What is Offshore Wind Energy?

Centuries ago, sailors used wind turbines at sea to propel their boats. Today, offshore wind turbines, a type of renewable energy, are used to generate clean energy for cities around the world. What is offshore wind energy and how has it helped to produce cleaner greener power?

By October 1990, news publications in Denmark were happily reporting a new development. The big, unsightly, and noisy wind turbines that elicited complaints from residents were going offshore. The company building the offshore wind energy turbines, Elkraft, estimated the new electricity cost to be around 0.63 Danish kroner (5.8p) per kilowatt-hour, an increase of 70 per cent from the cost of using inland wind turbines. Although the wind turbines would not affect life on land with their noise, they were coming at a higher financial cost.  

Elkraft succeeded in 1991 by launching the first offshore wind farm in Vindeby, Southern Denmark. It consisted of 11 wind turbines each with a capacity of 450 kW. As at 2015, the farm was reported to have produced 450 GWh/billion-watt hours. Since the first successful launch, many offshore wind turbines have cropped up around the world. The biggest offshore wind farms are located in Northern Europe, specifically in the UK and Germany.

Vindeby Offshore Wind Farm
Vindeby wind farm in Denmark was the world’s first. It consisted of 2 rows and 11 turbines. Something of an experiment, it’s owner, DONG energy announced in 2017 pending decommission after 25 years of life. The lessons learnt here will no doubt allow ongoing improvement as more and more energy producers look to renewable sources as we endeavour to do out best to wean ourselves off fossil fuels.

Cost of Offshore Wind Energy

Initially, these offshore wind farms were too expensive for many governments to consider them as feasibly sustainable2. This was due to the high costs of constructing anything offshore, the price of mechanical parts for the wind turbines, and the constant maintenance needed to keep equipment working in a salty environment. Old reports revealed that at least 6 vessels were needed for the construction of each offshore wind energy farm3.

However, just like any other emerging technology, as it has advanced these costs have come down significantly. With newer parties coming into play (turbine manufacturing companies and offshore construction companies), the cost trajectory of offshore wind energy is lowering, while output continues to increase.

How Energy is Created with Sea Wind

Many of us are familiar with wind turbines, and that they are one of the few sources available for clean energy. If you’ve ever wondered why we don’t just power everything with wind turbines, the answer is quite simple. Not only do the gears (which turn to produce the electricity) need constant (and expensive) maintenance, the velocity of the wind on land is often not strong enough to produce enough output to match our energy needs.

With offshore turbines, there’s the advantage of high wind. If you’ve noticed, it’s almost always windy at the seaside. This is because of the relationship between air pressure and heat4. When the sun heats the land and sea, it never happens evenly. This means there is usually warm air and cold air present in the atmosphere. The warm air, which is lighter, rises. As this happens, cool air rushes under, and this is what we feel as wind.

Offshore wind turbines are constructed in bodies of water to harvest energy using the more forceful wind available. They are usually constructed on the continental shelf or in the ocean where the energy harvest would be higher5. With the right placement, these wind turbines can take advantage of high winds speeds and generate a higher amount of energy than could be feasible on land.

In Tune with Our Electricity Consumption

The operation of these offshore wind energy mills also lines up with consumer needs. In addition, offshore wind is usually stronger in the afternoon, which makes this its peak time for energy production. Consumers use the most electricity in the afternoon, and in this case, production and demand line up easily. There’s also the case of extremely long-distance transmission wires which line through most cities. With offshore wind turbines that are located close to cities, the need for these long-distance wires can be eliminated, along with more easily resourcing the demanding maintenance process that comes with them.

The Growth of Offshore Wind Energy

With Europe’s proof that offshore energy is a worthy investment, realising the advantages of renewable energy, many other regions around the world began their plans for offshore wind energy farms. As such, the success in Denmark and other European regions revealed that we could start making plans to reduce energy imports and cut down on fossil fuel which contributes to air pollution and greenhouse gasses.

