This paper investigates the optimal control solution using MPC for a typical offshore topside de-oiling process. By considering the combination of the upstream three-phase gravity separator and the downstream de-oiling hydrocyclone set-up as one integrated plant, the plant-wide control problem is formulated and handled using MPC technology. The de-oiling dynamics of the hydrocyclone are estimated via system identification while the key dynamics of the considered gravity separator are modeled based on mass balance and experimental parameter estimation. The developed MPC solution is simulated and experimentally validated via a lab-scaled pilot plant. The comparison of performances of the MPC controlled system with those of a PID controlled system, which emulates the commonly deployed control solution in most current installations, shows the promising results in optimally balancing the gravity separator's (level) control and hydrocyclone's (PDR) control.
Injection of water into wells is a common practice in offshore oil and gas installations, and here as in many other industries the water has to be deaerated before it is sent through miles of pipelines to reduce the risk of corrosion in those pipelines and other downstream equipment. It requires extremely low concentrations of dissolved oxygen for the corrosion of metals to begin, and removing the dissolved oxygen is currently done in large vacuum deaeration towers, a highly energy demanding process, along with additional injection of chemical oxygen scavengers. In many instances these processes are controlled in a feed-forward manner, where the operators rely on infrequent sampling and corresponding measurements to control the process. The possibilities for optimization in this field are thus numerous. The main challenges are online measurements of dissolved oxygen and their use in feedback control. This article gives a brief review of the state-of-the-art and investigates the potential of using dissolved oxygen as a reliable feedback parameter, taking inspiration from onshore waste water industries which have been dealing with dissolved oxygen feedback control since the 1970's.
From the process control point of view, any reliable and online Oil-in-Water (OiW) measurement could provoke a brand new control paradigm for produced water treatment. However, the real-time OiW monitoring is still an open and ad-hoc situation in recent decades. The fundamental issue, ie, the OiW measurement is methodology dependent, leads to numerous challenges, such as (i) how to verify the reliability and accuracy of a specific methodology/instrument; (ii) how to handle and interpret the measured data in a most objective manner; and (iii) how to keep a cost-effective on-site calibration and maintenance under the harsh offshore conditions etc. The paper reports our latest achievements and observations in usage of fluorescence- and microscopybased OiW monitoring technologies for advanced Produced Water Treatment (PWT) control and evaluation, particularly by focusing on the de-oiling hydrocyclone installations.
Incumbent clinker production practices fall short of meeting carbon-emission neutral targets, pressing the need to implement waste valorization approaches in cement plants to mitigate environmental impacts. However, there is a lack of knowledge on the future environmental performance of emerging waste-to-heat and fuel upcycling in clinker manufacturing. This study examines the prospective life cycle impacts of (1) solid recovered fuel (SRF) utilization and (2) on-site marine fuel production using integrated fluidized bed pyrolysis to substitute fossil fuels in clinker production and marine transportation. Environmental impacts are projected between 2025 and 2050 by applying learning effects in the foreground life cycle inventory and shared socioeconomic pathways (SSP1, SSP2), extended with the 1.9 W m−2 representative concentration pathway (SSP2-RCP1.9), in the background system. The highest decarbonization progress (−538.9 kg CO2-eq (t clinker)−1) is achieved under the SSP2-RCP1.9 development trajectory, driven by avoidance of emissions from waste management systems and converting biogenic carbon-rich municipal solid waste resources. The predicted CO2-eq impacts are found to be lower than the point source emission from raw meal calcination in several SSP scenarios, indicating that carbon-emission neutrality is attainable in combination with retrofitted carbon capture, utilization, and storage (CCUS) technologies. The assessment highlights the potential for burden shifting to other environmental impacts, e.g., particulate matter formation (+37.0 % by 2050), pointing to the need to evaluate additional pyrolysis oil upgrading and NOX emission mitigation strategies. Overall, synergizing waste pyrolysis with clinker production is found to be favourable due to (i) improved energy requirements, (ii) reduced fossil fuel use and impacts on climate change and ecosystem quality, and (iii) high potential for technological learning-driven environmental progress.
To achieve IMO’s goal of a 50% reduction of GHG emission by 2050 (compared to the 2008 levels), shipping must not only work towards an optimization of each ship and its components but aim for an optimization of the complete marine transport system, including fleet planning, harbour logistics, route planning, speed profiles, weather routing and ship design. ShipCLEAN, a newly developed model, introduces a coupling of a marine transport economics model to a sophisticated ship energy systems model – it provides a leap towards a holistic optimization of marine transport systems. This paper presents how the model is applied to propose a reduction in fuel consumption and environmental impact by speed reduction of a container ship on a Pacific Ocean trade and the implementation of wind assisted propulsion on a MR Tanker on a North Atlantic trade. The main conclusions show that an increase of the fuel price, for example by applying a bunker levy, will lead to considerable, economically motivated speed reductions in liner traffic. The case study sowed possible yearly fuel savings of almost 21 300 t if the fuel price would be increased from 300 to 1000 USD/t. Accordingly, higher fuel prices can motivate the installation of wind assisted propulsion, which potentially saves up to 500 t of fuel per year for the investigated MR Tanker on a transatlantic route.
