As the market for energy storage batteries continues to grow, the question of how to deal with them at the end of their life cycle becomes more urgent. Energy storage clearly underpins a sustainable energy grid, but how environmentally friendly are the key components?
Depending on the type of battery involved, incorrect disposal can cause a series of effects. Toxic chemicals can leak, making their way into water supplies and animal food chains. The tough battery components made to withstand these chemicals are clearly non-biodegradable, and in some cases, a battery wrongly disposed of can even explode. Due to these potential issues, disposal should only take place at dedicated waste management centres and in many cases are subject to standards or regulations relating to disposal of dangerous goods.
The popularity and cost effectiveness of energy storage battery recycling depends on the battery chemistry. Lead-acid batteries, being eclipsed in new installations by lithium-ion but still a major component of existing energy storage systems, were the first battery to be recycled in 1912. Perhaps thanks to this long history of usage, they are currently the only battery where recycling turns a profit.
Today, approximately 96%-98% of lead-acid batteries are recycled. Good news, as the lead and flammable acids they are made from are among the most toxic if they make their way into the environment. Nickel-cadmium is another battery chemistry still in use in existing systems, with similarly toxic chemical components and similarly high recycling rate.
The energy storage battery seeing the most explosive growth is undoubtedly lithium-ion. Lithium-ion batteries are classed as a dangerous good and are toxic if incorrectly disposed of. Support for lithium-ion recycling in the present day is little better than that for disposal — in the EU, fewer than 5% of lithium-ion batteries for any application are recycled. Companies such as Tesla are investing in battery recycling programs, but worldwide the efforts fall far short of the mark.
While valuable cobalt is profitable to recover, lithium, one of the most volatile components within the battery itself, is currently cheaper to mine than to recycle. Even then, lithium recovered from recycling is not suitable for reuse in energy storage batteries — it is recovered below the 99.5% purity required for battery use.
This does not mean the situation can’t change or improve; Umicore, European battery recycling giant, claim they are able to retrieve suitably pure lithium from the initial byproduct, however each extra process adds an additional cost. Research into new extraction processes, such as those published in the International Journal of Energy Technology and Policy by the International Islamic University of Malaysia, could also impact the business case for recycling.
The redox flow batteries in use in stationary energy storage systems, such as zinc-bromide and vanadium, have theoretically infinite lifespans — the electrolytes can keep being recharged —, although in practice, a 30 year lifespan is more realistic due to other factors. As the components are non or minimally toxic, disposal is a far easier prospect than for solid energy storage batteries.
There is no doubt that energy storage battery recycling is essential to the future viability of a majority renewable grid. However, as any chemistry or technology can eventually become obsolete, the ability to dispose of energy storage batteries safely as well as easily accessible facilities where this disposal can take place remain important. Exploring new markets and secondary uses for the recycled battery materials is another worthwhile venture.
Although energy storage battery recycling is essential both for a sustainable future and to avoid the problems associated with disposal, as it stands it is not a profitable venture. With the exception of lead-acid, recycling material from energy storage batteries is cost-negative. Repurposing electric vehicle batteries to use them in stationary energy storage applications is already under commercialisation — certainly a useful option, but one that delays fully dealing with the issue. Government subsidies are necessary to make battery recycling a palatable prospect for the energy storage sector as whole. For now, EU regulations pick up the slack by requiring the costs of battery collection, treatment and recycling to be picked up by the manufacturers.
The problem of large scale battery recycling and disposal is not yet upon us, but it’s on its way down the pipeline. This gives us several years to aggressively build the battery recycling industry that is required to support sustainable energy storage. Luckily, the problem is not that one caused by lack of ability, but one caused by unfavourable costs and lack of suitable infrastructure — both issues that renewable energy itself has faced.
Note: This article has been updated since publication.
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