Paths forward for Sustainable Maritime Transport - A techno-economic optimization framework for next generation vessels

Abstract

Recently, the decarbonization of maritime transport has received increased attention, in order to align with the targets of the Paris Agreement. In 2023, the International Maritime Organization unveiled their revised greenhouse gas strategy with an ambitious target: net-zero emissions by 2050. Addressing this challenge necessitates significant investments in technologies that enable net-zero emissions during vessel operations. While net-zero fuels present an environmental solution, their economic viability remains a challenge under present conditions. This thesis presents a comprehensive techno-economic framework tailored to assess investments in net-zero vessels.

A review of existing literature reveals that investing in vessels involves intricate decisions, often accompanied by high capital costs. Crucially, voyage costs, primarily determined by fuel expenditures, emerge as pivotal in assessing a vessel's financial sustainability. This insight underscores the need for an integrated approach that combines economic considerations with fuel efficient operation. To this end, the study introduces a dual-layer optimization framework: The outer layer optimizes for the vessel's net present value, while the inner layer models the vessel's operational control strategy. The applicability of this framework is then tested using the German container ship sector as a case study. The applied technology consists of a fuel cell electric propulsion system based on hydrogen.

The findings paint a complex picture. Net-zero vessels necessitate considerably higher capital expenditures than their diesel counterparts. The propulsion system contributes to this increase, but the main share of the cost arises from the liquified hydrogen storage system, accounting for 63% of the total costs. Furthermore, frequent replacements exacerbate costs, leading to an increase in capital expenditures of 3 times over the diesel base case. In contrast, the impact on the revenues is expected to be incremental. The cost of lost cargo is estimated at 0.2% of the total carrying capacity. In total, the investment case for the net-zero vessel is positive with an NPV of approximately 120 mil. USD and a payback after 6.48 years, however, still less attractive compared to the diesel base case.

In evaluating future scenarios, the study posits that achieving cost parity between net-zero and conventional vessels is plausible by early 2030. This projection suggests an alignment with currently demanded maritime and environmental regulations within the next decade.