Waste heat recovery steam systems techno-economic and environmental investigation for ocean-going vessels considering actual operating profiles

Abstract

Waste heat recovery steam systems is a proven technology for improving the ship power plant efficiency and reducing the ship environmental footprint, thus their usage can respond to the pressure for decarbonising the shipping operations. This study aims at investigating the techno-economic feasibility of various waste heat recovery steam systems whilst assessing their environmental impact for three ocean-going tanker vessels with their type spanning from Handymax size to very large crude carriers. Thermodynamic modelling of the investigated systems is employed for estimating the systems performance parameters including the generated electric power and fuel savings taking into account the vessels actual operating profiles and typical annual voyages characteristics. The systems net present value and the profitability index indicators are employed for assessing the systems economic feasibility, whereas the systems environmental impact is evaluated by using the achieved annual carbon dioxide emissions reduction. Two different nominal turbo-generator sizes matching the ship main engine full-load and part-load conditions are investigated, whereas a sensitivity analysis on the fuels prices is carried out to identify the marginal fuel price that renders the investment of each investigated system profitable. The derived results demonstrate that the single pressure waste heat recovery system sized for the ship engine part-load operation provides an attractive solution depending on the vessel type considering the technical, economic and environmental parameters. This study results in better insights on the impacts of the investigated energy efficiency improvement technologies for tanker ships, thus it can prove useful support for designing future sustainable ship power plants.