Bachelor’s Thesis

Name:

David Martín Rodríguez

Year: 2018

Degree:

Degree in Electrical Engineering

Tutor(s):

Teodoro Adrada Guerra

Renewable energy sources will undoubtedly prevail over traditional energy sources in the not too distant future. The rise of renewable energies will not only occur for reasons of environmental ethics, but also because of the need for alternative energy sources in the face of the depletion of traditional energy sources, such as oil, coal or natural gas, among others. It is for this reason and because of the great importance of wind energy production worldwide, and especially in Spain, that I have decided to carry out a final degree project on an increasingly fashionable subject such as offshore wind farms.

The main advantage of offshore wind farms is their energy production, which is 50% higher than that of onshore wind farms. This is mainly due to the low turbulence caused by the absence of obstacles in the sea to slow down the wind and a very low roughness coefficient which is reflected in the vertical profile of the wind speed, with high wind speeds at lower heights.

With regard to the project, a location with great wind potential has been chosen for the installation of the wind farm in the region of Cadiz, close to a large centre of energy consumption such as the city and port of Cadiz, specifically 27 km from Cape Trafalgar, The main idea was to try to reduce costs with regard to the type of foundation, as this location gave us the opportunity to use monopile foundations, which is the foundation par excellence in this type of wind farm, as approximately 80% of the farms currently use this type of structure. The wind study demonstrated the great potential of this area of Spain, since with only four wind turbines of 8 MW each, we were able to obtain an energy production, applying the corresponding loss factors, of approximately 133 GWh per year.

The electrical infrastructure of the wind farm consisted mainly of an internal 33 kV network starting at each of the four wind turbines. starting at each of the four wind turbines and running to the offshore substation.

At the substation, the voltage was raised from 33 kV to a transmission voltage of 132 kV, sufficient to minimise energy transmission losses. On leaving the substation, the 132 kV grid connected to an onshore substation from which a 132 kV overhead line ran to the Nuevo Parralejo substation, located at a distance of 10 km. The electrical infrastructure of these wind farms represents a significant percentage of the project’s investment. The economic study showed an initial investment cost of 113.34 million euros. Analysing some parameters to evaluate the profitability of the investment, such as NPV, IRR and pay-back, showed a clear rejection of the investment project since it generated losses and, in addition, the initial investment was not recovered during the years of operation of the wind farm.

Probably the main reason for the disastrous economic outcome is the size of the farm, which is comparatively very small compared to the large offshore wind farms that have been built in the last decade in the North Sea. On the other hand, the costs of offshore wind farms are very high compared to onshore wind farms, with high investment, operation and maintenance costs. In Spain, for a project of this type to be profitable, better remuneration would be needed, as there is currently no distinction in remuneration between wind farms located on land. 102 remuneration between onshore and offshore wind farms. Likewise, the economic savings that these wind farms represent in terms of 𝐶𝑂2 penalties and the savings in the purchase of fossil fuels could be invested in subsidies for this type of wind farm, thus making the construction of this type of facility more attractive.