Today almost the entire world's merchant fleet uses heavy fuel oil (HFO) as fuel for the main engine, auxiliary engines and boilers. Heavy fuel oil is "what's left over" after the refining process. It is considered a waste product to refiners. International treaties limit the sulfur content of HFO to 4.5% sulfur, but the world-wide average is substantially less at 2.7% sulfur. In addition to HFO, ships normally have a small quantity of marine distillate fuel (MDF). A common MDF is marine diesel oil (MDO). MDO is a lighter, cleaner fuel that is used to flush the engine, fuel lines and auxiliary engines prior to a shipyard visit or a long lay up. The worldwide average for MDO is 0.52% sulfur. MDO is generally readily available as is HFO in most ports in the world.
Over the past 5 years or so, studies have shown the emissions from ships in certain areas are a large contributor to air pollution and many jurisdictions are searching for ways to reduce vessel emissions. Because of the international nature of vessel commerce, ship owners/operators would prefer to have the International Maritime Organization (IMO) develop consistent regulations governing vessel and fuel emissions limits. IMO has a treaty with rules of NOx emissions and the maximum sulfur in fuel and is about to adopt new rules lowering sulfur and NOx even further, but the U.S. Congress must ratify these treaties for them to become law. So far, the U.S. Congress has not ratified the treaty. In the meantime there is one method for reducing emissions, which can be applied immediately – fuel switching.
Fuel switching can be defined as the substitution of a high sulfur fuel like HFO with a low sulfur fuel like MDO. This operation would occur as the ship approaches the port. There are certain ship requirements that must be in place before fuel switching can be considered. The ship must have dual fuel systems. Each system must have sufficient storage tanks, transfer pumps, separate piping, fuel treating equipment, and measurement equipment. The auxiliaries and boilers must have adjustable equipment so the different fuels will ignite and burn to provide power necessary to safely operate the ship. In addition, and most importantly, ship's personnel must be trained to safely complete the fuel switch operation.
The Pacific L. A. Marine Terminal LLC project at Port of Los Angeles Pier 400 (Berth 408) will require tankers calling at the facility to fuel switch at least twice. The first fuel switch will take place as the tanker approaches the coast of California. When the tanker reaches a distance of 40 miles from the Port of Los Angeles it will be required to be using low sulfur MDF in its auxiliary engines and boilers. This means the tanker will have to begin the fuel switching operation approximately 3 hours before the 40 mile mark. This will give the tanker adequate time to gradually and safely introduce the low sulfur fuel into the auxiliary engines and boilers. Fuel switching is not just turning a valve but a gradual introduction of a different fuel over time. The entire system must be slowly and steadily brought down in temperature from a high temperature to burn HFO (325 F) to the lowest temperature (100 F) required for burning MGO or MDO.
The second fuel switch will occur once the tanker is safely moored at the berth. Before any cargo unloading operations begin the tanker will be fueled with very low sulfur marine distillate fuel,. The terminal will have a fueling system to provide this fuel. Once the fuel is loaded the tanker will again switch the auxiliaries and the boilers to this very low sulfur fuel. The utilization of this very low sulfur fuel will greatly reduce tanker operation emissions while at berth.
When the tanker has completed its cargo transfer, it will use the very low sulfur fuel in its auxiliaries as it proceeds to sea. It will continue to use this fuel until it reaches the 40 mile mark at which time it can switch to any fuel it so desires.
While our research has shown that the process of fuel switching can be accomplished in a safe manner, Pacific L. A. Marine Terminal LLC has concerns that not all tankers calling at Berth 408 may have access to a supply of lower sulfur fuels. Tankers do not generally conduct cargo operations in an established port complex that provides all services needed by ships, especially the type of low sulfur fuel Pacific L. A. Marine Terminal LLC wants the tankers to use. Pacific L. A. Marine Terminal LLC is presently working with its customers to assure the proposed fuel switching requirements will be achievable.
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