Recently, we reported on the efforts of SolarCycle, a California startup that is struggling to recycle solar panels and do it profitably. Figuring this out is going to be hugely important as the number of solar panels that are no longer productive increases dramatically over the next several decades.
In 2016, the International Renewable Energy Agency forecast that by the early 2030s, the global quantity of decommissioned PV panels will equal some 4% of the number of installed panels. By the 2050s, the volume of solar panel waste will rise to at least 5 million metric tons a year. China, the world’s biggest producer of solar energy, is expected to have retired a cumulative total of at least 13.5 million metric tons of panels by 2050 — the largest quantity among major solar-producing nations and nearly twice the volume retired in the US by that time.
New Recycling Process For Solar Panels
The problem is how to make money recycling solar panels, because if there’s no money to be made, then it becomes charity work and it won’t get done on a large enough scale to matter. Researchers at Deakin University in Melbourne, Australia, have come up with a novel idea. The most valuable component of old solar panels is the silicon which is used to manufacture the solar cells that actually do the work of converting sunlight into electricity. The other components — glass and aluminum mostly — have some market value, but not enough to make dismantling old panels profitable.
You might think the answer is to recycle and reuse that silicon, but that is not as simple as it sounds. Dr. Mokhlesur Rahman is a lead researcher at the Deakin Institute of Frontier Materials. He says in a university press release, “Solar panel cells are fabricated using high-value silicon, but this material cannot be re-used without purification, as it becomes highly contaminated over the 25 to 30 years of the panel’s life.”
Rahman and his team say they have developed a sustainable and highly lucrative way to address two big issues in the clean energy transition by reclaiming the most valuable component from end of life solar panels and reconfiguring it to build better batteries. In Australia alone, more than 100,000 tons of used solar panels are estimated to enter Australia’s waste stream by 2035.
The researchers say they have successfully tested a new process that safely and effectively extracts silicon from old solar panels without the use of toxic chemicals. Then that regular-sized purified silicon is reduced in size to nanoscale using a special ball-milling process. That nano sized silicon has a market value of $45,000 per kilogram — far more than regular silicon which has a market price of around $650 per kilogram.
Uses For Nano-Silicon
But what is that nano-silicon good for? One potential use is to make silicon battery anodes. In laboratory experiments, silicon anodes have been shown to increase the capacity of lithium batteries to store energy by a factor of ten. “We are using that nano-silicon to develop low-cost battery materials that will help deliver the higher performing, longer lasting, affordable battery technology critically needed to drive Australia’s clean energy transition,” Dr Rahman says.
He adds that for Australia and the world to address the enormous issue of solar panel waste and develop a successful recycling program to divert it away from landfills, scientists must find a way to harvest and repurpose the panels’ most valuable components. “We have developed a process that returns silicon collected from used cells to greater than 99 per cent purity, within a day and without the need for dangerous chemicals. This thermal and chemical process is far greener, cheaper, and more efficient than any other technique currently on the market.”
Nano-silicon can be used for other purposes in addition to battery anodes. It can be used in the development of nano-fertilizers, innovative new methods for carbon capture, and on-demand hydrogen gas generation. The research team estimates their technique could generate recovered materials worth $15 billion, based on the 78 million tons of solar panel waste expected to be generated globally by 2050.
The new process is the result of years of research from a team led by Deakin Professor Ying Chen, Director of the ARC Research Hub for Safe and Reliable Energy, which is based at Institute of Frontier Materials.
“This Deakin developed technology — including purification, nano-silicon production and integration into new battery technology — is a giant leap forward in how we tackle the problem of solar panel waste,” Professor Chen said. “Silicon recovered from end of life solar panels can be a massive, sustainable source of nano-silicon to meet future demand for raw battery materials and hgelping to power the homes, transport and communities of the future.” The researchers are now talking with potential industry partners about plans to scale up their process.
CleanTechnica readers are used to announcements that promise wonderful things in the future. They also know that many of the breakthroughs that take place daily in laboratories around the world never find their way into commercial production. At the bottom of the Deakin University press release was this sentence: “For more information, email Dr Rahman at email@example.com.” I wanted more information, so I sent Dr. Rahman a polite email with a few questions.
“[CleanTechnica] readers are a well educated group and will want to know more about the practical side of this research, particularly with regard to its commercial aspects. Would you be able to tell me how expensive you anticipate a recycling facility to handle commercial quantities of used solar panels is expected to be? How large a facility would be required? How much energy is needed to complete the process? Do you obtain your raw material from a solar panel recycler or dismantle the solar panels yourself? Have you formed any alliances with industrial partners yet? I greatly appreciate your assistance and look forward to hearing from you. Any further information you may wish to share with my readers would be welcome as well.”
That email was sent a few days ago. The silence from Dr. Rahman has been deafening. Nada. Nothing. Bupkes. I take that as a bad sign. Usually if researchers have anything good to say, they are delighted to have someone show interest in their work. I cannot tell you if there is reason to believe this research is anything but a laboratory exercise, which is a shame.
Right now it costs more to recycle solar panels than the recaptured materials are worth. With the awesome power of profits waiting to be realized, that could change in a heartbeat. I want this to be true but right now, at this very moment, I cannot say there is any meat on the bones of this research. If I get a response from Dr. Rahman, I will update this story accordingly.
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