Low-carbon technology selection and carbon reduction potential assessment in the shipbuilding industry with dynamically changing grid emission factors

The shipbuilding industry is a vital sector involved in manufacturing ships and marine structures. It serves critical roles in shipping, maritime development, and national defense, which contributes significantly to employment, international trade, and national security. Nevertheless, the shipbuilding industry is under enormous pressure to curtail carbon emissions. The International Maritime Organization (IMO) requires a 40% reduction in greenhouse gas emissions (GHG) from both existing and new ships by 2030 compared to the 2008 baseline. This stems from the industry's high-carbon emission nature, making it imperative to adopt sustainable solutions that minimize its environmental impact. Given the capital- and energy-intensive nature of the shipbuilding industry, the implementation of suitable technologies can also improve the overall operational efficiency while meeting shipowners' sustainability standards and enhancing competitiveness. We selected a typical shipbuilding company in South China and categorized the 11 key low-carbon technologies into four categories based on their principles and application scenarios, i.e., equipment improvement, process upgrading, intelligent upgrading, and fuel alternative. The Long-range Energy Alternatives Planning system (LEAP) model was employed in this study to simulate the energy consumption structure of this shipbuilding enterprise and explore pathways to reach carbon emissions peak under six low-carbon technology scenarios. In addition, the impact of dynamically changing grid emission factors on long-term carbon emission reduction is taken into consideration. The results show that a sustained reduction in grid emission factors will have a positive impact on carbon emission reduction. The shipyard's planned requirements to achieve carbon peak before 2030 and reduce its carbon intensity by 18% from 2020 are only achievable under the application of all low-carbon technologies. The shipyard will achieve carbon peak in 2026, with a maximum emission reduction potential of 13.2 thousand tons. The primary contributors are equipment improvement and process upgrading technologies, with reductions of 6.73 and 3.11 thousand tons, respectively. Therefore, from a technical point of view, these can be prioritized for development, although some of the equipment has a high upfront investment. Notably, the technology diffusion is rapid, with most technologies projected to reach penetration saturation by 2025, leading to a payback period of 3-4 years thereafter.