INTRODUCTION TO ENERGY2.pptx

8/11/2019 INTRODUCTION TO ENERGY2.pptx

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INTRODUCTION TO

ENERGY SCIENCE

JULY - 2014


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Ability to do work or cause

change

Produces Warmth

Produces Light

Produces SoundProduces Movement

Produces Growth

Powers Technology

What is energy?

Courtesy of NEED


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POTENTIAL KINETICStored energyor energy of

positionGravitational, Stored

Mechanical,Nuclear, Chemical

Energy ofmotion

Motion, Electrical,Sound, Radiant,

Thermal

Classes of Energy

Courtesy of NEED


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Gravitational Energyenergy an object or substance

has because of its position

Anything up high

Potential Energy


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Stored Mechanical

Energystored in an objectby the application of force

Must push or pull on an object

Potential Energy


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Nuclear Energy

energy stored in thenucleus of an atom

Holds the atom together

Potential Energy


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Chemical Energy

energy stored in the bondsbetween atoms

Holds molecules together

Potential Energy


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Mechanical (Motion)

Energymovement ofobjects or substances from

one place to another

Kinetic Energy


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Electrical Energy

movement of electrons

NOT AN ELECTRON

PARADE!

Kinetic Energy


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Sound Energy

movement of energythrough substances in

the form of

longitudinal/compressi

on waves

Kinetic Energy


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Radiant Energyelectromagnetic energythat travels in transverse

waves

Kinetic Energy


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Kinetic Energy

Thermal (Heat) Energy

internal energy of asubstance due to the

vibration of atoms and

molecules making up the

substance


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1Energy can not be created nor destroyed, only

changed.Law of Conservation of Energy

First Law of Thermodynamics

2Energy will always transfer from high to low.

3No energy transfer is 100% efficient.

Energy Transfers

C ti


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Conservation

of Energy


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Units of Energy

Energy requires a force. Each form of energyhas its own force: gravity, strong & weaknuclear forces, electrical, and kinetic forces.

Kinetic Force = Mass x Acceleration Unit of force = 1 Newton = 1 Kilogram x 1 m/s

Energy is a measurement of work accomplishedby a force

Energy = Force x Distance 1 Joule = 1 Newton x 1 Meter


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Energy and Power

Energy is a quantity, like distance.

1 kilowatt-hour = 1000 Watts x 1 hour

1 kilowatt-hour = 3.6 x 106 Joules

Power is a rate, like speed, it is the rate thatenergy is converted from one form to another.

1 Watt = 1 Joule / Second


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The Difference Between Energy and Power

Energy Power

Quanti ty RateUnit kWhkWh kW, MW*kW, MW*

Water analogy Gallons Gal / Min

Car analogy- - How far?

- Gallon of gasEngine HP

Costexample 12 /kWh12 /kWh $1,500,000/MW$1,500,000/MW

Grid Consumption &

production

Installed

capacity


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Laws of Thermodynamics

First Law: In any transformation of energy fromone form to another, the total quantity of energyremains unchanged. Energy is neither creatednor destroyed, it only changes forms.

Second Law: In all energy changes, thepotential energy of the final state will be lessthan that of the initial state (useful energy isalways lost.) Lostenergy is usually energy that has been

converted to heat, but it could be noise (kinetic energyof air), or other forms of wasted energy.


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Efficiency

The ratio of the amount of useable energyobtained to the amount of energy input is theefficiencyof a process.

This is usually expressed as a percent and it isalways less than 100%.


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Energy definitions

Primary Energyamount of energycontained in the initial source of energy

Delivered Energyamount of useable

energy delivered to the customer Useful Energyamount of energy attributed

to the amount of work accomplished


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What is Electricity?

Electricity is energy transported by

the motion of electrons

**We do not make electricity, we CONVERTother

energy sources into electrical energy**

Conversion is the name of the game


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Energy Conversion Options for ElectricityNon-Thermal Paths

Source to Electrical

Source Converter

Sun Photovoltaic (photon to electron)

Chemical Fuel Cell

Source to Potential/Kinetic to Mechanical to Electrical

Source Converter Kinetic to Mechanical Mech to ElectricalDam Penstocks Turbine (water) Generator

Tides Machine Turbine (air or water) Generator

Wind N/A Turbine (air) Generator


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Energy Conversion Options for ElectricityThermal Paths

Heat to Mechanical to Electrical

Source Heat to Mechanical Mech to Electrical

Geothermal Turbine (vapor) Generator

OTEC Turbine (vapor) Generator

Stored Energy to Heat to Mechanical to Electrical

Source Reactor Heat to Mechanical Mech to ElectricalFuel Combustor Turbine (gas or vapor) Generator

