Hotel load is the largest controllable energy consumer on most commercial vessels. Getting the relationship between generation and hotel load right is the most important sizing decision in a maritime installation.
Hotel load -- the electrical demand from accommodation, galley, HVAC, lighting, navigation equipment, and auxiliary systems -- represents a substantial fraction of a commercial vessel's total fuel consumption. On a large bulk carrier or container vessel underway, hotel load may account for 15--25% of total fuel use. At anchor or in port, where propulsion is idle, it is the primary energy demand.
A wind turbine sized against the hotel load at anchor or in port can displace the majority of that load's fuel cost. Sizing it correctly requires understanding the load profile, not just the headline kVA figure.
The common mistake in maritime energy planning is treating hotel load as a fixed number -- the connected load or the nameplate rating of the electrical system. In practice, hotel load varies significantly between day and night, between sea passage and port, and between summer and winter in northern latitudes (where HVAC heating loads change the consumption profile substantially).
A 100 kW installation sized against a 200 kW peak hotel load will, in practice, displace a much higher proportion of total consumption than the 50% headline figure suggests -- because the peak load occurs for a relatively small fraction of the total operating hours. Against the median or average load, the turbine's contribution is proportionally larger.
The correct input to the sizing model is a load duration curve -- the distribution of hourly hotel load across a representative period -- rather than peak or average alone.
Battery storage is included as standard with every HNordic maritime installation. Its role in the hotel load context is to buffer the mismatch between generation and consumption.
When wind generation exceeds the instantaneous hotel load -- which happens frequently at sea on a beam heading -- the surplus charges the battery. When generation falls below the hotel load -- a calm period, a downwind heading, or a high-demand period in port -- the battery supplies the shortfall. The generator (or shore power connection) bridges any remaining gap.
Without storage, the turbine output that exceeds instantaneous demand is wasted. With storage, that surplus is captured and used, which materially improves the effective utilisation of the turbine's annual generation.
Anchor and port operation is the highest-value use case for maritime wind generation. Propulsion is idle, the vessel's fuel consumption is dominated by the hotel and auxiliary load, and the turbine can in many cases cover the majority of that demand -- particularly on vessels that anchor in exposed roadsteads with consistent wind.
For vessels that spend a significant proportion of their operational hours at anchor -- offshore standby vessels, vessels waiting for berth, vessels on seasonal lay-up -- the anchor and port generation figures are a major driver of the financial case. The site assessment process includes a trading pattern analysis to weight generation against the vessel's actual operating profile.
The sizing conversation starts with three inputs: the vessel's hotel load profile (ideally as logged data), the expected trading routes and the wind climate on those routes, and the proportion of time spent at sea versus at anchor and in port. HNordic's maritime site assessment maps these inputs to a specific turbine and storage configuration.
A single 50 kW installation is appropriate for smaller vessels or vessels where the hotel load is modest. Two turbines -- or a 100 kW single installation -- are appropriate for larger vessels or vessels with higher self-consumption potential. The battery storage included as standard with each configuration is sized to complement the turbine output; larger storage can be specified for sites with high overnight or anchor-period consumption.
See also: Fuel savings overview · ROI for maritime wind · Full FAQ