Abstract
Looking at shipping sector 2050 targets, different low-carbon solutions must be tackled to reduce vessels emissions. In order to pave the ground to zero-emission solutions (e.g., H2 and fuel cells - FCs), some transition solutions must be identified. Natural gas (NG - also stored on board as Liquified, LNG) is gaining more and more interest. It is therefore important to target energy systems efficiency maximization and emissions minimization. To this end, the Internal Combustion Engines (ICEs), powered by NG, and FCs, like Solid Oxide Fuel Cells (SOFC), already largely investigated for terrestrial application, could be suitably integrated. SOFFHICE aims to investigate the retrofit of a short-distance ferry (operating in lakes or among Italian minor islands) with a high efficiency NG driven SOFC+ICE energy system for propulsion and hoteling. Integration goal will be dual: i) to operate ICE+SOFC jointly in open-sea navigation, maximising ICE efficiency and reducing emissions/fuel consumptions; ii) to operate SOFC mostly in port/coastal areas, reducing pollutants emissions (e.g., NOx, SOx, PM). SOFFHICE has 3 main objectives: 1) carry out a pre-feasibility study for a NG fuelled SOFC+ICE ferry; 2) model and study the interaction of the two technologies (from a thermodynamic/control point of view); 3) develop replication/scale up guidelines for optimal sizing of the two energy systems in order to ensure their proper behaviour also targeting different type/size of vessels (thus having different volume/space capabilities - lake/sea vessels). To achieve these main objectives the project has 6 technical goals: 1. Assess energy demand of a reference vessel for SOFFHICE integration (UNIGE) 2. Optimize SOFC-ICE size according to the typical vessel journey profile in order to minimize emissions (and check if proposed sizes are technically viable and feasible on board according to available volumes/weight) (POLITO-UNIGE-UNIBO) via the following approach: i) hotelling/manoeuvring full driven by SOFC; ii) propulsion via a high-efficient SOFC+ICE system; 3. Develop a dynamic model and control strategies for SOFC+ICE system (UNIGE); 4. Understand capability and limitations/constraints as well as performances and emissions profile of ICE operating with SOFC off-gases (UNIBO); 5. Evaluate SOFC+ICE integration from an environmental (POLITO) and techno-economic (UNIGE-POLITO) point of view, also foreseeing the use of alternative gases (e.g., H2, NH3, biogas) (POLITO-UNIBO); 6. Create a set of correlations/maps for SOFC-ICE optimal coupling for future applications (POLITO-UNIGE-UNIBO). POLITO, UNIGE, UNIBO joined forces gathering their know-how about advanced energy systems and FCs for terrestrial (POLITO) and maritime (UNIGE) applications and ICEs (UNIBO). The project will exploit synergies with relevant EU as well as the support of relevant Maritime/SOFC/ICE Italian stakeholders' engagement. RESULT ACHIVED Within the SOFFHICE project, the University of Bologna (UNIBO) contributed to several activities across different work packages, primarily focusing on the design, dynamic simulation, and optimization of an internal combustion engine (ICE) to be integrated with a Solid Oxide Fuel Cell (SOFC) in the overall system layout. WP 1 – A comprehensive literature review was carried out to identify the state-of-the-art propulsion systems for marine applications. The study specifically targeted engine technologies compatible with sustainable fuels, aiming to replace conventional diesel engines widely used in maritime transportation. Analysis of manufacturers’ catalogues revealed that the most promising solutions are spark-ignition engines equipped with pre-chamber combustion systems, typically fuelled with natural gas and operated under lean-burn conditions. This configuration cuts out soot emissions while it enables reduced NOx emissions at promising efficiency values. WP 2 and WP 3 – both steady state and dynamic models have been developed in parallel. A zero-dimensional (0D) thermodynamic model of a gas-fuelled internal combustion engine was developed. The model solves mass and energy conservation equations for the intake and exhaust manifolds, the pre-chamber, and the main combustion chamber (cylinder). Additionally, a predictive combustion sub-model was implemented to estimate heat release rates and combustion phasing. The model was subsequently validated against experimental datasets, demonstrating good agreement in terms of in-cylinder pressure evolution and overall engine performance metrics. Together with the engine model development, a preliminary kinetic analysis of the fuel mixture adopted within the SOFFHICE framework was performed. The activity focused on evaluating the impact of Anode Off-Gases (AOG), mainly composed of hydrogen (H₂), carbon monoxide (CO), and carbon dioxide (CO₂), on the laminar flame speed of methane-air mixtures. This parameter is critical for combustion stability and engine performance under lean conditions. The analysis was conducted using the open-source software Cantera, simulating laminar flame speeds under engine-relevant thermodynamic conditions (pressure, temperature, and equivalence ratio). WP 4 – a dedicated algorithm for the design and sizing of a pre-chamber engine was developed, targeting the retrofit of the existing diesel engine installed on the vessel Anna Mur. Different system layouts for the integration of the ICE with the SOFC were then investigated. This phase was supported by Computational Fluid Dynamics (CFD) simulations of the engine, aimed at identifying the optimal fuel injection strategy. Results indicated that AOG should be injected into the intake manifold together with methane to ensure proper mixing, while an additional methane injector is required within the pre-chamber to guarantee reliable ignition and stable combustion. Engine performance maps were generated to characterize the behavior of the ICE across an operation range consistent with the Anna Mur mission profile. These maps include key parameters such as brake efficiency, power output, and fuel consumption, aimed at embedding into a dynamic model of the overall powertrain developed by UNIGE and UNITO. Finally, the focus has been moved on engine optimization. The optimization process primarily addressed the fuel injection strategy, with the objective of minimizing fuel consumption while ensuring the required power output for the vessel under real operating conditions. A comparative analysis was also conducted to quantify the benefits of the integrated SOFC+ICE powertrain. Results demonstrated a significant increase in system efficiency and a reduction in fuel consumption when utilizing AOG within the engine, compared to conventional operation with a methane-only ICE.
Dettagli del progetto
Responsabile scientifico: Stefania Falfari
Strutture Unibo coinvolte:
Dipartimento di Ingegneria Industriale
Coordinatore:
Politecnico di TORINO(Italy)
Contributo totale Unibo: Euro (EUR) 75.216,00
Durata del progetto in mesi: 24
Data di inizio
30/11/2023
Data di fine:
28/02/2026