U, Pu Reactor Turbine (gas or vapor) Generator

Sun Collector* Turbine (gas or vapor) Generator

H, H2, H3Reactor Turbine (gas or vapor) Generator

* More a modifier or concentrator than a reactor


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Faraday Effect

Faraday Effect

Basic ConceptsVoltage V Potential to Move Charge (volts)

Current I Charge Movement (amperes or amps)

Resistance R V = IxR (R in =ohms)

Power

P = IxV = I2xR (watts)


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Electric Motor

MElectrical

EnergyMechanical

Energy

DC Motor


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Model Electric Motor

Beakman Motor

What do you need?1. Electric Energy

2. Coil

3. Magnetic Field


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Electric Generator

GMechanical

EnergyElectrical

Energy

Stationary magnets - rotating magnets - electromagnets


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AC/DC(not the band)

Alternating Current

Large-scalegenerators produce

AC Follows sine wave with

n cycles per second

1, 2, 3-phase?

US:120 V,60 Hz

Europe: 240 V,50Hz

Transforming ability

Direct Current

Batteries, Photovoltaics,fuel cells, small DC

generatorsCharge in ONE direction

Negative, Positiveterminals

Easy conversion AC toDC, not DC to AC


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Generator Phases1 Phase 2 Phase 3 PhaseSmooth Power

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035150

100

50

0

50

100

150

200

250220

110

V t( )

V 1 t( )

V 2 t( )

V 3 t( )

0.0330 t

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035150

100

50

0

50

100

150110

110

V t( )

V 1 t( )

V 2 t( )

V 3 t( )

0.0330 t

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035150

100

50

0

50

100

150

200155.563

110

V t( )

V 1 t( )

V 2 t( )

V 3 t( )

0.0330 t

Polyphase Systems 3 phases for smoother torque delivery

Force Driving Motor (Red)

Single Phase Two Phase Three Phase


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WHERE DO WE GET

ENERGY FROM AND WHATDO WE USE IT FOR?


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Energy Sources

Non Renewable

Fossil Fuels

Natural Gas

Shale Oil Tar Sands

Nuclear Fusion Fuel

Renewable Solar

Geothermal

Tidal


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Solar

Direct Sunlight

Wind

Hydroelectric

Ocean Currents

Ocean Thermal Gradients

Biomass


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W ld P i E


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World Primary Energy

Consumption


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GDP


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2010 US Energy Flow


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US Energy Consumption


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Alaska Energy Consumption


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The United States uses more energy percapita than any other country in the world, and

Alaska as a state has the highest energy percapita energy use in the narration at 1112MMBtu per person. This is three times higherthan the national average of 333 MMBtu.

This is due to our cold harsh winters, high

level of air travel 43% of total energy is from jet fuel most of

which is for international flights.


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Climate Change Logic

1. The Burning of fossil fuels cause carbondioxide concentrations to rise.

2. Carbon dioxide is a greenhouse gas.

3. Increasing the greenhouse effect increasesaverage global temperatures (among otherimpacts)

Does Skeptic mean a person who has not looked at the data?


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1000 ears of CO2


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1000 years of CO2

Concentration

1000 Y f T t


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1000 Years of Temperature

Changes


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Every Year an Average Coal Plant Releases 3,700,000 tons of CO2

10,000 tons of SO2. 500 tons of particulates

10,200 tons NOx

720 tons of CO

220 tons of volatile organic

compounds (VOC)

170 pounds of mercury

225 pounds of arsenic

114 pounds of lead

And there are over 600 of them in the US.Source: Union of Concerned Scientists: www.ucsusa.org


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Types of Pollutants

CO2Global Warming

COHealth problem

PMRespiratory andheart disease, haze

SOxAcid Rain,respiratory illness, haze

NOxOzone formation,acid rain, smog, nutrientloading, global warming

MercuryNeurotoxin

LeadNeurotoxin

Arsenic- Poison

VOCs

Numeroushealth problems

OzoneHealthproblems, damage toflora & fauna

Hundreds of other toxicchemicals


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Power in the Wind


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Power in the Wind

Power = Work / t= Kinetic Energy / t

= mV2 / t

= (Ad)V2

/t= AV2(d/t)

= AV3d/t = V

Power in the Wind = AV3


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remember

Swept AreaA = R2 (m2) Area ofthe circle swept by the rotor.

