UT7. Parques Eólicos Marinos - Offshore PDF

# Gestión del Montaje de Parques Eólicos ## Parques Eólicos Offshore ### UT7. PARQUES EÓLICOS MARINOS - OFFSHORE - C.F.G.S. ENERGÍAS RENOVABLES ## Introduction The energy of marine origin, the so-called “Blue Energy”, is one of the levers for the energy transformation in the medium and long term a...

# Gestión del Montaje de Parques Eólicos ## Parques Eólicos Offshore ### UT7. PARQUES EÓLICOS MARINOS - OFFSHORE - C.F.G.S. ENERGÍAS RENOVABLES ## Introduction The energy of marine origin, the so-called “Blue Energy”, is one of the levers for the energy transformation in the medium and long term at national, European, and global level, as well as an industrial, economic, and social opportunity for our country. The offshore wind energy is accelerating its technological and industrial development, making its implementation viable in Spain thanks to the concepts related to floating offshore wind energy that allow its deployment in deep waters. Due to its high capacity factors, offshore wind energy can generate electricity in a stable and predictable manner, increasing production in the fall and winter seasons when there is less solar radiation and higher consumption. It therefore presents a high degree of complementarity with other renewable energies, contributing to supply security, adding value to the needs of the energy system, and allowing better use of endogenous resources. ## Characteristics of Marine Wind Energy Offshore wind installations present different and advantageous characteristics compared to wind installations onshore. The wind resource in the sea is higher and more regular than on land, increasing the electricity generation of wind turbines with the same dimensions. ### Conditions of the wind at sea - **Low roughness and few obstacles:** The surface of seas and lakes is obviously very smooth, so the roughness of the sea surface is very low (at constant wind speeds). With increasing wind speeds, part of the energy is used to produce waves, which implies an increase in roughness. Once waves have formed, the roughness decreases again. Therefore, we have a variable roughness surface (the same is true in zones covered with more or less snow). However, if we generalize, we can consider that the roughness of the water surface is very low and that wind obstacles are few. When carrying out calculations, islands, lighthouses, etc., must be considered in the same way that obstacles located in the direction of where the wind comes from or the changes in roughness on land would be considered. - **Low wind shear implies lower hub height:** With low roughness the wind shear in the sea is also very low, which implies that the wind speed does not experience large changes when the hub height of the wind turbine varies. Therefore, it can be more economical to use rather low towers, around 0.75 times the diameter of the rotor, for wind turbines located at sea, depending on local conditions (generally, towers of wind turbines located on land measure a rotor diameter, or even more). - **Low turbulence intensity = longer lifetime of wind turbines:** Wind at sea is generally less turbulent than on land, so we can expect a longer lifetime for a wind turbine located at sea than for another located onshore. The low turbulence in the sea is due, above all, to the fact that the temperature differences at different altitudes in the atmosphere that exist above the sea are lower than those above land solar radiation can penetrate several meters below the sea, while on land, solar radiation only heats the top layer of the soil, which becomes much hotter. As a consequence, temperature differences between the surface and the air will be smaller over the sea than over land. This is what causes turbulence to be lower. ### Geography of the sea - The Continental Shelf is the zone of a continent that extends into the ocean becoming part of the seabed. It extends from the coast to a depth of 200 meters. There is no exact width of a continental shelf. The shelves can be as wide as the few meters up to several hundred kilometers. - The concept of continental shelf should be interpreted in two different ways, a concept or geological interpretation that has a scientific point of view. However, it should also be known that there is a legal figure, which is even recognized under international law of the sea. The continental shelf is of great importance for navigation and for its geological and biological value. However, despite this, it only represents 18% of the surface of our planet. From a legal standpoint, the first internationally accepted definition is that of the Geneva Convention of 1958. This convention defined it as the submarine zone that is located adjacent to the coast of a state, including its seabed and subsoil. . - The Continental Shelf is unevenly distributed, as countries with coastlines in the Pacific Ocean have practically no submarine continental shelves, whereas countries bordering the Atlantic Ocean have large ones ### Selection of the location - The exploitation of offshore wind resources is particularly suitable for countries with a high population density which face difficulties to find suitable locations onshore