The Offshore, by the wording itself, it is clear that it is situated away from the shore. Offshore farms and turbines are installed in the ocean, where the wind is of very high intensity. It uses this stronger and steadier wind to generate electricity. Thus, offshore wind energy projects exploit the potential of wind in the open seas, where the wind blows with more power than land.
New physicist
The wind is a source of abundant power. This is not a recent discovery. The wind has been a source of energy for more than 1500 years. Still, the wind is in the top list of energy sources, not just an energy source, but a renewable source of energy.
As we know, fossil fuels are limited, which marks a near end of energy production. But, never-ending renewable energy sources are here for the rescue! Realizing the source of renewable energy is not enough, proper utilization can only shower us with clean energy for future use.
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How it is installed?
When we talk about wind power, make sure that you don’t confuse it with a windmill. Yes, of course, the windmill uses wind power but it converts wind power into mechanical work or rotational energy. At the same time, a wind turbine, like a nuclear power plant, generates electricity.
So, the output of windmill is mechanical work where wind turbine provides us with clean electricity. The wind has no fixed position. So to capture the power, human technology uses land, sea, and sky. Onshore, offshore, high altitude wind energy all do the same process; utilize wind power for power production.
Offshore Wind Energy
The Offshore, by the wording itself, it is clear that it is situated away from the shore. Offshore farms and turbines are installed in the ocean, where the wind is of very high intensity. It uses this stronger and steadier wind to generate electricity. Thus, offshore wind power projects exploit the potential of wind in the open seas, where the wind blows with more power than land.
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The first offshore wind turbine of the world was installed in 1990 in Nogersund, Sweden. Now, offshore wind power is the fastest-growing sector in wind power lead by UK and Germany. Most of these projects are funded by the Government or research institutions. These two countries together account for over two-thirds of the total offshore wind power installed worldwide.
You may have noticed that offshore wind turbines are generally bigger. We need more and more green energy, so when turbines are larger, larger the surface area, and the result is larger amount of clean electricity.
They are also extremely tall in order to capture the more strong wind. At the end of 2018, the total worldwide offshore wind energy capacity was 23.1GW. It is not surprising that we need more power during day time; human needs are at their peak during busy hours of the day.
Offshore wind energy is performing as if wind knew this! Yes, more powerful winds are available in the afternoon hours of the day. When the consumer demand is high, more efficient energy is thus available. The power then travels to the land through sophisticated cable systems that are buried in the seafloor. New inventions paved the way for floating offshore wind platforms so that they can be set up in the deep waters.
Challenges in installation and maintenance of offshore wind energy turbine
Even when offshore wind turbines and farms are shining with benefits and advantages; there are challenges that are associated with its installation and maintenance. Let us discuss some of them.
Corrosion
Corrosion is a general problem for offshore infrastructures. As we already said offshore wind system is placed in the seabed, so is subjected to harsh environments. The high salinity of seawater and humidity affect the turbines in a very adverse way.
Moreover, they are exposed to direct and reflected (reflections from the sea) UV- radiation. Corrosions are of two types, external corrosion, and internal corrosion. External corrosion occurs due to the severe environment on the outside of the system especially the free exposure to seawater.
When the saline water and the material of the offshore turbine react it results in corrosion on the outer part naturally. At the same time, internal corrosion is the one that occurs inside the system. Offshore wind energy structures are subjected to both internal and external corrosion.
Biofouling
Challenges of offshore wind energy cluster are many of which biofouling is important and cannot be ignored. Biofouling is the growth of marine organisms on artificial objects immersed in the water and the process is undesirable and causes harm.
By the colonization process, these organisms spread with high density and complexity. This eventually attacks the immersed parts of the offshore wind energy system and speeds up corrosion.
It also affects the underwater cable system used for transporting the produced energy to the shore, thus decreasing their efficiency and adds to weight gaining. Environmental influences for biofouling include salinity, nutrient availability, and optimum temperature, and so on.
Erosion
Erosion is another threat to offshore wind energy cluster. Ledge Edge Erosion (LEE) is nowadays a common word among the challenges of wind turbine. LEE is the process where the blades of wind turbine gets eroded due to the factors like rain, strong ultra violet rays from sun, sand, ice, dust etc.
This also makes the surface rough. The surface roughness produces resistance and drag which ultimately hinder the efficiency of the blade. This affects the overall performance of the wind turbine and causes reduced power production. To overcome LEE expensive ways are needed, which adds to the challenge.
Water depth
The performance of the turbine is highly influenced by the site where it is located. Offshore wind turbine needs more considerations since it is not installed on the land. Water depth is one of the specific parameters of the site; it limits the availability of spots for offshore wind farms. More the water depth, more the foundation cost.
Lightning Strikes
Offshore wind turbines are generally prone to lightning strikes. Why does this happen? Due to the long time exposure to marine environment blades of offshore wind turbine are coated with salt. This salt reduces the power of lightning protection system.
The damage caused by lightning strikes is causing troubles to offshore wind clusters. Studies show that nearly 5.56 wind turbines are spoilt due to lightning strikes for every 100 blades per annum, this is an average. So, it is a serious concern for wind farm owners and operators.
Transportation
Setting up a wind turbine is a heavy task. It’s problematic in the case of onshore and then imagine about offshore. Wind turbines are not silly structures, they consist of heavy towers, fragile blades and every part should be handled with great care. When we plant an offshore turbine successfully, the expense it caused is huge, really huge. Wind turbines have grown significantly since the 1980s and the process is going on
Foundation
No structure can remain long without a proper foundation. In the case of offshore wind turbines, this is a crucial point. To determine subsurface conditions field and laboratory tests are mandatory. Subsurface soil and rock determine the foundation strength from which one can obtain the overall stability of the turbine. Apart from this, remediation is required occasionally to existing tower foundations so as to correct large deflections.
High Cost
Comparing to onshore power plants offshore is costlier. All the above mentioned challenges finally results in high cost for wind production. Both hydrodynamic load and aerodynamic load makes offshore wind power technically complicated. When we consider foundations, maintenance and installation are more tedious than onshore. Transportation also accounts for high cost, where offshore wind turbines are larger in size
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Conclusion
Even when all these challenges remain as a threat to the offshore wind energy cluster, it is rapidly increasing over a decade. So, if we are able to find solutions for these issues, offshore wind energy can take the place of our future energy source. New technologies and inventions are welcomed to change the present challenges of the offshore wind energy systems for a better tomorrow.