## 1 Introduction
Environmental concerns about CO\({}_{2}\) emissions to the atmosphere from energy-intensive industries have promoted the study and implementation of oxy-fuel combustion in sectors such as oil refining [13], IGCC systems [14], and cement production [15]. In addition to CO\({}_{2}\) sequestration, oxy-fuel combustion is used, due to its high combustion temperature, for processes like High-Velocity Oxy-Fuel (HVOF) coating [16] and Basic Oxygen Furnace (BOF) for steel production [17]. The oxygen supply is the biggest challenge for oxy-fuel combustion in engines since it is not readily available in the environment and must, therefore, be obtained in another way. Offboard acquisition is a challenging option, as it entails additional storage and transport costs, and mainly because of the weight and space limitation in vehicles, which reduces the autonomy essential for means of transport such as airplanes and ships. On the other hand, in situ O\({}_{2}\) production techniques are foreseen to be a promising solution in the near future. Under this category, the production of O\({}_{2}\) via a cryogenic air separation unit (C-ASU) is the most developed technology, as it provides large quantities of high-purity oxygen. However, extensive capital investments and energy demand [18] make its implementation difficult in oxy-combustion processes [19]. As an alternative, the Oxygen Transport Membranes (OTMs), also known as Mixed Ionic-Electronic Conducting membranes (MIEC), present an energetic and economic advantage compared to C-ASU [20]. MIEC membranes rely on O\({}_{2}\) diffusion through the crystal lattice of the membrane material [21] caused by the O\({}_{2}\) partial pressure difference between the feed and permeate sides of the membrane (see Figure 1) [22]; for this reason, the selectivity of the membranes is superior to other technologies and it is possible to obtain high-purity oxygen [23]. The driving force that moves O\({}_{2}\) through the membrane can be achieved in two different ways: the 3-end design that generates a vacuum in the permeate side, and the 4-end design that reduces the partial pressure of O\({}_{2}\) on the permeate side with a sweep stream of recirculated flue gas. Although the second option increases the energy efficiency of the process, the membrane is exposed to species such as CO\({}_{2}\), SO\({}_{2}\), H\({}_{2}\)O than can deteriorate it. Regarding the membrane material, perovskites are the most commonly used for membrane manufacturing because they provide high oxygen flux; however, they are prone to poisoning when they come in contact with CO\({}_{2}\) and SO\({}_{2}\)[20]. BSCF is one of the perovskite materials which presents higher O\({}_{2}\) permeability [24], and it is important to consider that below 850 \({}^{\circ}\)C, the perovskite does not present the same permeation capability [20]. The study of oxy-fuel combustion technology in ship engines is still very new. The only research project in progress is RIVER, led by the education group YNCREA Hauts de France and co-financed by the European Union within the Interreg North-West Europe program. The objective is the reduction of NOx and CO\({}_{2}\) emissions from inland waterway vessels applying oxy-fuel combustion and CCS technology for diesel engines [25]. In this project, the oxygen is made available in cylinders that contain high-pressure oxygen and are located in a safety lifting cage in the narrowboat. This system has the capacity to supply O\({}_{2}\) for about one hour depending on the load and speed of the vessel, so refilling of the cylinders must be carried out by a mobile crane located on the dock [26]. The ultimate goal of the RIVER project is the installation and integration of the oxy-fuel combustion system with CO\({}_{2}\) capture and storage on a narrowboat operating on UK inland waterways in real conditions [27].