Exploitation of the far-offshore wind energy resource by fleets of energy ships – Part 1: Energy ship design and performance

Abstract

<jats:p>Abstract. This paper deals with a new concept for the conversion of far-offshore wind energy into sustainable fuel. It relies on autonomously sailing energy ships and manned support tankers. Energy ships are wind-propelled. They generate electricity using water turbines attached underneath their hull. Since energy ships are not grid-connected, they include onboard power-to-X plants for storage of the produced energy. In the present work, the energy vector is methanol. The aim of the paper is to propose an energy ship design and to provide an estimate for its energy performance as function of the wind conditions. The energy performance assessment is based on a numerical model which is described in the paper. Results show that the wind energy-to-methanol (chemical energy) conversion efficiency is 24 % and that such an energy ship deployed in the North Atlantic Ocean could produce approximately 5 GWh per annum of chemical energy (900 t of methanol per annum). </jats:p>

Optimal strategies of deployment of far offshore co-located wind-wave energy farms

“…The European Union considers hydrogen a key element in the ongoing efforts towards a cleaner economy, among other things, because it is an area where Europe is still leading [75]. In recent studies, on account of the low volumetric energy density of the hydrogen (in standard conditions of temperature and pressure), the use of methanol is proposed for energy storage in energy ships [18]. According to these studies, many advantages are related to the use of methanol instead of hydrogen, such as, a good efficiency in the production, a high market value and its liquid state in standard temperature and pressure conditions.…”

“…To avoid the difficulties associated to the anchoring/ mooring in far offshore locations, mobile offshore energy harvesting solutions have been proposed as well. These mobile technologies can be divided in two main groups: Sailing wind turbines [16] (the power is produced by a wind turbine located in the ship) and energy ships [18] (the power is produced by a turbine located at the hull of a wind propelled ship).…”

Conceptual Study and Development of an Autonomously Operating, Sailing Renewable Energy Conversion System

“…By comparing the sizes, the NIES proposal stands out with a length of around 2 km [3]. The concept design (74.3 m) and the FARWIND energy ship (31.7 m) [5] are on a much smaller scale. The same relationship holds for the electrical power output.…”

“…The ability to yaw the rotor enables a wide range of operating states to account for changing wind speeds and directions. The power generation could be described in the form of a polar plot as done by Babarit et al [5]. Based on a conservative estimation and since the SailREC System is smaller and therefore more manoeuvrable than the sailing type offshore wind farm by the NIES [3], a capacity factor of 50% is assumed.…”

“…To dimension the Buoyancy Component, the total mass of the SailREC System needs to be compensated for by the mass of water displaced. Considering the masses of all subsystems and components as listed in Table 3-with reserving 200 t for additional equipment and assuming the structural mass to be 40% of the system mass as done by Babarit et al [5]-a system mass of 1553 t is obtained. The displaced water volume, however, is increased by 20% to account for the floodable sections, resulting in a total of 1864 m 3 .…”