Shipping decarbonisation is a challenge that can only be tackled by a holistic approach that combines advancements in technology, optimisation of the ship design, taking into account also the decarbonisation solutions, operational strategies, whilst considering economic incentives and policies. Although several technological innovations in different ship areas (hull, propulsion, fuel, and others) are contributing towards decarbonisation, and operational strategies such as slow steaming, have been proposed, in practice, selecting the most effective ones for a specific ship and timeframe represents a multifaceted problem which slows down progress. This chapter's main focus is on how digital twining (DT) can support the selection of decarbonisation technologies and operational strategies in designing decarbonisation solutions in a rolling time-horizon to meet regulations with the goal of achieving green shipping (zero-emission shipping) by 2050. For this a DT-centric design methodology is described offering shipping companies continuous decision support to manage the decarbonisation transition, utilising a multi-objective optimisation approach that balances the conflicting goals of minimising investment, maximising profitability, and reducing emissions in line with regulations. Both solutions for retrofitting existing ships and new buildings are considered. Furthermore, the chapter illustrates the application of DTs to specific use cases, namely energy production, distribution, and recovery onboard process management with the help of a simulator, and hull performance prediction utilising simulation.
TopIntroduction
International shipping provides 80–90% of global trade, but strict environmental regulations around NOX, SOX and greenhouse gas (GHG) emissions create new imperatives for short-, medium- and long-term emission reduction targets. As shown in an EU survey (EU, n.d.), in 2018 the global shipping emissions represented 1076 million tonnes of CO2, which represents the 2.9% of global emissions caused by human activities. In that review it was also projected that, if no actions will be taken, the emissions from shipping can be increased by up to 130% of the 2008 baseline by 2050, which are far from the EU targets.
The shipping industry emissions generation continues to rise due to increased global trade and the growing demand for maritime transport. The greatest source of GHG emissions are the container ships, bulk carriers, and oil tankers, however due to their larger engines, their emissions intensity (emissions per unit of cargo transported) is often more favourable compared to smaller vessels (Olmer et al, 2017).
Figure 1.
Number of ships and their carbon emissions by category in 2017
The pathway to achieving the international target of 50% GHG reduction by 2050, which has been recently upped to 100%, is not certain, but numerous promising options exist. Efficiency measures, for GHG reductions can be classified along three axes:
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Operational efficiency, e.g., slow-steaming.
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New, more efficient ship designs and,
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Utilisation of renewable resources, such as wind, and carbon free or low carbon emitting fuels.
There is clearly no single route, and a multifaceted response is required for managing decarbonisation pathways for each ship. The scale of this challenge is explored by estimating the combined decarbonisation potential of multiple options. A recent study by Transport and Environment on Decarbonisation pathways for EU-related shipping concludes that a mix of different technologies is required to achieve the International Maritime Organization's (IMO) and EU targets leading to 2050 zero emission shipping. For instance, 50% decarbonisation with LNG or electric propulsion would likely require four or more complementary efficiency measures to be applied simultaneously. Broadly, as GHG reductions need to be achieved at increasing rates over the next 30 years we can differentiate between short- and long-term approaches. Short-term approaches can include operational changes and fuel switching, while long-term efforts involve developing and adopting new technologies and infrastructure.
The complexity of the challenge in achieving the IMO required emission reduction rates leading to full decarbonization underscores the need for a holistic and multifaceted approach. It also highlights the importance of ongoing research and development, investment in clean technologies, and global cooperation to transition the maritime industry toward zero-emission shipping by 2050 and beyond.
The Chapter is organised as follows:
The next section discusses the most important energy efficiency measures set by organisations such as IMO which current and future ships must adhere to. These provide the yardsticks against which decarbonisation technologies will be evaluated.
Section 3 outlines a methodology that employs digital twins to select and evaluate decarbonization measures for the physical ship. Then it describes methods to assess the effectiveness of specific decarbonization technologies and how these results can have added value employing a knowledge hub within a dataspace. Two applications of DTs for the selection and deployment of decarbonisation solutions are described in sections 4 and 5, pertinent to waste heat recovery and hull performance, respectively. The final section of the chapter reviews the potential of the presented methodology for the optimal selection of current and future decarbonisation technologies and resources.