Decarbonization of Maritime Transport

Maritime transport is the most important mode of transport. Ninety per cent of world trade is carried out by sea transportation. Although maritime transport is the cleanest type of transport considering the amount of carbon dioxide released per tonne transported, some measures must be taken to comply with the Paris Agreement on Climate Change. The International Maritime Organization, which sets the rules for international maritime transport, has conducted many studies to control and reduce emissions from ships. Studies on CO₂ have recently been accelerated, and the IMO Initial Greenhouse Gas (GHG) Strategy was announced in 2018. One of the objectives of this strategy is to reduce CO₂ emissions by 40% in 2030 and 70% in 2050 compared to 2008. The other aim is to reduce greenhouse gas emissions by 50% in 2050 compared to 2008. This strategy, announced by IMO, was the first study in which the maritime sector complied with the Paris Agreement on Climate Change. To achieve these goals, IMO has identified short-term, mid-term, and long-term candidate measures in this strategy and left it to the maritime transport stakeholders to use one or more of them on their ships. This book in the series is called “Decarbonization of Maritime Transport” and includes studies on decarbonization in shipping. The book consists of 10 sections apart from this section which is the introduction section. The book chapters are selected from studies on candidate measures announced in the IMO Initial GHG Strategy. The book includes studies on alternative fuels, carbon capture technology, green port studies, energy efficiency applications on ships, and market-based measures.

Maritime decarbonization is considered one of the most current and important issues in the maritime industry. The studies on the subject constitute a strong infrastructure for the rules and regulations that the International Maritime Organization should put forward as a top authority. Among these studies, papers and reports examining the subject from a life cycle perspective are of particular importance. Examining the environmental impacts of alternative fuels used on ships with a holistic approach from the cradle-to-grave perspective is very important to determine which method is “really” environmentally friendly. Life cycle assessment not only allows methods to be compared but also explains which process needs to be environmentally corrected among all the processes of the method. Within the scope of this study, first, basic information on the impacts of shipping to the climate change and life cycle assessment was presented, and then, alternative fuels (e.g., ammonia, hydrogen, liquefied natural gas, methanol, etc.) are examined from a life cycle perspective. Thus, it is aimed to evaluate the applications of life cycle assessment in the maritime sector holistically.

Climate change and global warming are among the most important problems that today's world is struggling with. Greenhouse gas emissions released into the atmosphere make these problems even more intractable. The leading organization of the maritime industry, the International Maritime Organization (IMO), is taking increasingly restrictive and stricter rules and regulations on the reduction of greenhouse gas emissions, as a significant amount of greenhouse gas emissions released into the atmosphere originate from commercial ships. Therefore, researchers focused on alternative marine fuels. Although there are many types of alternative marine fuels, biofuels are the most promising fuel for a smooth transition to zero-carbon alternative fuels. This is because biofuels can be burned in existing diesel-powered ships without any modifications or with minor modifications. Existing rules that seek to control emissions mainly monitor emissions from combustion of the fuel at the end user but are likely to take into account the entire lifecycle emissions of the fuel in the coming years. For this reason, in this paper, information about the stages and processes of lifecycle assessment is given. Then, the lifecycle emissions of fossil fuels, which are widely used today, and biofuels, which have an important position both in the decarbonization of maritime transportation and in the transition to zero-carbon alternative fuels, are examined. The aim of this study is to emphasize the importance of the lifecycle assessment model in the steps to be taken to reduce greenhouse gas emissions in order to overcome the problems on a global scale and then to compare fossil fuels and biofuels for the maritime industry within the scope of lifecycle emissions.

