Bunker fuel, a dense and viscous petroleum product, serves as the primary energy source for the global shipping industry. While maritime transport is an efficient method for moving goods across distances, the widespread use of traditional bunker fuel presents considerable environmental and health challenges.
Air and Marine Pollution
The combustion of bunker fuel releases various pollutants into the atmosphere, impacting air quality and contributing to climate change. Ships emit sulfur oxides (SOx), nitrogen oxides (NOx), particulate matter (PM), and carbon dioxide (CO2).
Sulfur oxides contribute to acid rain. Nitrogen oxides play a role in smog formation, particularly in coastal areas and port cities. Particulate matter can travel far inland, affecting air quality.
The shipping industry significantly contributes to greenhouse gas emissions, accounting for approximately 3% of global emissions. Beyond CO2, the sector emits methane and nitrous oxide, intensifying the greenhouse effect.
Beyond air pollution, bunker fuel poses risks of marine pollution through oil spills and the discharge of contaminated water from exhaust gas cleaning systems, known as scrubbers. Oil spills, even minor ones, can severely damage marine ecosystems. These spills involve heavy fuels that can be as damaging as larger crude oil spills.
Scrubbers, while reducing air pollutants like SOx, often discharge wash water directly into the ocean. This water can be contaminated with heavy metals, polycyclic aromatic hydrocarbons (PAHs), and nitrates, which accumulate in the marine environment and food web. Studies indicate that scrubber discharge water can be toxic to marine life and contributes to contaminant load in port environments.
Health Implications
Emissions from bunker fuel combustion have consequences for human health. Populations near ports and coastal areas are particularly exposed to pollutants like SOx, NOx, and particulate matter. These particles and gases can penetrate deep into the lungs, leading to respiratory and cardiovascular problems.
Exposure to SOx and NOx can cause respiratory issues such as asthma and bronchitis. Fine particulate matter (PM2.5) can trigger chronic respiratory diseases. These emissions are also associated with cardiovascular diseases, increasing blood pressure and the risk of heart attacks and strokes.
Research indicates that shipping emissions contribute to hundreds of thousands of premature deaths globally each year, with estimates around 250,000 to 265,000 premature deaths in 2020 alone. These health impacts disproportionately affect lower-income and minority populations living near port communities.
Addressing the Issues
International bodies and the shipping industry are exploring solutions to mitigate the effects of bunker fuel. A significant regulatory effort is the International Maritime Organization’s (IMO) 2020 sulfur cap, which reduced the global limit for sulfur content in marine fuel from 3.5% to 0.5%. This regulation aims to reduce sulfur oxide emissions and improve air quality.
To comply, ships can use lower-sulfur fuels or install exhaust gas cleaning systems, known as scrubbers. Scrubbers remove sulfur from exhaust gases, allowing ships to continue using higher-sulfur fuels. However, scrubbers do not remove NOx or CO2, and open-loop systems discharge contaminated wash water into the sea, raising concerns about marine pollution.
The shipping industry is also investigating alternative fuels to reduce its environmental footprint. Liquefied natural gas (LNG) offers lower CO2 and virtually eliminates SOx emissions, though methane slip remains a concern. Other promising alternatives include methanol, ammonia, biofuels, and hydrogen.
Transitioning to these alternative fuels involves economic and logistical challenges. Developing necessary bunkering infrastructure for new fuels like ammonia and hydrogen is a significant challenge, as is the cost of converting existing vessels or building new ones. Global efforts continue towards developing cleaner shipping practices to reduce pollution.