What do people usually do with dry, autumn leaves? Simple; they just burn it, right?
But what if I tell you that this seemingly normal and obvious way of dumping fallen leaves actually creates a big smoky problem little by little?
A lot of roads in the Northern part of China, for example, are lined with Paulownia trees commonly known as the phoenix trees. And while the government already disapproved the burning of trees' fallen leaves, locals just continue doing it.
Mind you, this "small" thing makes their well-known notorious air pollution worse! To give you a mental note of how bad it is, around million tonnes of leaves and other plant waste are burned every year--and that's just in Beijing alone!
So, to alleviate this problem, Hongfang Ma at the Qilu University of Technology in Jinan and her colleagues found a way to use the leaves into devices that store energy. They've figured out how to turn these into organic capacitors that can be used the same way as batteries.
First, they've prepared the leaves by cleaning and drying it. They then grinded them into fine powder before mixing it in water. The mixture was then heated at 220°C for 12 hours before its ash or any other contaminants were filtered. This created a brown powder of microspheres.
When mixed with a potassium hydroxide solution and heated at 800°C, the surface would corrode, leaving them a black powder covered in minuscule pores. This provides high surface area that enables capacitors (made of this) to store more charge.
And while this whole process also releases some carbon dioxide, the quantity emitted when burning the leaves is still way too much than the alternative. “Any type of use of any waste material is a good thing,” says Caroline Burgess Clifford at Penn State University.
Using biomass to create capacitors isn't actually new, says Fred Cannon at Penn State University. “Others have done the same sort of thing, only with wood or coal rather than leaves,” he says. Leaf-based devices, however, are found to be better at storing charge than the other counterparts.
Is it about time we normalize "recycling" natural resources into other useful materials?
Get weekly science updates in your inbox!