In the last few years, there is a noteworthy increase in the number of ships that use alternative fuels apart from diesel as LNG, methanol, etc., to meet the carbon emission mitigation strategies. Hydrogen (H₂) is a contemporary promising fuel solution to cope with strict carbon emission limits. The adaptation of conventional to alternative fuels with a familiar technology, the internal combustion engine (ICE) technology, is a reasonable solution for near future carbon strategies because of being a relatively prevailing technology compared to other hydrogen sourced power generators. This chapter analyzes the potential transition of the H₂ fuel engines according to the combustion capability of hydrogen in marine engines. The lack of knowledge of hydrogen combustion and ignition in the reciprocating engines is still a main challenge of the hydrogen engines. Hydrogen combustion properties and induction into ICEs are evaluated considering advantages and challenges. The applications show that LNG-powered engines significantly have similarities with hydrogen engines and enable the transition of H₂ combustion in the marine engines. On the other hand, hydrogen engines suffer from low volumetric efficiencies and pre-ignition problems but they are capable of operate from ultra-lean to ultra-rich combustions. Thanks to the turbochargers, the stoichiometry levels are obtainable for engines to satisfy the high-power. Adding the hydrogen into the cylinder with liquefied/gas phase is the issue to be determined with ease of vaporization and the mixing. The combustion comes with near-zero CO₂ and soot advantages. However, neat H₂ combustion in marine engines is still far from the final product.

This study aims to evaluate the use of LNG, methanol, and ammonia on ships as an alternative marine fuel. In this sense, firstly, the SWOT analysis is conducted, so the strengths and weak sides of the alternative fuels are determined. In the second step of the study, various criteria such as safety, cost, exhaust emission, global warming potential, sustainability, storage, and technical competence are specified, and the alternative fuels are analyzed with the TOPSIS method based on the identified criteria. As a result of the obtained judgments from the marine experts, the safety of fuel, its global warming potential, and its storage feature is determined as the most influential comparison weights. In addition, ammonia is determined as the best fuel option based on the 2.92 similarity value while values of LNG and methanol are calculated 2.21 and 2.18, respectively. Then, a sensitivity analysis where the various cases were created by improving the weights of criteria by 25% and applying the same weight value for each criterion is conducted to reveal the criticality of the criterion weighting. According to this analysis, it is observed that the analysis is highly sensitive to the global warming potential criteria. In line with this information, beneficial and significant key findings to policy-makers, stakeholders, and maritime companies are presented from the perspectives of short-term and long-term emission reduction strategies.

Zero-emission maritime transportation is the ultimate goal of the shipping industry. In this aim, new regulations lead to technical constraints which lead the naval industry toward efficient and environmentally friendly power and propulsion systems. Especially, minimizing the impacts of the ships operating in the coastal, harbor, or urban areas is a key feature considering environmental and human health concerns. Shortly, ferries or passenger ships operating in these areas will face reaching zero-emission constraints. Using electricity as a main vector of energy is one of the most promising ways to reach these goals. In particular, full electric or hybrid solution using multi-source energy systems appears to be a very relevant solution. This chapter is devoted to the study of the electrification and hybridization of ferries and passenger ships operating in coastal and urban areas. The first part of the chapter aims to review the fully electric and hybrid propulsion topologies and power management strategies that can be used for ferries and passenger ships operating in coastal or urban areas. Several relevant examples of vessels using this kind of technology are presented. Particular focus will be on full electric solutions based on batteries/fuel cells/supercapacitors as main energy sources and possible energy management strategies. In the second part of the chapter, a case study will be presented based on the specifications and mission profile of the Istanbul Ferries crosses the Bosporus straight. Several possible technical solutions are studied by giving mathematical models of the equipment respecting the state of the art in the first part.

Decarbonization strategies such as renewable energy, alternative fuels, and modifications on ships play an essential role in reducing global warming, but fossil fuel consumption is inevitable for meeting the sufficient energy demand. On the other hand, CO₂ is one of the reasons for global warming, which can be mitigated by using a carbon capture system. Up to 90% CO₂ reduction can be achieved by using a carbon capture unit on a ship. Carbon capture technologies are used in power plants, cement, and the steel industry. Also, after the introduction of stricter rules and the announcement of the decarbonization target by the International Maritime Organization, some studies are started to be made on using carbon capture in maritime transportation. This chapter reviews the carbon capture technologies such as absorption, adsorption, membrane, chemical looping, cryogenic and biological, also oxy-fuel combustion, pre-combustion, and post-combustion methods. In addition, means of storage, transportation, and utilization of captured CO₂ are explained. Finally, strengths, weaknesses, opportunities, and threat analyses are done to investigate the benefits and drawbacks of carbon capture systems on vessels. Although high energy demand, storage, and transportation of the captured CO₂ are the limiting factors of adopting a carbon capture system on a ship, its high CO₂ capture rate makes carbon capture technologies a promising option to meet the recent and upcoming regulations in maritime transportation.

