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
Bunker Tank
1 cm tape error = 0.25% error for a 4m level
Potential savings on 9000 tonne stem $7,500
°C°C
Bunker Sources of Error – Temperature
°C °C °C °C °C
Placement of temperature probe is critical for optimum volume to mass conversion
Is the temperature measurement representative of total bunker?
Average calculation vs single pointSavings can be significant 2°C error on temp (avg) = 0.1%
error for a 991g/l product at 50°CSavings $$$
Tank A Tank B
D
Sources of Error - Density & Stratification Sources of Error - Density & Stratification Sources of Error - Density & Stratification Sources of Error - Density & Stratification
Tank Stratification
Errors of 0.25% to 1.5% possible
Consider a Bunker with 5% Entrained Air
Mass for MassA direct mass measurement will give a negligible error
Mass for MassA direct mass measurement will give a negligible error
Volume for UncertaintyA volume measurementwill give a + 5% error
Volume for UncertaintyA volume measurementwill give a + 5% error
– $654/MTn x 3000tns = $1.96M/Bunker• (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
Manual
Conversion formula:Actual volume > net volume > weight(vac) > weight(air) =(?)% calc error
Volume-based Measurement
Automated
BDN
Direct Mass Measurement
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
• 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
• Repeatable, accurate measurement – globally accepted
• Reasonable capital costs to support operations
• Lifecycle cost considered for operational efficiency
Operating VesselBargeFuel Storage Terminal
Bunkering custody transfer needs are the same as other industries
Bunker Fuel Custody Transfer Challenges
• During Validation– Volume to mass conversions– Temperature compensations– Stacked uncertainties of reference
system– Product quality concerns
• Actual Operational Challenges– 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 VesselBargeFuel Storage Terminal
Fuel Bunkering Custody Transfer
Main Line
Storage
Barge
Refinery
PumpStation
Container Vessel
Fuel Bunkering Custody Transfer
Fuel Tank To Engines
Barge
On Barge Deck
Below the Deck of Vessel
Shipping Vessel
Hose