1/21/2010

1

Renewable Energy Sources

Class Slides

Energy and Power

Group 2

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

1/21/2010

2

Objectives

• Outline electrical energy consumption in different

regions of the world

• Describe and use load curves (demand curves)

• Describe and use load duration curves (LDC)

• Recognize “traditional” fossil-fueled power plants

• Describe main characteristics of renewable power

plants• Hydroelectric (dam, river and tidal)

• Wind farms

• Solar thermal and solar photovoltaic

• Geothermal

• Discuss the main advantages and disadvantages of

traditional and renewable power plants

• Define generation reliability

World Regions:

Electrical Energy Consumption

4,543.15

758.95

3,242.98

1,143.46

518.73 478.44

5,072.60

15,758.31

0.00

2,000.00

4,000.00

6,000.00

8,000.00

10,000.00

12,000.00

14,000.00

16,000.00

TW

h

North

Am

erica

Cent. &

Sth

Am

erica

Euro

pe

Eura

sia

Mid

dle

East

Afric

a

Asia

&

Oceania

World T

ota

l

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3

U. S. Average electrical Power Per Capita

(2005)

Average power per capita (2005)

297

1,460

0

200400

600

800

10001200

1400

1600

World US

Wa

tts

/in

ha

bit

an

t

Symbols for One-Line Diagrams of

Electrical Power Systems

Generator

Transformer

Switch (Isolator)

Circuit Breaker

Power Line

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Power System One-Line Diagram

Generation

12 kV or

18 kV, etc.

TransmissionDistribution

12 kV or

15 kV, etc.

Transmission

Line

Generators

Step-Up

TransformerStep-Down

Transformers

Substation Substation

115 kV or 345 kV or 765 kV, etc.

Generation needs are determined by the demand

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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Load Curve (Demand Curve)

0T t (hours)

Ppeak

P (MW)

U

Example of day curve (T=24 hours)

Peak demand = Ppeak

∫ ⋅=T

dtPU0

100

100

⋅⋅

=

⋅=

peak

peak

ave

PT

ULF

P

PLF

T

UdtP

TP

T

ave =⋅= ∫01

Energy:

Average demand:

Load factor:

Pave

[MWh]

Load Factor

0T

P (MW)

0T

P (MW)

Curve 1. Load curve with low LF

Curve 2. Load curve with a LF close to 1.0

Pave

Pave

Although the energy required in

both cases is similar (area under

the curve), the high peaks of

curve 1 impose a major

requirement. Generation has to be

set to cover the maximum (peak)

load.

How do we improve the LF?

time

time

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Load Duration Curve

P

AB

C

D

F

G

H

J

I

Load Curve

P

A

DF

G

J

I

Load Duration Curve (LDC)HC

B

time

time

Example: Load Curve for a Certain Region

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)

Pave≈13,300 MW

Ppeak ≈17,000 MW

U=319,200 MWh

LF=78.23 %

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Example Duration Curve (1 day)

Load Duration Curve (LDC)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0.00 5.00 10.00 15.00 20.00

Time (hours)

Lo

ad

(M

W)

Unit Commitment

- In a system with different power plant types and sizes, how do we

assign the generation units in order to cover the demand?

- Consider reserve

- Unit commitment by plant size, cost-efficiency, reliability

- Optimum power flow considers the effect of the transmission network

0T

P (MW)

0T

P (MW)

Base Base

Peak

Peak

Reserve

Intermediate Intermediate

LDCLC

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Example Duration Curve (1 day)

Base Power and Average Power

Load Duration Curve (LDC)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

0.00 5.00 10.00 15.00 20.00

Time (hours)

Lo

ad

(M

W)

Pave≈13,300 MW

Pbase=10,000 MW

Ppeak ≈17,000 MW

Power Production Methods

(Utility-Scale Size)

Hydroelectric Plants

Thermal Plants

Solar Plants

Wind Plants

• High Head

• Medium Head

• Low Head

• Gas Turbines

• Coal - Steam Turbines

• Combined Cycle Plants

• Nuclear – Steam Turbines

• Diesel

• Geothermal – Steam Turbines

• Photovoltaic

• Thermal (steam turbine)

• Several types

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Electric Power Generation Plants

