Marine Fuels – Current Issues

P. Kontoulis, M. Mastrokalos, E. Efstathiou & L. Kaiktsis

Division of Marine Engineering

School of Naval Architecture & Marine Engineering
National Technical University of Athens

Contact: kaiktsis@naval.ntua.gr

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 1
Air Pollutants

Major air pollutants emitted from marine industry:

 Carbon dioxide (CO2)

 Nitrogen oxides (NOx)
 Sulphur oxides (SOx)
 Volatile organic compounds (VOC)
 Particulate Matter (PM) or soot
 Black carbon (BC)

Impact on organisms and environment

 Respiratory symptoms, cancer

 Greenhouse effect
 Smog formation
 Acid rain

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 2
Air Pollutants
Shipping fuel consumption in MT

Shipping fuel consumption increases

continuously during the last decades
Annual emissions in MT

Contribution of shipping regarding

NOx and SOx emissions is evident

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School of Naval Architecture & Marine Engineering
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Emission Control Areas (ECAs)

 High air pollutant concentrations near

regions with high density of marine traffic

 IMO and local authorities set strict

emission control regulations (and areas)
Expansion of ECAs:
 Zone 1 = Northern Europe
 Zone 2 = Caribbean Sea
 Zone 3 = Northern Mediterranean
 Zone 4 = Singapore, Tokyo bay, Korea, Australia
 Zone 5 = China ports/sea passages
Emission Control Areas - ECAs
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Division of Marine Engineering 4
Emission Control Regulations

IMO MARPOL ANNEX VI

Regulations for the Prevention Jan. 2000

of Air Pollution from Ships

Jan. 2011
 GHG : EEDI & SEEMP (new Chapter 4) ~75%
 NOx : Tier I, II, III standards (Reg. 13)
Jan. 2016
 SOx : Limits on sulphur content (Reg. 14)
 Black carbon: pending

Energy Efficiency Design Index - EEDI:

 New-building vessels from 1 January 2013
 Exceptions:
• Diesel-Electric propulsion systems
• Steam-driven vessels MGO
• Hybrid propulsion installations only

Ship Energy Efficiency Management Plan - SEEMP:

 All vessels from 1 January 2013

extra LS HFO
availability ?
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Division of Marine Engineering 5
Marine Fuel Oils

Residuals Distillates
Grades (ISO 8217:2017) Grades (ISO 8217:2017)
DMX, DMA, DMB and DMZ
Residual (Non-distillate) fuels
are designated by the prefix RM
and their nominal viscosity
RMA10, RMB30, RMD80,
RME180
RMG180, RMG380, RMG500,
RMG700, RMK380, RMK500, RMK700

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 6
Classification of Marine Fuel Oils
MGO (Marine Gas Oil) – (also called DMA): is a general purpose marine distillate which contains
about 60% aromatics; it is free from traces of residual fuel. Due to high aromatic content, the
density will be higher than straight run gas oil (860 kg/m3 at 15 oC).

MDO (Distillate Marine Diesel Oil) - (also called DMB): is a blend of heavy gas oil that may contain
very small amount of black refinery feedstocks (low viscosity up to 12 cSt - no need to be heated).
Possible traces of residual fuel (high in sulphur).

Blended Marine Diesel Oil - (also called DMC): can contain up to 10% IFO with either marine gas
oil (MGO/DMA) or distillate marine diesel (MD/DMB).

HFO (Heavy Fuel Oil) - (also called MFO - Marine Fuel Oil): is pure or nearly pure residual fuel oil.

IFO (Intermediate Fuel Oil) - A blend of HFO with less gas oil than MDO
IFO-380 - Intermediate Fuel Oil with max viscosity of 380 cSt at 50oC
IFO-180 - Intermediate Fuel Oil with max viscosity of 180 cSt at 50oC

LS-380 - Low sulphur Intermediate Fuel Oil with max viscosity of 380 cSt at 50oC
LS-180 - Low sulphur Intermediate Fuel Oil with max viscosity of 180 cSt at 50oC

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School of Naval Architecture & Marine Engineering
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2020 Prospect

MGO
only

POSSIBILITIES:
1) Scrubbers
2) Dual-fuel engines
3) MGO

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 8
SOx scrubbers

NOx Selective Catalytic

Reducing Reduction (SCR)
Exhaust Gas devices
Treatment System
Wet
(EGTS)
SOx scrubbers

Dry

SOx scrubber:
 Allows an operator to meet SOx emission limits without using low-sulphur fuels
 Contributes to 70% up to 90% removal rates of Particulate Matter (PM)

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 9
 Wet SOx
SOx scrubbers
Scrubbers

Wet SOx scrubber types

‘Open Loop' ‘Closed Loop‘ ‘Hybrid'

Systems systems Systems

Use Use fresh water Can operate in both

Seawater + 'open loop' and
Alkaline Chemical ‘closed loop' modes

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 10
 Wet SOx
SOx scrubbers
Scrubbers

