Upcycling Plastics for Clean Energy
Spending his childhood summers on the idyllic island of Hydra, off the coast of Greece, Professor Yiannis Levendis enjoyed daily views of the blue, unspoiled waters of the Aegean Sea. “I was raised with a natural appreciation for nature and, because of that, I have always been passionate about environmental protection,” says Levendis, a distinguished professor in Mechanical and Industrial Engineering who is also affiliated with the Department of Civil and Environmental Engineering.
Levendis has spent much of his 33-year career at Northeastern focusing on problems related to clean energy — particularly improved combustion methods that reduce particulate emissions and their long-term climate impacts. Other environmental research led by Levendis has focused on wildfire containment and suppression, s acid rain prevention, and use of renewable biomass as an alternative energy source.
Today, Levendis is addressing an enormous and growing problem: waste plastics that are polluting the world’s oceans and littering the land.
Yiannis Levendis
“When you think about it, plastic waste is a fairly recent development,” notes Levendis. “Prior to World War II, liquids were sold in glass containers, other products were packaged in paper, and people used cloth bags for transporting things. Because plastic holds many advantages, such as ease of manufacturing and low cost, it’s taken over the consumer products industry. While there are many critically important applications of plastics in medicine, food preservation and many other industries, post-consumer plastics are too often not disposed of properly. And that has created serious environmental issues.”
Each year, more than 8 million metric tons of plastics make their way into ocean waters ― and that number is expected to triple by 2040.
“When we read about trash in the ocean, most of us think about plastic water bottles, but the material is actually very diverse,” Levendis says. “For example, it includes thin plastic films used to wrap products, polystyrenes, discarded fishing nets and plastic microbeads.”
Levendis points out that, while society needs to focus on diverting these materials from the ocean in the first place, an equally important goal must be to gather and re-use the waste plastics that are already there. “Plastics don’t decompose, and they can break down into microplastic debris and release harmful chemicals into seawater if they’re not removed. So my research focuses on upcycling this waste material to address other social and environmental needs,” states Levendis.
While the huge volume of plastic waste in the world’s oceans is diverse, it also shares one important characteristic: it is derived from petroleum. This fact is at the heart of Levendis’ research at Northeastern.
“One pound of plastic contains the same amount of petroleum as one pound of gasoline,” Levendis explains. “The problem is how to use waste plastics as a source of clean energy. If we can master that challenge, we will be addressing two critical environmental challenges at the same time.”
In his project at Northeastern’s Center for Research Innovation, Levendis has designed a combustion system that burns plastics as cleanly as natural gas — and has the added capability of producing carbon nanotubes as a byproduct of combustion.
Carbon nanotubes represent an emerging class of materials that exhibit incredible strength and structural stiffness, along with low weight. Their high rate of electrical and thermal conductivity makes them well suited for a range of applications in the aerospace, automotive and industrial manufacturing sectors.
“When I’m near the sea, and I notice trash or pollution, I see it as a problem,” says Levendis. “It spoils the natural beauty of the environment. But I also see it as an opportunity. And I think that is ultimately the key in addressing climate change. If we can work together to arrive at new, innovative solutions, we can restore the world to the way it should be — and turn back the clock on climate change.”
Picture caption: Waste plastic bottles are made of High Density Poly Ethylene (HDPE), which is a thermoplastic polymer made from petroleum. Distinguished Professor Yiannis Levendis has designed a combustion system that burns plastics as cleanly as natural gas—and has the added capability of producing carbon nanotubes as a byproduct of combustion.