Offshore energy hubs connect large amounts of offshore wind to a hub from where the generation can be transmitted to onshore, potentially linking to multiple surrounding countries. The benefits of such hubs, and the related meshed offshore grid to connect them, have been investigated in the North Sea. The system-wide impacts of offshore energy hubs in the Baltic Sea are less studied; however, the region is seeing increased interest in offshore wind development. This paper uses detailed offshore wind generation simulations and energy system optimisation to investigate the cost-effectiveness of offshore energy hubs in the Baltic Sea in different scenarios towards 2050. The results show that the largest deployment of offshore energy hubs occurs when the energy system is highly electrified. The strongest development of the offshore energy hubs occurs in the southern part of the Baltic Sea.
Nowadays, the coastal communities around the world face challenges related to increasing energy consumption, rising energy costs, enchaining of conventional or non-renewable energy resources, climate change, environmental problems, and so on. Therefore, many countries intend to implement different policies to develop clean energy production. There has been a new paradigm in policy from the utilization of greenhouse gases (GHGs), particularly CO2, toward sustainable energy resources to access a high level of security and reliability. This chapter discusses the new trends of hybrid marine power systems and analyzes various sustainable resources, such as PV, tidal turbines, and wind turbines. In addition, the applications of various battery systems to alleviate the randomness and unpredictable features of green energy resources have been studied. In this regard, the capability of various types of energy storage units, such as electrochemical, electromagnetic, and thermal, are presented. The restrictions and opportunities of combining the various technologies in the ship power systems have been investigated from both economic and environmental perspectives. Finally, the energy management problem of two case studies of sero-emissions ferry boats as a promising way to reduce GHGs is presented.
In the current transition of power industry from conventional sources to renewable energy sources, wind power generation is becoming one of the key sources of electrical energy. Although the development of wind power plants (WPPs) has made a significant contribution to addressing the demand for clean and cheap energy, the integration of large-scale WPPs introduces a series of technical challenges to power system operations. These challenges involved control, protection, and adherence to specified power quality standards. Particularly, power quality plays a vital role in utility systems and industries having direct technical and economic impact on both power consumers and suppliers. To tackle such issues, various grid codes have been initiated by regulation authorities. Moreover, different ancillary devices and control approaches have been adopted to comply with the established grid code. This article aims to review the state-of-the-art research and progress, while considering the main challenges related to dynamic performance and power quality enhancement of emerging grid-forming wind power plants. Various topologies of wind energy conversion systems (WECSs) are examined and compared, and their control strategies are investigated. A comprehensive review on power quality and dynamic response issues caused by large-scale wind power integration is presented. Moreover, the evolving grid code requirements for grid-connected WPPs in most leading countries including Denmark, U.K., Australia, Germany, and the USA are analyzed and compared. Furthermore, the improvement approaches proposed in the literature are investigated and classified on different basis and their pros and cons are discussed. A brief discussion on the solutions and future directions is presented. Finally, some conclusive considerations about the overall study are provided.
The paper presents a comprehensive review of the current status of integrated high temperature proton exchange membrane fuel cell (HT-PEMFC) and methanol steam reformer (MSR) systems. It highlights the advantages and limitations of the technology and outlines key areas for future improvement. A thorough discussion of novel reformer designs and optimizations aimed at improving the performance of the reformer, as well as different integrated MSR-HT-PEMFC system configurations are provided. The control strategies of the system operation and system diagnosis are also addressed, offering a complete picture of the integrated system design. The review revealed that several processes and components of the system should be improved to facilitate large-scale implementation of the MSR-HT-PEMFC systems. The lengthy system startup is one area that requires improvements. A structural design that is more compact without sacrificing performance is also required, which could possibly be achieved by recovering water from the fuel cell to fulfill MSR's water needs and consequently shrink the fuel tank. Reformer design should account for both heat transfer optimizations and reduced pressure drop to enhance the system's performance. Finally, research must concentrate on membrane materials for HT-PEMFC that can operate in the 200–300 °C temperature range and catalyst materials for more efficient MSR process at lower temperature should be investigated to improve the heat integration and overall system efficiency.
As maritime technology advances, multi-energy ship microgrids (MESMs) are widely used in large cruise tourism. In this context, studying cost-effective and highly reliable energy system planning methods for MESMs in their entire lifespan becomes paramount. Therefore, this paper proposes a joint planning method for a MESM during its lifetime. Firstly, a long timescale coordinated planning and operation scheme is formulated with the aim of maximizing the Net Present Value (NPV) value, thereby reducing both project investment and energy supply cost. In addition, this paper introduces novel operation models that incorporate customer thermal comfort levels, considering thermal inertia, and ship navigation, accounting for the effects of waves and wind. These models enhance the flexibility and practicality of the planning process. Finally, to ensure the safe operation of vessels and alleviate the negative effects of uncertain wind and waves during ship navigation, a robust optimization (RO) approach is employed. A case study demonstrates the effectiveness of the proposed method, with several comparison analyzes further highlighting its advantages.
