The Offshore Wind Dilemma
In 2020, wind power represents 6.2% the total power generated in the world, and offshore
windfarm represents 0.43% [1]. The capacity of offshore wind has grown by 29% in 2020 alone
[1]. Yet, in order to meet the IEA Net Zero Scenario, the wind power sector has to grow another
500% by 2030. Despite the growing of offshore windfarm projects in the world, the debate of
whether the benefits of offshore wind (OSW) farm outweigh the disadvantages is still ongoing.
These benefits and impacts of OSW ranges widely from technical to environmental, social, and
economical. They also started as early as the construction and as late as the decommissioning.
This article highlights the pros and cons of OSW on the following aspects.
Middle of the ocean
The fact that the wind farm is in the middle of the ocean, with almost nothing in the
surrounding, is the main reason why engineers put turbines there. Wind speed is generally
higher and more consistent due to the lack of geographical obstruction. The blade and the
building components are also not limited to the road and transportation infrastructure, making
them more efficient than their onshore counterparts.
Wind turbine has often been criticized about producing noises or humming sounds during
operation [2]. OSW avoids it by not being near human residences, but not so much for the nonhuman residences. Although, studies have shown that the operational noise of OSW is lower
than ships passing [3], the noise pollution to fishes and marine mammals aren’t very clear yet.
Transmitting the power back on shore is expensive, in the sense that new transmissions are
often needed to be constructed, and under water powerlines are more expansive to lay and
maintain. On the other hand, OSW benefits from being closer to the energy demand. Using the
example of the US, 80% of citizens live near coast lines which lowers the transmission lose for
wind power [4].
Structure
The effect of OSW structure starts as early as the construction phase. Although as mentioned,
the operational noise is minimal, the construction period causes much louder noises and stress
to marine mammals which relies on echolocation.
After the structures are constructed, they disturb the seabed and habitat underneath it.
Artificial reefs could be created from the structure to minimize the impact and promote
biodiversity [5]. However, when decommissioning happens at the end of the turbines’ lifespan,
these artificial reefs will be removed, causing damages once again. Moreover, the existence of
the OSW does not simply affect the immediate area. The displacement of fishery alters the
behavior of nearby marine lives which in turn affect further habitats, causing a chain effect on
surrounding areas.
The disruption to the seabed could be minimum with floating turbine technologies become
more and more common, the wind turbines still disrupt the sky for seabirds. These disturbances
could be direct collision, loss of habitat, blocking flight path (barrier effects) or loss of foraging
area (displacement) [6]. The choosing of site becomes critical and thorough research are
needed to minimize the impact.
The structure is also a nuisance for marine routes. The sites should have minimum impact on
cargo ships, fishing and rescue boats, helicopters routes, to maintain the marine traffic. The
structures could also cast lidar/radar shadows, making the navigation and searching within the
farm more difficult.
Economic
The development of the offshore wind is pushing the technology boundaries further, from new
LiDAR tech for wind speed data gathering, to offshore construction techniques, to marine life
studies. Instead of relying on decades old technologies, the research and development in
offshores are great driver to other industries and the economy. The construction creates job
opportunities and stimulates the supply chain of the components. With the growth of both
onshore and offshore wind capacity, the industry related to wind also sees a huge boost in
recent years.
On the energy cost side of the picture, the LCOE of onshore and offshore wind declined
dramatically over the years. The LCOE for OSW in 2020 reaches 0.084 USD/kWh and is expected
be lower than coal in the near future [7]. The lowering of LCOE benefits the consumer and the
industry, boosting economy.
Conclusion
When deploying offshore wind farms, we should take into account the whole picture, and
consider every aforementioned aspect. Despite not being perfect, offshore wind is still one of
the most important technology human processes. Decarbonizing the world and heading for a
net neutral scenario is the most important goal humankind should reach in the coming decades
and offshore wind farms are surly part of the picture in any of the scenarios.
Bibliography
[1] IEA, "IEA WIND ANNUAL REPORT – 2020," IEA, 2020.
[2] J. L. Davy, K. Burgemeister, D. Hilman and S. Carlile, "A review of the Potential Impacts of
Wind Turbine Noise in the Australian Context," Acoustics Australia, vol. 48, pp. 181-197,
2020.
[3] J. Tougaard, L. Hermannsen and P. T. Madsen, "How loud is the underwater noise from
operating offshore wind turbines?," The Journal of the Acoustical Society of America, vol.
148, no. 5, pp. 2885-2893, 2020.
[4] O. o. E. E. a. R. Energy, "Top 10 Things You Didn’t Know About Offshore Wind Energy,"
Energy.gov, 30 8 2021. [Online]. Available:
https://www.energy.gov/eere/wind/articles/top-10-things-you-didnt-know-aboutoffshore-wind-energy. [Accessed 17 3 2022].
[5] S. Degraer, D. Carey, J. W.P. Coolen, Z. L. Hutchison, F. Kerckhof, B. Rumes and J.
Vanaverbeke, "Offshore Wind Farm Artificial Reefs Affect Ecosystem Structure and
Functioning: A Synthesis," Oceanography, vol. 33, no. 4, pp. 48-57, 2020.
[6] A. Piggott, A. Vulcano and D. Mitchell, "Impact of offshore wind development on seabirds
in the North Sea and Baltic Sea: Identification of data sources and at-risk species.," BirdLife
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[7] IRENA, "Renewable Power Generation Costs in 2020," International Rrenewable Energy
Agency, 2021.