By Turning Plastic Into Fuel, Clean-Up Ships Can Power Themselves

A new study has shown that ships carrying reactors can convert plastic waste into "blue diesel" and thus power themselves while sailing, reducing the need for trips back to shore and the associated burning of fossil fuels, Nick Lavars reported for New Atlas.

Photo Insert: A Color Line hybrid ship

Trash-collection systems designed to gather plastic waste like that found in the Great Pacific Garbage Patch are gathering steam, largely thanks to the efforts of the Ocean Cleanup Project.

While these were originally conceived as floating systems that passively sweep up the trash with the help of ocean currents, the latest versions use vessels powered by fossil fuels to tow the barriers across the ocean.

The collected trash then needs to be ferried back to shore more than a thousand miles away, further adding to the carbon footprint of the operation.

The idea that plastic waste can be converted into usable fuels is one scientists have been exploring for a while, with one interesting example coming in 2017. This research sought to build on technologies that break down plastics into diesel-like fuels in large-scale facilities, by instead having the process take place in a mobile reactor that could be integrated into a ship.

This latest study on the topic is authored by scientists from Harvard University, Worcester Polytechnic Institute and Woods Hole Oceanographic Institution and centers on a technique called hydrothermal liquefaction.

This involves heating up plastic to temperatures of 300–550 °C (572 to 1,022 °F) and subjecting it to pressures 250 to 300 times that found at sea level, which reduces the material to oils that can act as building blocks for "blue diesel," a plastic-derived fuel said to have an energy density similar to marine diesel.

The study was published by the journal Proceedings of the National Academy of Sciences (PNAS).

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