[email protected] engr-10_lec-09_chp6_population_energy.ppt 1 bruce mayer, pe engineering-10:...

[email protected] • ENGR-10_Lec-09_Chp6_Population_Energy.ppt1

Bruce Mayer, PE Engineering-10: Intro to Engineering

Bruce Mayer, PELicensed Electrical & Mechanical Engineer

[email protected]

Engineering 10

Chp.6 Future

Challenges



FIRST and SECOND Laws ofTHERMODYNAMICS Class Question:

Can Anyone Describe Either of the FIRST or SECOND Laws

of ThermoDynamics?



Laws of ThermoDyamics

In the Instructor’s Opinion The SECOND Law is the GREATEST of all the “Laws of Physics”

The ThermoDyamic Laws • Describe the Relationships & Connections

Between Work↔Heat↔Energy• Describe and Quantify Reversibility and

IRReversibilty • Explains What’s “The Best we can Do”



The “Laws” What are they?

First Law of Thermodynamics• Energy can neither be CREATED nor

DESTROYED– But Energy Can be Moved, or Changed to

Other forms

Second Law of Thermodynamics• NATURALLY OCCURRING processes are

Directional– Natural process can go ONE WAY,

but NOT the OTHER



Reversibility

Reversibility is the ability to run a process back and forth (backwards and forwards) infinitely withOUT Losses

Money analogy: Currency Conversion• NO service fee (reversible):

$100 113000₩, and one hour later at the same place, 113000₩ $100

• WITH service fees (IRreversible: $100 68€, and one hour later at the same place, 68€ $90 (5% fee both ways)



Reversibility and Energy

Electric Current

Motor Generator

Voltage

Turbine Pump

Fluid Flow

Pressure

If IRreversibilities were ELIMINATED, these systems would run FOREVER.• These Systems would then be

Perpetual Motion Machines



Example: Popping at Ballon

Not reversible unless energy is expended

X

A “reversible process” can go in either direction, but these processes are rare

Generally, the irreversibility shows up as waste heat



Sources of Irreversibilities

Friction (force drops) Voltage (electrical

resistance) drops Pressure drops Temperature drops Concentration drops Magnetic Hysteresis

(H Drops)



Irreversibility Example It’s EASY To Mix the

Cream Into the Coffee

It’s extremely difficult to UNmix (separate) the Cream from the Mixed Coffee• It takes a LOT of

Effort, or WORK, to separate



First Law of ThermoDynamics

One form of work may be converted into Another,

Or, work may be converted to heat, Or, heat may be converted to work, But, ALWAYS

FINAL energy = INITIAL energy



11

2nd Law of Thermodynamics

We intuitively know that heat flows from higher to lower temperatures and NOT the other direction.• i.e., heat flows “DownHill”; just like water

WHY don’t we see Water flow UpHill, or Heat move Cold→Hot on Occasion?

Water & Heat Flow ONE-WAY Because These processes, which “down-flow-hill”, are inherently IRreversible.



Heat↔Work Conversions

Heat transfer is inherently irreversible. • This places LIMITS on the amount of work

that can be produced from heat.

Heat can be converted to work using heat engines; e.g.,• Jet engines (planes), • Steam engines (Old Locomotives)• Steam Turbines (Nuclear PowerPlants), • Internal combustion engines (automobiles)



Heat into Work (Power Plant)

A heat engine takes in an amount of heat, Qhot, and produces work, W, and waste heat Qcold Qhot = W + Qcold

Nicolas Sadi Carnot (kar nō) derived the LIMITS of converting heat into work

High-temperatureSource, Thot

Low-temperatureSink, Tcold

HeatEngine

W

Qhot Qcold(e.g. flame) (e.g. cooling pond)• W = Mechanical Work • Q = Heat

coldhot QWQ



Carnot Equation: Efficiency

Given the heat ENGINE on the previous slide, the maximum work that can be produced is governed by:

hot

cold

hot

max

T

T

Q

W1

• where the temperatures are absolute (e.g. Kelvins)

Thus, as Thot Tcold, Wmax 0

This ratio is also called the Thermal Efficiency, η

N.L.S

. Carn

ot



Example: PowerPlant

A BWR Nuclear PowerPlant Boiler Runs at about 1000 °F

The “Heat Sink” is the cold Pacific Ocean at 52 °F

What is ηmax ?

1000 °F = 1460 °R

52 °F =

512 °R

%9.641460

51211max

hot

cold

T

T



Moving Energy Cold→Hot

Not USING Heat, Just Moving it Around Moving Heat UPhill requires WORK The CoEfficient of Performance, CoP,

informs about the effectiveness of AirConditioners and HeatPumps

High-temperatureSink, Thot

Low-temperatureSource, Tcold

HeatEngine

W

Qhot Qcold(e.g. OutSide Air) (e.g. InSide AC)



Carnot Equation: CoP

Given the heat PUMP on the previous slide, the Minimum Work needed to move heat UpHill is governed by: 1

1

coldhotmin

cold

TTW

Q

• where the temperatures are absolute (e.g. ºRankine)

Thus, as Thot Tcold, Wmin 0

This ratio is also called the CoEfficient of Performance, CoP



Example: Air Conditioner

It’s REALLY Hot Outside, 105 °F

A “Cold Blooded” person Keeps the house at 65 °F

What is CoPmax?

