Offshore Wind Energy

Energy Sources from the social point of view has been the cradle of the modern civilization.  To continue it in a peaceful, sustainable way, humans nowadays have been interested on alternative sources of resources which do not bear any harmful consequences to the nature and its beings.  Of the alternative sources of energy that has been discovered, Wind Power plays a major role. It has been found out that out of the major renewable energy sources that are available on the earth, besides solar and hydro-power, Wind is another huge potential energy reservoir. Humans harnessed Wind Power from long time ago. In earlier times Wind Power has been used in Wind pumps for drawing up water, or in crushing wheat to make flour in Wind Mills. In modern times human found its application as a source for generating electricity. A little ago, thermal power was the only option for producing electricity. But it had adverse effects on Nature and also the raw material was a non-renewable source of energy. So, as an option for Eco-friendly technology Wind Power for generating electricity has been widely acceptable. In modern days, the harnessing of Wind Power for electricity can be categorized in two ways, Onshore and Offshore. Offshore Wind Energy generation has more benefits than the onshore process.


Wind Power from ancient times has been harnessed by people for using it in various purposes. It has been seen from earlier times recorded in history that Chinese people used wind power for Water pumping application using simple wind mills, while Persians and Middle-East people used woven reed sails for grinding application. And it has been known by people in almost every corner of the world where water and wind both are simultaneously and continuously available, how people used to sail around. So, if history is tracked, these common applications continued from 5000 B.C. up to late 19th century. But slowly times changed, and so its beings. People found its application in a new way by generating electricity. Throughout the 20th century, small wind plants, suitable for farms and residencies and some larger utility-scale wind farms that could be connected to electricity grids were developed in the European countries. This continued for the time being and then it was shut down due to the cheaper oil that was available then. But after 1970, the scenario somewhat changed due to people’s realization about non-renewable substances. So, their search for alternative sources began and again the importance of Wind Energy came into being.

The wind farms at the beginning were set up on land following the traditional method. But later on due to the realization of the power of winds in the offshore regions, an experimental setup was installed off the coast of Denmark in 1991. It was a huge success and immediately after that the commercialization for Offshore Wind Power followed around the world, mostly in Europe at that time.

Offshore Wind Power:

Offshore Wind Power refers to the construction of wind farms on the bodies of Water to generate electricity by harnessing the power of wind. Offshore Wind Power’s contribution to electricity is much more than the Onshore ones. Unlike the typical usage of the term “Offshore” in marine industry, Offshore wind power includes inshore water areas such as lakes, and sheltered coastal areas using Traditional fixed-bottom Wind Turbine technologies as well as in deep water areas  using Floating Wind Turbines. The idea of Offshore Wind power came into minds cause it was observed that the winds blowing over water bodies had more speed and were uniform than on lands. The potential energy gained is directly proportional to the cube of the wind speed. As a result a few miles per hour in the speed can result in significantly larger amount of electricity. For instance a turbine at a site with an average wind speed of 15 mph would produce almost 50% more electricity than at the same site with the same turbine and with average wind speeds of 13mph.

Global Scenario:

Currently Europe is the World leader in Offshore Wind power. After its first wind farm installation in Denmark in 1991 was a huge success, it started to expand its possibilities around the area in this field. In 2013, offshore wind power contributed to the 1567 MW of the total 11,159 MW that got produced by wind power. By January 2014, United Kingdom has by far the largest capacity of offshore wind farms with 3681 MW. Denmark is the second with 1271 MW installation and Belgium is third with 571 MW. Next comes Germany(520 MW) followed by Netherlands(247 MW) , Sweden (212 MW), Finland(26 MW), Ireland(25 MW), Spain (5 MW), Portugal(2 MW) and Norway(2 MW). Projections for 2020 calculate a wind farm of capacity 40 GW in European waters which would meet 4% demand of the European Union’s electricity.

Case Study: India

India has a very long coastline of 7500 kms including the island territories and also has an EEZ (Exclusive Economic Zone) of 2.172 million sq. km. it is surrounded by Bay of Bengal in the East, Arabian Sea in the West and Indian Ocean in the South. India has high Wind potential on the shore and offshore.

Essentially primary parameters such as bathymetry, wind velocity, proximity to the coast, ports, marine protected areas, harbours, marine sanctuaries which are used in assessing the feasibility of offshore wind farm using the GIS environment. Weekly Climatology of Quick SCAT wind speed data with resolution 0.25 x 0.25 degree was used for the period 1999-2009 for the exploration of the seasonal wind potential.

Bathymetry: The Water depth of the sea or ocean, is an essential parameter because decides the primary cost of the installation cause after a certain depth installation might not be feasible cause it will complicate structures that will unnecessarily increase the cost. The feasible depth for installation is 15-75m. The different range of Indian waters within which different designs are feasible are:

  1. 0m to-24.9
  2. -25m to -49.9m
  3. -50m to -74.9m

Wind Speed: Wind speed is a very important parameter that decides the feasibility of a particular site. Certain thresholds are to be followed for optimum power generation. The minimum wind speed of 5 – 5.5 m/s has been considered threshold for wind energy development. Therefore, for offshore installation it should be checked that the minimum wind speed is more than the minimum onshore desired.

Proximity to the coast, ports, harbours: All the traffic near the coast has to be kept in check so as to avoid collision of vessels with the farm or HV station thus preventing loss of potential energy. Areas near to ports or 50 kms distance from the coast are considered for study, so that the traffic by the ship and long cable laying could be avoided.


India has major scopes of putting Offshore Wind power into use if there is a little improvement in technology. It is due to India’s offshore wind speed which is a little less than the pacific one. So, an improvement in the turbines includes some technical advances like working in low wind speeds. Also wind varies here according to different seasons in India which will produce different results as par. So, technologies should be appropriate to cope up with that.

Prof. Subhro Chakraborty,
Head, Department of Civil Engineering,
University of Engineering & Management (UEM), Jaipur




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