Colloquia

Summary

Worldwide, millions of tonnes of Lead-Acid Batteries (LABs) reach end-of-life each year. While over 95% is recycled, this process is energy-intensive, requires transportation to specialized facilities and prematurely destroys cells that often still contain significant usable capacity. At the same time, demand for energy storage is growing rapidly, driven by renewable integration, backup power needs and electrification. New batteries remain expensive, while supply chains for critical materials such as lithium, cobalt and nickel face increasing strain from demand and geopolitical tensions. Finding pathways to reuse existing LABs is therefore not only a way to reduce waste, but also a strategy to cut costs, extend resource lifetimes and build resilience into local energy systems.

This thesis addresses the pressing issue of how to make energy storage both more sustainable and affordable by reusing salvaged LABs. Given that, a decision-making framework was developed to determine whether discarded LABs should be reused, reconditioned or recycled. The framework considered four key dimensions: technical viability, economics, environmental impact and human factors.

In collaboration with Riwald Recycling, the framework was validated in two real-world case studies: an off-grid storage system at a tiny house and a grid-connected installation at the  Fraunhofer Innovation Platform (FIP) building. These two case studies demonstrate that reused LABs can serve both small-scale, decentralized needs and larger, grid-interactive applications.  In addition, an important finding was that reconditioning could revive a large number of batteries previously rejected due to sulfation. This significantly increases the share of salvageable cells, strengthening the case for reuse.

Overall, the results show that reusing LABs is a practical and impactful way to reduce environmental footprint, recover economic value and alleviate pressure on critical material supply chains. By extending battery lifetimes before recycling, the framework helps bridge the gap between sustainability goals and the rapidly growing demand for energy storage. While lithium chemistries are advancing, LABs remain a robust, safe, and highly recyclable option, made even more relevant when integrated into circular strategies such as those explored in this work.