How Do Offshore Wind Farms Compare to Onshore Wind Farms?
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Picture a boat 7,000 years ago carrying pottery, iron tools and a fresh haul of fish from the Nile. Okay, now how is it moving? Wind, of course! Fast-forward 5,000 years to China in 200 B.C., and we see simple windmills used to pump water — once again, harnessing the impressive power of the wind.
While we are the first to commercially exploit the wind’s power on an industrialized scale, using the power of wind — and that of the other elements such as water and sun — is not a new concept. Nevertheless, the progression to today’s wind farms both on and offshore is striking.
In the UK alone, onshore wind farms have the capacity of more than 8,800 megawatts, and offshore farms have the capacity of over 5,000 megawatts. So how do wind farms produce all this energy? Let’s briefly go back to basics. Wind farms are made up of groups of wind turbines, located within relatively close vicinity to each other. More often than not, wind farms are home to hundreds of turbines across hundreds of square miles, and each one produces electricity.
Each wind turbine has carbon-fiber blades which are turned by the wind, and which turn a motor to convert energy from kinetic to electric. Initially, the energy is transferred to a gearbox, which turns slow speed into high-speed rotary motion, finally powering the drive shaft fast enough to fuel the electric generator.
Wind farms are found both on and offshore, and location is not the only difference between the two. So how do offshore wind farms compare to onshore wind farms, and which of the two technologies makes the most sense economically to further develop?
Offshore Wind Farms
It may not shock you to learn that offshore wind technology is far less developed than onshore wind technology; it arrived around 100 years after its predecessor, going into effect in the 1990s close to Denmark.
Advantages of Offshore Wind Farms
Unsurprisingly, an offshore location provides an exceptional amount of freedom in the actual dimensions of the wind turbines — they can be built far larger and higher, therefore enabling more energy to be collected.
Being out at sea means that wind farms are far less imposing on otherwise scenic countryside. Larger wind farms can be constructed per square mile without bothering or affecting nearby locals or tourism income.
Being in the middle of the ocean does mean higher wind force. A nightmare for sailors, but a goldmine for wind farmers, high wind speed means more energy can be produced at any given moment. Furthermore, they tend to be more efficient because of better consistency and the fact that fewer turbines are needed to produce a similar amount of energy as onshore farms.
The impact on the environment of offshore wind farms could be positive. Firstly, manufacturers avoid shipping lanes, delicate ecosystems and fishing areas. More importantly, wind farms create safe zones around them — they restrict access to specific waters and increase artificial habitats.
Disadvantages of Offshore Wind Farms
The specific technology required for offshore use remains expensive. While it could change going forward, this is one of the main reasons it’s hard to justify offshore development over onshore. Offshore farms are about 90 percent more expensive than fossil fuel generators.
Offshore turbines suffer greater damage from wind and waves, thereby incurring greater maintenance and operational costs. Furthermore, it takes longer for engineers to reach repair sites to get them running again.
Onshore Wind Farms
Is the original form of something always the best? Onshore wind farms have certainly dominated the market for a long time — the first wind turbine was put together in the late 1800s.
Advantages of Onshore Wind Farms
Onshore wind farms cost very little in comparison to most other forms of energy harnessers for the infrastructure required to transmit electricity. They’re competitive among renewable energy solutions as well — onshore wind farms produce the cheapest available type of renewable energy.
Onshore wind farms can boost local economies — if manufacturing plants are nearby, it brings wealth to businesses in close proximity.
What’s more is that wind farms erected close to their manufacturing sites are more carbon neutral, given the reduction in emissions caused by transport. Finally, the shorter the distance between wind turbine and end user, the less need for voltage drop-off on the cabling.
Disadvantages of Onshore Wind Farms
The most significant disadvantage of onshore wind farms is the eyesore they create on otherwise beautiful landscapes. Some individuals argue that onshore farms endanger bird life and cause noise pollution. Public buy-in is key to the success of onshore wind farm development, and while it is strong now, it can always get stronger.
Onshore wind farms do not produce energy all year round, making them less efficient. Poor wind speed is often a problem as well as physical obstacles, including large buildings, mountains and hills.
As with every project, the individual toss-ups between developing onshore and offshore wind farms usually come down to political, financial and geographical variables. Therefore, they are assessed on a case-by-case basis.
Wind power is gaining popularity globally — at the start of 2016, the international capacity was 432,884 MW, 17 percent higher than what it was in 2014. The industry is extremely fast-paced, and we can expect the technology for both onshore and offshore wind farms to improve rapidly. At the moment, however, while it can be argued that offshore is a more efficient option, it remains quite undeveloped — the capital costs and maintenance are still too expensive for many.
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About the author
Starting from an early age, Jane Marsh loved all animals and became a budding environmentalist. Now, Jane works as the Editor-in-Chief of Environment.co where she covers topics related to climate policy, renewable energy, the food industry, and more.