and have a windy coastline. Northern Europe is particularly well equipped for the exploitation of offshore wind energy, with wind speeds exceeding 8 m/s, at 50 m high, meaning there is a power density exceeding 600 W/m2. - To select a location for a wind farm, different parameters must be considered, such as bathymetry, availability of wind resources and terrain. - **Bathymetry** is the study of the seabed, that is, its depth and relief. This parameter is crucial in the installation of the wind farm, as it will determine the difficulty of installing the facility. - **Wind resource** is the amount of energy that can be harnessed from the wind. This parameter is also very important because wind turbines need to be located in areas where the wind is strong and consistent. - **Terrain** can influence the installation of wind turbines, particularly in terms of the ability to move heavy equipment and materials. - The seabed depth increases rapidly a few kilometers away from the coast, significantly reducing the installable surface as in the Mediterranean and Atlantic coasts. - When selecting a location, bathymetry and wind resource considerations must be combined, as they are usually inversely proportional criteria. The optimum location involves a balance between these two elements: a greater distance from the coast usually implies a lower environmental and landscape impact, but significantly increases the depth, making it more difficult to install. - In terms of terrain availability, a further constraint comes from the fact that the installation of energy facilities is prohibited in areas with protected flora and fauna. These protected areas are usually in coastal environments, which implies that the installable surface is further reduced, and therefore the useful area as well. ### The wind turbine - An offshore wind turbine, in other words, one installed at sea, allows the conversion of wind power into electricity. The offshore wind turbine operates according to the same principle as conventional onshore wind turbines, using wind kinetic energy to convert it into electricity. - The type used in offshore wind farms is largely based on the design and manufacturing of onshore wind turbines so the most common is a three-bladed upwind horizontal axis wind turbine. - If early offshore wind turbine prototypes were simple replicas of onshore wind turbines, the machines have subsequently adapted to sea conditions. Technological developments, particularly in the size and power of the machines expected, are characteristics of offshore wind turbines. - Offshore wind turbines are different from onshore wind turbines in their technical design, being specifically adapted to the marine environment. While they might appear identical, their operational conditions differ. - They are specifically designed to withstand corrosion. They also have specific sensors and have to withstand storms and stresses created by the surrounding water masses. - Different components are provided with multiple anti-corrosion protection (in all parts). The rotor has additional protection with a zinc metallised spraying. Furthermore, wind turbines commonly have a transition element that allows the connection between the support structure and the tower, correcting any deviations from the vertical. - The platform and the tower are fitted with humidity and temperature control systems to prevent any risk of internal corrosion. - The nacelle is fitted with two hydraulic cranes for handling tools and spare parts at any point of the wind turbine. ### Access to the wind turbine - There are two possibilities: - **By air:** Access is via a fibre ‘basket’ located at the end of the nacelle. This type of access system has longer operating hours than access by sea, as it is not affected by waves. However, this is a much more expensive system with a lower carrying capacity than sea access, so its use is now declining. - **By sea:** Access would be made via mooring areas and ladders located on the transition part of the supporting structure in each case. Steel tubes would have to be installed on either side of the ladder as a precaution against falls and protection against gusts of wind that would also ensure the relative position of the boat using the bow fastening. ### Foundations of offshore wind farms - Marine foundations are the most significant aspect of their specific features, as they have to be either anchored or submerged in the seabed. This topic is developed in the next section - On land, due to limitations associated with the topography and transportation, 5 MW is a maximum power of wind turbines, with a clear trend to increase the rotor size for better use of space. At sea, which poses fewer limitations for the transportation of different components, offshore wind farms have recently used wind turbines with powers greater than 8 MW, with prototypes under development reaching powers of 12 and 15 MW. There is a specific international standard for wind turbines used in offshore wind farms, IEC 61400-3. ### Technology in the foundations of offshore wind farms - We can distinguish two main types of offshore wind energy technologies: structures mounted on fixed structures and floating structures. The