Design of an offshore wind farm and power fluctuations handling via thermal power plants and energy storage - A case study of Vindplas Göteborg

This report consists of two distinct parts. The first one is focused on the design of an offshore wind farm based on a project called Vindplats Göteborg and led by Göteborg Energi AB. This survey encompasses the site assessment, the choice of foundations, cables and turbines as well as the optimization of the layout and the calculation of the energy output. The second part of this report is an investigation of the technical potential to compensate the power fluctuations entailed by the wind farm previously designed. Two major technologies have been explored to be used as energy back-up: the Rya Combined Heat and Power plant (CHP) owned by Göteborg Energi AB and a Vehicle to Grid (V2G) system to be implemented in Göteborg area. The design of Vindplats Göteborg wind farm was performed in the perspective of learning engineering know-how within the field of wind power and trying to develop innovative tools to assess and optimize the power production of a wind farm. The study of the compensation of the fluctuations was driven by the significant growth of wind power in Europe entailing a strong dependence on the power exports, especially for countries that became large wind power producers. The issues related with power quality and frequency fluctuations involve a very small time resolution and will not be addressed in the present study. The site assessment performed in the first section combined with the economic evaluation of the project indicate that the construction of 9 turbines Vestas V164 seem to be the most cost-effective and well adapted choice considering the available space in the prospected area. The optimization of the layout enables to reach the annual energy output of 200 GWh and the investigations on the potential power fluctuations shows that 20 MW/min ramp-down are to be expected under extreme wind conditions. The introduction of Vindplats Göteborg will save a significant amount of CO2 and increase the local electricity production capacity even though power imports are still required to meet the highly fluctuating demand. A V2G system can back-up the wind farm in case of extreme wind conditions up to a 24h-outage but requires then almost 50% of the current fleet to be electric cars. The Rya CHP plant does not have the reserve power and a sufficient ramp-rate to back-up Vindplats Göteborg wind farm but several improvements could be done to ensure both the heat supply and a local steady electricity production. The fast-response of the V2G system combined with upgraded gas turbines could however be an optimal solution to compensate the wind power fluctuations and in term, the local consumption pattern, hence reducing the maximal transfer capacity and the dependence on the surrounding network