Discarded car batteries could be recycled to build new, long-lasting solar panels, according to US researchers.
The system devised by the MIT researchers is based on emerging solar cell technology that uses a compound called perovskite, which contains lead whose production from raw ores can produce toxic residues.
By using the lead from old car batteries instead, the process not only prevents the creation of these residues, but also diverts toxic material from landfills – a growing problem as new, more efficient batteries, such as lithium-ion technology, make older lead batteries obsolete.
“Once the battery technology evolves, over 200 million lead-acid batteries will potentially be retired in the USA, and that could cause a lot of environmental issues,” said Professor Angela Belcher, co-author of a paper appearing in the journal Energy and Environmental Science.
Currently, roughly 90 per cent of the lead recovered from the recycling of old batteries is used to produce new batteries, according to Belcher, but over time the market for new lead-acid batteries is likely to decline, potentially leaving a large stockpile of lead with no obvious application.
But as perovskite solar cell technology only requires a thin film just half a micrometer thick of the photovoltaic material, the team’s analysis shows that the lead from a single car battery could produce enough solar panels to provide power for 30 households.
The technology has rapidly progressed from initial experiments to a point where its efficiency is nearly competitive with that of more common types of solar cells. Other studies have shown perovskite-based photovoltaic cells have achieved power-conversion efficiency of more than 19 per cent, close to that of many commercial silicon-based solar cells.
“It went from initial demonstrations to good efficiency in less than two years,” said Belcher. “It has the advantage of being a low-temperature process, and the number of steps is reduced.”
According to the authors, in a finished solar panel the lead-containing layer would be fully encased by other materials limiting the risk of lead contamination of the environment and when the panels are eventually retired, the lead can simply be recycled into new solar panels.
“It is important that we consider the life cycles of the materials in large-scale energy systems,” said co-author Professor Paula Hammond. “And here we believe the sheer simplicity of the approach bodes well for its commercial implementation.”