1/12/2010

1

Renewable Energy Sources

Class Slides

Energy and Power

Group 1

Prepared by

Luis G. Pérez

School of

Electrical Engineering and

Computer Science

Important Preliminary Note

The material presented here is not to be used for profit purposes. The document is for the

sole use in the undergraduate class “Renewable Energy” at the School of Electrical

Engineering and Computer Science of Washington State University. This course is being

partially sponsored by Puget Sound Energy, Inc.

The material was prepared using, among other sources, figures and data tables which can be

found in public sites in the INTERNET. However, the slides –as a set– are not public

documents, they are intended for the exclusive use of the students registered in this class.

Some of the slides were originally created by the instructor, and some have been copyrighted

by Schweitzer Engineering Laboratories, Inc. Those slides are used here with permission. In

general, the document should not be copied, reproduced or used for any purpose without

citing the original sources.

It is strongly recommended that the students consult the original sources of the figures and

schemes using INTERNET search engines and the list of references shown at the end of this

document.

Luis G. Pérez

Instructor

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2

Objectives

•Define energy and power under a practical point view

•Identify the “usable” sources of energy

•Define efficiency and losses

•Identify existing commercial energy sources

•Identify where the energy is consumed

•Identify renewable energy sources

•Justify the need for electrical energy

•Explain the difference and application of energy and power

•Recognize the price of energy

•Explain home energy consumption and cost

The Energy Concept

Energy (Physics): A quantity that describes the

capacity to do work; commonly divided into three

major classifications:

– Kinetic (dynamic)

– Potential (static)

– Radiant (electromagnetic)

A Human Need:

To Control, Manipulate, Use Natural Energy

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Human Traction

Animal Traction

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Animal

Traction

Device

(Mill)

Animal

Traction

Device

(Mill)

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The Windmill

• A wind wheel is a

mechanical Energy

transformer

Modern Wind Wheels

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Forms of Energy

• Chemical

• Nuclear

• Stored Mechanical

Energy

• Gravitational

• Thermal (heat)

• Motion

• Sound

• Electrical

• Radiant (?)

POTENTIAL KINETIC

Energy (U) Formulae

dfU ⋅=

hgmU ⋅⋅=

2

2

1vmU ⋅⋅=

Energy (work) in joules:

Potential energy:

[J]

[J]

[J]Kinetic energy:

Units:

1 J = 1 N·m = 1 W·s

1 BTU =1055.05585 J

1 kcal = 4184 J

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Energy Conservation: Efficiency.

• Energy output is always less than energy input

– Efficiency=[(Output Energy) ÷ (Input Energy)] x 100

• Efficiency is always less than 100 %

– Engineers try to design machines with efficiency close to 100%

PROCESSOutput

Energy

Input

Energy

Energy Conservation “Losses”

In many processes, loss is an amount of energy

which is transformed to a useless type of energy

PROCESS

Output

EnergyInput

Energy

Heat produced by friction

and other effects

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Efficiency Formula

100

100

xLossesEnergyOuput

EnergyOutputEfficiency

LossesEnergyOutputEnergyInput

xEnergyInput

EnergyOutputEfficiency

+=

+=

=

Energy Transportation or

Transmission

?

?

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Energy Transportation or Transmission

?

?

To Transport?

Trucks?

Pipelines?

Train?

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Another Idea…

A 10-mile-long Pulley?

How Do We Transport this Energy in a Secure and

Economical Way?

Electrical Energy:

Special type of

energy

efficient for

transmission along

great distances Motion

Converter

Light Heat

Converter Heater

DistributionConverter

Mechanical

Energy

Transformer

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Electrical Energy

• A special form of energy

• Its main purpose is to transmit the useful energy

from one place to another in a simple, versatile,

efficient and clean way

• It is natural; however, we obtain it with the

proper energy conversion process

Energy Conversion

• Energy converters produce a form of energy different

from the input energy

• Examples:

– Mechanical to Electrical

– Electrical to mechanical

– Chemical to Mechanical

– Chemical to Electrical

– Radiant to Electrical

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Electromechanical Energy Conversion from Mechanical to

