Energy-efficient hydrodynamic design of ships for inland waterways of Bangladesh based on fuel consumption and emission control

Abstract

The adoption of the Energy Efficiency Design Index (EEDI) by the International Maritime Organization (IMO) for seagoing ships has improved the situation, however, controlling emissions from inland shipping was included in the national target. As a result, though the reduction possibility of CO2 emission from inland shipping found a significant prospect, the world lacks real-time emission data for inland waterways. In addition to that, the other carriers that compete with inland navigation are making advances in reducing their greenhouse gas emissions. To retain the competitive advantage of inland navigation as being ‘low cost’ and ‘environmentally friendly, the inland shipping industry also needs to further reduce its greenhouse gas emissions. The focus of this study is to reduce CO2 emissions from inland ships of Bangladesh by developing an energy-efficient ship design method based on fuel consumption and emission control.

It has been observed that direct use of the EEDI by IMO formulation for the inland ships will not provide the correct result. The prime reason is the effect of shallow water on the ship resistance. In addition to that, cargo availability and fuel quality issues for the inland vessels of Bangladesh forbid the use of IMO guidelines. Furthermore, a generalized formulation is not possible for inland ships either, mainly because of the variations in the geographic condition, economic size, and inland maritime law. Therefore, the EEDI formulation needs to be modified to be useful for an individual country.

To find out the necessary modification of EEDI by IMO to be useful for inland ships of Bangladesh, several field visits, investigations, and laboratory tests have been conducted. The results of these visits, investigations and tests have been used to quantify the hydrodynamic effect of shallow water on ship resistance, actual average operational condition, cargo availability and actual carbon content in fuel. These corrections have been integrated with EEDI by IMO which has been used for the inland ships of Bangladesh.

To quantify and set up the CO2 emission level of the Inland Maritime sector of Bangladesh, verified ship data and operational profiles are necessary. A good number of inland ship data were collected which have undergone several data verification processes. Using the verified ship data, EEDI baselines for Bangladeshi inland cargo, oil tanker and passenger ships were established. These baselines are one of the first steps in the world for inland ships using verified ship data and are termed as EEDIBD.

To a ship design method that will ensure the reduction of CO2 emission, sensitivity analysis has been carried out. Three existing ships (cargo, oil tanker and passenger) of Bangladesh have been analysed in

EEDI by IMO aimed at the reduction of CO2 emission from the atmosphere, stepwise. To do that IMO provides several guidelines, which are most appropriate for seagoing ships. This research assessed the possibility to reduce CO2 emission from the current stage. To do that, a sensitivity analysis was carried out on the inland ship design parameters of Bangladesh.

The outcome of the sensitivity analysis is a set of inland ship design suggestions that will lower the EEDIBD value from the current stage. These ship design suggestions have been implemented on three existing inland ships (cargo, oil tanker and passenger) of Bangladesh. These existing ships resistance have been examined in commercial Computational Fluid Dynamics (CFD) software, named ‘Shipflow.’ Those ships’ designs have been improved based on the ship design suggestions and reanalysed in the same CFD software. For fare comparison, the capacity and speed of both parent and the redesigned ship kept the same. It has been found that remodelled ship designs have 10-15% less resistance in comparison with the parent hull.