Wet 'open loop' SOx scrubbers

 Seawater is pumped from the sea through the scrubber, cleaned and then
discharged back to sea
 Wash-water is not re-circulated
 Wash-water flow rate: ~45 m3/MWh
 SOX removal rate close to 98% + full alkalinity
 Compatibility with 2020 regulations for sulphur

(*) In the design process seawater temperature also has to be considered (SO2
solubility reduces at higher seawater temperatures)

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 11
 Wet SOx
SOx scrubbers
Scrubbers

Wet 'open loop' SOx

scrubbers

"Exhaust Gas Cleaning", Aalborg Industries technical presentation, January, 2011

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 12
 Wet SOx
SOx scrubbers
Scrubbers

Wet 'closed loop' SOx scrubbers

 Use fresh water treated with sodium hydroxide (NaOH - commonly known as
caustic soda) as the scrubbing media
 Removal of SOX from the exhaust gas stream as sodium sulphate
 Wash-water passes into a process tank where it is cleaned before being re-
circulated and relevant sludge is stored onboard
 Measurement and control of PH of wash-water by dosing with sodium hydroxide
enables re-circulation rate
 Power consumption is estimated to be about half than ‘open loop’ systems and
equal to approximately 20 m3/MWh and between 0.5 – 1% of the power of the
engine being scrubbed
 Can also be operated when the ship is operating in port or estuary waters, where
the alkalinity would be too low for ‘open loop’ operation
 By addition of a wash-water holding tank in the system can operate in ‘zero’
discharge mode for a period of time

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 13
 Wet SOx
SOx scrubbers
Scrubbers

Wet 'closed loop'

SOx scrubbers

"Exhaust Gas Cleaning", Aalborg Industries technical presentation, January, 2011

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 14
 Wet SOx
SOx scrubbers
Scrubbers

Wet 'hybrid' SOx scrubbers

 Can be operated in either ‘open loop’ mode or ‘closed loop’ mode

 Operate in ‘closed loop’ mode (including ‘zero’ discharge mode) where the water
alkalinity is insufficient or wash-water discharge is restricted
 Operate in ‘open loop’ mode without consuming sodium hydroxide.
 Limited use of sodium hydroxide by reducing handling, storage and associated
costs.
 Reduction in fresh water consumption.
 More complex than ‘open loop’ or ‘closed loop’ SOX scrubbers.

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 15
 Wet SOx
SOx scrubbers
Scrubbers

Wet 'hybrid' SOx

scrubbers

"Exhaust Gas Cleaning", Aalborg Industries technical presentation, January, 2011

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 16
2020 Prospect

MGO
only

POSSIBILITIES:
1) Scrubbers
2) Dual-fuel engines
3) MGO

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 17
Dual-fuel marine engines

Separate backup
Liquid Fuel Mode
Operation liquid fuel system
Gas Fuel Mode

Multi fuel flexibility: Wärtsilä

 Distillate fuels or HFO (Liquid mode) 4T 50DF engine

 Natural Gas or LPG (Gas mode)

Marine applications:
 Redundancy
 Reliability
 Safety
 Emission regulations compliance
MAN Diesel & Turbo
2T ME– (L)GI engine
Switch-over procedure:
 Instantaneous
 Automatic
 No power and speed oscillations

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 18
Gas fuel mode

Low pressure  Natural gas (gaseous form)

admission  Homogeneous lean-burn air-gas mixture
4T & 2T engines  Independent ignition sources and methods
• pilot injected liquid fuel
• pre-combustion chamber
Gas mode  Premixed air/gas mixture combustion

 Diesel pilot injection

High pressure  Diesel auto-ignition
injection  Natural Gas (gaseous form) or LPG (liquid form)
4T & 2T engines injection after pilot injection
 Gas diffusion combustion

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 19
 Low pressure
Gas fuel mode admission

Homogeneous lean-burn principle 4T engines

Global air/fuel ratio: 2.2

Homogeneous air/gas mixture
Gas admission during inlet stroke
Low pressure gas delivery system (less than 16 bar)
Inlet stroke

2T engines

Narrow window for optimal operation:

 High efficiency
 Low NOx emissions
 Knock and misfiring prevention
Gas admission Ignition Source: Wärtsilä

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 20
 Low pressure
Gas fuel mode admission
Operation window depends on site conditions:
 Ambient temperature
 Methane Number (MN)
Methane Number:
 Representative of ignition quality
 Defined in terms of composition
of a prototype mixture:
• Pure methane - MN=100
• Pure hydrogen - MN=0

Higher alkanes (i.e. LPG) => Low MN values Expansion of knocking limit

 Mechanical stress
Operation outside  Reduction in thermal efficiency and power
optimal window  Methane slip: High unburned [HC] driven to atmosphere
 Knock
 Misfiring •Safety (fire inside exhaust gas receiver)
•Environment (Greenhouse effect)
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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 21
 Low pressure
Gas fuel mode admission
First low pressure 2-T large dual fuel marine engine  Low pressure gas admission
 Ignition by means of pilot injection

