The CO2 footprint of a cleanup operation using conventional methods (boats and nets) would indeed be staggeringly high and would indeed likely offset the positive effects of removing plastic from the oceans. The difference is that our cleanup method is not a conventional method.
The Ocean Cleanup’s systems are 100% powered by the natural forces of nature. The current, wind and waves propel the cleanup systems through the oceans, while the solar energy is used to power the electronics aboard the units. The only thing that does require fuel is the vessel that collects the plastic and service the systems.
Estimations (based on assumptions on the number of required vessels and collection frequency) indicate the expected carbon footprint of plastic collected from the Great Pacific Garbage Patch is not much higher than regular virgin plastic once we are fully operational. But this assumes we use regular marine diesel, while we may be able to use bio-based fuels.
South Pole is also partnering up with us to help us offset a substantial part of the vessel CO2 emissions for the first cleanup system.