In recent years, shipboard microgrids (MGs) have become more flexible, efficient, and reliable. The next generations of future shipboards are required to be equipped with more focuses on energy storage systems to provide all-electric shipboards. Therefore, the shipboards must be very reliable to ensure the operation of all parts of the system. A reliable shipboard MG should be pro-tected from system faults through protection selectivity to minimize the impact of faults and facili-tate detection and location of faulty zones with the highest accuracy and speed. It is necessary to have an across-the-board overview of the protection systems in DC shipboards. This paper provides a comprehensive review of the issues and challenges faced in the protection of shipboard MGs. Furthermore, given the different types of components utilized in shipboard MGs, the fault behavior analysis of these components is provided to highlight the requirements for their protection. The protection system of DC shipboards is divided into three sub-systems, namely, fault detection, lo-cation, and isolation. Therefore, a comprehensive comparison of different existing fault detection, location, and isolation schemes, from traditional to modern techniques, on shipboard MGs is presented to highlight the advantages and disadvantages of each scheme.
This article aims to present the most relevant practices of offshore oil contracting at an international level, in order to better understand the legal dynamics of the sector. The problem investigated deals with the terms of the legal relationship between the State and national and foreign public companies, as well as the relationship between States, with a view to the exploitation of shared offshore oil resources. This problem is current, taking into account both the fact that oil is a scarce resource, as well as the fact that its offshore exploration is particularly complex and risky. This article presents, in a non-exhaustive way, some examples of practices that illustrate contractual trends that have already crystallized. The approach to its content is made from an international law perspective, focused on the transnational challenges posed to States and operators. It is concluded that the sector is characterized by a huge variety of practices, which reveals an ability of operators to adapt to the characteristics of the concrete challenges of an offshore exploration project. It also shows the political and economic particularities of the States involved in the process.
A computational fluid dynamics study of the scavenging process in a large two-stroke marine engine is presented in this work. Scavenging which is one of the key processes in the two-stroke marine engines, has a direct effect on fuel economy and emissions. This process is responsible for fresh air delivery, removing the combustion products from the cylinder, cooling the combustion chamber surfaces and providing a swirling flow for better air-fuel mixing. Therefore, having a better understanding of this process and the associated flow pattern is crucial. This is not achievable solely by experimental tests for large engines during engine operation due to the difficulties of measuring the flow field inside the cylinder. In this study, the axial and tangential velocities are compared and validated with the experimental results obtained from Particle Image Velocimetry (PIV) tests [1]. The simulations are conducted using both Unsteady Reynolds Averaged Navier Stokes (URANS) and Large Eddy Simulation (LES) turbulence models. We observe in general, there is a good agreement between the numerical and experimental results. The flow inside the cylinder is studied in different locations related to the bottom of the scavenging ports during the period with open exhaust valve. Moreover, the replacement of combustion products with fresh scavenge air is analysed. The effective flow angle is calculated for the air flow through the scavenging ports. It is found that the effective flow angle is different from the geometrical angle of the ports (20°). Results illustrate better performance of LES, especially in the prediction of the tangential velocity which is crucial for the simulation of an accurate swirl and air-fuel mixing inside the marine engines. LES predicts a uniform profile for the tangential velocity at the top of cylinder which is consistent with the experimental results while URANS predicts a solid body rotation.
Thermal energy storage, with its low energy storage cost and wide distribution in industrial processes, is an effective way to improve the operational flexibility of power plants. Due to colossal energy storage capacity and small deployment costs, this article proposes connecting district heating networks to combined cycle gas turbine (CCGT) plants as a thermal energy storage capacity, improving the flexibility of CCGTs. The main focus here is on developing an appropriate control strategy to effectively control the power-heat conversion, meet the heat and power demands of the connected network, and the operational flexibility of the plant. The major problem is that the intrinsic static and dynamic conversion relationship of power and heat in the CCGT and district heating network and the buildings are multi-factor interactive and unknown. Therefore, the CCGT bottom cycle and district heating network, and building models were built to obtain the power-heat conversion parameters and the dynamic model for control design. Then, the energy storage coefficient of 0.105 MW/kg/s is obtained through the model simulation instead of a complex thermodynamic calculation, corresponding to the 113.22 GJ energy storage capacity of the district heating network. Based on the obtained conversion rules, a new control strategy called ‘conversion coordinated control’ is designed and applied, using load signal decomposition and synergistic load response of flue gas mass flow rate and steam extraction valve. The simulation results show that the proposed method can promote a ramping load rate of 8.6 MW/min in the first 30 s with only 0.3 °C building temperature variation. The control strategy can effectively reduce the gap between the grid demand and CCGT power and ensure grid stability without compromising thermal users’ comfort.
Denmark has set ambitious targets, to reduce emission with 70% by 2030 and become independent of fossil fuels by 2050. To achieve those targets, Denmark is planning to accelerate the de-carbonization of the power system, by replacing fossil fuel generation plants with renewable energy sources (RES). Offshore wind power will form the backbone of power generation in a decarbonized system. Already world leading in electric consumption share covered by wind power, Denmark plans to install an additional 6.8 GW of offshore wind by 2030, quadrupling the 1.7 GW already connected to the system.