Knowledge of ecosystem services (ES) and the benefits provided by offshore marine areas, including the welfare impacts from the establishment of marine protected areas (MPAs) is still limited. In the present study we evaluated benefits from ES, citizens' willingness-to-pay for potential changes in the provision of ES, and welfare losses to citizens due to restrictions on economic activities from establishing new offshore MPAs in Latvian waters. The scenarios for the economic valuation were based on analyzing the supply of ES from the protected marine habitats, showing changes in the ES supply in policy relevant scenarios of the MPA size. Our study evaluates a wide array of ES delivered by offshore protected habitats and reveals that citizens' willingness-to-pay for preserving habitats and ES supply exceeds their welfare losses from restrictions in economic activities. Our approach supports the prioritization of habitat types according to their contribution to ES supply and benefits for citizens. The analysis can be complemented with spatial data regarding the distribution of habitats, providing an opportunity to identify areas with the highest ES benefits to support marine protection and spatial planning.
Life depends on healthy oceans that provide ecosystem services (ES) to humans, including provisioning, regulating, supporting, and cultural ES (Kovalenko et al., 2023). However, biodiversity, habitats, and the delivery of marine ES and resources are increasingly threatened by growing human activities in the oceans (Worm et al., 2006). Blue-growth activities, such as shipping and energy, eutrophication, and climate change represent major pressures that affect marine ecosystems (Halpern et al., 2008; Ehlers, 2016). Over the past two decades, increasing scientific attention has focused on the need to preserve and restore healthy marine waters and their role in adapting to climate change (Santos et al., 2020). This challenge calls for holistic approaches that advance our knowledge. Within the contributions to this Research Topic (see Figure 1), three themes are central to driving further research to expand our understanding in this interdisciplinary field.
We investigate piston-mode fluid resonance within the narrow gap formed by two identical fixed barges in a side-by-side configuration, utilizing a two-dimensional fully nonlinear numerical wave tank. The focus is on examining the effects of uniform and shear currents. Under ‘wave+uniform-current’ conditions, a certain current speed is identified, beyond which the gap resonance reduces dramatically and monotonically with the current speed. This reduction is attributed to a stronger increase in damping compared to wave excitation, qualitatively explained by a linearized massless damping lid model. Furthermore, we study the effects of waves propagating on shear currents, maintaining an identical ambient current speed at the gap depth. Complementary to previous studies on this topic, our study reveals that the velocity profile of the studied shear current has an insignificant effect on the resonant gap amplitudes. The ambient current velocity at the gap depth is a more important key parameter to consider when assessing wave-induced gap responses, leading to a non-negligible increase in the resonant gap response. Consequently, disregarding the influence of currents in engineering practices is not a conservative approach.
As more offshore wind energy projects are implemented, the risk of interactions between farms becomes more pronounced. While reduced surface roughness over water enhances airflow stability, it can also extend wake effects on downstream turbines. The study aims to enhance the understanding of wake interactions and efficiency variations based on the distance between neighboring farms. To assess the impact of neighboring farms across different scenarios and features, a methodology is developed to achieve computational optimality using an open-source Python-based library, PyWake, then verified by a well-established CFD software, Meteodyn. Then, the methodology is applied to a Brazilian offshore wind project currently under licensing as a reference point. The results indicate a 1–3% reduction in Annual Energy Production following the current Brazilian regulation for onshore projects of 20 times the blade tip height, as the minimum distance. This reduction translates to an approximate 3% increase in the Levelized Cost of Energy and a nearly 24% decrease in Net Present Value. These findings are crucial for offshore wind energy planning and its sustainable growth, indicating the need to define a minimum distance for the regulatory bodies. This would not only avoid future disputes but also enhance investor confidence.
The present numerical study aims to assess the performance of an Eulerian Stochastic Field (ESF) model in simulating spray flames produced by three fuel injectors with different nozzle diameters of 100 µm, 180 µm and 363 µm. A comparison to the measurements shows that although the simulated ignition delay times are consistently overestimated, the relative differences remain below 28%. Furthermore, the change of the averaged pressure rise with respect to the variation of nozzle diameter is captured by the model. The simulated flame lift-off lengths also agree with the measurements, with a maximum relative difference of 13%. The spray flame produced by a larger nozzle diameter has a fuel-richer premixed core region despite the longer lift-of length, indicating that the higher fueling rate used with the larger nozzle diameter is a more dominating factor than the lift-off length is in influencing the air entrainment into the upstream of the spray flames. In addition, the simulated normalised flame lengths are found to decrease when the nozzle diameters increase. These predictions are in good qualitative agreement with the experimental observation. This work proves that the ESF model can serve as an important tool for the simulation of spray flames in marine diesel engines, where fuel injectors with different nozzle diameters are applied for pilot and main injections.
A numerical study on effects of the injection direction of the pilot diesel fuel on combustion and emissions under two-stroke dual-fuel marine engine-like conditions is presented in this paper. It is found that the injection direction of the pilot fuel has significant effects on the methane start of combustion as well as flame propagation direction which leads to different heat transfer trends to combustion chamber walls and flame- wall interaction. Furthermore, the injection direction of the pilot fuel changes the methane combustion intensity which leads to different trends for emission formation.
