Offshore Energy Systems Research Articles

Techno-economic designs of hybrid wind-wave offshore energy systems and comparison with TOPSIS analysis: an Italian case study

This study assesses multiple hybrid wind and wave floating offshore systems, utilizing a preliminary approach for dimensioning and the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) analysis method for comparison. It aims to provide an initial evaluation of diverse concepts, emphasizing state-of-the-art combinations of Floating offshore Wind Turbine (FOWT) with Wave Energy Converters (WECs). The criteria for evaluation include system cost, power extraction, WEC integration, dynamic and environmental responses, offering a comprehensive view of performance, economic viability, constructability, operational efficiency, and environmental impact. The findings, derived from the application of these methodologies, are informed by an Italian case study, enriching the insights and illustrating the practical implications of the evaluated hybrid systems within the Italian context. Preliminary results suggest a tendency for semi-submersible platforms to be more suitable for combined with WEC devices.

A power dispatch allocation strategy to produce green hydrogen in a grid-integrated offshore hybrid energy system

A dedicated grid-tied offshore hybrid energy system for hydrogen production is a promising solution to unlock the full benefit of offshore wind and solar energy and realize decarbonization and sustainable energy security targets in electricity and other sectors. Current knowledge of these offshore hybrid systems is limited, particularly in the integration, component control, and allocation aspects. Therefore, a grid-integrated analytical model with a power dispatch allocation strategy between the grid and electrolyzer for the co-production of hydrogen from the offshore hybrid energy system is developed in this paper. While producing hydrogen, the proposed offshore hybrid energy system supplies a percentage of its capacity to the onshore grid facility, and the amount of the electricity is quantified based on the electricity market price and available total offshore generation. The detailed controls of each component are discussed. A case study considers a hypothetical hybrid offshore energy system of 10 MW situated in a potential offshore off the NSW of Australia based on realistic metrological data. A grid-scale proton-exchange membrane electrolyzer stack is used and a model predictive power controller is implemented on the distributed hydrogen generation scheme. The model is helpful for the assessment or optimization of both the economics and feasibility of the dedicated offshore hybrid energy farm for hydrogen production systems.

Numerical study of the influence of amplitudes on heat transfer in a tube bundle

The objective of this study is to investigate the impact of different surface roughness levels on a staggered arrangement of tubes in a cross-flow configuration, with water as the fluid being used. The focus lies in comparing the data obtained from the rough surface configuration with that of a smooth cylinder reference point. To assist this comparison, a comprehensive two-dimensional computational fluid dynamics (CFD) model is created, which accurately represents the distinctive characteristics of each surface shape. This study also included modifying the Remax within a range of 10 000–16 000 and analyzing the outcomes of using four different tube types, each with different supernatant thicknesses labeled as [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] accordingly. Surprisingly, the tube with a 0.4 wave surface had significantly higher average Nusselt numbers (Nu) compared to the other tubes, indicating superior performance. The ideal tube design was found based on three main metrics: The performance evaluation criterion (PEC), the global performance criterion (GPC) and the average Nu. The performance metrics encompassed the PEC, GPC and the Colburn factor [Formula: see text]. The average Nu of the wavy_0.4 tube was higher than that of the SM by 31.66–32.54%, higher than that of the wavy_0.2 tube by 19.76–20.74%, and higher than that of the wavy_0.1 tube by 9.38–16.58%. According to the statistics, a heat exchanger that cools and has a wave with an amplitude of 0 is the most efficient choice for offshore energy systems. The smooth bundle tube (SBT) demonstrated the most significant increase in GPC, with values of 9.3–12.7% and 20.3–28.3% higher than those of wavy tubes with amplitudes of 0.1 and 0.2, respectively. In addition, correlations for the Nu are given, with results verified using empirical data from Balabani et al.

