Decoupling Power Generation from Consumer Demand
FIHS – Fully Integrated Hybrid System is a patented marine power-system architecture developed by Trygve Johannes Økland. In FIHS, the energy storage system (ESS) acts as the active interface between power production and consumption, allowing generating sets to operate at predetermined efficient load points regardless of the continuous variations in vessel demand.
Stop chasing optimal load. Operate at it.
The FIHS principle
In conventional diesel-electric operation, generating sets are required to follow vessel demand. FIHS changes that relationship. Generating sets can operate at predetermined efficient operating points while the ESS absorbs surplus generation or supplies the difference when vessel demand exceeds generator output.
Predetermined operating point
Active balancing interface
Continuously varying demand
This means the operating condition of the generating plant can be determined by the characteristics of the generator set rather than by instantaneous consumer demand.
Why the architecture matters
Generator efficiency
The generating set can be operated around a selected efficient operating point instead of continuously following a fluctuating electrical load.
Energy storage
The ESS is not only used for peak shaving. It actively balances the difference between power production and vessel consumption.
System design freedom
Separating generation from demand creates new possibilities for generator sizing, engine selection, operating philosophy and hybrid vessel architecture.
Marine applications
FIHS is intended for diesel-electric and hybrid vessels where electrical demand changes substantially with vessel operation. The architecture is particularly relevant where generator loading, running hours, emissions performance, redundancy and energy storage are important design considerations.
Potential applications include offshore and service vessels, dynamic-positioning vessels and other electrically propelled ships.
The architecture is supplier-neutral and can be considered with medium-speed or high-speed generating sets and with diesel, dual-fuel or gas engines. The optimum operating point should be established from the actual characteristics of the selected engine and generating set.
See the FIHS principle in operation
A short visual explanation of the FIHS operating principle and how the architecture separates generator operation from changing vessel demand.
Technical paper
Decoupling Power Generation from Consumer Demand: The FIHS Architecture for Marine Hybrid Power Systems
Trygve Johannes Økland, 2026.
The paper describes the engineering background and development of FIHS, including propulsion efficiency investigations, hybrid power-system studies, generator operating efficiency, energy storage, dynamic positioning, redundancy, emissions and maintenance.
Patent and intellectual property
FIHS – Fully Integrated Hybrid System is the marine power-system architecture developed by Trygve Johannes Økland and protected by U.S. Patent No. 11,964,747, Fully integrated hybrid power generation system for a vessel.
Publication of technical information on this website or in the technical paper does not grant a licence or authorization under FIHS patents, patent applications or related intellectual property. Commercial implementation may require a separate licence from the patent owner.
Discuss a vessel or project
If you are evaluating FIHS for a vessel, newbuild, power-system study or technical collaboration, send a short project enquiry below. The information is stored privately for FIHS project follow-up.
Trygve Johannes Økland
Inventor & Patent Owner | FIHS
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