In recent years the issue of sulfur emissions from maritime transport has seen newfound attention. This chapter presents an overview of the main issues of sulfur emissions and the legislative framework that seeks to reduce the sulfur footprint of the maritime sector. It also analyzes potential modal shifts toward less efficient land-based modes which may happen as a result of sulfur regulations and investigates the related potential economic damage to ship operators. To that effect, this chapter presents findings from a recently finished project at DTU and the developed methodological framework that can be used to estimate such modal shifts, as well as to measure the efficacy of policy and ship operators’ measures to reverse such shifts.
The BBNJ Agreement will affect legal frameworks for the conservation of marine biological diversity in various regions of the world ocean and the marine Arctic is no exception. As biological diversity in the marine Arctic is particularly vulnerable, the implications of the BBNJ Agreement for the conservation of biological diversity in the marine Arctic deserves serious consideration. Of particular note is the procedure for an environmental impact assessment (EIA). Given that damage to the environment may be irreversible, it is a prerequisite to conduct an EIA before authorizing planned activities, with a view to preventing environmental harm. An EIA constitutes a crucial element in the conservation of the marine environment, including biological diversity. Hence, this article examines the potential implications of the procedure for an EIA as set out under the BBNJ Agreement for the conservation of biological diversity in the marine Arctic beyond national jurisdiction.
With expanding human uses at sea, the objective of maritime spatial planning (MSP) to promote sustainable coexistence between marine uses becomes an increasingly challenging task. In order to assess coexistence options, both use-use interactions and use-environment interactions are important to explore. Tools for doing cumulative impact assessments (CIA) on the environment provide a means for spatially exploring environmental impacts. Finding inspiration in such ecosystem-based spatial use-environment approaches while drawing on pairwise marine use compatibility knowledge from existing literature, a spatial approach to model potential synergies and conflicts between marine uses through an expert-based scoring system is presented and implemented in SEANERGY, an ArcMap-based opensource toolbox. A test based on Baltic Sea GIS data demonstrates how SEANERGY supplements CIA analyzes with knowledge about potential use-use synergies, potential use-use conflicts, and their spatial extents, useful for optimizing the use of marine space in MSP without putting too much cumulative pressure on the environment.
With expanding human uses at sea, the objective of maritime spatial planning (MSP) to promote sustainable coexistence between marine uses becomes an increasingly challenging task. In order to assess coexistence options, both use-use interactions and use-environment interactions are important to explore. Tools for doing cumulative impact assessments (CIA) on the environment provide a means for spatially exploring environmental impacts. Finding inspiration in such ecosystem-based spatial use-environment approaches while drawing on pairwise marine use compatibility knowledge from existing literature, a spatial approach to model potential synergies and conflicts between marine uses through an expert-based scoring system is presented and implemented in SEANERGY, an ArcMap-based opensource toolbox. A test based on Baltic Sea GIS data demonstrates how SEANERGY supplements CIA analyzes with knowledge about potential use-use synergies, potential use-use conflicts, and their spatial extents, useful for optimizing the use of marine space in MSP without putting too much cumulative pressure on the environment.
Any ecosystem based fisheries management system is necessarily faced with the problem of multiple objectives that trade-off against one another. Typically, objectives such as the maximization of yield, employment or profit or minimizing environmental impacts will be optimized in different parts of the decision space, which is formed of the fishing mortality rates that can be applied to the various species, given the constraints imposed by the mixed species nature of many fishing fleets. Since objectives cannot be simultaneously achieved, managers need to consider how such objectives trade-off against one another in order to choose a balanced strategy. Normally, they also have to consider the views of different groupings of stakeholders, who often favour widely different and conflicting objectives. This is particularly difficult if stakeholders are reluctant to expose their negotiating positions. This article explores two possible approaches to developing a Decision Support Framework for the North Sea. The first is a classic Multi- Criteria Analysis (MCA) approach that was developed in cooperation with North Sea stakeholders. The implementation went smoothly for the definition of suitable scenarios, decision trees and criteria, but failed in facilitating consensus on how to set priorities at the stakeholder level. However, it remains a possible approach for higher level management to adopt. Consequently, to aid effective decision-making a simpler approach was designed to visualise stakeholders concerns both to themselves and to the managers in charge of actual decision-making. Rather than trying to achieve some joint optima of the objectives that stakeholders wish to achieve this approach seeks to avoid the solutions various stakeholder groups resent the most. This ‘N dimensional potato approach’ proposed here treats the decision space as analogous to a partially rotten potato that has to be prepared for the table: each group of stakeholders cut away those parts of the decision space that they consider unacceptable. Ideally, this would leave a decision space where somewhat acceptable compromise solutions exist. But, if no decision space is left after all have made their cuts, this approach will still inform managers about the consequences of different solutions in terms of which group will be disappointed and by how much. Making this approach operational requires both uncovering various stakeholders’ views of the unacceptable areas, and also displaying these areas in a convenient fashion together with areas of stakeholder consent. The article describes the steps taken to address these two tasks by the North Sea case study of the MareFrame research project.