Plastic shopping bags can be converted into diesel fuel and other petroleum products, using a new process developed at the University of Illinois.
Shopping bags made from plastic are not biogradable. They fill landfills, adding significantly to the financial problems of many large cities. Many municipal areas are considering banning the items from local stores. The government of China recently announced a ban on the manufacture and sale of ultra-thin plastic bags, which are rarely re-used.
Brajendra Kumar Sharma, of the Illinois Sustainable Technology Center had an idea to turn this waste product into a valuable energy source. He and his team found a way to create several useful materials from ordinary shopping bags.
Production of petroleum products from shopping bags is even more efficient than using crude oil.
"You can get only 50 to 55 percent fuel from the distillation of petroleum crude oil. But since this plastic is made from petroleum in the first place, we can recover almost 80 percent fuel from it through distillation," Sharma said.
If this process could be carried out on an industrial level, trash could be turned into fuel, taking millions of tons of garbage out of the waste stream. The products could then power trucks, and heat homes. In addition to diesel fuel, the new process is also able to convert the bags into natural gas.
Shopping bags similar to those used in the research are becoming a major environmental problem. Over 100 billion bags are thrown away around the world each year. Just 13 percent of all plastic shopping bags produced are ever recycled. The refuse threatens wildlife, who often choke on, or eat, the discarded bags. These items also make up a significant portion of the islands of garbage floating in oceans around the world.
Researchers have tried to convert these bags into usable fuels, but have never been successful. Sharma and his team divided the products of processing into different classes of chemical. They then combined two of the products, and added an antioxidant. This final mixture simulates the behavior of diesel #2. It also meets nearly all the standards for fuel established by the United States government.
To make this happen, the team heated material from bags in a cask, free of most oxygen. This technique, called pyrolysis, permanently alters the chemical composition of the substance being treated. A change of state - for instance from solid to liquid - is accomplished at the same time. The liquid was then distilled in the presence of hydrocarbons to create the fuels. Oxygen was removed from the system to avoid the production of unwanted contaminants, such as ether and alcohols.
By converting plastic bags into fuel, society may able to reduce pollution which greatly affects wildlife. According to the Worldwatch Institute, animals from at least 267 species have been found dead after ingesting plastic from bags. Tens of thousands of marine animals die each year from floating debris, according to the group.
Taking plastic out of the oceans and landfills is a step toward a healthier planet.
