Used plastic shopping bags can be converted into diesel fuel
Living in a culture that is inundated with stuff made from plastic, from shopping bags to toys to car parts, and one that also suffers from the environmental issues that arise from our throwaway mentality, it seems rather obvious that we need to find better ways to deal with the effects of plastic waste. We can find replacements for some things, such as bio-based plastics, or work to change people's behaviors when it comes to purchasing and using single-use plastic items, but unless those changes get adopted much faster and across a much wider range of the population, we're still going to be responsible for massive amounts of plastic waste.
In the 1967 film The Graduate, when Mr. McGuire tells Benjamin (Dustin Hoffman) that "There's a great future in plastics.", it was rather prophetic, and yet, over the last 40 years or so, with the mass adoption of plastic as the go-to manufacturing material, plastic has also been responsible for a huge host of environmental issues. Little did we know that not only would plastic open up a whole new world for makers and creators, but that it would also open up a huge can of worms, in terms of litter and pollution. The data on plastic shopping bags alone is staggering, with Americans reportedly throwing away some 100 billion plastic shopping bags each year, which end up fouling water, polluting the ocean, and harming wildlife, both on the land and in the sea.
But there may be a small silver lining to the waste plastic story. Researchers at the University of Illinois have found that these used plastic shopping bags can be converted into a compatible drop-in diesel fuel, along with a host of other petroleum products, potentially recovering a large percentage of the initial manufacturing inputs.
"The conversion produces significantly more energy than it requires and results in transportation fuels – diesel, for example – that can be blended with existing ultra-low-sulfur diesels and biodiesels. Other products, such as natural gas, naphtha (a solvent), gasoline, waxes and lubricating oils such as engine oil and hydraulic oil also can be obtained from shopping bags." - University of Illinois
The researchers used a process called pyrolysis, which involves heating the plastic bags in an oxygen-free chamber, and although previous studies used this same process to convert bags into a crude oil product, the team at the Illinois Sustainable Technology Center continued to refine the resulting material into different petroleum products, in the hopes of producing a fuel that met standards for ultra-low-sulfur diesel and biodiesel fuels.
Their results, which were published in the journal Fuel Processing Technology, indicate that their plastic-derived diesel could be blended into regular diesel at rates of up to 30%, with no compatibility issues.
"It’s perfect. We can just use it as a drop-in fuel in the ultra-low-sulfur diesel without the need for any changes." - Brajendra Kumar Sharma, senior research scientist
While this discovery has potential for recovering some of the initial material inputs from manufacturing plastic shopping bags, and reducing the amount of petroleum required for diesel and other fuels, it remains to be seen whether this type of process can be successfully scaled up to the point that it makes a big dent in our plastic waste problem. After all, if we're throwing out hundreds of billions of plastic bags each year right now, even knowing that it's wasteful, what would the incentive have to be for us to instead collect them for use as a fuel feedstock?