Bunker fuel is a waste product of traditional fuel oil processing, a cross between a solid and a liquid that is too thick for road vehicles and small ships to burn efficiently. Its high sulfur content and the difficulty of installing the proper technology to use it make bunker fuel a cheap source of power for larger ships and power plants.
Bunker fuel degrades even less rapidly in the environment than standard fuel oil, and is difficult to remediate because of its thickness. When burned, it produces a mixture of sulfur dioxide, carbon dioxide, nitrogen oxides and other pollutants that have been linked to acid rain, increased asthma, lung infections and tens of thousands of premature deaths every year in port communities around the world.
The shipping industry largely adopted bunker fuel in the 1950s as its primary power source as it became more available due to increased petroleum refining. A lack of comprehensive international regulations has meant that bunker fuel remains the industry standard even as studies continue to demonstrate its serious health and environmental drawbacks. The State of California is currently the strictest regulator of shipping fuel, with tighter standards for sulfur content than any single country or international organization in the world. The International Maritime Organization, charged with overseeing the industry on behalf of the United Nations, has outlined a plan that will not match California’s standards for years.