Review on sustainable development of island microgrid

Renewable energy is a sustainable and green energy converted from renewable energy resources in the nature. There is a huge amount of renewable energy resources in the ocean that can be changed into useful energy like electricity, store for long time use, or apply in the daily energy consumption. These marine renewable energies (MRE) include wave energy, ocean thermal energy, tidal energy, ocean current energy, salinity gradient energy, and offshore energy. With a big area, the oceans have been prospected that it brings endless renewable energy sources for social development and human demand. The renewable ocean energy shows many advantages of sustainable energy, clean energy, and non-carbon dioxide emissions by generating from wave and water in the ocean with an enormous amount of natural energy resources. The MRE can service at many areas of off-shore, on-shore, and remote areas where need energy to drive daily living demands. The MRE reveals some disadvantages such as the influence of daily, monthly, season, and period of time. The solutions have been developed to solve the limitations of the MRE such as developing the storage method to store energy for long time use or making the balance of the output performance to improve quality of the renewable energy. The MRE has also received many concerns from countries by promulgating policies, strategies, and plans to develop the renewable ocean energy such as green economy development, blue economy strategy, carbon dioxide emission reduction, and encouragement of using marine renewable energy. This paper reviews current marine renewable energy with its generation, storage, and application. The work also mentioned some advantages, disadvantage, policies, strategies, and solutions to encourage the development of the renewable ocean energy in over the world. The results hope that it will be spread development, exploitation, and application of marine renewable energy in the near future. Keywords: Marine renewable energy, energy storage, generation, application, sustainable energy

This chapter presents ocean wave energy, tidal energy, ocean current energy, ocean thermal energy, and geothermal energy techno‐economic summaries including information on resource characteristics, conversion technologies, power electronics approaches as applicable, and grid interface issues. It also presents autonomous, non‐grid‐connected ocean wave energy applications, including adapting utility‐scale wave energy devices for small‐scale autonomous and sensor applications. Ocean thermal energy conversion systems convert the energy available in the temperature gradient of the warm surface‐water layers and the deep, cold ocean depths of approximately 800‐1000m. Marine renewable energy can also be harnessed from the tides, from tidal currents, and non‐tidal ocean currents. Geothermal energy conversion is an abundant, renewable resource consisting of the natural heat generated and stored in rock and fluids in the Earth's crust that can be used for electricity generation and for heating and cooling purposes.

Marine energy is one of the forms of renewable energy that is one of the most widely available sources of energy; the oceans cover around 71% of the earth's surface, which means that there can be huge potential in energy. The majority of the technologies that are used to harvest marine energy are still in their developmental stages. Marine energy includes tidal energy, wave energy, osmotic energy, ocean thermal energy, and ocean current energy. Researchers all across the world, as well as people developing industries, are paying attention to the potentially lucrative field of marine energy. Since more than half of the US population lives within 50 miles of the coast, marine energy resources are spread out and in a good place to power cities. These resources are prospective contributors to a reliable, steady sustainable energy infrastructure because they are also quite predictable. This article provides an overview of the current state of the art in marine energy and explores tidal and wave energy in detail including the benefits and limitations of both.

As installed capacity of Chinese renewable energy (RE) power generation has been expanded rapidly, the gap between subsidies and funds is more and more huge. Chinese government has urgently sought other incentive policies in place of subsidy. Considering incentive policies such as RE quota scheme, green certificate trade, and subsidy in scenarios, the performances of RE power generations in the liberalized power market are measured in this article. Centralized renewable energy (CRE) and distributed renewable energy (DRE) generations are distinguished in this study. The results show that even if the subsidy is canceled, there will be no significant reversal of RE power generation. It is best to terminate subsidies after 48 months. With the interaction of the incentive policies, the on-grid market price is rising initially and then falling. The price of tradable green certificate (TGC) fluctuated with electricity demand. Subsidy influences the demand in the TGC market by affecting the amount of power generated by DRE, thereby affecting the profit of the CRE power generation. In addition, the changes in RE quota not only keep the price of TGC at a stable level, but also make the installed capacity of CRE power generation exceed the installed capacity of traditional energy power generation after 80 months.

