Optimizing Bulk Shipping: The Advantages of Using Scrubbers with Heavy Fuel Oil

Image Credits: MIT

In 2020, the International Maritime Association (IMO) introduced a crucial regulation to limit sulfur levels in marine fuels, aiming to tackle environmental and health issues. This left shipping companies with three primary choices: switch to low-sulfur fossil fuels like marine gas oil, install exhaust cleaning systems known as scrubbers for heavy fuel oil, or consider biofuels—though the latter is frequently enough impractical due to limited supply.

Among these options, scrubbers have emerged as a popular choice due to their cost-effectiveness. However, there’s been ongoing debate about how environmentally amiable they truly are.

A recent study by researchers from MIT and Georgia Tech has shed light on this issue.They discovered that using heavy fuel oil with scrubbers can be just as eco-friendly—or even better—than low-sulfur alternatives when considering various environmental factors.

The team analyzed data from both the operation of scrubbers and emissions from an oceangoing cargo ship. Their findings revealed that when looking at the entire lifecycle of these fuels and technologies, burning heavy fuel oil with scrubbers resulted in lower environmental impacts across nearly all ten categories studied—including greenhouse gas emissions and ozone formation.

Neil Gershenfeld from MIT emphasized the importance of grounding claims about environmental policies in solid scientific evidence. “To make informed decisions,” he said, “we need comprehensive data that allows for fair comparisons.”

Patricia Stathatou led this research while at Georgia Tech; she collaborated with experts from Greece’s National Technical University and maritime company Oldendorff Carriers. Their work was published in Environmental Science and Technology.

Tackling Sulfur emissions

Heavy fuel oil is commonly used by bulk carriers—about 30% of global shipping—and typically contains around 2-3% sulfur content. This far exceeds IMO’s cap of 0.5% in most ocean areas and even stricter limits near populated or sensitive regions.

sulfur oxides contribute substantially to air pollution problems like acid rain which can harm human health too.

Before regulations took effect in 2020, fewer than a thousand ships had installed scrubbers; however, rising costs for low-sulfur fuels pushed many companies toward adopting this technology instead. Now over 5,800 vessels are equipped with them—most utilizing wet open-loop systems.

Stathatou noted that scrubber technology isn’t new; it has been effectively used on land for years in power plants aimed at reducing pollutants.

So how do these systems work? A wet open-loop marine scrubber consists of a large tank fitted into a ship’s exhaust stack where seawater is sprayed onto hot exhaust gases exiting engines. The seawater reacts chemically with sulfur dioxide converting it into harmless sulfates before being released back into the ocean along with cleaned exhaust gases containing minimal sulfur dioxide emissions.

However, concerns linger regarding whether washwater produced during this process might contain harmful substances like heavy metals compared to burning low-sulfur fuels—a question previous studies failed to fully address until now.

A Comprehensive Lifecycle Analysis

The research team conducted an extensive lifecycle assessment using global databases covering fossil fuel production processes including those related specifically to heavy fuel oil versus cleaner alternatives like very-low sulfur fuel oils (VLSFO).They found that producing low-sulfur options involves additional refining steps leading up to higher greenhouse gas emissions overall compared against customary heavy fuel oils—which actually turned out less impactful environmentally when viewed holistically!

stathatou also spent time aboard a bulk carrier vessel off China collecting real-time emission data while testing both types of fuels under similar conditions—a challenging task given safety protocols onboard moving ships!

Their results indicated that using scrubbing technology could reduce sulfur dioxide emissions by an impressive 97%, aligning its impact closely alongside those achieved through lower-sulfur alternatives based solely on this metric alone!

Moreover testing washwater samples revealed concentrations well below regulatory limits set forth by organizations such as EPA or EU standards—even after dilution upon release into vast ocean waters!

These insights suggest employing scrubbing systems alongside heavier oils may indeed offer comparable—or potentially superior—environmental benefits relative towards cleaner-burning counterparts across multiple impact categories assessed throughout their study period!

scott Bergeron from Oldendorff carriers remarked on how important these findings are amidst ongoing discussions within IMO circles regarding future regulations surrounding maritime practices emphasizing reliance upon scientifically-backed conclusions rather than assumptions alone moving forward!

Ultimately Stathatou advocates for integrating lifecycle assessments into future policy-making efforts aimed at reducing ecological footprints within shipping industries worldwide stating: “As we explore choice energy sources down the line let’s ensure we’re comparing apples-to-apples so we understand true costs versus benefits.”