Electrical Energy:

The Electric Generator

GENERATOR

Electrical

Energy

Mechanical

Energy

Generator

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Your Bike Dynamo is a Generator

Your Car’s Alternator is a Generator

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Energy Converters with

Electrical Energy as Input

Light bulb:

Electrical to

Radiant

Electric Motor:

Electrical to

Mechanical

Heater:

Electrical to

Thermal

Efficiency

Energy ConverterOutput

Energy

Input

Energy

100⋅=

input

output

U

Uη

(Efficiency is always less than 100%)

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Efficiency of Some Energy Converters

Device Input energy form Ouput Energy formApproximate

Efficiency (%)

Electric Heater Electrical Thermal 99

Hair drier Electrical Thermal 99

Electric Generator Mechanical Electrical 95

Large Electric motor Electrical Mechanical 90

Battery (dry cell) Chemical Electrical 90

Steam boiler (power plant) Chemical Thermal 85

Home gas furnace Chemical Thermal 85

Home oil furnace Chemical Thermal 65

Small Electric motor Electrical Mechanical 65

Home coal furnace Chemical Thermal 55

Steam turbine (power plant) Thermal Mechanical 45

Gas turbine (aicraft) Chemical Mechanical 35

Gas turbine (industrial) Chemical Mechanical 30

Automobile engine Chemical Mechanical 25

Fluorescent lamp Electrical Light 20

Silicon solar cell Light Electrical 15

Steam locomotive Chemical Mechanical 10

Incandescent lamp Electrical Light 5

Energy Needs (Scales)

• Small scale (home scale)

• Medium scale (factory, communities)

• Large scale (utility production, cities,

states, countries)

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Major Natural Energy Sources

Petroleum

Coal

Natural

Gas

Nuclear

Hydro

Wind

Solar

Biomass

Other

Considered non

renewable sources

Considered

renewable sources

Non-renewable Natural Resource

Demand

Production

Time (years)

Units

Peak production

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Major Natural Energy Sources

Where is Energy Used?

Residential/

Commercial

Industrial

Transportation

Electrical

Sector

L

L

L

L

LL=LossesPetroleum

Coal

Natural

Gas

Nuclear

Hydro

Wind

Solar

Biomass

Other

Energy Flow

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Energy Sources for the Electric Sector

(2006)

Recommended Web Site

U. S. Department of Energy

Energy Information Administration (EIA)

Official Statistics from the U. S. Government

http://www.eia.doe.gov/

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Enerfy – Electric Sector

Energy Sources Considered “Renewable” and/or “Green”

Wind turbine generation systems

Solar thermal and photovoltaic energy

Fuel cells Geothermal energy Tidal energy

Hydroelectric power

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Traditional Electrical Power System

The Big Picture

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The Difference Between Energy and Power

Power is the rate at which energy is

consumed (or produced):

Power [Watts] = (Energy) ÷ (Time)

• Power is in watts

• Energy is in joules

• Time is in seconds

Energy = (Power) x (Time)

• joules = watts x seconds

• 1 Calorie ~ 4.2 Joules

Units of Power

1 watt = 1 W100 watts = 100 W

1000 watts = 1 kilo watt

1000 W = 1 kW

1 million watts =

= 1000 kilo-watts =

= 1 mega-watt =

= 1 MW

1 Large Bulb

Small Residential Zone

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Common Units of Energy and Power (1)

Power

1 Watt

1 second time

Energy = (Power) x (time)

1 Joule = 1 Watt x 1 second

This area is

equal to

1 Joule

Power

1 hourtime

Energy = (Power) x (time)

1 kWh = 1 kW x 1 h

This area

is equal to

1 kWh1 kW

Precise Formulae

dt

dUP =

∫ ⋅=

2

1

t

t

dtPU

Power:

Energy:

P

tt1 t2

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Electric Power: Direct Current Source (D. C.)

LoadD. C.

SourceV

I

Power produced by the source:

IVP ⋅=

-Battery

-D. C. generator

-Etc.

-Light bulbs

-D. C. motors

-Etc.

