If your city has a program for converting old Christmas trees into mulch or compost, that's good, but … evergreen needles do take a long time to decompose, and they give off greenhouse gases as they do. According to new research, those needles could instead be harvested and used in products such as paints or sweeteners.

Cynthia Kartey, a PhD student from Britain's University of Sheffield, has been looking into methods of breaking down lignocellulose – it's a complex polymer that makes up about 85 percent of individual pine needles.

She found that by combining eco-friendly inexpensive solvents such as glycerol with a process known as pyrolysis, she could convert that polymer into a liquid bio-oil and a solid bio-char (pyrolysis involves thermally decomposing biomass in the absence of oxygen). The bio-oil contains glucose, acetic acid and phenol, which could be used in food sweeteners, paints/adhesives and disinfectants, respectively.

The charcoal-like bio-char byproduct could likewise be used as a catalyst in various industrial chemical reactions, resulting in a zero-waste pine needle-recycling process. Both fresh trees and older ones that have dried out could be used.

"Biorefineries would be able to use a relatively simple but unexplored process to break down the pine needles," says Kartey. "In the future, the tree that decorated your house over the festive period could be turned into paint to decorate your house once again."

Scientists at the UK's University of Bath previously developed a renewable plastic, made with a chemical derived from waste pine needles.