Onshore vs Offshore Wind Power: Need to Know for 2020

Onshore vs offshore wind powerWind power is present in the renewable energy industry as one of the most natural, cheap, and reliable sources of energy. Wind power is one of the first sources of renewable energy, also providing slightly fewer limitations than other clean sources of energy.

United Kingdom, Denmark, Germany, Sweden, and Holland were the pioneers on wind power generation up until the last decade. Now, with more countries like the U.S. considering the benefits of this technology, in the present year, the world wind market has 650.8 GW of installed capacity, with 9.17% of this value installed last year.

Now, when considering wind power, there is one question that comes to mind: What is better? Onshore vs offshore wind? It’s important to decide which one provides the best cost-effective performance for each specific location. Onshore energy requires turbines installed on land, harnessing the wind to generate power, while offshore energy requires wind farms to be installed over open seawater, to take advantage of faster winds for power generation.

Similarities Between Onshore vs Offshore Wind Power

Onshore vs. offshore wind
Figure 1: Onshore vs. Offshore turbines. Source: GE, Vox research

Onshore and offshore wind power generation are among the most prominent technologies to provide clean energy for the U.S. Both sources of energy reduce the carbon footprint, providing clean and renewable energy for the grid.

Even though offshore wind turbines are larger in size than onshore turbines, both share the same mechanical principle to provide wind power generation. In both cases, the turbines consist of rotor blades spinning around a horizontal hub. Passing wind through the blade, starts a lift motion that provides a rotating force used in a complex process by an asynchronous generator that finally generates energy.

While offshore wind farms cost more due to installation materials and other factors, materials used in both turbines are basically the same, with offshore turbines needing small variations to provide safety in the presence of higher wind speeds. Onshore and offshore technologies could potentially provide the same energy, if two similar-sized turbines were exposed to the same wind speeds, with output energy difference being close to none.


Differences Between Onshore vs Offshore Wind Power

Even if onshore and offshore wind power generation have some similarities like using wind to provide energy, these also have some disparities. The most obvious difference between onshore vs offshore wind is the place where turbines need to be installed. Onshore wind farms can be located on land while offshore ones are installed in large bodies of water.

Because onshore wind farms are installed on land, costs can be much lower than the other option. Offshore wind farms require platforms, underwater cables, interconnection, and other factors that increase installation costs; maintenance for these farms also need employee transportation on helicopter or vessels.

Onshore wind power generation can be slightly less predictable than offshore. To properly install onshore farms and provide clean energy generation, there is a required study of the terrain and wind currents that must be performed. Offshore farms enjoy a less troublesome inconsistency due to constant winds with higher speeds, providing a more reliable and efficient power generation.

Onshore Wind Review

Costs

Figure 2: Onshore wind farm. Source: Mint Selection

Onshore wind energy is quite cheap. Required materials for installation and additional infrastructure for energy transmission provide lower costs than offshore farms. By 2020, onshore wind prices can be as cheap as 20 $/MWh. Estimations foresee an even lower energy cost for 2030 since there might be three times as many onshore wind farms installed than in 2018.

Space required

One disadvantage of onshore wind farms is that they require land space usage to be installed and provide clean energy. To provide an uninterrupted flow of air ensuring power generation, onshore wind turbines require a minimum distance of 150 m from any obstructions and a turbine-to-turbine separation of 7 times the diameter of the rotor.

Benefits

Onshore wind is one of the most popular renewable energy options. The technology provides many benefits due to the nature of wind power generation and in comparison to offshore wind power.

  • It provides lower installation costs. In some cases, investment payback can be as fast as two years.
  • Energy generated can be easily hooked to the grid.
  • More companies specialize in onshore farm installation.
  • The maintenance cost can be quite low.

Disadvantages

Not everything can be entirely good, so onshore wind farms also have some disadvantages.

  • Onshore wind farms require a more careful analysis of wind current and speeds than offshore wind, to provide high-efficiency generation without interruption.
  • Potential space can be more limited due to terrain costs and potential urban expansions.
  • Population discontent due to visual and noise pollution generated by onshore wind farms in proximity to residential areas can be quite high.

Offshore Wind Review

Costs

Figure 3: Offshore wind farm. Source: AZO Cleantech

Costs for offshore wind installations can be 20% higher than onshore due to energy transmission infrastructure, extra materials required, and other technical challenges. By 2019, offshore wind power costs have fallen 32% concerning 2018, estimating generation costs at  78 $/MWh. By the year 2038, estimations state that offshore wind power might be already as cheap as fossil fuel.

Space required

Offshore wind power generation doesn’t provide a challenge about the space required for wind farms installation. The minimum required distance for offshore farms is at least 200 nautical miles from the shore and 50 feet deep into the ocean floor. Power density for offshore turbines oscillates around 1, requiring 2 for a 2 MW turbine.

Benefits

While onshore wind farms seem to be the leading trend in the present, offshore wind farms provide some competent benefits concerning its counterpart.

  • Installations are more suitable for larger areas, therefore providing opportunities for major renewable energy generation projects.
  • Offshore wind farms have a higher potential for power generation due to faster and more constant winds, also providing energy at a more stable rate.
  • There are no visual or noise pollution disadvantages as those caused by onshore wind farms.
  • Offshore wind turbines can be twice or three times larger than onshore options, due to noise pollution not being an inconvenient. This larger size provides higher power generation and more efficiency for the cost of materials
  • There is no interference with land terrains, providing smarter space usage in high-density populated areas.

Disadvantages

Offshore wind farms provide lots of benefits like decreasing public health costs and ensuring clean renewable energy. However, there are some disadvantages to the technology.

  • Higher costs for installation and power transmission concerning onshore wind power.
  • Underwater noises and turbines can impact fauna over bodies of water and kill migrating birds by impact in the process.
  • Over time, offshore wind farms require maintenance that is harder to perform and more expensive.
  • Energy restoration time after a malfunction can be higher than with onshore wind farms.

Conclusion: Onshore vs Offshore Wind, Which Is Best?

Figure 4: Onshore vs. Offshore investments 2000-2030. Source: European Wind Energy Association

Onshore wind power provides a much better choice than offshore due to the actual costs of generation and installation. However, offshore investments have been greatly increasing since 2008, providing a wind scenario for 2030 that surpasses the onshore technologies, increasing potential installed capacity in Europe by up to 70GW.

Even though by 2020 onshore wind power generation is much cheaper than offshore, it is not the definitive option, since it also has many disadvantages. There are visual and noise pollution, low wind reliability, and high costs of land space. Offshore wind generation surpasses onshore technology in many aspects, ensuring a renewable energy choice that avoids pollution and provides constant high generation due to offshore winds.

While the trending balance might be tipped for onshore wind in 2020, that might not be so in the future. Investments are increasing for the offshore wind farms and costs will get low enough for it to even be cheaper than fossil and gas generation in the future. Offshore wind power might be pricy today but it is the most promising option for the future of the world wind market.