In 2010, the US Energy Information Agency publicly announced their plans for offshore wind farm constructions. They stated that “Offshore wind power is the most expensive energy generating technology being considered for large scale deployment1”. The first offshore wind farm in the United States, however, did not go online until 2016. It was developed by Deepwater Wind, an energy company, to replace the diesel generators used to power resorts in Rhode Island. Today, there are a lot more offshore wind farms active in the United States, with 15 active proposals to install more, waiting to be approved.

Europe still holds the position of the highest producer of energy through offshore wind farms, with a significant increase every year. Europe boasts of 105 offshore wind farms across 11 countries. When combined, their total output capacity is currently at 18.5GW. Most of these numbers can be attributed to The UK and Germany, which produce about 85% of the total capacity. The world’s biggest offshore wind farm, Walney 3 extension, is located in The UK. However, some European countries, such as Sweden and France, have shown little interest in offshore wind energy so far.

China

China, like with every other world development, is catching up quickly with Europe on the deployment of offshore wind farms. In 2018, China was responsible for almost half of the global $25 billion investment into offshore energy. Further, the Chinese government recently approved 24 new offshore energy farms which they estimate will provide a yearly capacity of 6.7GW. After all, the country maintains its economic strength from manufacturing, and the Chinese government is hoping to reduce the impact of manufacturing on the environment. With these new projects, their aim is to cut down on coal power and combat air pollution which is a problem we’ve all most likely seen in the news, denting their reputation.

Environmental Concerns with Offshore Wind

A man looks out whilst swimming at a sea of offshore wind turbines. Photo by Jack Hunter on Unsplash

As promising as offshore wind energy is, we cannot ignore some environmental concerns which have been raised on its effects. Marine experts have expressed concern that the noise generated underwater could interfere with marine life. Thus, sound-sensitive marine animals such as whales and dolphins are the most vulnerable to this possible harm. And the noise could affect their ability to communicate, feed, or even identify migration paths. Thankfully today, engineers working to solve this problem have solutions in play.

Developers are being encouraged to install special foundation types which will lower the noise being produced by the energy turbines. Sadly, it might be impossible to completely silence these mills when they are at work.

Other concerned parties exist. These include people subjected to the noise due to their proximity to the shore. Fishers also fear that their access to fishing waters may be cut off. Offshore developers will have to come up with solutions to manage these concerns.

We can say that the government is, largely, doing its part, in maintaining marine and human interest, specifically in Europe. Before applications are approved, the government must verify that the intended area is not an exclusion zone6; nature reserve, shipping lane, lighthouse cone, exploration area, or possible site for finding archaeological remains.

Offshore Wind Beyond the Developed World

In turn, as developed countries enjoy the benefits of offshore wind energy, the World Bank is considering installing offshore energy farms in developing countries with offshore potentials.

Riccardo Puliti, the Senior Director and Head of Energy and Extractives at the World Bank, said:

“Offshore wind is a clean, reliable and secure source of energy with massive potential to transform the energy mix in countries that have great wind resources. We have seen it work in Europe – we can now make use of global experience to scale up offshore wind projects in emerging markets.”

With a budget of $5 million, the first countries being considered for this project are Brazil, Indonesia, India, the Philippines, South Africa, Sri Lanka, and Vietnam. As a result, this project could become an effective solution to the power problems which these countries currently struggle with.

Frederik Schönfeldt

Further Inspiration:

Sources and References:

#Description
1Levelized Cost and Levelized Avoided Cost of New Generation Resources in the Annual Energy Outlook 2019. U,S. Energy Information Administration. February 2019.
2Wind in our Sails: The Coming of Europe's wind energy industry, 2011.
3Wind in our Sails: The Coming of Europe's wind energy industry, 2011.
4Arshad, Muhammad & O'Kelly, Brendan. (2013). Offshore wind-turbine structures: A review. Proceedings of the Institution of Civil Engineers – Energy. 166. 139-152. 10.1680/ener.12.00019.
5Arshad, Muhammad & O'Kelly, Brendan. (2013). Offshore wind-turbine structures: A review. Proceedings of the Institution of Civil Engineers – Energy. 166. 139-152. 10.1680/ener.12.00019.
6Giebel, Gregor & Hasager, C. (2016). An Overview of Offshore Wind Farm Design. 10.1007/978-3-319-39095-6_19.

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