’Tis the season … to kick millions of Christmas trees to the curb.
In some places they’ve gotten creative with these abandoned evergreens, turning them into mulch, using them as erosion barriers or sinking them in lakes to create fish habitat. But in many places the trees are simply tossed in the landfill, where their pine needles break down, emitting greenhouse gases. Now, researchers at the University of Sheffield are offering a sustainable alternative to this sad fate.
The problem with pine needles is that they are mostly composed of a complex polymer known as lignocellulose, whose chemical structure makes it unsuitable for biomass energy, in which wood, grass and paper and other organic materials are broken down into ethanol. However, as Mark Kinver at the BBC reports, Cynthia Kartey, a chemical engineer, found another use for pine needles. As it turns out, they are a great feedstock for creating other chemicals.
“My research has been focused on the breakdown of this complex structure into simple, high-valued industrial chemical feedstocks such as sugars and phenolics, which are used in products like household cleaners and mouthwash,” says Kartey, a doctoral candidate at Sheffield, in a press release. “Biorefineries would be able to use a relatively simple but unexplored process to break down the pine needles.”
Using heat and solvents like cheap, environmentally friendly glycerol, the needles can be broken down into bio-oil and bio-char. Bio-oil can be further refined into glucose, which is used as a food sweetener, acetic acid used in making paint and adhesives, and phenol, which is used in mouthwash. The solid-bio char also has industrial uses. “In the future, the tree that decorated your house over the festive period could be turned into paint to decorate your house once again,” Kartey says.
The BBC reports that in the U.K., about 8 million real Christmas trees are purchased each year. Seven million of those tress end up in landfills. Utilizing the trees as a chemical feedstock, instead, would reduce the country's carbon footprint and help replace toxic chemicals with less harmful ones. That’s something the U.S. should take note of, considering 25 to 30 million real Christmas trees are put up each year here.
Mouthwash and paint are not the only things pine needles are good for. Earlier this year, chemists at the University of Bath found that they could convert an organic compound found in pine trees called pinene (aptly named, as its responsible for producing that distinct scent), into a type of sustainable plastic through a four-step process, reports Alyssa Danigelis at Seeker.
While this work suggests we may see a more sustainable Christmas tree tradition going forward, there’s no word on how mistletoe, holly, poinsettias or stale Christmas cookies will pull their weight to bring about a greener tomorrow.