Bulk Electricity Sea Transport from Remotely Located Power Plants

Electricity is one of the most utilized energy carriers for energy transmission in the world. In recent years more electricity is generated from renewable energy sources. The main drawback of renewable energy sources is that renewable energy power plants are often connected to certain locations. Sometimes these renewable energy power plants are located in very long distant areas across the sea, so consequently bulk electricity transport to major electric power consuming areas across the sea is not done due to economical difficulties. Therefore the aim of the report is to develop and to analyse different electricity transport concepts to achieve bulk electricity transport across the sea in energy efficient and cost efficient manner. In this case the feasibility of bulk electricity transport between the hydroelectric and geothermal energy sources in Iceland and the electric power consuming areas such as Scotland and European mainland is investigated. During the development of the electricity transport concepts three electricity transport concepts emerged. The three electricity transport concepts are the submarine electric power transmission, the battery ship and the synthetic fuel. In the study the three electricity transport concepts are further developed and analysed. The three electricity transport concepts are analysed by investigating the energetic performance and the cost performance of the three electricity transport concepts for the distances from 0 nautical miles till 6000 nautical miles. In addition the influence of the cost per MWh of power plants on the three electricity transport concepts is examined for the distances of 500 nautical miles and 1000 nautical miles. Currently the electric power transmission with submarine electrical power cables is the only way to deliver electrical energy across the sea. The electric power transmission system is composed of two converter stations and one or two submarine power cables. The other electricity transport concept consists of a battery ship and two small offshore terminals. The battery ship is a 300.000 dwt ship with integrated redox flow batteries. The battery ship is charged and discharged at small offshore terminals. In this report the battery ship is developed till conceptual design. The last electricity transport concept consists mainly of a production plant for the conversion of electricity into synthetic fuel, a cargo ship and a power plant. In the thesis different synthetic fuels are compared. The different synthetic fuels are hydrogen, ammonia, methanol, ethanol, dimethyl ether (DME), sodium borohydride and zinc. The results of the investigation are that the synthetic fuels hydrogen and ammonia are attractive synthetic fuels for bulk electricity sea transport. Hence follows that the bulk electricity sea transport by means of compressed hydrogen and ammonia is examined in more details and afterwards the two synthetic fuels are compared. The comparison shows that ammonia is a more energy efficient and cost efficient synthetic fuel than hydrogen, so ammonia is the appropriate synthetic fuel for the purpose of bulk electricity sea transport. Finally, all electricity transport concepts are compared with each other and evaluated.Section Ship Design, Production & OperationMechanical, Maritime and Materials Engineerin