main difference lies in the way the wind turbine is anchored to the seabed. - So far, most offshore wind farms are not installed in areas where the depth exceeds 40 meters. - Some “inshore” installations in the open sea (more than 30 km from the coast), with floating bases, are now in the design phase. #### Wind turbines with fixed foundations - These are support structures built on the seabed and classified according to the foundation used in its construction: - **Monopile** (steel cylinder anchoring the tower to the seafloor). - **Gravity based** (concrete or steel platform that rests on the seabed). - **Jacket or Tripod** (structures with 3 or 4 points of anchorage). - So far, all commercial offshore wind farms globally (of which 80% are located in the North Sea of Europe) have been built using these fixed foundation concepts. #### Wind turbines on floating platforms - Floating structures offer significant opportunities for the offshore wind energy industry and open up new locations further from the coast. Fixed foundations were technically and economically unfeasible for deployment in such locations. However, the depth constraint now comes from the laying of electricity submarine cables, which reach several hundred meters deep. Floating concepts allow the deployment of wind turbines in vast marine areas with higher wind resources in deep water while also allowing turbines to be arranged in different configurations. - Floating support structures can be classified according to the seabed anchoring system, which can involve: - **Tension Leg Platform (TLP):** - **Spar (Floating monopile):** - **Semi-submersible Platform:** - Floating platforms allow the use of new techniques that minimize potential environmental impacts compared to fixed designs, due to less seabed disturbance during installation. And because of their location further out at sea, visual and acoustic impact is lower than for onshore wind farms. ## Future perspectives for the use of offshore wind resources - Europe has several zones with sufficient wind resources and seabed depth (water depth) suitable for the installation of offshore wind farms: North Sea, Baltic Sea, English Channel, South of France, Aegean Sea and the Atlantic coast of Andalusia. - Andalusia has a high offshore wind resource, which is potentially more exploitable in the areas of Huelva and Cadiz. - As explained earlier, profitability of an offshore wind farm depends on the bathymetry (seabed depth) at the location. A shallow seabed implies lower costs than a deep seabed. An offshore wind farm is cost-effective with current technology when the depth is below 50 meters. - In Andalusia, these depths, more than 8 kilometers from the coastline, only exist on the Atlantic coast. The estimated total potential for this Atlantic coast is 6.600 MW, which is divided between the coasts of Huelva and Cadiz with 3.900 MW and 2.700 MW, respectively. ### Current status of offshore wind energy in Europe - The United Kingdom has the first offshore wind farm in the world, ahead of Germany and China. - Offshore wind energy in Europe is largely concentrated. According to WindEurope’s report “Offshore Wind Europe”, in 2017, the network was connected with a record capacity of 3.148 MW for offshore wind energy, representing double the capacity of the previous year. - At the end of 2017, almost 84% (15.780 MW) of all offshore wind installations were located in the waters of the coast of eleven European countries. The remaining 16% is mainly located in China, followed by Viet Nam, Japan, South Korea, the United States and Taiwan. - In Europe, amongst the top two large leading companies in the sector, we find Iberdrola, a Spanish company. The Danish company Ørsted holds the top spot with 19% of the wind farm installations, followed by Iberdrola with 11%, completing the top five with Macquarie Capital (10%), Northland Power (9%), and Statoil (5%) which together account for 54% of the new capacity. - 2017 marked the emergence of a new technology that promises to open up new markets, which are generally difficult for the industry: floating offshore wind energy. Hywind Scotland, the first floating offshore wind farm was launched in Scottish waters in the North Sea. It was built by the Norwegian state-owned oil and gas company Statoil, in partnership with Masdar, an Emirati renewable energy company. - The United Kingdom is a pioneer in the construction of new offshore wind farms. As a result, 53% of the new capacity (1.7 GW), has been built in British waters. Germany is the next major contributor, with 40% of the overall European capacity (1.3 GW), due to the large scale. - Other European countries have also wanted to participate in this technological race: France, which installed the Floatgen demonstration project, which demonstrated the viability of floating offshore technology in deep waters for the first time in the southern waters of Europe. ### Manufacturers of wind turbines - Siemens Gamesa Renewable Energy accounts for 51.3% of the new capacity and MHI Vestas Offshore Wind for 24.7%. In 2017, other manufacturers installed new turbines but the Spanish-German and Danish companies accounted for more than 75% of the total installed capacity. The range of turbines used was very wide, from 2 MW to 8 MW. - Following a brief standstill, the offshore wind energy sector is ready to continue breaking records in the coming years. As Giles Dickson, CEO of WindEurope, noted, "that the installed capacity has grown by 25% in one year is amazing. Offshore wind energy is now a key part of the European energy system. Since costs have decreased rapidly, investing in this technology is no more expensive than investments in conventional energy generation today. This clearly shows that Europe is ready to adopt a much more ambitious target for renewable energy by 2030. 