Comparison of the capacity factor of stationary wind turbines and weather-routed energy ships in the far-offshore

Abstract

Offshore wind energy technology has developed rapidly over the last decade. It is expected to significantly contribute to the further increase of renewable energy in the global energy production in the future. However, even with floating wind turbines, only a fraction of the global offshore wind energy potential can be harvested because grid-connection, moorings, installation and maintenance costs increase tremendously as the distance to shore and the water depth increase. Thus, new technologies enabling harvesting the far offshore wind energy resource are required. To tackle this challenge, mobile energy ship concepts have been proposed. In those concepts, electricity is produced by a water turbine attached underneath the hull of a ship propelled by the wind using sails. It includes an on-board energy storage system since energy ships are not grid-connected. Thus, the ships route schedules could be dynamically optimized taking into account weather forecast in order to maximize their capacity factors (CF). The aim of this study is to investigate how high the capacity factors of energy ships could be when using weather-routing and compare them to that of stationary wind turbines that would be deployed in the same areas. To that end, a modified version of the weather-routing software QtVlm was used. Velocity and power production polar plots of an energy ship that was designed at LHEEA were used as input to QtVlm. Results show that capacity factors over 80% can be achieved with energy ships and stationary offshore wind turbines deployed in the North Atlantic Ocean.

Exploitation of the far-offshore wind energy resource by fleets of energy ships. Part A. Energy ship design and performance

“…In comparison to the power production polar plots of the FARWINDER considered in (Abd-Jamil et al, 2019), the energy ship proposed in this study is able to produce more power and in a greater range of wind conditions. Therefore, its capacity factor can be expected to exceed the value of 80% reported in (Abd-Jamil et al, 2019). However, that estimation did not take into account downtime due to planned and unplanned maintenance (availability).…”

“…Since energy ships are mobile, their route schedules can be dynamically optimized based on weather forecasts in order to maximize energy production. This was performed by Abd-Jamil et al (Abd-Jamil et al, 2019) for a 1 MW energy ship deployed in the North Atlantic Ocean, assuming the arrival point to be the same as the starting point, whose coordinates are: N 54.51660; W 27.551844 (mid-distance between Ireland and Newfoundland, Canada). Over the three years 2015, 2016 and 2017, it was found that an average capacity factor of over 80% can be achieved.…”

“…Moreover, high capacity factors could be achieved as the wind energy resource is the strongest and the steadiest at sea (Liu et al, 2008). In this respect, it has already been shown that capacity factors greater than 80% could be obtained for floating grid-connected stationary offshore wind turbines deployed in the far-offshore (Dupont et al, 2018;Abd-Jamil et al, 2019). However, it is not possible to deploy such turbines because grid-connection cost, moorings and installation cost, and maintenance increase dramatically as distance to shore and water depth increase (Offshore wind programme board, 2016).…”

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

“…They can be operated between 20 % and 100 % of their design capacity, and capacity can be varied from 20 % to 100 % in approximately 10 min (Agersted, 2014). Their use in the offshore environment was studied in the H2OCEAN European project (Agersted, 2014), which concluded that it is feasible. Thus, the AEL technology has been retained for the FARWINDERs.…”

“…Moreover, high capacity factors could be achieved as the wind energy resource is the strongest and the steadiest in the open ocean (Liu et al, 2008). In this respect, it has already been shown that capacity factors greater than 80 % could be obtained for floating gridconnected stationary offshore wind turbines deployed in far offshore (Dupont et al, 2018;Abd-Jamil et al, 2019). However, it is not possible to deploy such turbines because gridconnection cost, moorings and installation cost, and main-A.…”