PLASTICS TO GREEN ENERGY
PLASTICS TO GREEN ENERGY
Plastics deliver many benefits that make our modern daily life possible. They keep food fresher and longer. They reduce the weight of cars, therefore using less fuel. They insulate homes, so people use less energy. And they keep medical supplies safe and sterile.
But while some plastics are recycled, most are not. So they are buried in landfills or dispersed into marine ecosystems.
Today, emerging technologies can harness fuel from plastic, in a rather new approach to create value from the trash people leave behind.
PLASTIC DOESN’T BIODEGRADE
Most plastics are derived from propylene, a simple chemical component of petroleum. When heated up in the presence of a catalyst, individual chemical units monomers of propylene link together by forming extremely strong carbon-carbon bonds with each other. This results in polymers long chains of monomers called polypropylene.
“Nature doesn’t make things like that,” said Kenneth Peters, an organic geochemist at Stanford University, “so organisms have never seen that before.”
The organisms that decompose organic matter the ones that start turning your apple brown the instant you cut it open “have evolved over billions of years to attack certain types of bonds that are common in nature,” Peters told Life’s Little Mysteries.
“For example, they can very quickly break down polysaccharides to get sugar. They can chew up wood. But they see a polypropylene with all its carbon-carbon bonds, and they don’t normally break something like that down so there aren’t metabolic pathways to do it,” he said.
PLASTICS TO FUEL
New technologies – widely detailed in this article – help converting non-recycled plastics into fuels, crude oil and industrial feedstocks. Of course, the processes differ from one fuel to another, but basically they involve three major steps.
In the first place, plastics are collected and sorted for recycling. Then the non-recycled plastics (or residuals) are shipped to a plastics-to-fuel facility, where they are heated in an oxygen-free environment, melted and vaporized into gases. The gases are then cooled and condensed into a variety of useful products. Plastics-to-fuel technologies do not involve combustion.
Secondly, depending on the specific technology, products can include synthetic crude or refined fuels for home heating; ingredients for diesel, gasoline or kerosene; or fuel for industrial combined heat and power.
Finally, companies sell the petroleum products to manufacturers and industrial users, while fuels can help power cars, buses, ships and planes.
Fuels derived from plastics is a more clean-burning one, due to the low sulfur content of plastics. So, plastics-to-fuel technologies are expected to be particularly helpful in island nations where fuel prices are high and landfill options are limited.