In 2021, the global wind power capacity achieved through onshore and offshore wind farms reached 837GW, up from the 597GW accounted for in 2018.
President Biden, along with the Department of Energy (DOE) and The National Renewable Energy Laboratory, recognises the potential of advancing offshore wind energy development in the United States. You can read more about this topic in the evolution of offshore wind energy in the United States.
Similarly, the UK, which along with China are world leaders in wind energy, revealed that between now and 2050, 400,000 jobs would be needed for onshore and offshore projects if the UK is to reach net zero.
As the global debate between onshore and offshore wind energy continues to grow, we look at both advantages and disadvantages. But first, let's determine the difference between onshore and offshore.
Onshore vs Offshore: What's the difference?
Both onshore and offshore wind farms utilise wind power through wind turbines. These turbines are constructed out of carbon fibre which is then connected to a motor that rotates the turbine.
As the turbines rotate, they turn kinetic energy into electricity. The electricity is transferred to a gearbox that converts the slow speed of the blades into a higher-speed rotary motion. From here, the drive shaft is rotated enough to power the electricity generator.
But what's the difference? Essentially the difference between offshore and onshore wind farms is that onshore are based on land, and offshore are located at sea. So, with this being the key difference between the two, let's explore the pros and cons of onshore vs offshore wind farms.
The Pros of Onshore Wind Farms
Cost-effective
Onshore wind turbines are less expensive than offshore and, along with nuclear and solar power, are one of the cheapest sources of renewable energy. Infrastructure and maintenance costs of onshore wind farms are significantly cheaper, sometimes costing half the price of an offshore wind farm. Additionally, onshore can deliver an investment payback in as little as two years, and the power generated is cost-effective for consumers.
Quicker Installation
Not only is the installation of onshore wind farms cheaper, but it is quicker too. Unlike nuclear power stations and other utility-scale energy sources that can take decades to install, onshore farms can be constructed and ready for commercial operations in a matter of months.
Boosts Local Economy
Onshore energy companies who look for the best location for wind turbines will consider the benefits their farms can bring to the local economy. The economic value can be the income generated for the onshore farm owners, local land owners, and the jobs created for individuals in the community.
The Cons of Onshore Wind Farms
Disrupt the landscape
Arguably the most significant issue of onshore wind farms is how they affect the local people and landscape. Often considered an eyesore, onshore farms can draw complaints from residents within the area. Noise pollution also disturbs locals, who often describe the sound of the turbines to be similar to a lawnmower.
Inconsistent Wind Speeds
Due to the unpredictability of the weather, the amount of wind power generated from onshore will differ year-round. In addition, if the wind is blowing in varying directions, this can negatively affect the efficiency of the turbines. Finally, as onshore farms are on land, buildings and the surrounding landscapes can also hinder the amount of wind from getting to the onshore turbines.
Generates Less Power
For context, annually, onshore wind farms can produce around 2.5MW of wind energy compared to offshore wind turbines, which can create an average of 3.6MW annually. With onshore wind farms not operating all year round, fossil fuels are required to provide a backup when wind speeds are low. Therefore, the more onshore wind farms, the more fossil fuels will be needed.
The Pros of Offshore Wind Farms
Generates more energy
As mentioned, offshore wind power farms have the potential, on average, to produce over 1MW more than onshore annually. Unlike onshore, where turbines can be limited to being constructed up to a certain height, offshore turbines can be scaled much larger, allowing more energy to be captured. Additionally, wind speeds are typically higher at sea, resulting in more energy generated than on land.
More Efficient
Offshore wind farms are considered more efficient than onshore in terms of the energy they can produce. The reason for this is that offshore farms can generate the same amount of energy as onshore but with fewer turbines. This is due to there being higher wind speeds with a more consistent direction at sea than on land.
Less Intrusive
Unlike their counterparts, as offshore wind farms are located out at sea, they are less intrusive. Offshore wind farms don't interfere with neighbouring countries, land usage or have any buildings or obstacles in their way that onshore farms do. Because their physical impact on the environment is less, offshore wind farms are often larger than onshore per square mile.
The Cons of Offshore Wind Farms
More expensive
Offshore wind projects are more complex to build and install than onshore. Due to the complexity of construction and installation, especially in deeper waters, offshore wind farms come at a higher financial cost. However, as space on land to build onshore farms is scarce, companies may need to rely on offshore as they scale for the future.
Maintenance Challenges
Although there are higher wind speeds out at sea that can produce more energy, this does mean that offshore wind turbines are more susceptible to damage. In addition, due to their susceptibility to high winds, particularly during storms, offshore wind farms often need maintenance repairs. Not only are these repairs expensive, but because they are so far off the coast, offshore farms are more difficult to access and consequently often take longer to repair, despite corporations' best efforts to find the best location for their wind farm.
Less Local Involvement
Unlike onshore farms that local businesses can own, offshore farms demand more investment and are usually owned by big corporations. As a result, although offshore wind farms provide the opportunity for jobs, they are not necessarily created to benefit a particular local community. Ultimately, the offshore wind industry doesn't offer the same economic opportunities that onshore offers.
Get in touch
At CMC, we understand the advantages onshore and offshore wind energy can bring to the global economy, jobs market and people's lives. Our specialist renewable energy experts support engineering, construction and project management. We know the challenges your onshore or offshore wind farm project can face, and we understand how to help you overcome these obstacles so you can achieve your business goals. So get in touch with us today and discover more with CMC.