The oceans’ systems offer significant potential for electrical power generation for hydrokinetic, ocean current and ocean thermal energy. Currently, the technologic readiness is premature for implementation on a grid scale. There has been limited testing of tidal and wave devices in the US on the east and west coasts. However no full-scale field tests for ocean current have been conducted. There is ample opportunity for crosscutting, multidisciplinary research and development to bring ocean energy to the grid. The North Carolina Legislature has taken the initiative to create the opportunity for exploring renewable ocean energy for the mid-Atlantic region and specifically for the State by funding a significant research program primarily directed at the technology.

The U.S. Department of Energy Ocean Energy Technology (DOE/ OET) Program was instituted to develop options for extracting and distributing significant amounts of ocean energy in a reliable, environmentally acceptable and cost-effective manner. Since it's inception in 1974, the program originally emphasized the identification of the most viable ocean energy options and determination of their resource potential. Ocean current devices, wave energy extraction techniques and ocean thermal energy conversion (OTEC) systems were investigated. Because the OTEC projected energy extraction potential is one to two orders of magnitude greater than the other ocean energy options, 90% of ocean energy funding has gone to this area. The DOE role is in technology development and basic and applied research. Generally, engineering development activies fall within the domain of private industry. Both wave and current devices extract kinetic energy from the ocean using a variety of methods. Ocean thermal conversion uses the difference in temperature between surface waters heated by the sun and colder deep (up to 3000 feet) ocean waters. These two sinks provide a temperature difference of about <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20\deg</tex> C in ocean areas between <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\pm 20\deg</tex> of the equator. There are two power cycles under development in OTEC; open cycle and closed cycle. Open cycle uses sea water as the working fluid and dosed cycle uses ammonia or freon as the working fluid in a closed loop. The summary of OET Program activities during the period FY 1980 through FY 1983 represents the more significant findings of DOE-sponsored research and development in each of six program elements: Advanced Power Systems Development, Closed-Cycle Power Systems Development, Alternative Energy Systems Development, Environmental Research, Ocean Engineering, and Engineering Development. Although the FY 1984 program is still being formulated, twenty of the areas of uncertainty remaining to be resolved are listed and indicate the thrust of present planning.

Marine renewable energy in China: Current status and perspectives

Adopted by the 196 Parties of the United Nations Framework Convention on Climate Change (UNFCCC) last December, and signed by 175 countries on 22 April 2016, the Paris Agreement provides guidelines for global efforts in addressing climate change, and establishes a five-year review cycle for detailedwork programs of cutting emissions, differentiation between countries as to their responsibilities for action, and financing for poor countries to deal with rising temperatures. ‘Governments have ushered in a new era of global cooperation on climate change—one of the most complex issues ever to confront humanity. What was once unthinkable is now unstoppable. For the first time, every country in the world has pledged to curb their emissions, strengthen resilience, and act internationally and domestically to tackle climate change’, acclaimed UN Secretary-General Ban Ki-moon. In a nutshell, Paris Agreement sets a target of holding the increase in the global average temperature towell below 2◦Cprior to 2100 and pursuing the efforts to limit the temperature increase to1.5◦C.The landmarkAgreementhas 29 articles, includingmitigation, adaptation, loss and damage, finance, technology development and transfer, capacity building, transparency of action and support, and global stocktake, which pose many new global opportunities and challenges for climate research and services. Global warming has caused ice melting in polar regions and the northern hemisphere and elevation of sea level, extreme weather and climate events such as tropical cyclone and ENSO, acceleration of global water cycle, as well as ocean acidification and hypoxia. Since the earth’s climate system is highly non-linear, even if the global temperature increase could be limited to 1.5◦C via emission reduction, risks and vulnerability may remain that could result in more frequent extreme weather events, regime shifts of non-equilibrium ecosystem, and persistent rise of global and regional sea level. Therefore, in response to the Agreement, scientific community should build up a massive research effort on the mechanisms and adaptation of climate changes, including reliable assessment of climate changes and their impacts in global and regional scales, especially decadal predication that could provide scientific evidence in support of the reduction of carbon emission. While the Agreement represents a monumental step in the international efforts in controlling global warming, many difficult problems remain to be solved. Most notably, it is unclear what amount of reduction in greenhouse gas emission is required to control the global warming below 2◦C by 2100. Multi-components of the earth’s climate system and multiscale spatial-temporal variations call for interdisciplinary research through collaboration and innovation, in order to improve the prediction of decadal and longer timescale climate changes. To achieve this goal, we need to build global comprehensive observational networks, reliable earth system models as well as develop more effective prediction-assessment approaches. In this regard, China’s investment still lags behind developed countries, and increased investment in fundamental research on the mitigation and adaptation strategies of climate changes are called for. The good news is that the government has recently approved the ‘Earth System Simulator’ project and is planning for the establishment of comprehensive ocean observation systemover theChina’s 13th ‘Five-Year Plan’ as well. In terms of social economic development, ambition of the Agreement in emission reductions could be achieved by restructuring the world’s energy usage from fossil fuels to renewables, which influences geopolitics and world economy as well as will enhance the innovation-driven development in renewable energy. Key renewable marine energies, such as tidal wave energy, ocean thermal energy, and sea-water chemical energy, together with solar and wind energy, will contribute larger shares of energy sources and help to reduce carbon emission. With increasing use of marine energy, we can expect technological advances in equipment innovation andmanufacturing, newmaterials, and ocean engineering, all of which benefit economy, promote upgrade and transformation of industries as ‘Marine Energy Plus’. The Paris Agreement will undoubtedly bring opportunity for a drastic restructuring of China’s energy industry, and we should bemaking early preparation tomeet this upcoming adjustment. In short, the Paris Agreement will promote climate research, industrial structural adjustment, and economic social development, in spite of potential difficulties in its implementation and the deficiency in current technologies