An increasing water to oil ration in the North Sea oil and gas production motivates for an optimization of the current deoiling facilities. Current facilities are operated on matured methodologies, which in most cases fulfill the government regulations. However, it has also observed that these solutions could be further improved. In order to more precisely monitor the deoiling operations, this study investigated the real-time monitoring of the deoiling efficiency of the hydrocyclone facilities which are commonly used in offshore oil and gas production. Fluorescence based monitors were applied to measure hydrocyclone inlet's and underflow's Oil-in-Water (OiW) concentrations in real-time. Image-based microscopy was used to analyze the oil droplet size distribution at inlet and underflow to investigate the droplets' influence on hydrocyclone's efficiency. Performance experiments were carried out to identify how pressure difference ratio (PDR) and the droplet's sizes affect the deoiling efficiency. The performance of the deoiling hydrocyclone was significantly influenced by the inlet flow rate, while less or marginally dependent on the PDR. The droplet size distribution experiment proved that large droplets have a high probability to be separated by the hydrocyclone. The findings suggest that the coupled separator tank and hydrocyclone system can be further improved upon by deploying coordinated control as the two systems are strongly interdependent.
A major challenge in next-generation industrial applications is to improve numerical analysis by quantifying uncertainties in predictions. In this work we present a formulation of a fully nonlinear and dispersive potential flow water wave model with random inputs for the probabilistic description of the evolution of waves. The model is analyzed using random sampling techniques and nonintrusive methods based on generalized polynomial chaos (PC). These methods allow us to accurately and efficiently estimate the probability distribution of the solution and require only the computation of the solution at different points in the parameter space, allowing for the reuse of existing simulation software. The choice of the applied methods is driven by the number of uncertain input parameters and by the fact that finding the solution of the considered model is computationally intensive. We revisit experimental benchmarks often used for validation of deterministic water wave models. Based on numerical experiments and assumed uncertainties in boundary data, our analysis reveals that some of the known discrepancies from deterministic simulation in comparison with experimental measurements could be partially explained by the variability in the model input. Finally, we present a synthetic experiment studying the variance-based sensitivity of the wave load on an offshore structure to a number of input uncertainties. In the numerical examples presented the PC methods exhibit fast convergence, suggesting that the problem is amenable to analysis using such methods.
Productive activity in the North Sea Region (NSR) is expected to intensify, diversify, and expand further offshore. Pressure to decarbonize and “electrify” the existing and emerging industries of the ocean economies offer an opportunity as the electrification of the seas has captured the imagination of industry and policymakers as a pathway to achieving sustainable growth. Using the methods of morphological analysis, thematic analysis, and structural analysis, this article identifies and reports on six innovation concepts for the electrification of the seas: Charging at wind farms; Charging at fish farms; Charging at thermal-powered platforms; Charging by floating solar panels; Charging at tidal plants; Charging at offshore container terminals. This article provides a base for entrepreneurship by generating insight into the affecting variables for each configuration as well as the identification of the strategic variables. It furthermore contributes a novel methodological approach to produce said understanding. The paper concludes with prospects for the electrification of the seas and charts a pathway for sustainable transition of the ocean economies.
This paper presents a detailed BC, NOx and SO2 emission inventory for ships in the Arctic in 2012 based on satellite AIS data, ship engine power functions and technology stratified emission factors. Emission projections are presented for the years 2020, 2030 and 2050. Furthermore, the BC, SO2 and O3 concentrations and the deposition of BC are calculated for 2012 and for two arctic shipping scenarios – with or without arctic diversion routes due to a possible polar sea ice extent in the future.
In 2012, the largest shares of Arctic ships emissions are calculated for fishing ships (45% for BC, 38% for NOx, 23% for SO2) followed by passenger ships (20%, 17%, 25%), tankers (9%, 13%, 15%), general cargo (8%, 11%, 12%) and container ships (5%, 7%, 8%). In 2050, without arctic diversion routes, the total emissions of BC, NOx and SO2 are expected to change by +16%, −32% and −63%, respectively, compared to 2012. The results for fishing ships are the least certain, caused by a less precise engine power – sailing speed relation.
The calculated BC, SO2, and O3 surface concentrations and BC deposition contributions from ships are low as a mean for the whole Arctic in 2012, but locally BC additional contributions reach up to 20% around Iceland, and high additional contributions (100–300%) are calculated in some sea areas for SO2. In 2050, the arctic diversion routes highly influence the calculated surface concentrations and the deposition of BC in the Arctic. During summertime navigation contributions become very visible for BC (>80%) and SO2 (>1000%) along the arctic diversion routes, while the O3 (>10%) and BC deposition (>5%) additional contributions, respectively, get highest over the ocean east of Greenland and in the High Arctic.
The geospatial ship type specific emission results presented in this paper have increased the accuracy of the emission inventories for ships in the Arctic. The methodology can be used to estimate shipping emissions in other regions of the world, and hence may serve as an input for other researchers and policy makers working in this field.