Tidal energy

1. Tidal Energy
Dr Fayaz A. Malla
Assistant Professor, Environmental Sciences
GDC Tral
Higher Education Department, Govt. of J&K

2. Tidal power or tidal energy is
harnessed by converting
energy from tides into useful
forms of power, mainly
electricity using various
methods.
Tides are created by the
gravitational effect of the
moon and the sun on the
earth causing cyclical
movement of the seas.
One of the strengths of
harnessing power from tidal
ranges and tidal streams over
other forms of renewable
energy is that the process is
entirely predictable.

3. Energy from the
moon
• Tides generated by the combination of the moon
and sun’s gravitational forces
• Greatest affect in spring when moon and sun
combine forces
• Bays and inlets amplify the height of the tide
• In order to be practical for energy production,
the height difference needs to be at least 5
meters
• Only 40 sites around the world of this magnitude
• Overall potential of 3000 gigawatts from
movement of tides

4. How it works
• First generation, barrage-style tidal
power plants
• Works by building Barrage to contain
water after high tide, then water has to
pass through a turbine to return to low
tide
• Sites in France (La Rance), Canada
(Annapolis), and Russia
• Future sites possibly on Severn River in
England, San Francisco bay,
Passamaquoddy

5. Second-generation
tidal power plants
• Barrage not need, limiting total
costs
• Two types- vertical axis and
horizontal axis
• Davis Hydro turbine….. Successfully
tested in St. Lawrence Seaway
Harness the energy of tidal streams
• More efficient because they allow
for energy production on both the
ebbing and surging tides
• One site has potential to equal the
generating power of 3 nuclear
power plants

6. According to the estimates of the Indian government, the country
has a potential of 8,000 MW of tidal energy. This includes about
7,000 MW in the Gulf of Cambay in Gujarat, 1,200 MW in the Gulf of
Kutch and 100 MW in the Gangetic delta in the Sunderbans region
of West Bengal.

7. Energy from tide can be
generate in three ways
• TIDE MILL
• TIDEL BARRAGE
• TIDEL STREAM

8. Tide mill
The generation of energy from
the tides is not a new idea.
Mills, which used tidal flows in
bays and estuaries to drive
machinery to grind, were used
in medieval times and changing
labour markets following the
First World War, resulted in
traditional tide mills becoming
rare and of historical interest
only.

9. Tidal Barrage
A tidal barrage is a dam-like
structure used to capture
the energy from masses of water
moving in and out of a bay or river due
to tidal forces a tidal barrage first
allows water to flow into a bay or river
during high tide, and releasing the
water back during low tide. This is
done by measuring the tidal flow and
controlling the sluice gates at key
times of the tidal cycle. Turbines are
then placed at these sluices to capture
the energy as the water flows in and
out.

10. Working of Tidal Barrage

11. The Rance Tidal Power Station is
the world's first tidal power
station and also the world's
second biggest tidal power
station. Opened on the 26th
November 1966, With a peak
rating of 240 Megawatts,
generated by its 24 turbines it
supplies 0.012% of the power
demand of France.

12. TIDAL STREAM
Also known as tidal energy
converter (TEC). The
technology involved is very
similar to wind energy, but
there are some differences.
Water is 800 times denser than
air and has a much slower flow
rate this means that the turbine
experiences much larger forces
and moments. This results in
turbines with much smaller
diameters

13. TYPE OF TIDAL TURBINE
VETICAL AXIS
TURBINE
HORIZONTAL AXIS
TURBINE
VENTURI TYPE TURBINE

14. Vertical axis turbine
The rotational axis of the system is
perpendicular to the direction of water
flow. Vertical axis turbines can
harness energy from flows in any
direction and may be more efficient
than horizontal axis turbines in low
flow conditions. However, horizontal
axis turbines have greater efficiency
and survivability in strong flows

15. Horizontal
axis turbine
A horizontal axis turbine has the
traditional form of “fan” type system
familiar in the form of windmills and
wind energy systems. As water is
approximately 800 times denser than
air and has a much slower flow rate,
water turbines experience much larger
force sand moments than wind
turbines. This leads to the
development of turbines with smaller
diameters and blades with different
designs.

16. They can operate in slow
moving water with a smaller
turbine at sites where large
turbines are restricted. A
shroud of suitable geometry
can increase the flow velocity
across the turbine by 3 to 4
times the open or free stream
velocity.

17. Advantages
• No pollution
• Renewable resource
• More efficient than wind
because of the density of
water
• Predictable source of energy
vs. wind and solar
• Second generation has very
few disadvantages
• Does not affect wildlife
• Does not affect silt
deposits
• Less costly – both in
building and
maintenance

18. Disadvantages
• Presently costly
• Expensive to build and maintain
• A 1085MW facility could cost as
much as 1.2 billion dollars to
construct and run
• Connection to the grid
• Technology is not fully developed
• Barrage style only produces energy
for about 10 hours out of the day
• Barrage style has environmental
affects
• Such as fish and plant migration
• Silt deposits
• Local tides change- affects still
under study