Onshore versus offshore wind power trends and recent study practices in modeling of wind turbines’ life-cycle impact assessments

Wind energy has gradually become one of the most efficient and reliable forms of sustainable energy, and it is being globally utilized to accelerate the expansion of green power production. However, recent projections of onshore & offshore wind energy systems indicate that further improvements are continuously required in terms of the deployments, capacity factors, costs, etc. to achieve an optimal wind power generation. According to these projections, the most critical current issue is the offshore systems' high levelized cost of energy, which demands the enhancements of the technologies to ensure the cost reduction in the future. Moreover, a number of reports are underscoring that offshore power systems can also leave a larger carbon footprints through their life-cycles compared to the onshore counterpart. On the other hand, the modelling methods of the power plants' life-cycle impact assessment (LCIA) have nowadays become among the most compelling research problems in the field of wind power systems engineering. In addition to comparatively assessing the characteristics of onshore & offshore energy systems based on some reports & studies, this work is therefore aimed at rigorously exploring the existing study practices in modelling the wind power plants' LCIA. A number of these practices were based on the implementation of various conventional modelling methods that may not help to make accurate assessments of the wind power plants’ life-cycle impacts. Hence, one of the main contributions of this study is to summarize a novel LCIA modelling approach based on Internet of Things (IoT) and predictive digital twin technologies. Unlike the conventional methods, real-time data extraction from the power plants makes these technologies possible to conduct the most accurate assessments of the life-cycle impacts.

Lifetime assessment for riser systems

As marine renewable energy technologies developing, there is a growing need for energy transportation systems. During offshore operations, deep sea risers can be subjected to excessive environmental loadings, causing operational risks. In this study, hydrodynamic loads, caused by in situ sea currents, acting on a riser under real-world sea conditions were modelled and examined, with experimental data being used as a calibration tool. Major safety problems for various offshore energy systems being an accurate assessment of excessive riser external loads, under influence of local sea currents, and hence resulting vortex induced vibrations (VIV).The method outlined in this study may be applied to complex sustainable energy systems, that are exposed to environmental loads, throughout the whole period of their intended service life. Approach advocated in this study offers practical way to estimate failure risks for nonlinear multidimensional dynamic offshore riser systems in an easy yet accurate manner.With regard to defense technology, risers and umbilicals play an important role for modern submarine operations.

Exploring agenda-setting of offshore energy innovations: Niche-regime interactions in Dutch Marine Spatial Planning processes

The foreseen large-scale growth of offshore wind energy towards 2050 in pursuit of an energy transition obliges scholars and policymakers to start considering its integration in the wider offshore energy system. Both technological innovations and advances in spatial policy are necessary to facilitate offshore system integration. This study draws from agenda-setting theory to explore barriers and opportunities affecting the prioritization processes surrounding three offshore energy storage and transport concepts in Dutch marine spatial planning practice. The findings demonstrate that although various arenas for agenda-setting exist, they are geared to the input of established stakeholders, including the oil and gas and offshore wind sectors. Also, prioritization is hindered by a short-term (2030) governmental fixation and long-term institutional ambiguity. Therefore, supportive institutions are needed, providing regulatory certainty and reliable incentive mechanisms, whilst remaining adaptive to address imminent uncertainties, in pursuit of system integration needed for an energy transition.

Modelling and analysis of offshore energy hubs

Clean offshore energy hubs may become pivotal for efficient offshore wind power generation and distribution. In addition, offshore energy hubs may provide decarbonised energy supply for maritime transport, oil and gas recovery, and offshore farming, while also enabling conversion and storage of liquefied decarbonised energy carriers for export. In this paper, the role of offshore energy hubs is investigated in the transition of an offshore energy system towards zero-emission energy supply. A mixed-integer linear programming model is developed for investment planning and operational optimisation to achieve decarbonisation at minimum cost. We consider offshore wind, solar, energy hubs and subsea cables. A sensitivity analysis is conducted on CO2 tax, CO2 budget and the capacity of power from shore. The results show that: (a) a hard carbon cap is necessary for stimulating a zero-emission offshore energy system, (b) offshore wind integration and power from shore can more than halve current emissions, but offshore energy hubs with storage may be necessary for zero-emission production, and (c) at certain CO2 tax levels, the system with offshore energy hubs can potentially reduce CO2 emissions by 49% and energy losses by 10%, compared to a system with only offshore renewables, gas turbines and power from shore.

