Hydrokinetic Energy Types Small hydroelectric system Barrage System Water stream System Wave System Types of small hydro systems ReservoirType DiversionType ReservoirType Small Hydro System ID: 760798
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Slide1
Renewable Energy
Part 4
Professor Mohamed A. El-Sharkawi
Slide2Hydrokinetic Energy
Slide3Types
Small hydroelectric
system
Barrage System
Water
stream System
Wave System
Slide4Types of small hydro systems
Reservoir-Type
Diversion-Type
Slide5Reservoir-Type Small Hydro System
Generator
Turbine
Reservoir
Penstock
Discharge
Head (
H
)
H
is the physical head
Slide6Potential Energy in Reservoir
Weight of water in reservoir
Water head
Generator
Turbine
Reservoir
Penstock
Discharge
Head
PE
r
For variable head
N:
number of hours in one year
H
i
: head during
n
i
hours
Slide7Potential Energy of Water Exiting Penstock
mass of water leaving
penstock
Effective water head
Generator
Turbine
Reservoir
Penstock
Discharge
PE
p
-out
Slide8Potential Energy of Water Exiting Penstock
Water flow in penstock
:
w
ater density, 1000kg/m
3
Generator
Turbine
Reservoir
Penstock
Discharge
P
E
p
-out
Slide9Theoretical Head
Generator
Turbine
Reservoir
Penstock
Discharge
P
E
p
-out
P
r
is the pressure at the end of the penstock in N/m
2
.
vol
is the volume of water passing through the pipe (m
3
)
When water flows
When water is blocked
Slide10Effective Head
Generator
Turbine
Reservoir
Penstock
Discharge
P
E
p
-out
Slide11Evaluation
The amount of electric power generated by a small hydroelectric system depends on three parameters:
1
) Effective head
h
2
) Water flow
rate
3
) The efficiency
Slide12System Efficiency
Power at the end of penstock
P
p-out
Blade Power
P
blade
Input power to Generator
P
m
Output electric power
P
g
Hydro losses
Turbine losses
Generator losses
Penstock losses
Power at the entrance of penstock
P
p-in
Slide13Example
A small hydroelectric site has a reservoir with 80 meter effective head. The penstock passes water at the rate of 100 kg/s. The hydro efficiency is 95%, the turbine efficiency is 85% and the efficiency of the generator is 90%. Assume that the owner of this small hydroelectric system sells the generated energy to the local utility at $0.15/kWh. Compute his income in 1 month.
Slide14Solution
Slide15Diversion-Type Small Hydro System (Water Stream System)
Generator
Turbine
Discharge
Slide16Water Stream System
Slide17Water Stream System
Slide18Water Stream System
The technology required to convert tidal energy into electricity is very similar to the technology used in either wind energy or hydroelectric power plants
For the same blade size, the tidal mills produce much more power than wind turbines
Water density is 800-1000 times the air density
Slide19Water Stream System
A
s
is the sweep area of the blades of the turbine in one revolution.
Assuming a water density of 1000 kg/m
3
Slide20Coefficient of Performance
Slide21Example
A diversion-type small hydroelectric system is installed across a small river with current speed of 5 m/s. The diameter of the swept area of the turbine is 1.2 m. Assume that the coefficient of performance is 50%, the turbine efficiency is 90%, and the efficiency of the generator is 90%. Compute the output power of the plant and the energy generated in one year. If the price of the energy is $0.05/kWh, compute the income from this small hydroelectric plant in one year
Slide22Solution
Slide23Barrage System at High Tide
Water Flow
Dam
Turbine
Shore
Lagoon Side
Sea Side
Slide24Barrage System at Low Tide
Water Flow
H
Slide25Barrage
Slide26Barrage System
A
is the area of the base of the lagoon
H is the maximum hydraulic heads.
Slide27Barrage System
PE: Potential energy of Barrage Systemm: the mass of water moving from the high to low head sideg: the acceleration of gravityH: the average of the difference in heads between the waters on the two sides of the dam
Slide28Barrage System: Semidiurnal tide
Slide29Barrage System: Semidiurnal tide
Slide30Issues
Dams can
slow the flow of water
, thus potentially stimulate the
growth of the red tide organism.
Tidal energy is
expensive
method.
Most of the energy is generated when the current is strong around
peak or the slack
of the tied.
Slide31Wave Energy
Slide32Wave Energy
Hinges
Hydraulic Motor
Pistons
Generator
Wave
Slide33Slide34Wave Energy
Slide35Wave Characteristics
Trough
Height (
h
)
Wavelength (
l
)
Crest
Amplitude (
a
)
Seawater Level
Period of wave
Power/m of costal line
Slide36Geothermal Energy
Slide37Slide38Slide39Cross Section of Earth
Slide40Earth Temperatures
Temperature
40km
100-200 km
5
o
-20
o
500
o
-600
o
1400
o
Mantle
Depth
Slide41Slide42Heat Pump
Hot water Tank
Pump
and Heat Exchangers
Ground
Geo-exchanger
Warm air to house
Return cool air
Slide43Geothermal Reservoir
G
Mist eliminator
Cooling
Tower
Steam
Heat
Magma
Reservoir
Turbine
Slide44Hot Dry Rock
Slide45The first geothermal power plants in the US (The Geysers) in northern California
Slide46Slide47Types of Geothermal Power Plants
Dry Steam Power Plants:
Steam temperature is very high (300
o
C)
Flash Steam Power Plants:
When the reservoir temperature is above 200
o
C and below 300
o
C
the reservoir fluid is drawn into an expansion tank that lowers the pressure of the fluid. This causes some of the fluid to rapidly vaporize (flash) into steam.
Binary-Cycle Power Plants:
At moderate-temperature (below 200
o
C)
the energy in the reservoir water is extracted by exchanging its heat with another fluid (called binary)
The binary fluid has a much lower boiling point thus it is flashed into steam
Slide48Geothermal Energy
Geothermal site must have the
magma
close
enough to the surface to heat reservoirs accessible by current drilling technology..
Underground reservoirs are often surrounded by very
hard rock
; hard to reach
The geothermal fluid can cause
water pollution
due to the presence of some gases and metals in the reservoirs.
Geothermal fields could also produce
carbon dioxide
.
Processing the reservoir fluid can produce objectionable
odors
.
Slide49Biomass Energy
Slide50Landfills
Housings are being expanded closer to landfills
Landfills and the trucks are considered
sight pollution and safety hazards
.
Landfills produce unpleasant
odors
.
Leachate
, which is the fluid resulting from water mixed with garbage contaminates underground water.
Ethanol (alcohol) and Methanol
can be generated in landfills increasing the fire hazards
Slide51G
Filter
Storage
Stack
Water pipes
Steam
Furnace
Condenser
Heavy ash
to landfills
Light ash
To landfills
Turbine
Slide52Slide53Biomass Burning
Biomass incineration produce
heavy metal and Dioxins
Heavy metal is mixed with ash posing serious
pollution to water
.
Dioxin is the most dangerous element. It is highly carcinogenic and can cause cancer and genetic defects.