The pros and cons of onshore & offshore wind

Wind turbines work when air turns the carbon-fibre blades attached to the units. The blades are connected to a motor, which turns kinetic energy into electricity. The energy is transferred to a gearbox, which converts the slow spinning of the blades into a high-speed rotary motion. This then turns a drive shaft quickly enough to power an electric generator.

Traditionally, onshore wind turbines dominated the market, however, in recent years, advances in technology have led to the development of offshore wind farms.

For more information on the history of wind power, take a look at our post on how wind turbines have evolved.

Onshore wind power refers to turbines located on land rather than over water. They are typically located in sparsely-populated areas with low conservation value. According to the International Energy Association, onshore wind electricity generation increased by 12% in 2019. Capacity additions also grew by 22% after stagnating for a couple of years.

Take a look at this video on how onshore wind farms work:

Besides the obvious advantages of sustainability, what else is advantageous about onshore wind?

Less expensive

The infrastructure required for onshore wind power is significantly less expensive than what’s required for offshore wind. In some cases, it’s half the cost and can provide investment payback as quickly as two years. It’s also the least expensive form of renewable energy compared to solar and nuclear power sources, which means it’s more affordable to consumers. Because they’re cost-effective, onshore wind farms tend to be larger, producing more energy per site.

Shorter cables

With less distance between the turbines and the consumer, there’s less voltage drop-off in the cabling.

Quick installation

Onshore wind turbines are quick to install and can be constructed within a few months, unlike other energy sources like nuclear power stations, which can take over two decades to build. When in operation, onshore wind turbines also have low maintenance costs.

Low impact on surroundings

Onshore wind farms have less physical impact on their surrounding areas. Toxins aren’t released, the site can be farmed around, and there’s very little impact to wildlife. 

Varying wind speeds

The speed of onshore wind turbines is somewhat unpredictable. Because wind speed and direction vary on land, achieving consistent power generation can be challenging. As a result, wind speed and direction need to be carefully monitored to plan for energy generation.

Potential wind blockages

Physical blockages from buildings and surrounding landscape like hills or mountains can also cause production inconsistencies. For this reason, onshore wind can’t produce energy year-round and can only achieve around 2.5 MW, compared to offshore wind’s approximate 3.6 MW.

Intermittent energy

Because onshore turbines don’t run year-round, they require fossil-fuel backups when the wind speed is slow. As we come to rely more heavily on wind farms for our energy, increasing amounts of fossil fuels will also be required.

Visual and sound factors

Onshore wind farms can be an eyesore on the landscape. Wind turbines that are built on high ground to generate more power can be imposing on surrounding residential areas. Wind turbines also aren’t silent, meaning they cause noise pollution if located near a residential area. To illustrate, up close, a wind turbine sounds like a lawnmower.

Overall, the advantages of onshore wind and the sustainable energy it can create outweighs the potential disadvantages. 

Offshore wind power refers to wind farms that are located over shallow open water, usually in the ocean, where there are higher wind speeds. The term ‘offshore wind’ can also refer to inshore water areas like lakes and fjords. Most offshore wind farms use fixed-foundation wind turbines in shallow water. However, as technology advances, wind farms will be able to be built over deeper waters. According to the Global Wind Energy Council, offshore wind will surge to over 234 GW by 2030, led by Asia-Pacific.

Check out this video for an overview of how offshore wind power works:

More energy generated

Offshore wind speeds are typically faster than on land, and even small increases in speed can produce large increases in energy generation. As such, fewer turbines are needed to produce the same amount of energy as an onshore turbine.

More wind consistency 

Wind speeds offshore don’t vary as much and the wind direction doesn’t change as often, so offshore turbines are more consistent (meaning more reliable power generation).

Less visual impact

Offshore turbines don’t have as much visual impact as those on land. They don’t interfere with land usage, and there are no physical obstacles that can interrupt the wind flow. For this reason, offshore wind farms can be made larger and generate more energy than those onshore, with less physical impact.

Bigger turbines

Offshore turbines can also be built taller than those onshore, which means they can harness more wind energy and produce more electricity.

Higher cost

Creating the infrastructure for offshore wind farms can be expensive and complex, especially over deeper waters.

Maintenance & repairs

Sea waves and very high winds can damage turbines, so they need more maintenance than their onshore counterparts. Offshore wind farms are also difficult to access, which means longer wait times for repairs.

Noise & visibility 

The underwater noises from turbines can impact fauna and other marine life. Further, not all offshore wind farms are built out of public view. Some are built within 26 miles of the coastline, so can still be an eyesore for local residents.

Less local jobs

Unlike onshore wind farms, those offshore have a limited capacity to benefit local economies. As the manufacturers’ offices are situated inland and often far away from the offshore site, jobs aren’t created in the local community and other investments aren’t made.

With a surging global electricity demand and an urgent need of more sustainable energy sources, the advantages of both on- and offshore wind far outweigh the disadvantages. With the construction and engineering of windfarms poised for exponential growth in the coming decade, more workers will be needed in this field than ever.

Do you want to be a part of this exciting and innovative sector? Brunel helps jobseekers secure roles in nearly 40 countries, recruiting for dozens of Renewable Energy companies worldwide. If you’re ready to take the next step in your career, check out the global opportunities below.