Development and analysis of a solar‐based offshore energy system for sustainable island communities

Development and analysis of a solar‐based offshore energy system for sustainable island communities

3D numerical study and comparison of thermal-flow performance of various annular finned-tube designs

With the increase of heat transfer problems in marine vehicles and submerged power stations in oceans, the search for an efficient finned-tube heat exchanger has become particularly important. The purpose of the present investigation is to analyze and compare the thermal exchange and flow characteristics between five different fin designs, namely: a concentric circular finned-tube (CCFT), an eccentric circular finned-tube (ECFT), a perforated circular finned-tube (PCFT), a serrated circular finned-tube (SCFT), and a star-shaped finned-tube (S-SFT). The fin design and spacing impact on the thermal-flow performance of a heat exchanger was computed at Reynolds numbers varying from 4,300 to 15,000. From the numerical results, and when the fin spacing has been changed from 2 to 7 mm, an enhancement in the Colburn factor and a reduction in the friction factor and fin performances were observed for all cases under study. Three criteria were checked to select the most efficient fin design: the performance evaluation criterion PEC, the global performance criterion GPC, and the mass global performance criterionMGPC. Whatever the value of Reynolds number, the conventional CCFT provided the lowest performance evaluation criterion PEC, while the SCFT gave the highest amount of PEC. The most significant value of GPC was reached with the ECFT; however, GPC remained almost the same for CCFT, PCFT, SCFT, and S-SFT. In terms of the mass global performance criterion, the S-SFT provides the highest MGpcas compared with the full fins of CCFT (41–73% higher) and ECFT (29–54% higher). Thus, the heat exchanger with S-SFT is recommended to be used in the cooling of offshore energy systems.

Analysing long-term opportunities for offshore energy system integration in the Danish North Sea

This study analyzes future synergies between the Oil and Gas (O&G) and renewables sectors in a Danish context and explores how exploiting these synergies could lead to economic and environmental benefits. We review and highlight relevant technologies and related projects, and synthesize the state of the art in offshore energy system integration. All of these preliminary results serve as input data for a holistic energy system analysis in the Balmorel modeling framework. With a timeframe out to 2050 and model scope including all North Sea neighbouring countries, this analysis explores a total of nine future scenarios for the North Sea energy system. The main results include an immediate electrification of all operational Danish platforms by linking them to the shore and/or a planned Danish energy island. These measures result in cost and CO2 emissions savings compared to a BAU scenario of 72% and 85% respectively. When these platforms cease production, this is followed by the repurposing of the platforms into hydrogen generators with up to 3.6 GW of electrolysers and the development of up to 5.8 GW of floating wind. The generated hydrogen is assumed to power the future transport sector, and is delivered to shore in existing and/or new purpose-built pipelines. The contribution of the O&G sector to this hydrogen production amounts to around 19 TWh, which represents about 2% of total European hydrogen demand for transport in 2050. The levelized costs (LCOE) of producing this hydrogen in 2050 are around 4 €2020/kg H2, which is around twice those expected in similar studies. But this does not account for energy policies that may incentivize green hydrogen production in the future, which would serve to reduce this LCOE to a level that is more competitive with other sources.

Modelling and Analysis of Offshore Energy Hubs

Clean, multi-carrier Offshore Energy Hubs (OEHs) may become pivotal for efficient offshore wind power generation and distribution. In addition, OEHs may provide decarbonised energy supply for maritime transport, oil and gas recovery, and offshore farming while also enabling conversion and temporary storage of liquefied decarbonised energy carriers for export. Here, we investigate the role of OEHs in the transition of the Norwegian continental shelf energy system towards zero-emission energy supply. We develop a mixed-integer linear programming model for investment planning and operational optimisation to achieve decarbonisation at minimum costs. We consider clean technologies, including offshore wind, offshore solar, OEHs and subsea cables. We conduct sensitivity analysis on CO$_2$ tax, CO$_2$ budget and the capacity of power from shore. The results show that (a) a hard carbon cap is necessary for stimulating a zero-emission offshore energy system; (b) offshore wind integration and power from shore can more than halve current emissions, but OEHs with storage are necessary for zero-emission production and (c) at certain CO$_2$ tax levels, the system with OEHs can potentially reduce CO$_2$ emissions by 50% and energy losses by 10%, compared to a system with only offshore renewables, gas turbines and power from shore.

