Renewable energies are the future, and offshore wind is undoubtedly one of the renewable energy sources for the future. Foundations of offshore wind turbines are essential for its right development. There are several types: monopiles, gravity-based structures, jackets, tripods, floating support, etc., being the first ones that are most used up to now. This manuscript begins with a review of the offshore wind power installed around the world and the exposition of the different types of foundations in the industry. For that, a database has been created, and all the data are being processed to be exposed in clear graphic summarizing the current use of the different foundation types, considering mainly distance to the coast and water depth. Later, the paper includes an analysis of the evolution and parameters of the design of monopiles, including wind turbine and monopile characteristics. Some monomials are considered in this specific analysis and also the soil type. So, a general view of the current state of monopile foundations is achieved, based on a database with the offshore wind farms in operation.

In recent years, the offshore wind industry has seen an important boost that is expected to continue in the coming years. In order for the offshore wind industry to achieve adequate development, it is essential to solve some existing uncertainties, some of which relate to foundations. These foundations are important for this type of project. As foundations represent approximately 35% of the total cost of an offshore wind project, it is essential that they receive special attention. There are different types of foundations that are used in the offshore wind industry. The most common types are steel monopiles, gravity-based structures (GBS), tripods, and jackets. However, there are some other types, such as suction caissons, tripiles, etc. For high water depths, the alternative to the previously mentioned foundations is the use of floating supports. Some offshore wind installations currently in operation have GBS-type foundations (also known as GBF: Gravity-based foundation). Although this typology has not been widely used until now, there is research that has highlighted its advantages over other types of foundation for both small and large water depth sites. There are no doubts over the importance of GBS. In fact, the offshore wind industry is trying to introduce improvements so as to turn GBF into a competitive foundation alternative, suitable for the widest ranges of water depth. The present article deals with GBS foundations. The article begins with the current state of the field, including not only the concepts of GBS constructed so far, but also other concepts that are in a less mature state of development. Furthermore, we also present a classification of this type of structure based on the GBS of offshore wind facilities that are currently in operation, as well as some reflections on future GBS alternatives.

The scour phenomenon is critical for monopile structures in offshore wind farms. There are two possible strategies: allowing the development of scour holes around the monopile or avoiding it by placing scour protection. The last one is the most used up to now. This paper is focused on the determination of the weight of the stones forming the scour protection. There are some formulas for the design of these parameters, having a lot of uncertainties around them. Some of them were created for fluvial environment, with a different flow to the marine one. Other formulas were elaborated specifically for coastal structures, closer to the coast than offshore wind farms, and with dimensions completely different. This paper presents the analysis of three formulas: Isbash, corresponding to fluvial environment, and Soulsby, and De Vos, corresponding to marine environment. The results of the application of those formulas are compared with real data of scour protection systems showing good results in five offshore wind facilities in operation (Arklow Bank phase 1, Egmond aan Zee, Horns Rev phase 1, Princess Amalia, and Scroby Sands), giving conclusion about the uncertainties of the use of these formulas and recommendations for using them in offshore wind.

Renewable energies play a fundamental role within the current political and social framework for minimizing the impacts of climate change. The ocean has a vast potential for generating energy and therefore, the marine renewable energies are included in the Sustainable Development Goals (SDGs). These energies include wave, tidal, marine currents, ocean thermal, and osmotic. Moreover, it can also be included wind, solar, geothermal and biomass powers, which their main use is onshore, but in the near future their use at sea may be considered. The manuscript starts with a state-of-the-art review of the abovementioned marine renewable energy resources worldwide. The paper continues with a case study focused on the Spanish coast, divided into six regions: (I) Cantabrian, (II) Galician, (III) South Atlantic, (IV) Canary Islands, (V) Southern Mediterranean, and (VI) Northern Mediterranean. The results show that: (1) areas I and II are suitable for offshore wind, wave and biomass; (2) areas III and V are suitable for offshore wind, marine current and offshore solar; area IV is suitable for offshore wind, ocean wave and offshore solar; (3) and area VI is suitable for offshore wind, osmotic and offshore solar. This analysis can help politicians and technicians to plan the use of these resources in Spain.

Climate change is one of the issues of greatest concern to today’s society. The increase in temperatures has affected sea levels, polar masses and extreme events, among others. There are many scientific studies that analyze the impacts of climate change on coastal communities, but most of them focus on beach erosion and coastal recession. Scientific literature on the effects of climate change on ports and harbors and their adaptation is much less abundant. Ports are essential for the economy and society of their cities, so studying the impact of climate change on them is an urgent need. The Mediterranean and the Spanish Mediterranean coast is one of the areas that will be most affected by climate change in the future. In addition, the Spanish economy depends a lot on its tourism and, thus, on its coastal cities. Therefore, the study of the impact of climate change on Spanish ports and coastal communities is essential. This article presents a review of the studies carried out until now on the effects of climate change on Spanish ports, and it identifies research gaps and weaknesses and suggests new research lines.