Demonstration of fuel switching on oceangoing vessels in the Gulf of Mexico

Figures & data

Table 1. International ship engine and fuel standards (MARPOL Annex VI)

	Year	Fuel sulfur	NOx
Emission control area	Pre 2010	15,000 ppm
	2010	10,000 ppm
	2015	1,000 ppm
	2016		Tier III (Aftertreatment—forcing)
Global	Pre 2011		Tier I (Engine-based controls)
	2011		Tier II (Engine-based controls)
	Pre 2012	45,000 ppm
	2012	35,000 ppm
	2020 ^a	5,000 ppm
Note: a, Subject to a fuel availability study in 2018, may be extended to 2025.

Figure 1. North American emission control area.

Table 2. Fuel switching times

Total propulsion power	Fuel switching time
0–10,000 kW	0.50 hr
10,000–30,000 kW	0.75 hr
> 30,000 kW	1.00 hr

Table 3. Vessel movements and time-in-mode descriptions

Activity	Description
Fuel switch	This is time during which the ship is switching fuels. This mode is modeled as operating half the time on distillate fuel and half the time on residual fuel. Fuel switching is estimated to occur at service speed. Fuel switching times are determined by total vessel propulsion power.
Cruise	Time at service speed considered to be 94% of maximum speed and 83% of MCR. Calculated for 24 nm from the finish of fuel switching to the coastline.
Transit	For the Port of Houston, transit time is calculated for movements within the Houston Ship Channel. There is no transit for the two Mexican ports.
Maneuver	Time in the port area between the breakwater and the dock. Maneuvering within a port is assumed to occur at 3 knots on average.
Hotelling	Hotelling is the time at the dock when the vessel is operating auxiliary engines only. Auxiliary engines are operating at some load conditions the entire time the vessel is manned, but peak loads will occur after the propulsion engines are shut down. The auxiliary engines are then responsible for all onboard power or are used to power off-loading equipment, or both.

Figure 2. Port of Houston emissions assuming a 24-nm fuel switching zone.

Figure 3. Port of Alta Mira emissions assuming a 24-nm fuel switching zone.

Figure 4. Port of Veracruz emissions assuming a 24-nm fuel switching zone.

Figure 5. Dispersion modeling sources and receptors.

Figure 6. Estimated 24-hr average concentrations of PM_2.5 on HFO.

Figure 7. Estimated 24-hr average concentrations of PM_2.5 with fuel switching.

Table 4. Estimated annual total deposition of SO₂

Reef		Units	HFO	MGO	Difference	Percent reduction
Reef 1
Total annual SO2 flux		g/m^2	0.19	0.01	0.18
Total annual deposition		kg	53,000	1,900	52,000	96%
Reef 2
Total annual SO2 flux		g/m^2	0.0093	0.00081	0.008
Total annual deposition		kg	540	47	490	91%
Total
Total annual SO2 deposition		kg	54,000	2,000	52,000	96%

Figure 8. Propulsion engine SOx emissions.

Figure 9. Propulsion engine NOx emissions.

Figure 10. Propulsion engine PM_2.5 emissions.

Figure 11. Propulsion engine speciated PM_2.5 emissions.

Figure 12. Speciated PM_2.5 emissions comparisons with other ships.