The disposable plastic shopping bag is the ultimate symbol of convenience and waste. Between 500 billion and 1 trillion plastic bags are manufactured each year, and according to the Worldwatch Institute, 100 billion of these are discarded in the United States alone during the same timeframe. These bags are a large portion of the plastic debris in the world's oceans, and create a major hazard for wildlife.
Scientists at the University of Illinois at Urbana-Champaign have developed a better end-of-life scenario for plastic shopping bags: diesel fuel. A method called pyrolysis involves heating the bags in an oxygen-free chamber, producing a crude oil that researchers turned into a fuel with the same energy content and better lubricity than ultra-low-sulfur diesel.
"You can get only 50 to 55 percent fuel from the distillation of petroleum crude oil," said senior research scientist Brajendra Kumar Sharma in a university news release. "But since this plastic is made from petroleum in the first place, we can recover almost 80 percent fuel from it through distillation."
The method requires much less energy than it produces, and the resulting product complies with national fuel standards after minimal modifications.
"It's perfect," Sharma said. "We can just use it as a drop-in fuel in the ultra-low-sulfur diesel without the need for any changes."
Hopefully, the new conversion process will lead to a change in our widespread culture of plastic disposal, particularly if fuel prices continue to rise.
Blaine Brownell, AIA, is a regularly featured columnist whose stories appear on this website each week. His views and conclusions are not necessarily those of ARCHITECT magazine nor of the American Institute of Architects.