Ports with logistics mobility have a critical role in the green transition and decarbonization targets of the sector. The decarbonization determination of maritime transport, supported by the COP 26 sectoral call and the 2050 targets, was expressed in a structure that also includes ports. In this context, ports need new strategic approaches to support port authorities in terms of energy and environmental sustainability. For this purpose, a new approach, which is defined as the “green concept framework,” was developed in this study, together with the sustainability principles of ports. The study was handled from two perspectives in terms of energy management and sustainability principles based on the green concept over the reference port area. A holistic energy efficiency potential for reference ports and 13 criteria for the green concept evaluation were examined. The analyses identified primarily energy use and waste management as the main problem areas for the port. In addition, the areas that need to be improved were defined by the port authorities based on ISO 50001 principles. In the analysis made, suggestions were developed to support energy and environmental sustainability in ports depending on the emission savings potential of 8,21%.

Toward decarbonization of entire maritime transport chain, it is important to develop not only greener ships but also port and maritime logistics systems that work with alternative energy sources providing significant environmental and economic benefits. Ports are essential energy consumers and one of the key elements of the maritime transport chain. The green port concept, on the other hand, is an approach aiming to minimize fossil fuel consumption to reach more environmentally friendly and economically sustainable port operations. The aim of this chapter is to investigate different perspectives on how to make sustainability assessment in ports. The chapter defines a green port development model by evaluating new green technologies, low or zero-carbon alternative terminal equipment, and other energy-consuming components of ports. To achieve these aims, environmentally friendly green port applications in all forms are being reviewed on a global scale. In green port applications, issues such as energy conservation, air pollution, water pollution, hazardous substances management, and habitat are specially pointed out due to their direct relevancy with port operations. This chapter reveals the contribution of green port practices to energy efficiency, environmental protection, and sustainable industrial and regional development. The chapter also draws attention to the importance of environmental awareness in ports, especially located in or nearby urban areas.

Maritime transport, which makes up 90% of the world's transport, has improved its responsibilities in combating global climate change with its 2050 commitments within the scope of COP 26. In this context, ships are developing their studies on alternative solutions to reduce fossil fuel consumption. However, the institutional lack of energy management and sustainable energy efficiency for ships is an important problem. In this study, first of all, the energy management framework was developed, and the energy efficiency potential was evaluated by performing a gap analysis for a tanker ship. Basic indicators for the manageability of energy were defined and compared. While the energy efficiency potential was 10.17% in the study, the thermal performance average was found to be 36.48%. At the end of the study, the effect of energy management was evaluated, and suggestions were developed for sustainable energy management processes.

Market-based Measures (MBM) are deemed one of the feasible methods to achieve sustainable maritime transportation in the mid-term by International Maritime Organization (IMO). Recently, shelved discussions of MBMs reopened at the Marine Environment Protection Committee’s 76th meeting to possibly apply to shipping operators after European Commission decided on including shipping in Emission Trading Scheme (ETS). This chapter will go over the proposed candidate MBMs and address the possible drawbacks of each emission reduction scheme. Included are background information, a comparison of MBMs, an illustration of the impact of carbon pricing and fuel levies on shipping operators, and policy improvements. Assessment made on their effectiveness considering their harmony to the existing legal framework, availability of the implementation in terms of time windows, impact on various states in terms of development and geographical disadvantages, administrative burden, practical feasibility, and impact on the profitability. Outcomes interpreted over today’s conditions are listed. Within these possibilities, the best MBM scenarios have been tried to be drawn. As a result of the interpretation, medium-level levy and low-to-medium-level ETS were the most reasonable options based on the literature. Levy and ETS are the most important among MBMs. In addition to this, levy still has a significant advantage over ETS.