Marine Energy is not necessarily same as Ocean Power. Marine energy can be created in the ocean as also in rivers, lakes, streams, estuaries, and more. The difference between ocean energy and tidal energy is that tidal energy uses gravitational pull of earth, moon and sun to produce energy whereas wave energy uses kinetic forces of waves to generate electricity. The tides at shorelines of oceans will rise and fall twice a day. Marine energy or marine power is also referred to as ocean energy, ocean power, or marine and hydrokinetic energy. energy refer to the energy carried by ocean waves, tides salinity, and ocean temperature differences. The movement of water in the world’s oceans creates a vast store of kinetic energy, or energy in motion. Some of this energy can be harnessed to generate electricity to power homes, transport and industries. The term marine energy encompasses both wave power i.e., power from surface waves, and tidal power obtained from the kinetic energy of large bodies of moving water. The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential of providing a substantial amount of new renewable energy around the world. substantial amount of renewable energy around the world.

State-of-the-art review of the flexibility and feasibility of emerging offshore and coastal ocean energy technologies in East and Southeast Asia

This paper describes the analysis and conclusions from an Office of Naval Research SBIR study entitled " Integration and Optimization of Hydrogen Production with Ocean Thermal Energy Conversion Technology in Offshore Floating Platforms.?? This 2005-2008 study commenced with defining a future large offshore OTEC industry and comparing that industry to alternative sources for hydrogen (or ammonia) fuel. OTEC is a renewable technology based on an immense resource, it has a low environmental impact, produces 24/7, and does not compete with other resources such as land, water and food; OTEC on a very large scale was found to be an economically and environmentally viable candidate for future hydrogen production. This technology will be available tomorrow only with investment today. The OTEC process is straightforward, is technically feasible, and has been demonstrated several times. However, OTEC has not been commercialized due to high capital costs and competition from cheap fossil fuel. As the study progressed, energy costs became extremely volatile and that together with global warming and national security issues have made firm renewable energy like OTEC desirable. OTEC is a first choice renewable for firm, large-scale electrical power at island communities such as Hawaii, Guam and Puerto Rico; at these locations the gap between the willingness to pay and the cost of OTEC energy has considerably narrowed if not disappeared. This point of entry for commercialization is sufficiently large for OTEC to evolve and be poised for the next step of providing ammonia or hydrogen for the US mainland. The technical challenge for the engineer today is perfecting and testing " low cost?? options for the more challenging OTEC components, and the challenge for the developer is financing these first critical steps. Introduction During the energy crisis of the 1970-80's, there was a tremendous interest in Ocean Thermal Energy Conversion (OTEC) and the Department of Energy (DOE) invested significantly in OTEC technology. Several programs concentrating on heat exchanger performance, cold-water pipeline development, overall plant design, and both open and closed-cycle development were completed. OTEC appeared to be a very attractive renewable energy source: the global resources suitable for OTEC are huge; OTEC is a continuous and steady source of energy; and OTEC is among the most environmentally friendly alternate energy sources. At the end of this era, OTEC remained an exciting but expensive technology and DOE refocused on different technologies. Public awareness of peak oil, energy security, and environmental issues has elevated to a new high. There is now a new national willingness to come to terms with energy; this is a new age for renewables. In 2005, the Office of Naval Research (ONR) awarded Makai a Small Business Innovative Research (SBIR) study to investigate the role of OTEC for hydrogen production in offshore floating platforms. OTEC had traditionally been too expensive to be a near-term energy provider at a moderate scale. However, in a future world without oil and on a massive scale, would OTEC be a viable contender when compared to other available and acceptable energy sources? A technical and cost model was developed of a floating OTEC plant which was expanded to include a massive OTEC industry supplying hydrogen (via ammonia) to the US. For validation of this model, a conceptual design and cost estimate of a 100MW plant was completed and costs were included based on similar offshore structures built today. The study concluded that OTEC is attractive; the background on this study and conclusions are provided in this paper.

