The oceans are full of garbage. One of the most depressing facts about humanity’s degradation of the natural world is the presence of the Great Pacific Garbage Patch, a gigantic vortex of plastic and other marine debris that could be up to twice the size of the continental United States. Generally speaking, plastic takes around 450 years to completely degrade, and we’re dumping more of it into the oceans all the time – so this patch isn’t going away anytime soon.
Although our priority should be to clean up this mess and stop any more of it entering the geological cycle, there are other things science has conjured up that may also help. Writing in the journal Science Advances, a joint US-China endeavor has described a way in which this type of plastic can be converted into a source of fuel.
This is all based on the fact that plastics – combinations of hydrogen, carbon and oxygen atoms arranged in long chains – are made from fossil fuels, so it stands to reason that they can be converted into a type of fossil fuel. The authors decided to focus their efforts on polyethylene (PE), a simple chain molecule that is also one of the most commonly used types of plastic in the world.
“PE is the largest-volume plastic in the world, with annual production exceeding 100 million metric tonnes [110 million US tons],” the scientists, led by Xiangqing Jia, a researcher at the Chinese Academy of Sciences, write in their study.
PE takes a remarkably long time to degrade and requires vigorous chemical processes in order for it to react to anything – or be converted back into a fuel. Simply heating it doesn’t work, as the molecule chains (or “polymers”) will break down chaotically into many smaller variants, all of which have their own properties. Being aware of this, the team turned to catalysts, chemicals that accelerate reaction processes.
A visualization of the plastic garbage patches in our oceans. NASA's Scientific Visualization Studio