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1 Renewable Energy Mohamed A. El-Sharkawi Department of Electrical Engineering University of Washington Seattle, WA 98195 Renewable Energy Solar Wind Fuel Cell Small Hydro Geothermal Tidal Biomass Solar Energy Solar Energy (Whr/m 2 /day) 0% 20% 40% 60% 80% 100% 0 2 4 6 8 10 12 14 16 18 20 22 24 Time Density ratio Daily Solar Power Density 2 σ Types of Solar Systems Passive Solar System Active Solar System (Photovoltaic or PV)

Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Page 1: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Renewable Energy

Mohamed A. El-SharkawiDepartment of Electrical Engineering

University of WashingtonSeattle, WA 98195

Renewable Energy• Solar• Wind• Fuel Cell• Small Hydro• Geothermal• Tidal• Biomass

Solar Energy

Solar Energy (Whr/m2/day)

0%

20%

40%

60%

80%

100%

0 2 4 6 8 10 12 14 16 18 20 22 24

Time

Density ratio

Daily Solar Power Density

2 σ

Types of Solar Systems

– Passive Solar System

– Active Solar System (Photovoltaic or PV)

Page 2: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Passive Solar System

Lens

Sun rays

Warm water

New supply of cold water Warm water to the house

Cold water back

to solar collector

Tank

Collector

Passive Solar

Active Solar Cell (PV)Active Solar Cell (PV)• PV cell is built like a diode out of semiconductor

material.

• Sunlight is composed of photons, or particles of solar energy. Photons are the energy byproducts of the nuclear reaction in the sun.

• When photons strike a PV cell, some of the protons energy is absorbed by the semiconductor material of the PV cell.

Active Solar Cell (PV)Active Solar Cell (PV)

• With this extra energy, the electron in the semiconductor material become excited and break off its atom, and eventually begin an electric current.

• Because PV cells are built like diodes, free electrons are forced to flow in only one direction

P-Type

Base

N-Type

Lens

-

-

I

Load

Page 3: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Structure of Solar SystemStructure of Solar System•• PV cell:PV cell: 4X4 inches. The cell can produce

about 1 watt which is enough to run a calculator.

•• Panel or Module:Panel or Module: To increase its energy rating, the PV cells are connect together in parallel and series.

• Parallel cells increase the current rating

• Series cells increase the voltage rating.

Structure of Solar SystemStructure of Solar System

•• Array:Array: PV panels connect together in parallel and series to form a high power system.

Structure of Solar SystemStructure of Solar System

Page 4: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Stand Alone PV System

ChargerDischarger

Con

verte

r

Local loadBattery

Solar array

House

dc current

ac current

PV System without battery

Con

verte

r Meter To utility

Local load

Solar array

House

dc c

urre

nt

ac current

Solar Power and the Environment

• 6kW from a photovoltaic system instead of a thermal power plant can reduce annual pollution by – 3 lbs. of NOx (Nitrogen Oxides),

– 10 lbs. of SO2 (Sulfur Dioxide), and

– 10530 lbs. of CO2 (Carbon Dioxide).

Solar Power and the Environment

• Solar system uses large areas of land.• PV systems are costly. • The efficiency of the solar panel is low.• Toxic chemicals are used to manufacture

solar cells.– Arsenic and Silicon.

– Since water is used in the process, the runoff causes pollution into local streams.

Wind Energy

Page 5: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Kinetic Energy of Air

2

21 vmKE =

δδ tvA*volumem ==

• m: mass of air

• v: speed of wind

• A: sweep area

• δ: air density (kg/m3)

• t: time

Generator

High speed shaft

Low speed shaft

Rotating blades Gear box

Tower

Housing

Wind TurbineTehachapi System

Off-Shore Wind System

Page 6: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Horizontal Axis Wind Turbine (HAWT) Vertical Axis Wind Turbine (VAWT)

Wind Energy and the EnvironmentWind Energy and the Environment

• Wind turbines don’t emit any pollution gas.

• Concerns include noise pollution, aesthetics, and bird collision.

• Wind is normally strongest at night when the power demand is the lowest.

Fuel CellFuel Cell

Page 7: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Generation of Hydrogen

H2

CO2

CO

CO

conv

ersi

on

H2O CO2

H2

Fuel Cell

Water(H2O)

Ref

orm

er

CH2

O2

Hydrocarbon fuel

Cat

hode

Ano

de

Electrolyte

Fuel Cell (Electrochemical Process)

Load

----

Hydrogen

2H2

Ions4H+

Oxygen (Air)

O2

Water2 H2O

I

- ---

- - --

Fuel Cell

• Produces power without combustion or rotating machinery.

• Makes electricity by combining hydrogen ions, drawn from a hydrogen-containing fuel, with oxygen atoms.

• The current is proportional to the size (area) of the electrodes.

• The voltage is limited electrochemically to about 1.23 volts per electrode pair, or cell.

• Cells can be “stacked” until the desired power level is reached.

Issues• Pure hydrogen is a volatile gas, and requires

special storage and transportation. • Hydrogen cannot be found free in nature, it is

often extracted by reformers• Efficiency of fuel cells including the reformer

process is 26 to 40%• Efficiency of internal combustion engines is

15 to 22%

Page 8: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Fuel Cell System for Water Treatment

Page 9: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Small Hydro

Types of small hydro systems

• Reservoir-Type• Diversion-Type

Reservoir-Type Small Hydro System

Generator

Turbine

Reservoir

Penstock

Discharge

Head

Diversion-Type Small Hydro System

Generator

Turbine

Discharge

Page 10: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Geothermal Energy

Heat Pump

Hot water Tank

Pumpand Heat

Exchangers

Ground Geo-exchanger

Warm air to house

Return cool air

Geothermal Power Plant G

Mist eliminator

CoolingTower

Steam

HeatMagma

Reservoir

Turbine

Page 11: Renewable Energy Solar Wind Fuel Cell Small Hydro ......• Tidal energy is expensive method. • Energy can only be generated when the current is strong around peak or the slack of

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Geothermal 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.

• 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, but at much lower level (1/6) than what a natural gas power plant produces.

• Processing the reservoir fluid can produce objectionable odors.

Tidal Energy

High Tide

Water Flow

Dam

Turbine

Shore

Lagoon Side

Sea Side

Low Tide

Water Flow

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Issues

• Dams can slow the flow of water, thus potentially stimulate the growth of the red tide organism.

• Tidal energy is expensive method. • Energy can only be generated when

the current is strong around peak or the slack of the tied.

Biomass Energy

Landfills• 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

G

Filter Storage

StackWater pipes

Steam

Furnace

Condenser

Heavy ashto landfills

Light ashTo landfills

Turbine

Biomass 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.