PTO ENERGY • AUXILIARY FUEL DISPLACEMENT • MAIN-ENGINE PENALTY • CAPEX • NPV • IRR
Ship Shaft Generator ROI & Fuel Savings Calculator
Screen a shaft-generator retrofit by comparing auxiliary-generator fuel avoided with the incremental main-engine fuel needed to produce electrical power through the PTO efficiency chain. Advanced mode adds operating eligibility, capacity limits, separate fuel and CO2 factors, maintenance displacement, off-hire, lifecycle escalation and downside sensitivity.
↑Need gearbox, converter, separate fuel prices or PTO-eligibility detail? Click Advanced above.Simple uses one overall shaft-to-electric efficiency and fixed lifecycle assumptions for a fast owner-level investment screen.
EnergyAnnual PTO electricity
FuelAux fuel avoided vs ME fuel added
ReturnPayback, NPV & IRR
Electrical Load & PTO Use
Use realistic sea-going electrical demand and the share expected to be supplied by the shaft generator.
kW average sea-going vessel demand.
days/year.
% of sea hours usable after operating/availability limits.
Target % of vessel electrical load.
kW electrical rating.
Fuel Efficiency & Investment
g/kWh electrical.
g/kWh of added shaft power at the expected operating point.
PTO + generator + converter chain.
$/MT, applied to both avoided and incremental fuel in Simple.
$ total installed project cost.
Simple lifecycle assumptions: 24 operating hours/sea day, 10-year analysis, 8% discount rate, 2% annual fuel escalation, $12/MWh auxiliary maintenance avoided, $50,000/year shaft-generator service cost and 3.114 tCO2/MT fuel factor. Use Advanced to overwrite these assumptions.
↑Advanced separates operating eligibility, system availability and the mechanical-to-electrical efficiency chain.Use OEM engine maps, PTO limits, class/yard data and actual electrical load profiles where available.
PTO Operating Profile
Share of sea time where shaft speed, engine load and electrical conditions permit PTO.
Used to estimate equivalent genset running hours displaced.
Efficiency & Fuel Consumption
%/year screening allowance for performance/availability drift.
Fuel Prices, Carbon & Maintenance
$/MWh shaft-generated electricity.
$/MWh additional mechanical shaft energy.
Retrofit CAPEX
Lifecycle Assumptions
Integration Readiness
These checks do not change the ROI math. They identify assumptions that should be closed before investment approval.
Stress Cases
Multipliers are applied to the base case. PTO utilization changes annual usable hours; efficiency changes the overall shaft-to-electric chain.
| Case | Fuel price × | PTO utilization × | Efficiency × | CAPEX × |
|---|