It seems the India has finally caught the offgrid wind energy fever. C-WET – the leading wind energy R&D institute in the country has started putting together plans to undertake an offshore wind energy feasibility study in Dhanushkodi near Rameswaram in Tamil Nadu. It should come as no surprise that the state which has the highest wind energy installed capacity – about 42% of the total installed capacity in the country has taken the first step in this direction.
The move is likely to have been inspired by the fact that most of the available (onshore) high wind density areas in the state have already been exploited. The state is estimated to have an onshore wind energy generation potential of about 6000 MW while the installed capacity is much higher and stands at 6548 MW (as of Oct.2011). It is plausible that project developers are finding it increasingly difficult to acquire suitable land for developing wind farms considering the fact that most of the high wind power density sites (i.e. sites which are most likely to generate high revenues) have already been occupied. The fact that the southern peninsular region (primarily southern half of costal Tamil Nadu) is estimated to have the highest offshore wind energy potential in the country further bolsters the case.
Big name players such as Suzlon, Vestas and Gamesa who have a significant presence in the country are likely to benefit from this exercise. These companies have the upper hand due to the fact that they are already big players in the international offshore wind energy market. Suzlon, more than anyone else should aim to capitalize on this market as they have taken a significant beating over the past year – from having lost a lot of market share in India to getting sued by US based Trinity Structural Towers Inc for breach of contract.
It is also possible that other companies such as ABB (who too has an Indian presence) could be a beneficiary by providing the required evacuation infrastructure for the electricity generated. For instance, ABB recently signed a $1 billion deal to establish a HVDC evacuation infrastructure that evacuates electricity from the North Sea wind farms to German power grid. This system is supposed to be more efficient than AC based evacuation and is most suitable for short distance power evacuation (which in this case would be from a few meters offshore to the land).
Cost of offshore wind has been the main hinderance to its large scale uptake. Wind farm facilities, such as wind turbines, foundations and electric cables, make up 79 percent of the total wind farm construction costs. Installation constitutes 15 percent of total costs. The domestic content requirements for the onshore wind energy sector which are likely to come into effect in the country as part of the next five year plan could extend to the offshore wind energy sector too. This could help drive down the offshore wind energy costs by ensuring most of the manufacturing and implmentation is done indigeneously. China for instance reduced offshore installation costs in the country by 60% compared to European levels by using technology developed within the country.
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Undertakings such as this is bound to take India higher up the global wind energy rankings in the years to come.
This refers to the News item’Plans afoot to develop offshore wind energy’
I have had been advocating Offshore Wind farms in India for
over a decade.
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.
Power P = 0.5 p A V3 Watts.. .. (1)
Where P = Power,p density of air,V=speed of the wind and A
is the area of the intercepted airstream(equal to the ‘swept’
by the rotor).
In standard conditions(sea level, temperature 15 degrees
Celsius) the density of the air is 1.225 kg/m3. So the amount
of Power intercepted by each square rotor is:
P=0.612 V3 Watts …(2)
For Example,if the wind speed is 6 m/s(a moderate breeze)
the power intercepted per square meter is 0.612 X 63 =
132 W; but if the speed rises to 24 m/s(a severe gale) the
power becomes 0.612 X 243 = 8460 W. This massive
increase is due to cubic relationship between wind speed
and power by equation (2). Here the word’intercepted’ rather
than ‘captured’ is used because the above figures relate to
the power in the wind, not the amount actually extracted by
a turbine rotor. 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.
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