—lithium-ion battery storage. However, the cost of lithium-ion battery storage is also expected to fall as more is deployed across the world.

The greatest technical risk to achieving this low cost for the SLFB is the ability to repeatedly deposit lead with sufficient thickness, as thinner deposits make the battery more costly and less efficient.

However, testing of deposits of this thickness has not been performed across many cycles of the battery (a cycle being the battery charging and then discharging), and so there is an important gap in the knowledge of the SLFB which future research must address.

Lead author Diarmid Roberts said, "Our work is the first cost analysis of the SLFB as a small scale modular system. The approach allows us to test how changes in the lab scale performance translate to benefits in terms of efficiency and cost, and so prioritize future research.

"We are applying for additional funding with our colleagues at The University of Southampton to develop a pilot system, and have been included as co-inventors on a recently submitted patent application."