35% is easily achievable, especially considering that floating offshore wind farms are already ready to start operating." - The favorable winds for this technology have remained constant in recent years. - In 2018, Ørsted inaugurated the Walney Extension wind farm in the Irish Sea, off the coast of England. With a capacity of 659 MW, it is the largest offshore wind farm in the world. - With the official opening of the Walney Extension, as well as the completion of the Race Bank (2018) and Dudgeon (2017) projects in the UK and the Veja Mate (2017) project in Germany, the ranking for the world's largest offshore wind farms has changed significantly. - In 2020, Siemens Gamesa supplied 1.386 MW to the largest offshore wind farm in the world: the SG 8.0-167 DD new turbine has a 167-meter rotor. The blades, measuring 81.5 meters long, offer an 18% increase in swept area and a 20% increase in annual energy production compared to its predecessor. - Investment continues to be much higher than for onshore installations but the trend is declining. - In 2018, the UK dominated the ranking, adding three new offshore wind farms and occupying six spots in the top-10 ranking (12, in fact, as tenth place featured three offshore wind farms with 400 MW of installed capacity each). Germany followed with four offshore wind farms, and Holland and Denmark completed the list, each with one offshore wind farm. ## Status of offshore wind energy projects in Spain - Offshore wind energy in Spain is still in the early stages of development, but the pace of its development is determined by factors such as: The national legislation setting out the procedure for the designation of Environmentally Suitable Areas or ESZs for the construction of offshore wind farms and issuing permits for their construction. - The costs associated with emerging or developed technologies, and the existence of a stable remuneration framework that provides profitability for projects. -Adequate development of infrastructure (ports, highways etc.), and industrial (metal, civil engineering etc.) industries that allows large-scale projects. ### National Energy Framework of Spain - **Royal Decree 661/2007:** This decree regulates the production of electricity under special regimes. It also sets out remuneration and premiums for energy produced under these regimes. - **Royal Decree 1028/2007:** This decree sets out the administrative procedure for applications to authorize electrical installation in different generation modes (not only wind), in the marine territory. - It is the responsibility of the Ministry for the Environment, through the Directorate General for Coasts, to issue permits and concessions for the occupation of the maritime-terrestrial public domain, acting as the environmental authority. - The Environmental Impact Assessment (EIA), for the installation of renewable energy generation projects, becomes even more significant as a whole system that generates clean energy cannot generate an imbalance in the local ecosystem that outweighs the benefits in terms of reducing pollutants. - The EIA is one of the factors to consider in the selection of the wind farm's location. It must be located exclusively in those areas that are deemed "suitable", according to the Strategic Environmental Assessment (EEAL) of the Spanish Coast, which evaluates the suitability of each location for the installation of offshore wind farms. - Once the location has been defined, a full impact assessment, including the following aspects identified in the EEAL as particularly significant, will be carried out: - Fishing resources and activities - Cultural heritage - Maritime-terrestrial public domain - Environmental safety - Biodiversity and protected zones - Landscape ## Impact of offshore wind energy - Potential environmental impacts rely on information from studies in other offshore wind farms and on the Law 21/2013 of 9th December 2013 on environmental assessment. ### Visual impact - The Strategic Environmental Assessment requires a minimum distance of 8 km between the offshore wind farm and the coastline. The following photo-animation shows the visual impact at different distances. ### Detailed Environmental Strategic Assessment - Zoning - The following is an example for zoning (Area no. 15) according to RD 1028/2007. The “limitations of areas” column shows the type of impact assessed during preliminary studies. This example refers to fishing vessel berths, marine conditioning zones,, temporary concessions, biodiversity, etc. ### Impacts on the biotic environment - The evolution of recent years referring to the multiple