Evert Bouman
Norwegian University of Science and Technology
Evert Bouman is a researcher at the Industrial Ecology Programme at the Norwegian University of Science & Technology (NTNU). He completed his PhD in Industrial Ecology in 2015 at NTNU and holds an MSc in both Industrial Ecology and Chemical Engineering from Leiden University and Delft University of Technology.
During his PhD, he worked on the environmental impact assessment of low-carbon electricity generation in combination with power market modelling. Currently, Evert is responsible for developing a life-cycle based assessment model to aid in the design of environmentally friendly maritime transport. In this model, life cycle assessment (LCA) is applied and combined with shipping route statistics to capture accurate operational profiles that feed data into the LCA model.
International ship transport accounts for a significant amount of annual anthropogenic greenhouse gas (GHG) emissions, though emissions per unit ship transport are relatively low compared to other transport modes. However,... [ view full abstract ]
International ship transport accounts for a significant amount of annual anthropogenic greenhouse gas (GHG) emissions, though emissions per unit ship transport are relatively low compared to other transport modes. However, projected demand increases exceeding 200% in some scenarios, necessitate emissions reduction of the sector. Various emissions mitigation and abatement options are available to reduce impacts resulting from ship operation. In order to make substantial emissions reductions, it is often necessary to combine independent measures, such as the use of cleaner burning fuels and the installation of scrubbers to clean exhaust gases.
In this study, we focus on hybridization of the drivetrain as a means of reducing environmental impacts of shipping. We perform a process-based comparative life cycle assessment (LCA) of two bulk carrier ships: one with a conventional marine diesel engine and one with a hybrid set-up. Within shipping, dry bulk carriers carry a total of 4.8 million metric ton of commodities annually, emitting approximately 166 Mton CO2. The rationale for hybridization is that the specific fuel oil consumption (SFOC) of a marine engine is dependent on engine load, with lowest SFOC occurring at a specific optimal load. During operation, engine load often lies far away from this ideal operating point, resulting in considerably higher SFOC per unit energy output. Hybridization of the drivetrain, by means of a battery, allows for utilization of a smaller engine operating longer times within its optimal range. Excess energy can be temporarily stored in the battery and is used when more energy is required than the smaller engine can provide.
We model the Life Cycle Inventory (LCI) at a high level of detail, based on estimations of engine load during several modes of operation, and account for different engine emission factors. In addition, we include ship construction, fuel oil production, battery production, and ship end-of-life explicitly in the model. Ecoinvent v3.2 and ReCiPe v1.11 are used as LCI database and impact assessment method.
We show a minor reduction in combustion related environmental impact categories during the operation of the hybrid bulk carrier compared to the conventional carrier. This is especially relevant for cases in which simultaneously speed is reduced to below design speed. However, reduction in impacts during operation is largely offset by additional impacts associated with battery construction and battery end-of-life. The results indicate that the life cycle model is sensitive towards initial assumptions about the energy storage capacity of the battery. Therefore, a better understanding of hybrid operation and the interplay between battery and main engine is required to optimize battery size, while simultaneously not compromising operational constraints. Smaller battery storage capacity minimizes environmental impacts resulting from hybridization. Hybridization as an impact mitigation strategy is therefore only viable under certain conditions.
• Life cycle sustainability assessment , • Business and industry practices / case studies , • Sustainable consumption and production