Wires

Units: 1 watt = 1 ampere x 1 volt

1W = 1 A x 1 V

Electric Power:

Single-Phase Alternating Current (A. C.) Source

LoadA. C.

SourceV

I

Power produced by the source:

)(PFIVP ⋅⋅=

-Single-phase tap

-A. C. generator

-Etc.

-Light bulbs

-A. C. motors

-Heaters

-Etc.

V and I are the effective (RMS) values of voltage and current

PF = power factor

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The Price of Electrical Energy

(relatively old values ~1999)

Industrial

Rates

Residential

Rates

US $/kWh US $/kWh

Austria 0.08 0.16

Belgium 0.05 0.15

Canada 0.04 0.06

France - 0.12

Germany 0.06 0.15

India 0.07 0.03

Italy 0.09 0.15

Japan 0.17 0.24

Switzerland 0.09 0.13

United

Kingdom 0.07 0.12

United States 0.04 0.08

What is going on in my House?

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Typical Power Consumption of Home

Appliances

DeviceTypical Wattage

(not a constant)

Light bulb 60 watts

Fan 75 watts

Small black/white

television 100 watts

Color television 300 watts

Home computer and

monitor 400 watts

Electric blanket 400 watts

Microwave oven 750 watts

Furnace fan 750 watts

Refrigerator 300 watts

Hair Dryer 750 watts

Electric water heater 4,500 watts

Whole-house A/C or

heat pump 15,000 watts

Load Curve for Typical House

House Load

0

500

1000

1500

2000

2500

3000

3500

4000

1 3 5 7 9

11

13

15

17

19

21

23

Hours

Wa

tts

MISC.

TV

COMP

KITCHEN

LIGHTS

REFRIG.

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Energy and Money Consumption

Energy consumption during the day

0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20

Ho urs

Money consumption during the day

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 5 10 15 20

H our s

(Based on a flat price of 0.087 $/kWh)

Monthly cost: $ 45 Approx.

Generation needs are determined by the demand. Figures:

energy, load curve, peak load, average load, load factor.

Load Curve

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0.00 5.00 10.00 15.00 20.00 25.00

Time (hours)

Load

(M

W)

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Energy and Power Consumption

Monthly (kWh) Load (kW) Number of Habitants

Monthly

consumption per

habitant (kWh)

House type 1 (USA) 4,150 5.8 4 1,037.5

House type 2 (Latinamerica) 1,300 1.8 4 325.0

Apartment type 1 (USA) 2,150 3.0 2 1,075.0

Apartment type 2 (Latinamerica) 1,250 1.7 4 312.5

Commercial Zone in Town ( Typical US

average commercial client)3,750 5.2

Mall Size 1 (12 average US commercial

clients with not big supermarket)45,000 62.5

Mall Size 2 (12 average US commercial

clients with supermarket or big Store)95,000 131.9

Industry 1 (Latinamerica) 52,150 72.4 ----

Industry 2 (Small US Industry) 103,275 143.4 ----

Industry 3 (USA) 306,474 425.7 ----

City type 1 (Latin america 100,000

inhabitant)20,174,500 28,020 100,000 202

City type 2 (USA) 545,267,893 757,317 1,000,000 545

City type 3 (USA Hot city) 2,350,267,893 3,264,261 3,000,000 783

Country type 1 (Vzla) 5,011,936,010 6,961,022 24,135,280 208

Country type 2 (Guatemala) 1,761,936,010 2,447,133 11,986,558 147

Country type 3 (San Francisco Area) 6,761,936,010 9,391,578 8,636,243 783

Continent (*)Mexico - USA - CANADA 410

millions of habitants380,000,000,000 527,777,778 409,000,000 929

Planet Earth 463,600,000,000 643,888,889 6,300,000,000.00 74

(*) The consumtion of North America is 4.5 times the consumption of the rest of the World

Typical power consumptions

(approximated)

Residential

Commercial

Industrial

Community

Countries

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2 .- ElectricPower and Machines.url

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8 .- DOE's ConcentrSolar Power Overview.url

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21 .- Hydro Turbines.url

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28 .- PATIO DE DISTRIBUDE GURI.url

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