uses of the sea, has motivated the Public Authorities in Spain to give a new function to Public Authorities in Spain, which is the sustainable use and conservation of marine biodiversity. This function includes tackling threats on a local, regional, and global level, which affect both the coastal Autonomous Communities and Spain itself, as well as the supranational and international communities. #### Birds - One of the key concerns associated with offshore wind farms is the risk of birds colliding with wind turbines, potentially leading to significant mortality rates. Most of the birds at risk are seabirds, but some migratory land birds might also be affected. - Key considerations related to bird impact include: - Bird species - Flight altitude and migratory routes #### Benthic environment - In ecology, the benthic environment refers to the community of organisms living on the seabed of aquatic ecosystems. The main impacts on benthic fauna occur during construction and dismantling phases. Turbidity generated during these phases can temporarily affect primary producers, impacting fish species that feed on them. Once the wind farm is installed, it is expected to be quickly recolonized by benthic communities. #### Fish - Foundations for offshore wind farms can potentially impact fish populations. However, they can also create a new habitat, similar to oil platforms and artificial reefs. - It is also worth noting that fishing is prohibited in the area, which can actually benefit the growth of specific marine species. #### Marine mammals - Marine mammals are one of the species that can be affected by offshore wind farms in a variety of ways. - During construction noise and vibrations resulting from assembly work and other activities deter marine mammals. The energy emitted is high enough to adversely affect the auditory capacity of porpoises and seals in the surrounding area. - During the operational phase, the noise and vibrations emitted into the water make communications difficult and affect the behaviour of marine mammals. - Generally, these animals use underwater sound for communication, prey location and characterization, orientation, and avoidance of predators. #### Flora - New habitats creation, as well as habitat alteration and elimination. ### Impacts on the abiotic or physical environment - Abiotic factors or abiotic components are the non-living chemical and physical elements of the environment that influence organisms, as well as ecosystem functioning. They include all non-living components of an ecosystem such as atmospheric conditions, water resources, gases, concentrations of organic and inorganic substances, and energy flows, often referred to as abiotic factors. - Here are some of the most important abiotic factors: #### Land (geology/geomorphology) - Foundations displace large amounts of sediment, leading to seabed changes in terms of their morphology. - The excavation of areas could possibly affect wave regimes. - The materials used for construction have implications for port activities in the surrounding area. - Furthermore, the laying of submarine cables requires excavations that can lead to the displacement of sediments and death of specific seabed communities. - As with any other human activity, offshore wind farm construction and operation can lead to seabed pollution. #### Air - The rotation of the blades and the internal mechanisms of the nacelle produce noise that causes vibrations in the sea and the air. - Light pollution from beacons. #### Water - Noise and underwater vibrations. - Impact from electric fields generated near the underwater electricity cable. - Spill of fuel or lubricant from ships and machinery. - It can have a negative impact on marine mammals that use the earth’s magnetic field to navigate. ### Impacts on the socioeconomic environment - Public acceptance is crucial for the development of offshore wind energy. - Current offshore wind energy projects show that social acceptance is strongly linked to environmental impacts. #### Impacts on tourism - There can be both positive and negative effects on tourism. - It could potentially boost tourism with new activities on land related to assembly and installation, and for the local community in general. - On the other hand, the visual and environmental impact of installations might deter tourist activity. - While installations need to be positioned further away from the coast, so that the offshore wind farms are visible as small objects on the horizon, they should be situated in areas with sufficient distance to avoid becoming a major eyesore. #### Impacts on the local population - The economic impact of operating offshore wind farms is expected to be positive, contributing to the development of the regional economy and technology. - In those regions where they are installed, the operation of wind turbines will have a positive impact on regional development, boosting local industry and creating jobs for the maintenance of the facilities. #### Conflicts of use - The presence of wind turbines can pose a collision risk for ships, including fishing vessels, requiring a no-go zone of at least 500 meters. - Potential impacts include: - Interference with fishing during