“Innovative propulsion, energy efficiency, and sustainable fuels are key to the maritime sector”

The update of the Strategic Research and Innovation Agenda (SRIA) for Zero-Emission Waterborne Transport (ZEWT), published last year, aims to accelerate the transition of this sector in Europe by 2050. This is not just about reducing CO₂ emissions, but also about limiting nitrogen oxides, sulphur oxides, and fine particles, while eliminating polluting discharges into the sea. The environmental impact of port infrastructures must also be considered, as well as the need to prevent negative indirect effects on biodiversity and natural resources. Audrey Kelle, a key figure in the maritime field within the Transport knowledge area at Zabala Innovation, highlights the importance of the three technical pillars of the SRIA: “Innovation in propulsion technologies, energy optimisation of ships, and the integration of sustainable alternative fuels.”

What are the foundations of these pillars?

They were chosen because they address the immediate needs of the maritime transport sector, while also preparing it for long-term transformation. They are also in line with the principle of retrofitting, which involves modernising existing ships rather than building new ones, maximising cost-effectiveness for the sector.

What propulsion technologies could transform the maritime sector?

One of the main options is sail-assisted propulsion, which is based on the integration of automated rigid sails or kites [giant sails], which can reduce fuel consumption by between 20% and 30%, depending on the route. An example of this is Winnew, an OceanWings project that Zabala Innovation had the honour of supporting to success. Partial electrification, using high-capacity batteries or supercapacitors, is also growing, especially for ferries and ships that travel short distances.

And what innovations could increase the energy efficiency of ships?

Currently, solar sails, air lubrication systems, optimised hulls, and the use of digital twins for real-time energy performance management are some of the key innovations that help reduce fuel consumption and emissions. One example of this is Marpower, a project in which Zabala Innovation is a partner. The project is developing a flexible gas turbine that enables the use of alternative fuels (methane, hydrogen, or ammonia), achieving an electrical efficiency of between 50% and 55% and a thermoelectric efficiency of 76%.

What obstacles hinder the integration of alternative fuels into traditional propulsion systems?

The main challenges include the compatibility of existing engines with these fuels, their safe storage on board, the high cost of refuelling infrastructure, and the limited availability of sustainable supply chains (especially at large scale).

Which alternative fuels are the most promising for reducing emissions in the maritime sector?

Green ammonia, for example, does not produce CO₂ during combustion, but its use requires adapted engines or high-temperature fuel cells. However, it poses challenges related to its toxicity and cryogenic storage. Green methanol is another interesting alternative: easier to handle than ammonia, it can be used in dual-fuel engines and burns more cleanly, thereby limiting nitrogen oxides and fine particle emissions. Some shipping companies have already invested in ships that operate with this fuel. Liquid hydrogen also represents a promising option, especially for ships equipped with hydrogen fuel cells, but it requires cryogenic storage at -253 °C, which poses limitations in terms of infrastructure and space on board.

What about carbon capture and storage?

There are now onboard systems capable of capturing CO₂ directly from engines. This can be stored as liquid on board before being transferred to underwater storage facilities or used in industrial applications.

What are the specific characteristics and challenges of the maritime sector regarding decarbonisation?

The constraints are not the same as in other sectors. The maritime transport sector must deal with the long duration of some routes and therefore the need for high autonomy with adapted port infrastructures, in addition to the need for significant investments to renew fleets and modernise existing ships, without necessarily building new ones to optimise costs.

How can the maritime sector overcome the obstacles related to ship electrification?

Electrification can be accelerated, among other things, through the development of high-capacity batteries for short routes, hybridisation with other technologies for long routes, and the installation of fast-charging infrastructures in ports. Advances in energy storage and electrification of ferries and coastal ships are promising. But there is a standardisation and certification issue with batteries for the maritime transport sector, which could take time.

What role can ports play in the transition to greener, lower CO₂ emitting shipping?

Ports are an integral part of the challenges to decarbonise the maritime transport sector, with electrification of quays, the development of alternative fuel refuelling hubs, optimisation of logistics operations, and the integration of renewable energies to power port infrastructures.

How can digitalisation accelerate the decarbonisation of the maritime sector?

It plays a key role, especially in optimising the energy efficiency of ships and reducing their emissions. Thanks to technological advancements, it is now possible to fine-tune routes in real time, considering weather conditions and ocean currents. Digital twins and artificial intelligence enable navigation to be optimised, which translates into lower fuel consumption and therefore fewer CO₂ emissions.

How does energy management on ships benefit from technological advancements?

It has made significant progress with the integration of IoT sensors and smart management systems capable of automatically adjusting consumption based on real needs. This approach is complemented by predictive maintenance, which continuously monitors the performance of engines and equipment to anticipate potential failures. In this way, by optimising maintenance, unnecessary overconsumption is avoided, and the lifespan of facilities is extended.

What impact digitalisation has on ports?

In ports, digital platforms facilitate the coordination of calls. By synchronising ship arrivals and departures with port infrastructures, waiting time at the quay is reduced, and therefore the use of auxiliary engines, further decreasing emissions. Finally, the rise of automation and advanced control systems is transforming the management of maritime operations: with integrated AI and edge computing, some decisions, such as adjusting propulsion or sails for hybrid ships, can be made in real time without human intervention, further optimising energy efficiency.

What European programmes support the decarbonisation of the maritime sector?

The Horizon Europe programme includes calls for the development of new propulsion and energy efficiency technologies, especially under Cluster 5 (Climate, Energy, Mobility). The topics of the Zero Emission Waterborne Transport partnership are also included in the calls of this cluster, with closing dates expected in September 2025.

Are there other European initiatives in this regard?

Since last year, the Net Zero Technologies call under the Innovation Fund programme has also included the maritime transport sector. Among the projects funded in the 2023 edition, five large-scale initiatives supported by Zabala Innovation have been selected, which has resulted in a success rate twice the average. The 2024 call for projects is underway, with the deadline set for April 24. It is too late to participate given the time required to prepare the application, but it is an initiative renewed each year. There is also the Connecting Europe Facility (CEF) Transport programme, which supports both the modernisation of port infrastructures in the traditional call, whose closing is expected in January 2026, as well as the deployment of green infrastructures for the maritime sector (shore-side energy supply, ammonia and methanol bunkering, hydrogen refuelling stations) in its AFIF priority. The last two closing dates for this programme will be June 11, 2025, and March 4, 2026.