CO2 NOx SOx PM

Emissions:
-25% -85% -99% -98%
Source: Winterhur Gas & Diesel

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 22
 High pressure
Gas fuel mode injection
Operation principle
 A minimal metering of distillate fuel (MGO, MDO) or HFO is pilot injected (~5%)
 Auto-ignition
 Premixed combustion of pilot injected fuel
 Natural Gas (gaseous form) injection - 350 bar or LPG (liquid form) injection - 550 bar
 Gas diffusion combustion
• Short time window for combustion
• No sufficient time for mixing and chemical reactions No significant reduction
• Local air-fuel ratio close to stoichiometric at flame front of NOx emissions
• High local temperature levels

2T engine 4T engine

Combination with advanced technology:

 EGR
 State-of-the-art supercharging
 Exhaust gas after-treatment

Source: MAN Diesel & Turbo Source: Wärtsilä

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 23
 Current
Gas fuel mode
portfolio
Marine Engine Builders DF Portfolio

4T GD: Gas Diesel Engines – HP 4T DF: Dual-Fuel Engines – LP

Output range : 2.5 ~ 19 MW Output range : 6 ~ 18 MW
 Offshore constructions (FSO, FPSO)  Offshore supply vessels, coastal vessels,
as prime mover for alternators tugs and passenger ferries for propulsion
4T DF: Dual-Fuel Engines – LP  LNG tankers and offshore constructions
(FSO, FPSO) as prime mover for alternators
Output range : 1 ~ 18 MW
 LNG tankers, offshore supply vessels, coastal 2T ME-GI: Natural Gas Injection – HP
vessels, tugs and passenger ferries for propulsion 2T ME-LGI: LPG Injection – HP
 LNG tankers and offshore constructions Output range : 4.5 ~ 87 MW
(FSO, FPSO) as prime mover for alternators  LNG tankers, offshore supply vessels,
coastal vessels and tugs for propulsion
2T RT-flex & X DF: Dual-Fuel Engines – LP
Output range : 5 ~ 64 MW
 LNG tankers, oil tankers, container vessels,
bulk carriers, RoRo ships for propulsion Source: Winterhur Gas & Diesel

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 24
What about 2020?

Approach for a number of owners: run with MGO

- By choice (MGO price?)
- Due to not implementing changes

New fuels will be developed (by 2019) – Previous

experience with HDME 50, AFME 200 of ExxonMobil
Questions:
- Availability
- General uncertainty on landscape !!!

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 25
HFO - LFO Spray Visualization

Experimental test
configuration

Non-reactive (N2) spray evolution: 900 K / 90 bar (33.7 kg/m3)

HFO LFO

fuel preheating no preheating

Source: WinGD

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 26
Biodiesel (FAME)

 FAME (Fatty Acid Methyl Esters) Biodiesel from soybean oil

is the chemical name of Biodiesel.

 It is a product manufactured through the trans-esterification

of vegetable oils and animal fats with methanol which is blended
with diesel.

 FAME can be manufactured from waste cooking oils, animal fats,

and vegetable oils. Oils such as rapeseed, palm, and sunflower are
among the most common.

 When FAME is added to conventional diesel to make ‘BX’ blends, the ‘X’ stands for
the percentage of biodiesel added. For example; a B5 blend contains 5% biodiesel and
95% regular refinery diesel.

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 27
Biodiesel (FAME) Advantages
Advantages:
 Fuel system and engine combatibility
Many marine engine manufacturers have certified their engines for operation on biodiesel or a
blend of biodiesel and diesel fuel.
B20 represents a fuel of 80% diesel fuel and 20% biodiesel.

 Lower SOx emissions

Neat biodiesel contains almost no sulfur, so SOx exhaust emissions are practically zero. Blending
with regular diesel lowers the sulfur content proportionally.

 Safety
It has a higher flash point than diesel, is biodegradable, and degrades quickly in water. The flash
point of B100 is approximately 300°F (149°C), compared to 120–170°F (49–77°C) for petroleum
diesel.

 Availability
Biodiesel is commercially available at prices comparable to those of marine diesel fuel. For quality
control, it is produced to specifications set by the American Society for Testing and Materials
(ASTM) and the European Union (EU).

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 28
Biodiesel (FAME) Drawbacks
Drawbacks:
 Low temperature operation
Biodiesel has a high cloud point compared with petroleum diesel that can result in filter clogging
and poor fuel flow at low temperatures (i.e., 32°F (0°C) and lower).

 Fuel system and engine compatibility

In higher concentrations, can dissolve certain non-metallic materials, such as seals, rubber hoses,
and gaskets and metallic materials, such as copper and brass.
For an existing ship, the fuel system and engines may have to be modified.

 Cleaning effect
In higher concentrations, has a solvent/scrubbing action that cleans/removes deposits from the
fuel system, resulting in clogged fuel filters. The fuel system should be thoroughly cleaned,
removing all deposits and residual moisture before using biodiesel or there will be inordinate high
use of fuel filters.

 Long term storage stability

Biodiesel can degrade over time, forming contaminants of peroxides, acids, and other insolubles.

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School of Naval Architecture & Marine Engineering
Division of Marine Engineering 29
 Questions?

National Technical University of Athens

School of Naval Architecture & Marine Engineering
Division of Marine Engineering 30