Polystyrene foam (commonly known as Styrofoam) has been a notorious environmental problem due to its slow degradation and massive use as a packaging material. But a new approach could help solve this issue by turning recycled polystyrene (PS) into an energy source for the Internet of Things (IoT) through innovative triboelectric nanogenerators (TENGs).
Polystyrene foam, or foamed polystyrene (FPS), is used worldwide for packaging due to its lightweight and protective qualities. Once in landfills, it remains "essentially inert," meaning it doesn't break down in a reasonable time frame. Moreover, its high air content (about 95%) makes it economically unfeasible to transport or store large volumes of FPS waste, leading to minimal recycling.
Although the FPS industry claims that about 12% of foam is recycled, government estimates put the number closer to 1%. This gap is largely due to the cost: recycling polystyrene is simply not as economically viable as producing new foam.
As the world becomes more interconnected through the Internet of Things (IoT), the demand for low-cost, efficient, and environmentally friendly energy sources grows. Currently, IoT devices often rely on piezoelectric materials, like fluoropolymers, to convert motion into energy. The environmental damage caused by fluoropolymer production, however, has prompted many governments to restrict their use. This opens the door to alternative materials, such as triboelectric nanogenerators (TENGs).
TENGs are devices that convert ambient motion—such as vibrations or low-frequency movements—into electricity. Traditionally, these devices were thought to require different polymers for optimal energy generation. However, recent studies have shown that using the same material with different textures can achieve similar results.
TENGs operate by using two surfaces that repeatedly come into contact and then separate. This process causes one surface to gain a positive charge and the other to gain a negative charge, creating energy.
TENGs made from the same material (such as polystyrene) have historically generated less energy than those made from different materials. This has limited their widespread adoption. To address this, researchers have started experimenting with creating polystyrene laminates (layers of material) to boost energy output.
Researchers recently demonstrated a breakthrough: they successfully created a laminate that generates electricity through “same-material” contact electrification, using recycled polystyrene foam.
When tested under mechanical stress, these laminates produced a significant amount of energy. The energy came from friction between the layers of fibers as they moved against each other. As force was applied and released, the friction between the fibers generated electric charges, which could then be captured as electrical energy.
This breakthrough could significantly reduce the environmental burden of polystyrene waste by giving it a new life as a material for energy harvesting. By converting waste foam into a valuable resource, this innovation not only addresses a major pollution issue but also helps meet the growing energy demands of the IoT.
The creation of polystyrene-based TENGs shows that the environmental problems caused by FPS can be tackled in innovative ways, offering a sustainable solution for both waste management and energy production.