What is Bunkering?
• Bunkering
– Filling ships and barges with fuel used to power ships
• Bunker
– Gets its name from the containers on ships and in ports
that it is stored in
– In the days of steam they were coal bunkers but now
they are bunker-fuel tanks
• Bunker fuel
– Technically any type of fuel oil used aboard ships
Fuel Bunkering Market
• Bunker Fuel Brokers
– Work as independent agents brokering fuel between two parties
• Shore Supplier (terminal)
– Might sell fuel to the barge company or directly to ship
• Barge/Bunkering Company
– Transfers fuel to the ship owners
– May or may not own oil
• Ship Owners
– Purchases fuel from barge owner or shore supplier
Tank Strapping / Gauging
Bunker Sources of Error
1 cm tape error = 0.25% error for a 4m level
Potential savings on 9000 tonne stem $7,500
Bunker Tank
Bunker Sources of Error – Temperature
Placement of temperature probe is
critical for optimum volume to mass
conversion
 Is the temperature measurement
representative of total bunker?
 Average calculation vs single point
 Savings can be significant
 2°C error on temp (avg) = 0.1%
error for a 991g/l product at 50°C
 Savings $$$

°C
°C
°C
°C
°C
°C
°C
Sources of Error - Density & Stratification
Errors of 0.25% to 1.5% possible
D
D
D
D
Tank
Stratification
Tank A
Tank B
Consider a Bunker with 5% Entrained
Air
Volume for Uncertainty
A volume measurement
will give a + 5% error
–
A direct mass measurement
will give a negligible error
$654/MTn x 3000tns = $1.96M/Bunker
•
–
Mass for Mass
(A 1% volume error due to air = ~$20,000)
Drive Gain can be used to indicate presence of entrained gas
Bunker Sources of Error –
Volume to Mass Conversion
Conversion formula:
Actual volume > net volume > weight(vac) > weight(air) =(?)% calc error
Volume-based Measurement
Manual
Direct Mass Measurement
Automated
Custody Transfer Processes
• Custody transfer is simply an agreement between two Parties:
Buyer and Seller
However, the Bunkering process is not so simple
Bunker Fuel Custody Transfer
Bunkering custody transfer needs are the same as other industries
• Make sure “I’m getting what I’m
paying for”
• Eliminate idle/downtime due to
refueling operation
• Reduce the number of billing
discrepancies and arbitration claims
Fuel
Storage
Terminal
Barge
• Repeatable, accurate measurement –
globally accepted
• Reasonable capital costs to support
operations
• Lifecycle cost considered for
operational efficiency
Operating Vessel
Bunker Fuel Custody Transfer Challenges
• Actual Operational Challenges
• During Validation
– Volume to mass conversions
– Temperature compensations
– Stacked uncertainties of reference
system
– Product quality concerns
Fuel
Storage
Terminal
Barge
– Inherent differences between tank
measurements
– Entrained gas (Air bubbles)
– Product holdup in barge pipelines
– Placement of meter for buyer’s confidence
– Potential for backflow through meter
Operating Vessel
Fuel Bunkering Custody Transfer
Refinery
Pump
Station
Container Vessel
Storage
Main Line
Barge
Fuel Bunkering Custody Transfer
Below the Deck of
Vessel
Barge
Hose
Fuel Tank
To Engines
On Barge Deck
Shipping
Vessel