Rethinking green energy circular economy

Upon completion of an exhaustive review of the circular economy for solar and battery technologies, researchers at the U.S. Department of Energy's National Renewable Energy Laboratory found that alternatives to recycling – reducing the use of virgin materials in manufacturing, reusing for new applications, and extending product life spans – may offer untapped potential to build an effective circular economy for renewable energy.

As demand for photovoltaic (PV) panels and lithium-ion batteries is expected to increase as the United States shifts away from fossil fuels to deploy more clean energy, the completion of a circular economy is the goal for mitigating the demand for new materials as well as reducing waste and environmental impacts.

To gain a complete understanding of the possibilities, the NREL research team completed a comprehensive analysis of more than 3,000 scientific publications exploring the life cycles of the most common PV and lithium technologies, including necessary starting materials, environmental impacts, and end-of-life options.

The NREL researchers further examined 10 possible pathways toward a circular economy that is not necessarily reliant on recycling alone. The findings highlight additional key insights, gaps, and opportunities for research and implementation of a circular economy for PV and batteries, including avenues that are currently underutilized.

Examples of some of the pathways include rethink, which suggests designing products with circularity in mind, or reuse, which extends a product's lifetime by finding another owner after the product stops fulfilling the needs of the previous owner.

"If you can keep them as a working product for longer, that's better than deconstructing it all the way down to the elements that occurs during recycling," said Garvin Heath, senior environmental scientist and energy analyst at NREL. "And when a product does reach the end of its life, recycling is not the only option."

While recycling often consumes more energy and generates more associated greenhouse gas emissions, if the product functions for longer, then the overall outcome is a widening of the gap between the time a product would be recycled, essentially extending the time a new product would need to be made.

"People often summarize the product life cycle as 'take, make, waste,'" said Heath. "Recycling has received a lot of attention because it addresses the waste part, but there are ways to support a circular economy in the take part and the make part, too."

"Recycling to recover the materials used in the technologies is preferable to discarding them in a landfill," Heath added. "But if we can think about designing a product to use less materials to being with, or less hazardous materials, that should be the first strategy."

The researchers also noted that challenges remain in developing PV and battery recycling methods, as there are currently no integrated recycling processes that can recover all the materials for either technology. Furthermore, any existing research on these methods has not come out of lab-scale experimentation.

NREL is already leading efforts to improve PV reliability, extend PV lifespans, reduce the use of hazardous materials, and decrease demand for starting materials. This includes leading the Durable Module Materials Consortium (DuraMAT), which is researching ways to extend the useful life of PV modules, and the Bio-Optimized Technologies to keep Thermoplastics out of Landfills and the Environment (BOTTLE) Consortium, which is developing ways to improve the recycling of plastics.

NREL is also a partner in the Argonne National Laboratory-led consortium ReCell, which works with industry, academia, and national laboratories to advance recycling technologies along the entire battery life cycle for current and future battery chemistries.

Heath, along with his NREL colleague Dwarakanath Ravikumar, are lead authors of the 52nd annual Critical Review of the Air & Waste Management Association, titled " A Critical Review of Circular Economy for Lithium-Ion Batteries and Photovoltaic Modules – Status, Challenges, and Opportunities," which appears in the June edition of the Journal of the Air & Waste Management Association.