Post-Macondo Focus on Safety

Editor’s Note: The oil and gas industry is under public scrutiny like never before on a host of health, safety, and environmental issues. These concerns are already affecting how companies operate and interact with the public. This series is intended to shed light on how the industry is actively confronting these challenges and how it should address them going forward. Ten years ago, on 20 April 2010, the oil and gas industry suffered a significant human and environmental catastrophe, and a major blow to its reputation. The Deepwater Horizon semi-submersible drilling rig was preparing to temporarily abandon the Macondo well in 5,000 ft of water in the Gulf of Mexico (GOM) when the well blew and ignited causing a massive explosion that killed 11 people. The incident resulted in an oil spill of 4 to 5 million bbl (the biggest offshore oil spill in US history) and a cost to the operator (BP) in the order of $60 billion. This seminal event in the history of the industry caused a moratorium on drilling in the GOM which could have been extended indefinitely but for a comprehensive response by the industry to convince the regulators that the industry could operate safely. Immediately following the incident, the US oil and gas industry assembled four Joint Industry Task Forces (JITFs) to focus on critical areas of GOM activity (American Petroleum Institute, www.api.org); President Obama established a national commission to provide an analysis of the incident and make appropriate recommendations (National Commission on the BP/Deepwater Horizon Oil Spill and Offshore Drilling 2011); and the Secretary of the Interior requested the National Academy of Engineering (NAE) to form a committee to examine probable causes and identify means to avoid future occurrences (National Academies Press 2011). This article outlines the status of two initiatives: (1) the current National Academy of Science, Engineering, and Medicine (NASEM) program to enhance offshore safety; and (2) a new initiative by regulators and industry to improve the collection of safety data. The article concludes with a summary of the current focus areas to enhance offshore safety. The contribution of the Society of Petroleum Engineers (SPE) to some of these initiatives is described. It is important to note that although the incident occurred in US waters, the lessons learned are applicable to oil and gas operations worldwide, including land operations. The Gulf Research Program Part of the criminal settlement between the US Department of Justice (DOJ) and BP/Transocean was the establishment of an endowment fund of $500 million to be spent over 30 years to conduct science-based programs in three general areas of concern in the GOM and other continental shelf regions: (1) offshore energy system safety; (2) human health; and (3) environmental resources. The management of this fund was awarded to the NASEM, which established a program called “The Gulf Research Program” (GRP). NASEM was selected by the DOJ to administer the program because of its excellent reputation in organizing appropriate experts in the nation to provide advice on critical science and technology issues.

A Markovian reliability approach for offshore wind energy system analysis in harsh environments

AbstractFor an effective monitoring strategy of offshore energy systems in harsh environments, it is vital the system reliability dynamics be fully understood. This article presents the application of a Markovian process for dynamic reliability prediction of an offshore energy system. In the proposed approach, a three‐state Markovian process is developed for the analysis of the subsystem states, which dynamically determines the overall system reliability performance, overcoming the static limitation of fault tree analysis. The multistate subsystems are discretized into normal, degraded, and failed states to demonstrate the performance dynamics of the system for condition monitoring. The proposed approach is tested on a case study and the most critical influencing elements are identified. The application of the methodology efficiently identifies the system vulnerability path so as to assist in system integrity management and to provide a guide to early remedial action against total failure and downtime in offshore energy generation.

Understanding values embedded in offshore wind energy systems: Toward a purposeful institutional and technological design

The challenge of a purposeful design addressed in this article is to align offshore energy systems not only with technical and economic values like efficiency and profitability, but also with moral and social values more generally. We elaborate a theoretical framework that allows us to make a systematic inventory of embedded values of offshore energy systems and relate them to their societal acceptability. By characterizing both objects and subjects of acceptability, we shed light on ways to identify areas of value conflicts that must be addressed in purposeful design. We suggest the capabilities approach as a normative theory to deal with the arising value conflicts.

Deployment Challenges of Offshore Renewable Energy Systems for Sustainability in Developing Countries

This research aims to expose deployment challenges of offshore renewable energy systems in developing countries. The investigation of the deployment model covers climate conditions, economic conditions, necessary infrastructure services and wind power by considering the case of Cyprus Island which is one of the Small Island Developing States (SIDS) countries. The convenience of Offshore Energy Systems to the territory and their systematic proper work is an important issue. Because of that, the setting up of Offshore Wind Energy Tribunes in Cyprus, the planning process, structuring of cost values and necessary resources, the investigation of the geographic conditions for obtaining the energy flow and assessment of these conditions for Offshore Wind Tribunes are the prime objectives of this study. The orientation period and the applicable qualifications of the offshore energy systems were evaluated on the basis of the world wide references. The study is concluded by the estimation of the advantages and disadvantages of the system for Cyprus.