Alternative propulsion technology

The shipping industry is facing a transformation of propulsion technology and energy systems. The Emission Control Areas, which set emission limits for SOx, NOx and particulate matter, and the global limit of 0.5 percent sulfur in fuel for all ships over 100 GRT, require new propulsion systems and fuels. Within the next few years, the maritime industry expects the introduction of effective greenhouse gas (GHG) emission reduction measures, both from the IMO and the EU. Fraunhofer Waterborne develops technologies with which the emission limits can be achieved.

Catalysts or scrubbers can mitigate emissions from SOx, NOx and particulate matter. Fuels such as LNG need complex cryogenic systems and new bunkering infrastructure. Mitigating greenhouse gas emissions, however, requires carbon-neutral propulsion systems. Fraunhofer Waterborne is researching new energy chains for low carbon  synthetic fuels. This includes systems and materials for hydrogen applications in engines and fuel cells. Technologies for safety and reliability are also developed. Wind propulsion is also being considered, which has a high potential for mitigating greenhouse gas emissions. This benefit can be maximized if,  the operation of ships is rethought. The development of software for weather routing and speed optimization is also a research focus. The market potential and transition paths for sustainable shipping are developed and analysed.

Wind propulsion

© HSEL/Martin Bönsch
Installation of the eco-Flettner on the Fehn Pollux

The focus is on the development of wind technology and hybrid propulsion systems. All aspects of ship-waterway-sea-environment interaction are included. The spectrum of scientific services ranges from the provision of interdisciplinary large-scale laboratories, the construction of prototypes on a laboratory and operational scale, to performance predictions and validation, as well as testing and inspection. Areas of expertise are maritime hydro- and aerodynamics, automation and systems engineering, materials technology and hybrid model concepts from the intersection of powerful modeling and simulation with measurement technology. A special expertise lies in the use of so-called crossover and upscaling effects between sail technology and classical wind energy systems.

The use of fiber-reinforced plastics can open up lightweight construction potential. However, if these materials are used for safety-critical components, shorter maintenance intervals have to be foreseen, as is the case, for example, with components of conventional steel construction. This leads to significantly higher costs and inhibits the acceptance of fiber-reinforced plastics in shipbuilding. For this reason, Fraunhofer is working on monitoring procedures that will allow information to be obtained about the loads that have occurred and the reliability of these components, thus making it possible to extend maintenance intervals to the usual periods. 

Project examples:

AHOY scenarios for wind propulsion in maritime shipping (Fraunhofer ISI)

Köhler, J., Ewa Dönitz, Frank Schätter, (2022) Transitions for ship propulsion to 2050: The AHOY combined qualitative and quantitative scenarios, Marine Policy, Volume 140, 2022, 105049,

Köhler, J., Dönitz E. and Schätter, F. (2021) Transition Wind Technologies in Shipping to 2050: Factors and Challenges for a Sustainability Transition, In: RINA International Conference on Wind Propulsion, pp. 1-6, London, UK. ISBN No: 982-1-911649-19-9

InnoSegler - Design of a CO²-free passenger and research vessel with an efficient sail propulsion system (Fraunhofer IWES)

Synthetic fuels

© DNV -Energy Transition Outlook 2021
Forecasted shipping fuel mix

The reduction of greenhouse gases in shipping is essential for global environmental protection, as it is responsible for almost 3% of annual CO2 emissions. The IMO has therefore stipulated that CO2 emissions must be reduced by 70% by 2050. This target can only be achieved by means of alternative fuels. A central research strand here is the production of synthetic fuels, so-called e-fuels, from renewable electricity. These fuels have lower emissions than conventional fuels and can be easily stored. A fundamental component in the production of synthetic fuels is green hydrogen produced in electrolysers, which is the starting point for the generation of power-to-liquid fuels such as methanol or ammonia. With appropriate engine technology, these can replace fossil fuels in the long term. In the medium term, they can also be blended with conventional fuels to significantly reduce the emissions of the overall system.

In the medium to long term, however, new carbon-free fuels could also be used.  For example, elemental silicon, the second most abundant element in the earth's crust, burns with air or water to form harmless silicon dioxide, the basic component of rock. Combustion with water also produces large quantities of hydrogen. Thus silicon, like hydrogen and carbon, fulfills the requirement for fuels not to be directly recycled. Silicon has twice the volumetric energy density of heavy oil and is suitable as a fuel for ocean-going vessels. In one study, it was shown that when burned with water, the heat generated can be used for ship propulsion and the hydrogen produced at the same time is sufficient to meet the electrical energy needs of a large passenger ship generated in fuel cells.

Project examples:

Hydrogen Application Center as part of the Hydrogen Research Factory MV (Fraunhofer IGP)

SiShip: Regeneratively produced silicon as a carbon-free volumetric energy carrier for overseas ships with high energy density (Fraunhofer ICT)


© AA+W -

Hydrogen from renewables offers the opportunity to develop climate-neutral marine propulsion systems and produce climate-neutral fuels for shipping. Our expertise is in production, logistics, propulsion, and safety, reliability, and durability. Technologies for off-shore hydrogen electrolysis, fuel cells as converters, hydrogen storage and distribution are developed. Fraunhofer is active in the field of optimization of manufacturing hydrogen plants and their components to reduce costs and increase efficiency. Another field is the development of test procedures, in the form of methods and measuring devices, for operational stability and the safety of plants and processes. Market scenarios are developed in collaboration with stakeholders to identify the use of hydrogen in shipping and inland waterways and to simulate transition paths for sustainable shipping.

Project examples:


Köhler J. (2020) Zero carbon propulsion in shipping - scenarios for the development of hydrogen and wind technologies with the MATISSE-SHIP model, International Shipbuilding Progress, vol. 67, no. 1, pp. 79-95, 2020 doi: 10.3233/ISP-190269

Gas, Low Flashpoint Liquid (LfL) fuels

© vladsv -

The Emission Control Areas and Annex VI of the MARPOL Convention, which sets global limits of a maximum sulfur content of 0.5 percent of fuel for all seagoing vessels over 100 GRT, has created an incentive to use existing LNG and dual-fuel engines for gas carriers as well as for other types of vessels.

Fraunhofer Waterborne conducted market analyses for the development of the LNG engines. This addressed the development of a global bunkering infrastructure, from delivery by truck LNG tankers as well as 'truck-to-tank' processes to LNG bunkering vessels and bunker barges. The application of LNG technologies as ECA-allowable and transition technology towards power-to-fuel offers an important potential transition path. Furthermore, market diffusion is simulated and measures that promote the diffusion of LNG are designed.

Project examples:

Scientific Advice to BMVI on Mobility and Fuel Strategy: Sub-study " Studie über die Marktreife von Erdgasmotoren in der Binnen- und Seeschifffahr" (Fraunhofer ISI)