In the marine industry, energy efficiency has become a very important issue. This practice, which involves saving energy without sacrificing service levels, has become even more relevant due to the stringent requirements set by the International Maritime Organization (IMO) and the European Union (EU) to reduce greenhouse gas (GHG) emissions.
There are several ways to achieve more efficient energy consumption on board, but undoubtedly one of the most significant is to reduce the power used, both for navigation and for self-consumption of electricity. This can be achieved through a variety of approaches, such as improving drag, reducing sailing speed, optimizing routes and taking advantage of favorable conditions during the voyage. It should be noted that some methods have a greater impact than others in achieving this goal.
These power reductions not only lead to lower fuel consumption, but also result in lower GHG emissions. Thus, improving on-board energy efficiency contributes significantly to the reduction of gases such as carbon dioxide (CO2) and nitrogen oxides (NOx), although it still does not reach the total percentage required by the EU. Therefore, it is essential to implement both pre- and post-combustion actions, such as carbon capture and storage (CCS) and selective catalytic reduction (SCR) systems.
The SCR catalyst is an exhaust gas post-processing system that reduces pollutants by partially converting them into environmentally friendly compounds. This technology has been consolidated in the marine sector and has proven to be highly effective in reducing NOx emissions, thus complying with the strict requirements established by the IMO.
Carbon Capture Systems: An opportunity for emissions reduction
As for CCS, they are technologies designed to capture carbon dioxide (CO2). In the marine field, research and tests are being carried out to adapt and optimize different carbon capture technologies, such as pre-combustion capture and post-combustion capture. These technologies are in constant development and evolution.
In pre-combustion capture, the process consists of separating the CO2 from the natural gas prior to combustion. Using this method, the natural gas is broken down into hydrogen and CO2, with the hydrogen being used as fuel and the CO2 being captured and safely stored. This technology is currently under development in the marine sector, although it may require large amounts of energy and other resources, which could reduce its efficiency.
For carbon dioxide post-combustion capture, there are three main technologies: absorption, membrane and cryogenic separation. In the marine sector, the most developed technologies are based on CO2 absorption and cryogenic separation. After passing through an exhaust gas cleaning system, which removes SOx and reduces its temperature, the gases undergo a chemical process in which they are mixed with a solvent that absorbs part of the CO2 present in them. The purified gases are cooled and released into the atmosphere.
On board, there are two options: either store the solvent with CO2 and manage it for sale as a solution in the CO2 market, or subject it to heat input to separate the solvent from the CO2. In this process, the solvent is recirculated to capture CO2 again, while the separated CO2 in gaseous form is cooled and treated in a liquefaction unit for storage in pressurized C-type tanks. The CO2 market is experiencing significant growth due to industries such as biofuels, cement and fertilizers, which require CO2 for their processes.
Energy optimization on board ships not only leads to considerable energy savings, but also plays a key role in protecting the environment and combating climate change. Thanks to innovations such as SCR catalysts and carbon capture systems, the maritime sector is in a privileged position to sail towards a cleaner and more sustainable future.
In Sener’s marine area, we believe that combining improved energy efficiency of ships with carbon capture systems helps to significantly reduce GHG emissions in the marine sector. All our projects are designed on this sustainable basis, as the environmental benefits they bring help to meet IMO and EU regulatory requirements related to energy efficiency improvement and emissions reduction.
María Ángeles López Castejón
Naval Architect and Oceanic Engineer from the UPM (Polytechnic University of Madrid) and certified professional Co-Active Coach. 25 years of experience as a Naval Architect in shipyards, technical offices and consultancies. She is currently a Project Manager specialized in Liquefied Natural Gas LNG, Biofuels and Hydrogen Installations, elaborating market studies, sustainability analysis, digitalization and energy efficiency of the fleet. She has participated in more than 50marine projects for shipowners around the world, of all types of cruise ships, ferries, bunkering vessels, asphalters, icebreakers, tankers, chemical tankers, tugboats, etc.