= air density in Colorado its

about 1-kg/m3


R

Example Calculating Power in the Wind


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Example Calculating Power in the Wind

V = 5 meters (m) per second (s) m/s

= 1.0 kg/m3

R = .2 m >>>> A = .125 m2


= (.5)(1.0)(.125)(5)3

= 7.85 WattsUnits = (kg/m3)x (m2)x (m3/s3)

= (kg-m)/s2 x m/s= N-m/s = Watt


(kg-m)/s2 = Newton


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Wind Turbine Power

Power from a Wind Turbine Rotor = CpAV3

Cp is called the power coeff ic ient.

Cp is the percentage of power in the wind that is

converted into mechanical energy.

What is the maximum amount of energy that canbe extracted from the wind?

T bi


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Betz Lim i twhen a = 1/3

Vax= 2/3V1 V2= V1/3

TurbineWhere

Free stream velocity, V1

Wake velocity, V2=(1 2a)

Velocity at rotor, Vax

= V1(1-

a)

Induction factor, a

5926.27

16C m ax,p

Rotor Wake

Rotor Disc


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Tip Speed Ratio

Capacity

Factor

Reality Check


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Reality Check

Whats the most power the .6 ft turbine in theexample can produce in a 5 m/s wind?

7.85 Watts x .5926 (Betz Limit) = 4.65 Watts

Maximum Possible Power Coefficient


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0.60

0.50

0.40

0.30

0.20

0.10

0.00

Cp

109876543210Tip Speed Ratio

Betz - Without Wake Rotation

With Wake Rotation

Tip-Speed Ratio


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p Speed at o

Tip-speed ratio is the ratioof the speed of the rotatingblade tip to the speed of

the free stream wind.

RV

=

R

R

Where,

= rotational speed in radians /sec

R= Rotor Radius

V= Free Stream Velocity

Blade Planform Types


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ypWhich should work the best??

Rectangular Reverse

Linear

Taper

Linear

TaperParabolic Taper

Airfoil Nomenclature


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wind turbines use the same aerodynamic principals as aircraft

VR= Relative Wind

= angle of attack = angle between the chord line and the

direction of the relative wind, VR.

VR= wind speed seen by the airfoilvector sum of V (freestream wind) and R (tip speed).

V

R r

V

Airfoil Behavior


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Airfoil Behavior

The Lift Forceisperpendicular to thedirection of motion. Wewant to make this force

BIG.

The Drag Forceisparallel to the direction

of motion. We want tomake this force small.

= low

= medium


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Airfoil in stall (with flow separation)

Stall arises due to separation of flow from airfoil

Stall results in decreasing lift coefficient withincreasing angle of attack

Stall behavior complicated due to blade rotation

Making Good Airfoils


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Gradual curves

Sharp trailing edge

Round leading edge

Low thickness to chordratio

Smooth surfaces

Making Good Airfoils

Good

Not so good

Energy Production Terms


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Energy Production Terms

Power in the Wind= 1/2AV3

Betz Limit- 59% Max

Power Coefficient- Cp

Rated PowerMaximum

power generator can

produce.

Capacity factor

Actual energy/maximum

energy

Cut-inwind speed where

energy production begins Cut-outwind speed where

energy production ends.

Typical Power Curve

Performance Over Range of Tip


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g p

Speed Ratios

Power Coefficient Varies with Tip Speed Ratio

Characterized by Cp vs Tip Speed Ratio Curve

0.4

0.3

0.2

0.1

0.0

Cp

121086420

Tip Speed Ratio

Considerations for Optimum Blade


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Considerations for Optimum Blade

Optimum blade will have low solidity (10%) and tip speed

ratio, ,about 5-7. (match speed to generator)

High means lower pitch angle (blade tip is flat to the

plane of rotation).

Lower means higher pitch angle (feathered).

Pitch angles should be equal for all blades.

Optimum blade has large chord and large twist near hub

and gets thinner near the tip. Optimum blade is only "optimum" for one tip speed ratio.

The optimum blade will have smooth streamlined airfoils.


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Number of BladesOne

Rotor must move morerapidly to capture sameamount of wind Gearbox ratio reduced Added weight of

counterbalance negates somebenefits of lighter design

Higher speed means morenoise, visual, and wildlifeimpacts

Blades easier to installbecause entire rotor can beassembled on ground

Captures 10% less energythan two blade design

Ultimately provide no costsavings


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Number of Blades - Two

Advantages &disadvantages similarto one blade

Need teetering huband or shockabsorbers because ofgyroscopic imbalances

Capture 5% lessenergy than threeblade designs


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Number of Blades - Three

Balance ofgyroscopic forces

Slower rotation

increases gearbox &transmission costs

More aesthetic, lessnoise, fewer bird

strikes

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INTRODUCTION TO ENERGY2.pptx