Ship Shaft Generator ROI & Fuel Savings Calculator
Estimate shaft generator fuel savings, annual electrical energy,
auxiliary generator fuel avoided, incremental main-engine fuel,
maintenance savings, CO2 reduction, payback, NPV and IRR.
Advanced mode models PTO operating hours, generator capacity,
gearbox and converter losses, separate fuel prices, maintenance
effects and full retrofit CAPEX.
PTO Energy
Model the electrical load transferred from auxiliary gensets
to the main propulsion shaft
Fuel Economics
Compare auxiliary fuel avoided with the incremental main-engine
fuel needed to generate the same electricity
Investment Case
Calculate annual savings, payback, NPV, IRR,
break-even fuel price and required annual SG energy
Electrical Load & Operating Profile
Use average sea-going electrical demand and the share expected
to be supplied by the shaft generator.
kW
days
hours/day
%
%
kW
Fuel Efficiency Comparison
The model compares auxiliary generator fuel avoided with
incremental main-engine fuel through the PTO /
shaft-generator efficiency chain.
g/kWh
g/kWh
Use the incremental fuel rate for producing additional
shaft power at the expected operating point.
%
$
/MT
tCO2/MT
$
/tCO2
%
Maintenance & Project Cost
$
/MWh
$
/year
$
years
%
%/year
%/year
%/year
PTO Operating Profile
Advanced mode caps generator output at rated capacity and applies
PTO-eligible time and system availability to annual energy production.
kW
days
hours/day
%
Share of sea operating time where shaft speed,
propulsion load and electrical conditions permit PTO operation.
%
%
kW
kW
Used only to estimate equivalent auxiliary-generator
running hours displaced.
Efficiency & Fuel Consumption
%
%
%
g/kWh
g/kWh
Fuel Prices & Carbon Value
$
/MT
$
/MT
tCO2/MT
tCO2/MT
$
/tCO2
%
Maintenance Impact
$
/MWh
$
/MWh
$
/year
Retrofit CAPEX
$
$
$
$
$
$
$
%
days
$
/day
$
Lifecycle Assumptions
years
%
%/year
%/year
%/year
$
Shaft Generator ROI & Fuel Savings Results
Simple PTO investment screen
Enter operating data
Enter electrical load, operating days, fuel-consumption assumptions
and project cost to calculate shaft generator fuel savings and ROI.
Annual Net Benefit
N/A
Fuel-value savings plus maintenance and carbon value
after shaft-generator annual OPEX
Net Fuel Saved / Year
N/A
Auxiliary fuel avoided less incremental main-engine
fuel required for PTO power
Shaft-Generated Energy
N/A
Average SG Output
N/A
Average SG Load
N/A
Aux Fuel Avoided
N/A
Incremental Main-Engine Fuel
N/A
Fuel-Only Savings
N/A
CO2 Avoided
N/A
Net Fuel Reduction
N/A
Installed Project Cost
N/A
Simple Payback
N/A
Project NPV
N/A
Internal Rate of Return
N/A
Lifetime ROI
N/A
Break-Even Fuel Price
N/A
Break-Even Annual SG Energy
N/A
Aux Genset Equivalent Hours Displaced
N/A
Year 1 Savings Breakdown
Shaft Generator Investment Summary
Energy & Fuel Balance
Annual operating case
Metric
Result
Lifecycle Cash Flow
Fuel, carbon and maintenance escalation included
Year
Fuel Savings
Maintenance Net
Carbon Value
Net Cash
Discounted
Cumulative PV
Shaft Generator ROI Sensitivity
Annual SG utilization vs fuel price
SG Utilization \ Fuel Price
-20%
Base
+20%
Shaft generator estimate ready:
project guidance will appear after calculation.
Model approach:
shaft-generated electrical energy is based on average vessel
electrical demand, target load share, rated shaft-generator
output and usable operating hours. Auxiliary fuel avoided equals
electrical energy multiplied by auxiliary-generator SFOC.
Incremental main-engine fuel is calculated from the mechanical
shaft energy required after PTO, generator and converter losses.
Net fuel savings equal auxiliary fuel avoided minus incremental
main-engine fuel. Financial results add maintenance effects and
optional carbon value.
Planning estimate only.
Actual shaft-generator performance depends on propulsion-engine
loading, engine SFOC at the relevant operating point, propeller and
shaft speed, gearbox and PTO arrangement, generator loading,
converter losses, electrical demand, auxiliary-generator dispatch,
fuel types, maintenance strategy, vessel route and integration
constraints. A shaft generator does not create free power: PTO
electrical output increases mechanical load on the propulsion system.
Use OEM, class, shipyard and vessel-performance data for investment
decisions.
