Abstract
The goal of reducing the climate impact of shipping requires many different activities. To reduce greenhouse gas emissions, the International Maritime Organization prepared some proposals to meet and fulfill the requirements. It sets out the provisions of the International Convention for the Prevention of Pollution from Ships 73/78 Annex 6—Prevention of the Air Pollution from Ships (1997) with the amendments and the future objectives set. The main objective is to achieve climate neutrality from shipping by 2050. One method is the decarbonization of marine fuels. The types of fuels that are transient fuels, with the final target fuel being hydrogen, are shown. Carbon dioxide emissions depend on the chemical composition of the fuel, its Lower Heating Value and the engine efficiency. The aim of the manuscript is to demonstrate that the use of fuels with lower carbon content is a transitional process enabling the hydrogen era to take place. An analysis of this problem is presented as a review of the subject along with the author’s comments and observations. The development of technologies for adapting potential fuels to combustion requirements in marine diesel engines and gas turbines, together with their storage and bunkering capabilities, are the main barriers to their limited use. The efficiency of marine diesel engines reaches a value of about 50%, while that of fuel cells are close to 100%. It seems that hydrogen will be the fuel of the future, including in shipping. Its basic use is in fuel cells, the efficiency of which is almost twice that of current thermal internal combustion engines.