Yes, Under Three Years Is Realistic -- and Conservative

Maritime Wind Turbine Payback Period -- Is Under Three Years Realistic? -- H Nordic Maritime

The under-three-year payback figure for a four-turbine 100 kW installation is based on standard industry data: 6,500 operating hours per year, 0.295 kg/kWh diesel consumption, and USD 700 to 1,000 per tonne fuel cost. It is a conservative calculation -- it excludes aerodynamic drag reduction, uses the lower end of the fuel cost range, and applies a 10 to 30% wake reduction to multi-turbine output.

How the payback period is derived

The payback period is the time to recover the capital cost of the installation from annual fuel savings.

Annual saving: A four-turbine 100 kW configuration produces approximately 780,000 kWh per year at 6,500 operating hours with a 10 to 30% wake reduction applied. At 0.295 kg/kWh, that displaces approximately 230 tonnes of diesel. At USD 700/t the annual saving is USD 161,000; at USD 1,000/t it is USD 230,000.

Capital cost: Exact capital figures are provided during the vessel assessment -- they depend on vessel type, deck configuration, and installation complexity. The payback period is calculated against the assessed capital cost for that specific installation.

Payback: Annual saving divided by capital cost gives the payback period. At the savings figures above and typical installation costs for the reference four-unit configuration, the result is under three years across the prevailing fuel price range.

Why the figure is conservative

Three deliberate conservatisms are built into the calculation.

Drag reduction excluded. The Stena Jutlandica result -- 80 to 90 tonnes of annual fuel saving from 8 kW of installed turbines -- is explained primarily by aerodynamic drag reduction, not direct generation. H Nordic turbines in the 50 to 100 kW range produce substantially more direct generation and proportionally greater drag reduction. Excluding this contribution from the payback calculation is a deliberate understatement.

Lower end of fuel price range. The USD 700/t figure is the bottom of the current bunker fuel range. At USD 850/t -- the midpoint -- the annual saving for a four-turbine 100 kW installation is approximately USD 196,000. At USD 1,000/t it is USD 230,000. The payback period shortens at higher fuel prices.

Standard operating hours. 6,500 hours per year is approximately 74% annual utilisation. Vessels on continuous trading routes -- tankers, bulk carriers, deep-sea container services -- routinely exceed this. At 7,500 hours, savings are approximately 15% higher and payback proportionally shorter.

What operating beyond payback looks like

After payback, the turbines continue generating savings for the remainder of their operating life with no fuel cost and minimal maintenance requirements. H Nordic turbines are designed for a 20-year service life.

A four-turbine 100 kW installation that pays back in three years has 17 years of net savings ahead of it. At USD 850/t fuel cost and 6,500 operating hours, that represents approximately USD 3.3 million in cumulative direct generation savings over 17 years -- before accounting for drag reduction and any future fuel price increases.

For fleet operators evaluating a decision across an expected vessel life of 15 to 25 years, the economics are substantially more compelling than the headline payback figure alone suggests.

Variables that shorten payback

Higher fuel prices -- each USD 100/t increase adds approximately USD 23,000 per year to direct generation savings for a four-turbine 100 kW configuration
Higher operating hours -- vessels above the 6,500-hour baseline see proportional savings increases
EU or Nordic grant support -- qualifying maritime decarbonisation projects may receive grant funding covering a portion of capital costs. At a 30% grant rate, a three-year payback becomes approximately two years
Multiple vessels -- fleet installations allow capital cost efficiencies that reduce the per-vessel installation cost

Variables that lengthen payback

Low fuel prices -- the lower bound of USD 700/t produces the longest payback
Lower operating hours -- vessels with high port time and limited sea passage time generate less
Complex installation -- unusual deck configurations or electrical integration requirements can increase capital cost

Key takeaways

The under-three-year payback for a four-turbine 100 kW configuration is derived from standard industry data and is deliberately conservative
Drag reduction savings -- which can equal or exceed direct generation savings -- are excluded from the payback calculation
Vessels with higher operating hours, higher fuel costs, or access to grant funding will see shorter payback periods
After payback, 17 years of net savings remain at a 20-year design life -- the lifetime economics are substantially more compelling than the headline payback figure
Fleet installations and EU/Nordic grant support can improve project economics beyond the base calculation

References

IMO -- MARPOL Annex VI energy efficiency measures -- IMO fuel consumption and efficiency measurement framework
Ship & Bunker -- bunker fuel price index -- current and historical bunker fuel pricing data
EU Innovation Fund -- maritime sector -- EU grant funding for maritime decarbonisation
Nordic Environment Finance Corporation -- maritime -- Nordic financing for maritime sustainability projects
DNV -- return on investment for wind-assisted propulsion -- classification society ROI framework for vessel wind energy systems