105 °F = 565 °R

65 °F = 525 °R

1.131525565

1

1

1max

coldhot TTCoP



Nicolas Léonard Sadi Carnot

Founder of the Science of ThermoDynamics

BORN: Paris, France,June 1 1796

DIED: Paris, France,August 24 1832



“Water Powered” Hydrogen Car A “Hydrogen” car is the

SAME THING as any Other “Electric Car”

In BOTH Cases an Electric Motor turns the Wheels• In an “Electric Car” The

Energy is stored in traditional Batteries

• In an H2 car the energy is stored in Hydrogen Tanks– Sometimes at 5,000 psi



“Water Powered” Car

It’s Easy Just get some H2O,

split it into H2 & O2

Store the H2 in Big Tanks in your Car,

Run it thru a “Fuel Cell” to turn an Electric Motor• Could also burn the H2 in

a Heat Engine

Off you go



“Water Powered” Car – Not so Fast



Energy & Humans

James Watt and His Predecessors (e.g., Savery & Newcomen) FREED Human-Kind From Muscle Power

The Heat Engine Was One of the Great Advances in Human History• Enabled the “Industrial Age”

The Generation & Application of Energy Multiplies The Capabilities of EVERY Person



Watt’s EngineWatt, James (1736-1819)

Scottish inventor and mechanical engineer, renowned for his improvements of the steam engine. Watt was born on January 19, 1736, in Greenock, Scotland. He worked as a mathematical-instrument maker from the age of 19 and soon became interested in improving the steam engines, invented by the English engineers Thomas Savery and Thomas Newcomen, which were used at the time to pump water from mines.



Energy Sources

Let’s LIST Real And Potential Energy Sources OTHER Than Fossil Fuels

1. ?

2. ?

3. ?

4. ?

5. ?

6. ?



44.52%

23.35%

20.25%

6.93%

1.87%

1.38%

0.99%

0.38%

0.30%

0.02%

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50%

Coal

NaturalGas

Nuclear

Hydro

Wind

Wood &BioMass

Fuel Oil

GeoThermal

Other

Solar

Fraction of Total Electrical Generation

Ele

ctri

cal P

ow

er S

ou

rce

USA Electricity Production Mix - 2009

USA_Electricity_Mix_1010.xls

Source = USA Energy Information Adminsistration * http://www.eia.gov/cneaf/electricity/epa/epates.html



Energy Sources Fact & Fancy Wind Power

• Wind Turbines Are VERY Attractive– Energy Input to Produce is Low– Incremental Added Capacity– NO Emissions of Any Kind

• Limitations– Low Energy Density

Must Cover Large Areas to Produce Much EnergyLimited Viable Sites

– Balance of System Costs (AC→AC Freq Converter)– Danger to WildLife; Particularly Birds (Raptors)



Energy Sources Fact & Fancy

Split Wood, Not Atoms → BioMass• Burning Garbage or Plant Matter

is Attractive– Simultaneous Solution to Energy

and Solid-Waste Problems – “Renewable” Resource– Low Energy Input to Produce

• Limitation: Emission Stream is VERY Unpleasant– Scrubbing Wood-Smoke is MUCH Harder than

Cleaning Gasoline Combustion ByProducts



Glen Canyon Dam – Page, AZ Electrical Power Generation

• River: Colorado River• Plant Type: Conventional• Powerhouse Type: Above Gnd• Turbine Type: Francis• Original Nameplate Capacity:

950,000 kW (950 MWe)• Installed Capacity:1,304 MWe• Year of Initial Operation:1964• Net Generation (FY 2005):

3,208,591,407 kWh• Rated Head:510 feet



Glen

Can

yon

Dam

Aerial V

iewGenerators

Tran

smis

sio

n

Tow

ers

Transformer

Switch

Yard

Visito

r Cen

ter

Bridge

Lawn



Glen Canyon Dam – Page, AZ



Glen Canyon Dam – Power Gen

150 rpm48

Poles




Set-UP Transformers

13.8kV 230kVor

13.8kV 345kV



Fran

cis Turb

ine

Gen

erator S

ystem




Hydroelectric Power • Fancy: Can Provide for Future Growth• Fact: Almost ALL Viable Hydro Sites

Have Been USED– Damming More Rivers is a Political Issue

Ethanol as AutoMobile Fuel• Fancy: Ethanol Can Replace Oil As a

Source for Automobile Fuel• Fact: Making Ethanol from Corn May Use

MORE Energy than It Produces




Ethanol Continued• DISTILLATION of Ethanol from Fermented

Corn Requires Large Amounts of Energy– Usually Provided by Burning Fossil Fuels at the

Distillation Site, or at the Electrical Power Plant

Solar PhotoVoltaics (solar cells) Can Supply Future Energy Needs • Photovoltaic Solar-Electric Cells Have