Fuel - First Stage Second Stage Third Stage Fourth Stage

Main Conversion

Devices

Wind (G, R) Mechanical Electrical Wind turbines

Water-River (G, R) Mechanical Electrical Hydroturbines

Gas (FF) Thermal Mechanical Electrical Gas turbines

Gasoil (FF) Thermal Mechanical Electrical Diesel engine

Coal (FF) Thermal (Steam) Mechanical Electrical Steam turbines

Biomass (G, R) Thermal (Steam) Mechanical Electrical Steam turbines

Gas (FF) Thermal (Steam) Mechanical Electrical Steam turbines

Uranium [Nuclear] (G?,R?) Thermal (Steam) Mechanical Electrical Steam turbines

Solar (G,R) Thermal (Steam) Mechanical Electrical Solar heaters

Solar (G, R) Electrical Solar photovoltaic cells

Hydrogen (G, R) Electrical Fuel Cells

Chemical Elements (G?, R?) Electrical Batteries

Generation of Electrical Energy

Note:

This is how most experts consider these energy sources. There is not absolute consensus on this matter,.

G = Green; R= Renewable; FF = fossil fuel

Diesel Generation Plants

Generator

DieselEngine

Biodiesel? Alcohol? Biofuel? Transportation sector

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Basic Diagram of a Steam Generation Unit

Steam Turbine

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Also a Steam Machine

--James Watt (1736-1819)

Basic Diagram of a Coal Plant (Steam TG)

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Basic Diagram of a Nuclear Plant

Basic Diagram of a Gas Generation Unit

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Basic Diagram of a Combined Cycle Generation Compound

Basic Diagram of a Hydroelectric Generation Unit

RESERVOIR

AFTERBAY

Generator

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Hydroturbine and Generator Rotor

Also an Old Idea

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Power Formulas - Head

Pwt = ρwt·Q · g · h

Pel = η ·Pwt

h < 10 m 10 < h < 100 m h > 100 m

ρwt= 1000 kg/m3

Q= water flow rate in m3/s

g= 9.8 m/s2 (accel. of gravity)

h = effective height in m

Efficiency

η < 0.85

Three Types of Hydro Turbines

Pelton Kaplan Francis

1/21/2010

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100

101

102

103

100

101

102

103

HE

AD

(m

)

FLOW (m3/s)

0.1 MW

0.1 MW

10 MW

100 MW

1000 MW

Plot of the Power Formula (Efficiency not Included)

100

101

102

103

100

101

102

103

HE

AD

(m

)

FLOW (m3/s)

0.1 MW

0.1 MW

10 MW

100 MW

1000 MW

Approximate application Range of Water Turbines

Pelton

Francis

Kaplan

1/21/2010

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Nuclear, hydro, coal, combined-cycle powerful facts:

Installed capacity of a traditional plant may be very large

and the storage capacity is enormous

• A single turbine-generation unit of a coal-fired thermal

plant may reach near 1000 MW

• Typical plant capacities (steam, combined cycle) are

500 – 5,000 MW

• Largest hydroelectric plants in the world:

-Three-Gorges (China): 22,500 MW (final)

-Itaipu (Brazil): 12,000 MW

-Guri (Venezuela): 10,000 MW

-Grand Coulee (U. S. A.): 7000 MW

Basic Diagram of a Wind Generation Unit

Pwind=(1/2) · ρ · A · v3

Pelec=Cp · η · Pwind

A= turbine area in m2

V= wind speed in m/s

Cp = Betz’s coefficient≈ 0.4

η=0.85 …0.95

Air density: ρ=1.2256 kg/m3

Type of generator used:

-Synchronous (PM or traditional)

-Induction (asynchronous)

-D.C. (small units)

In all cases the generator needs

power electronic controllers.

Utility Scale Range: 1.5 .. 3.6 MW

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Talking about old ideas

Power vs Wind Speed Curve

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Wind power in the World

Wind Farms Examples

Terminology

-Capacity factor

-Capacity credit

-Wind penetration

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One-line diagram of Conventional Plants

(Thermal or Hydroelectric)

200 MW 200 MW 200 MW 200 MW

Generators

Step-Up

Transformers

Transmission

Substation

To HV Transmission System

(230 kV,345 kV, 500 kV, etc.)

Example One-line Diagram of a Wind Plant

(“Wind Farm”)WTG

Example:

2 MW

35 kV

Collector Buses

Sub-

Transmission

Substation

To other WTG

115 kV

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Wind: Advantages and Disadvantages

Disadvantages

• Operation problems (frequency and

voltage incursions, dynamic

response), harmonics

• Noise, landscape aesthetics, bird

collision

Advantages

• Practically endless fuel source

(wind)

• Costless fuel

• No pollution into the air (green,

“environmentally friendly”): no

CO2 emissions, no heat to the

atmosphere

• Minimum paperwork on

permissions

• Relative expedite construction

Other issues

1. Many generators and large areas are

needed to reach high capacity

2. Transmission infrastructure needed

3. Intermittency

4. Even worse, no-coincidence (sorage)

5. Energy in excess and storage issues

6. Low capacity factor

7. The figure of “capacity credit” is

used

A Powerful Reason

Marginal emissions in New England for the year 2002(*)

1 GWh of wind power will avoid the following amounts

(*) Source: ISO New England Inc.