Rapid advancements in renewable energy technologies have been primarily driven by the increasing global energy demand for energy and the growing concerns over environmental pollution. Among these technologies, tidal current energy has achieved significant attention due to its high energy density and stable energy output. Compared to other renewable energy sources, such as solar and wind power, tidal current energy is more stable and predictable, offering considerable potential for integration into future energy systems. However, despite its promise, several key technological challenges must be addressed to enable the widespread development of tidal current energy technology. To address these challenges, this paper presents a comprehensive review of recent advancements in ocean tidal current energy technology, with particular emphasis on the analysis of the main types of energy harvesting devices and support structures. Furthermore, it evaluates representative tidal current energy devices based on their operational principles, technical features, and applications. By systematically reviewing mainstream hydrodynamic analysis methods, this paper evaluates their applicability and limitations in assessing the performance of tidal current energy devices. This assessment improves the accuracy of performance predictions and offers theoretical support for the optimal design of the energy harvesting systems. In addition, the paper addresses key issues in the development of tidal current energy technology, including technological feasibility, cost management, and environmental impact. These discussions provide a foundation for identifying emerging trends and major technical challenges in the field. Finally, the development prospects of tidal current energy technology are explored from the perspectives of technological advancement, economic viability, and sustainability. It is concluded that achieving widespread adoption of tidal current energy depends on factors such as technological maturity, effective cost control, and the balanced integration of environmental and social benefits.

Greening seaports: Evaluating impacts and policies for renewable energy systems

For a remote island country like the Maldives, there are two main reasons for the need for a renewable source of energy. One is the increasing oil prices and the other is to overcome the environmental problems that arise from the burning of fossil fuels. Taking into account the climate of the country, the renewable energy resource available that has the highest potential for producing the necessary electricity was found to be wave energy and ocean thermal energy. These two resources are almost completely environmentally friendly. The thesis examines the possibilities of these two resources to determine the most suitable system for generating power to supply to the remote islands. Out of the many existing wave energy converters, the most promising ones have been analysed to determine the power that can be produced with the available climatic conditions. Similarly, ocean thermal energy conversion (OTEC) have been studied and the different systems are analysed. Factors such as cost and the devices’ environmental impact are also taken into account. The thesis concludes that wave energy is more commercially advanced than ocean thermal energy. However, wave energy conversion devices are not suitable, not because the devices themselves are improperly designed, but rather because of the wave climate in the Maldives. Therefore, the best possibility is the use of OTEC systems.

China introduced the Renewable Portfolio Standard (RPS) in 2019 to boost renewable energy (RE) consumption across provinces, yet the policy overlooks associated employment impacts. To fill this gap, this paper constructs an inter-provincial cooperation model for non-hydro RE power consumption that integrates a dual-objective optimization (minimizing quota completion cost and maximizing employment) and a minimum-deviation benefit allocation approach. The model identifies the roles of green power buyers and sellers, and quantifies optimal RE generation, employment, and costs under both non-cooperation and cooperation scenarios. An empirical analysis is conducted for five representative provinces (Hebei, Yunnan, Jiangxi, Anhui, and Hunan). The results indicate that, compared with the non-cooperation mode, inter-provincial cooperation increases non-hydro RE power generation by 13.42 × 10⁹ kWh (27.4%), creates an additional 1.39 × 105 jobs, and increases total comprehensive benefits by 3.38 × 10⁹ CNY (9.9%). The proposed minimum-deviation allocation method achieves fairer benefit distribution than single methods such as the Shapley value and game quadratic programming. This study provides a practical framework for provincial governments to balance RE consumption, cost efficiency, and employment growth in cross-regional green power cooperation.