Sea waves are the result of transfer of mechanical energy of
wind to wave energy. The wave quality varies for different periods
and seasons. It is possible to have a realistic formula to calculate
the overall wave energy potential. A general study of the wave
nature has shown that there is potential of 40,000 MW along
the Indian coast.
A similar study along the coast of Maharashtra
has shown that there are some potential sites such as Vengurla rocks,
Malvan rocks, Redi, Pawas, Ratnagiri and Girye, possessing an average
annual wave energy potential of 5 to 8 kW/m and monsoon potential
of 15 to 20 kW/m. Considering this, the total potential along the
720 km-stretch of Maharashtra coast is approximately 500 MW for wave
energy power plants. Fortunately after decades of research and development
activities all over the world, some technologies are now available
commercially. We need to explore the possibility of wave energy power
plants at the identified sites by inviting proposals from private
investors / promoters / technology providers from all over the world.
They attract the private investment to the tune of Rs3000 crores.
The Govt. of Maharashtra and Govt. of India have plans to announce
policies to attract private investors in this field on BOO (Build
Own Operate) basis.
Energy Potential of Sea Waves
Wave energy is, in fact, the storage of mechanical
energy of wind in the sea water. Sea waves are variable in nature
and their height and width changes with time and season. The power
available in a sea wave is expressed as the following formula :-
P = 0.55 H2 s Tz kW per metre length of wave crest.
Where Hs = average of one-third of the highest waves in metre
Tz = zero crossing period in seconds.
That means a significant wave height of 3 metre.
with a zero crossing period of six seconds will have the wave power
of 29.7 kW per metre length of the wave crest.
The average potential along the Indian coast is
around 5 to 10 kW /m. India has a coast line of approximately 7500
km. Thus the total potential comes to around 40,000 MW. Even a 15%
utilization would mean the availability of approximately 6000 MW.
Generally it has been observed that the western coast is more useful
than the eastern coast. This is because the former has more stable
waves and is less vulnerable to cyclones that can damage the power
All over the world many types of technologies have
been tried way back since1970s. They are :
- Cockerel raft
- Flexible Bag energy Converter
- Submerged circular cylinder converter
- Clamp wave energy converter
- Oscillating water column Converter
- Ocean swell powered renewable energy Converter
Of these, the oscillating water column
converter (OWC) has been found to be more dominant due to its
simplicity and adaptability to use the existing coastal structure
of sea harbours. The OWC system consists of a chamber in the
sea exposed to wave action through an entrance at the bottom
or on the side. The air inside the chamber gets pressurized
or expanded owing to the wave action.
Wave Energy Illustration
The air movement through a small opening from or
into the chamber, depending on the pressure inside, is used to drive
an air turbine. This technology has been tried at Vizhinjam along
the Kerala coast, near Thiruvananthapuram by National Institute of
Ocean Technology, Chennai. (150 kW).
Status In Maharashtra
MEDA sponsored a study, conducted by Centre for
Earth Science Studies, Thiruvananthapuram, to find the wave energy
potential along the Maharashtra coast. The study completed in 1994,
has shown the Maharashtra coast has an annual wave potential ranging
between 4 to 8 kW per metre of the length of the wave crest. During
the monsoon, i.e., between June and August, the potential is quite
high, i.e. 12 to 20 kW/m. The wave energy potential of the most feasible
sites in Maharashtra are given in the following table :-
| Wave power at selected sites
along Maharashtra coast
Avg.Wave Power kW/m
Avg.Wave Power kW/m
The Vengurla and Malvan rocks and Redi
are on the top among the offshore locations. In the other group, Pawas
and Ratnagiri top the list followed by Girye and Miyet point.
Power Generation Projects based on Wave Energy
are not yet commercially established in India. MEDA has taken initiative
for establishing Demonstration Power Generation Project at Budhal,
Taluka: Guhagar, District: Ratnagiri. The Demonstrative Power Project
is of 15 to 25 kW Capacity. The Project is being installed and commissioned
with technical assistance from M/s Apar Urja Pvt. Ltd., Sangli and
is being commissioned.
On successfully completion of the project, the same is proposed to
be replicated at potential sites in India.