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Existing solar thermal plant

Basic Diagram of a Solar Generation Plant

(Solar-thermal)

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Basic Diagram of a Solar Generation Plant

(Photo Voltaic)

Photo-Voltaic Power. Some Figures.

P= η·E ·A

A= effective cell area in m2

E = Irradiance in W/m2

η = Efficiency ≈15 .. 30% at nominal

conditions

Calculate the area needed to generate power

for 100 homes at 10 kW per home.

Suppose E = 1000 W/m2 (perfect clear

day); and η=0.2

A = P/(η·E )=100x10,000/(0.2·1000 ) =

=5,000 m2 ≈1.24 acres

Notes:

1. Obtain more voltage and current by

arranging PV cells series-parallel

2. The largest solar PV plant has a

maximum capacity of 11 MW

Max. power

Small fuel cell I-V curve

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A solar (PV) plant

Solar Power Plants:

Advantages and disadvantages

Disadvantages

• Generates in d. c. (disadvantage?)

• Need power electronics �

harmonics

• Landscape aesthetics

Advantages

• Practically endless fuel source

(sun)

• Costless fuel

• No pollution into the air (green,

“environmentally friendly”): no

CO2 emissions, no heat to the

atmosphere

• Minimum paperwork on

permissions

• Relative expedite construction

Other issues

1. Extremely large areas are needed to

reach high capacity

2. May need transmission

infrastructure

3. Intermittency

4. No-coincidence and storage issues

5. Low capacity factor

6. The figure of “capacity credit” is

used

1/21/2010

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Small-Scale PV Solar

Power

Charger/

Rectifier

DC/AC

Inverter

BatteriesDC

Loads

AC

Loads

Sunlight

PV Panels

Solar Power - Thermal:

Parabolic Concentrator with Thermal Engine

Power ~ 3 kW per unit)

Source:

http://www.infiniacorp.com/

Thermal

engine

Parabolic

Mirror

Heat concentrator

1/21/2010

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Basic Diagram of a Tidal Plant

(a particular type of hydro plant)

Serious Power:

Pwt=(1/2) · ρwt · A · v3La Rance – France

1966 - (240 MW)

Geothermal Plants

-This is non-conventional but might be considered non-renewable

-There are many in the USA (43 in California with total 1.8 GW installed)

-Geyser � direct

-Water injection

Geysers Valley

Power Plant

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Geothermal Plants

Geothermal Plant Schematic

1/21/2010

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Summary

Wind turbine generation systems

Solar thermal and photovoltaic energy

Fuel cellsGeothermal energy Tidal energy

Hydroelectric power

Sources

1. U. S. Department of Energy. Energy Information Administration (EIA). Official Statistics from the

U. S. Government. WEB: http://www.eia.doe.gov/

2. “Renewable Energy: A power for a Sustainable Future,” 2nd edition, G. Boyle, Oxford University

Press, 2004, ISBN 0-19-926178-4.

3. http://www.power-technology.com/projects/san_joaquin/images/Combined3.jpg

4. http://www.powergeneration.siemens.com

5. http://www.gasturbine.pwp.blueyonder.co.uk/CT3201-schema.jpg

6. http://www.amrclearinghouse.org/Sub/landreclamation/cfb/diagram-hires.gif

7. http://blogs.orlandosentinel.com/community_conway_blog/files/Nuclear_Plant.gif

8. http://www2.cemr.wvu.edu/~smirnov/mae320/figs/F8-1.jpg

9. http://homebrewpower.blogspot.com/2008_01_01_archive.html

10. http://henk.elfwood.com/windmill.jpg.html

11. http://www.powerhousetv.com/stellent2/groups/public/documents/pub/phtv_eb_re_000315-2.jpg

12. http://vicerp.org/files/files/Anlagenschema_englisch.jpg

13. http://www.yourenergygeneration.com/images/energy/solar2.jpg

14. http://www.eas.asu.edu/~holbert/eee463/solar_photovoltaic.gif

15. http://www.infiniacorp.com/

16. http://www.edf.fr/html/en/decouvertes/voyage/usine/retour-usine.html

17. http://geothermal.marin.org/GEOpresentation/sld037.htm

18. http://www.solcomhouse.com/geothermal.htm

19. http://www.energy.ca.gov/geothermal/