Study Finds Heavy Fuel Oil with Scrubbers as Eco-Friendly as Low-Sulfur Fuels in Ocean Shipping

Researchers from MIT and Georgia Tech have found that burning heavy fuel oil with scrubbers in the open ocean can be as environmentally friendly as using low-sulfur fuels when considering various factors. By analyzing data on scrubber production and operation, along with emissions measurements from a bulk carrier, they determined that heavy fuel oil with scrubbers was the least harmful option in terms of greenhouse gas emissions, terrestrial acidification, and ozone formation among others. Lead author Patricia Stathatou emphasized the importance of using objective data to compare different options accurately.

The study revealed that over 5,800 vessels currently use scrubbers, with the majority being wet, open-loop scrubbers. These scrubbers interact with sulfur dioxide in engine exhaust gas, converting it into sulfates that are environmentally benign. While the washwater from scrubbers can contain other combustion byproducts like heavy metals, the team found that heavy fuel oil with scrubbers was more environmentally friendly than low-sulfur fuels when considering the entire lifecycle of each fuel. Scrubbers were shown to reduce sulfur dioxide emissions by 97%, making heavy fuel oil comparable to low-sulfur fuels in terms of emissions.

The researchers conducted a comprehensive lifecycle assessment using a global environmental database to evaluate the environmental impacts of producing and using different types of fuel. By collaborating with a scrubber manufacturer and gathering data from onboard a bulk carrier vessel, they were able to measure emissions, analyze washwater samples, and compare chemical concentrations to regulatory limits. The study’s findings have dispelled common fears and assumptions about scrubber waste streams, providing valuable input for ongoing discussions at the International Maritime Organization (IMO) and emphasizing the importance of making regulatory decisions based on scientific studies and factual data.

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