Offshore wind power refers to the construction of wind farms in bodies of water to generate electricity from wind. Better wind speeds are available offshore compared to on land, so offshore wind power’s contribution in terms of electricity supplied is higher.
In the power equation Wind speed is having cubic relation and as such any rise in wind speed will contribute much to the economics of wind energy. It is common sense that winds on the sea are higher than on land because the roughness factor of the water and ise are zero.
Large modern turbines typically capture up of about 50% of the wind power presented to them.
Betz’s law is a theory about the maximum possible energy to be derived from a wind turbine developed in 1919 by the German physicist Albert Betz. According to Betz’s law, no turbine can capture more than 59.3 percent of the kinetic energy in wind. The ideal or maximum theoretical efficiency n max (also called power coefficient) of a wind turbine is the ratio of maximum power obtained from the wind to the total power available in the wind. The factor 0.593 is known as Betz’s coefficient. It is the maximum fraction of the power in a wind stream that can be extracted.
Economics and benefits:
Offshore wind power can help to reduce energy imports, reduce air pollution and greenhouse gases (by displacing fossil-fuel power generation), meet renewable electricity standards, and create jobs and local business opportunities.
COST COMPARISON OF ONSHORE AND OFFSHORE WIND FARMS
Onshore
Investment of about $1.5 million per MW
Levelized cost of 6-7 cents per kWh
O&M – 1-3% of capital costs
May be built in smaller units
Offshore
Investment of $2.3 million per MW
Levelized cost of about 10-11 cents per kWh
Higher O&M – 40$ per kW and 0.7 cents per kWh variable
Large turbines and farms required
In spite of the higher costs and the uncertainties involved in offshore wind, research in this sector has been significant, and the main reason is the potential offered by offshore wind turbines, especially in lands close to water
At the end of 2011, there were 53 European offshore wind farms in waters off Belgium, Denmark, Finland, Germany, Ireland, the Netherlands, Norway, Sweden and the United Kingdom, with an operating capacity of 3,813 MW,[ while 5,603 MW is under construction
USA, China, South Korea, Taiwan, France and Japan have ambitious plans to go in for offshore wind farms on a massive scale.
Prospects for Offshore Wind Farms in India:
Length of coastline of India including the coastlines of Andaman and Nicobar Islands in the Bay of Bengal and Lakshwadweep Islands in the Arabian Sea is 7517 km. Length of Coastline of Indian mainland is 6100 km.
Thorough Wind studies have to be carried out along the coast to identify the prospective offshore wind farm sites. Based on these studies a Pilot project can be started by MNRE which will help as a Demonstration project .
Dr.A.Jagadeesh Nellore(AP),India
Wind Energy Expert
E-mail: anumakonda.jagadeesh@gmail.com