the deployment of wind turbines and related electric cable installations. - Potential interactions between wind turbines and fishing vessels - Potential interactions between electric cables and fishing gear. - On the other hand, the presence of wind turbine installations could affect military activities. - It is essential to know whether the Ministry of Defence carries out activities in the area. - The presence of wind turbines could also affect naval radio, radar (civil, military, and air traffic control), and navigation support systems. The magnitude of the impact will depend on the size, scope, and location of the wind farm as a whole. ### Impact on the economy - The manufacturing and construction phases of offshore wind farms generate the largest share of direct employment, even creating new companies in the region where the wind farm is installed. ## Advantages and disadvantages of offshore wind energy technology - Recent advances in onshore wind energy technology have also benefited offshore wind energy, which is now a well established renewable energy source. - A series of advantages makes offshore wind technology a key element in the decarbonization of our current energy system. - Some key advantages are: - The sea is flat, and winds face fewer obstacles, making them more consistent. - Winds at sea are generally more consistent and less turbulent than on land. - An isolated wind turbine at sea experiences less fatigue and has a longer lifespan. - Offshore wind turbines can produce up to double the electricity output compared to onshore wind turbines with the same capacity. - The sea has wide open spaces for deploying wind turbines which allows for larger offshore wind farms than those on land. - Being located far from populated areas, noise and visual impact is often mitigated and the constraints associated with noise regulations imposed by local authorities are less stringent. - The lack of stringent regulations regarding the load to be transported allows the use of larger and higher power wind turbines. This translates into higher electricity production per turbine installed. - However, as with all emerging technologies, there are still some significant limitations: - The initial investment for offshore wind projects is considerably higher than for onshore projects. - Building the wind farm and installing the evacuation cables can be even more complex and challenging. - ○ greater distances between the wind farm and power station. - ○ increased costs for the foundation, as the access constraints pose an additional challenge for the construction phase. - ○ Wind turbines in offshore installations need to be designed to withstand corrosion and harsh marine environments, making them more expensive that their onshore counterparts. - ○ The winds in the sea, while generally more consistent than on land, do not blow continuously. - Offshore wind turbines, as well as onshore wind turbines, are subject to mechanical stresses: not only from the force of the wind on the blades and the structure but also from forces generated by currents. - Installing wind turbines in the sea is more complicated than on land. - It requires the use of specialized vessels for installation. - The maintenance of offshore wind farms is more challenging, as it requires ships, floating cranes, etc. The work is also subject to sea conditions, which means that on occasions, it will be impossible to carry out assembly or repair work during storms, affecting the wind farm's availability and the total annual power generation. - If a fault occurs, it could take several days to repair, leading to production losses. - Electricity connection requires the laying of submarine cables on the coast, which can be several kilometers from the wind farm. - For long distances, high-voltage dc cables are used and electronic power converters must be combined to reduce power loss. - The harsh marine environment presents an extra challenge for offshore wind farm construction and operation. - It is important to consider preventative measures against potential pollution, as well as contingency plans (collisions, emergencies) to ensure the safe operation of the project. ### Investment costs - Offshore vs. Onshore - Offshore wind farms have a higher investment cost that onshore wind farms. The wind turbine itself accounts for about 80% of the total costs of an onshore wind farm, whereas the cost of an offshore wind farm is divided across four main components: wind turbine, foundations/structure, seabed cable installation, and connection to the grid. Onshore we can expect a cost of € 1.2 million per MW of installed capacity, while in offshore, the cost is estimated to be €2.8 million for each MW. The cost difference is mainly driven by factors such as the terrain, connection to the grid, and seabed conditions. [Image of a pie chart showing the breakdown of costs in offshore vs. onshore wind energy projects] - The technology applied in foundations is still under development, which means significant technical challenges and favors onshore wind farms. The key factor that will make offshore wind energy economically viable is further development and cost reduction in subsea foundations during the coming years.