According to recent estimates, rivers carry 1.15 to 2.41 million tonnes of plastic into our oceans every year. The global extravagant plastic usage has resulted in a large mass of floating trash, located in the North Pacific ocean. Following common ocean gyres, the waste plastics come together to form human-made garbage islands. Located between Hawaii and California, the “Great Pacific Garbage Patch” has a surface area that is twice the size of Texas and is still growing at a worrying rate.
We have previously covered ocean cleaning voyages of the environmental engineering organization The Ocean Cleanup. Just last October, the company scooped up a massive pile of garbage off of the ocean that led us to wonder whether we will ever be able to clean out the great Pacific Garbage Patch or not.
These cleanup vessels seem like the rays of hope that our oceans need. But where does the collected plastic waste go? Recycling is a well-known solution, but carrying these plastics to the shore for recycling means more fuel that is going to be wasted on the way.
However, the plastic waste these vessels collect could be turned into oil and made useful in, again, powering them, creating a circular economy. What’s more, a new study published in Proceedings of the National Academy of Sciences puts forward a new way of converting these collected plastics into oil that could prevent even further waste.
By modeling the most efficient way to run the cleanup operation for the garbage patch, researchers found that a method called hydrothermal liquefaction (HTL) can convert the plastic waste back to oil with less leftover than the thermal process of pyrolysis in which extreme heat is used to decompose of organic material in the absence of oxygen.
The authors note that “oil yields from HTL are typically below 90 percent even in the absence of catalysts and, unlike pyrolysis, yields of solid by-products – which would need to be stored or burned in a special combustor – are less than 5 percent,” while acknowledging HTL requires temperatures of 570-1020ºF (300-550ºC) and pressures 250-300 times sea-level atmospheric conditions, reports IFL Science.
According to the researchers’ calculations, a vessel that’s carrying a hydrothermal liquefaction converter could get enough oil from the collected plastic to operate safely at sea. However, in order to save up on oil for trips to and from the base whenever necessary, the plastic needed for fuel should be collected through a separate boom, not the vessel itself.
While ocean cleaning seems like our best shot at saving our oceans, for the time being, there are steps every responsible individual could take to help out. Simple changes in your daily routine such as demanding plastic-free alternatives to everyday plastics and reducing the usage of single-use plastics could help lead to a positive change in the future of our oceans.