Many Advantages – Remote Siting, Incremental Expansion




Solar Cells Continued• BUT Making a Solar Cell Requires

Large Amounts of Energy– Silicon Cells are Made by, in the

Beginning, MELTING SAND– Production Processes Can be

Energy Intensive as Well

• Connecting to the Existing Electric Grid Includes a Great Deal of “Balance of System” Components– DC→AC “Inverters”, Special Electrical boxes




Solar Cells Continued• Solar Radiation has a

Very Low “Energy Density”– Requires LARGE Areas to Collect

Significant Amounts of EnergyCan Crowd-Out Other Uses:

Solar-Farm vs. Tomato-Farm

Hydrogen Fuel Cells• Based on Chemical Reaction

OHOH 2222

Proton Exchange

Membrane (PEM) FC

http://fuelcells.si.edu/

basics.htm

See also http://www.olympusmicro.com/primer/java/fuelcell/



Solar-Farm vs. Orange Orchard




Hydrogen Fuel Cells Continued• The Fuel Cell Reaction Looks Very Good

– NO VOCs/HydroCarbon Emissions– NO NOx emission

– NO Greenhouse Gases (CO2)

• But WHERE Do We Get the HYDROGEN?– There are NO Hydrogen WELLS or MINES

• The Viable Sources of Massive Amounts of Hydrogen themselves Require Large Energy or Carbon Inputs




In Apr04 Gov. Arnold Schwarzenegger has proposed an ambitious network of hydrogen filling stations by 2010

See also http://www.hydrogenhighway.ca.gov/

But How can we MAKE all the Hydrogen needed to Replace Gasoline?

There are 3 Viable Alternatives

http://www.hydrogenhighway.ca.gov/




1. Use WIND or NUCLEAR Power to generate Electricity which, in Turn, would be Used to Electrolize WATER

• Electrolosis applies Electrical current to water and splits it into oxygen and hydrogen, which are then separated…

• The Chemical Reaction

222 22 OHOH EnergyElectrical This is a Very Energy Intensive Process;

about 75% efficient



Electric Cars: H2 vs ElectroChemUlf Bossel, “Does a Hydrogen Economy Make Sense?”, Proceedings

of the IEEE | Vol. 94, No. 10, October 2006, pp 1826-1837




2. Steam reforming of natural gas • If you take methane, the main component

of natural gas, and expose it to steam, the final products are primarily carbon dioxide and hydrogen. Chemically

• This is already a Large-Volume Industrial Process, but it produces a LOT of CO2 – a GreenHouse Gas

• Natural Gas Supplies seem ample

2224 42 COHOHCH




3. Coal gasification • hydrogen could be produced at

centralized plants, compressed and most likely transported in trucks.

• Coal is mostly carbon & hydrogen, but also contains some sulfur. Exposed to water at high temperature and high pressure, it chemically reacts to yield carbon monoxide (CO) and hydrogen.

– But CO is Poisonous to Humans




3. Coal gasification, cont.• Oxygen from additional water vapor turns

carbon monoxide into carbon dioxide. So the end products are primarily carbon dioxide and hydrogen gas. Chemically

• We have LOTS of Coal, but still need to clean up the CO2 and H2S

SwHzCOyHOxHSCH 2222005080 ..



US

A P

rimary E

nerg

y P

rod

uctio

n b

y So

urce

http://www.eia.doe.gov/aer/overview.html * 2009



USA Energy Production Mix - 2008

Coal, 32.36%

Natural Gas, 28.69%

Crude Oil, 14.27%

NGPL, 3.28%

Nuclear, 11.47%

Hydro, 3.33%

Geothermal, 0.49%

Solar/PV, 0.12%

Wind, 0.70%

BioMass, 5.29%

Energy Information Administration / Annual Energy Review 2008



Energy BackWork Ratio

The BIG QUESTION for Any Energy Src • For Every Unit of Energy OUTput, How Much

Energy was INput for the ENTIRE Production Stream?– In Electrical Power Generation, for the Steady-State

Condition, this is called the “BackWork Ratio”

Plant theofOutput Power

Plant Run the Power toBWR

Many Energy Sources Fail This Question• e.g., Many Solar-Electric Systems will NOT

Return the Energy Required to Make Them



All Done for Today

California’sHydrogenHighWay

There were 143 H2 vehicles in

2007



A Potential Energy Scenario



48.13%

21.69%

19.54%

6.18%

1.34%

1.33%

1.12%

0.36%

0.28%

0.02%

0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% 55%

Coal

NaturalGas

Nuclear

Hydro

Wind

Wood & BioMass

Fuel Oil

GeoThermal

Other

Solar

Fraction of Total Electrical Generation

Ele

ctr

ica

l Po

we

r So

urc

eUSA Electricity Production Mix - 2008

USA_Electricity_Mix_0810.xls

Total = 4 125 675GWhe

Source = USA Energy Information Adminsistration * http://www.eia.doe.gov/cneaf /electricity/epa/epates.html

[email protected] engr-10_lec-09_chp6_population_energy.ppt 1 bruce mayer, pe engineering-10:...

Documents

pe engineering

bruce mayer

separate slide

law of thermodynamics

reversibility reversibility

waste heat slide

laws of physics

thermodyamic laws