Bruce Mayer, PE Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege

[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 Chp.6 EnergyEnergyEROEI - EROEI - NuclearNuclear



EROEIEROEI

Energy Returned On Energy Invested Energy Invested – in order to:

• ACQUIRE energy, it TAKES ENERGY

• To PROCESS (Refine) energy, it TAKES ENERGY

• TRANSPORT a form of energy, it TAKES ENERGY.

• STORE energy, it TAKES ENERGY.

• USE energy, it also TAKES ENERGY



EROEIEROEI

Energy Returned On Energy Invested Energy Returned:

• After you have taken into account all the energy used in the last slide...how MUCH ENERGY do you have left?

• OR How much energy does it actually COST in order to USE a particular form of energy?



EROEI - AnalogyEROEI - Analogy Say that you have $100 that you want to

INVEST at a bank. The bank is offers an account for a year that

pays 10% interest. Check the TOTAL Gain or LOSS From this Investment

• What if you didn't have a car so you take the Bus to the Bank. It costs you $4 to catch the bus round-trip to go to the bank and deposit the money.

• After a year, you pay another $4 to catch another bus to the bank to withdraw your money and interest.

The math on This investment:• $100 + 10% interest = $110 at the end of the year.• MINUS $4 for the first bus and another $4 for the 2nd bus

= $8 total.• Subtracting the $8 from the $110 that leaves a total of $102;

the REAL return on your investment = 2/100 = 2%• Not such a good deal after all



EROEI GraphicallyEROEI Graphically

If there is NO Surplus, then Eout/Ein <1, and We have WASTED energy

Note: EROI ↔ EROEI

BackWork



EROEI – Fuel (Thermal) EnergyEROEI – Fuel (Thermal) EnergyEnergy Form EROEI/EROI

Oil & Gas: 1940's Discoveries > 100.0

Oil & Gas 1970's Production 23.0, discoveries 8.0

Coal (mine mouth) 1950's 80.0

Coal (mine mouth)1970's 30.0

Oil shale 0.7 to 13.3

Coal liquefaction 0.5 to 8.2

Geopressured gas 1.0 to 5.0

Ethanol (sugercane) 0.8 to 1.7

Ethanol (corn) 1.3

Ethanol (corn residues) 0.7 to 1.8

Methanol (wood) 2.6

Solar space heat (fossil backup)

1.9



EROEI – Electrical EnergyEROEI – Electrical Energy

Energy Form EROEI/EROI

Coal 9.0

Hydropower 11.2

Nuclear (light-water reactor) 4.0

Solar Photovoltaics 1.7-10

Geothermal 1.9-13 From these Lists We Spot a Couple of Dicey

Propositions• Solar Electricity

• Corn Ethanol as a fuel



EROEI Life Cycle Analysis ExampleEROEI Life Cycle Analysis Example

Consider the Production of a Wind Turbine with a 20-25yr Operating Life



Wind Turbine NacelleWind Turbine Nacelle

http://www.vestas.com/en/about-vestas/sustainability/wind-turbines-and-the-environment/life-cycle-assessment-(lca).aspx



Wind Turbine LCAWind Turbine LCA Turbine Production

Environmental NEGATIVE Impacts• Manufacturing of raw

materials

• Production of components

• The wind turbine’s energy production

• De-commissioning of the wind turbine

Energy Source Energy Consumption[MJ/kWh produced]

FOSSIL FUELS

Crude oil 2.46E-02

Hard coal 1.95E-02

Lignite 3.38E-03

Natural gas 2.24E-02

Nuclear power 2.05E-02

RENEWABLE ENERGY

Biomass, dry matter, fuel 7.29E-04

Biomass, dry matter, raw material 2.54E-05

Hard wood, dry matter, raw material 1.26E-04

Primary energy from hydro power 6.07E-03

Primary energy from wind power 4.51E-07

Renewable fuels 2.08E-08

Total (MJ/kWh produced) 9.82E-02

Total (kWh/kWh produced) 2.73E-02

Total Energy Invested (kWh/turbine) 4,304,222



3.0 MWe Wind Turbine EROEI3.0 MWe Wind Turbine EROEI

Energy Invested = 4,304 MWh/turbine Energy Returned = 173,580 MWh/turbine

• 7,890,000 kWh/Turbine٠Year

• 22 Year Operating Life

The EROEI Calculation:

3.40304 4

580 173EROEI

An EXCELLENT Return!



WindPower is NONDispactchable• Can NOT call it up at any time

– Needs Supplemental STORAGE

WindPower DownSideWindPower DownSide



Energy Sources – Fact & FancyEnergy Sources – Fact & Fancy QuestionQuestion – Which Energy Source Has

These Attractive Aspects• NO HydroCarbon or NOx Emissions• NO GreenHouse Gas Emissions• Very High Energy Density

– Easy to Transport Fuel

• Plug-Compatible With Existing Electrical Grid

• Can Easily Produce Hydrogen During “Off Peak” Hours

• Low Energy Inputs to Produce?



Answer Answer → → Nuclear (Fission) PowerNuclear (Fission) Power



Energy Sources – Fact & FancyEnergy Sources – Fact & Fancy

Nuclear Fission Limitations• Waste Handling is a Political Issue

– Have Technological SolutionsWaste Concentration, and Then Storage in Water-

Free, Geologically Stable Salt-Mine Structures

• Fear of Accidental Radiation Releases Due to Loss of Coolant Accidents Such as TMI– New Designs are Fail-Safe; LoCA’s can Be

Engineered OUT

• ByProduction of Nuclear-Weapons Compatible Materials; e.g., Plutonium



Energy Sources – FutureEnergy Sources – Future Any of the Previous Techniques Could

Benefit from Technology “BreakThrus”• Possible Examples

– A BioEngineered Fermentation Enzyme Greatly Reduces Energy Required to Make Ethanol

Nuclear FUSION• Fission: Break a Heavy Atom (Uranium) to

Liberate Heat (and Neutrons)• FUSION: Combine Light Hydrogen Atoms

to Liberate Heat (and Make Heavier Helium Atoms)



Energy Sources – Future contEnergy Sources – Future cont

• Fusion Produces MUCH LESS Radioactive Material Than Fission Reactors– But it’s NOT Zero

• Fuel is “Heavy Water” Isotopes That are in More than Sufficient Supply in Sea Water

• Fusion Limitations– An EXTREMELY Difficult Technical Problem;

Must Generate Local Temperatures That Approximate those found in STARS

– 50 Years of Intense Study Have barely Even Reached the Energy Break-Even Point



Fission & Fusion Nuclear ReactionsFission & Fusion Nuclear Reactions

Fission → Splitting 2nSr Xen U 100134235

Fusion → Joining n He H H 432

Dueterium → H with 1 Neutron (2 nucleons)

Tritium → H with 2 Neutrons (3 nucleons)



California Electricity Production Mix - 2006

36.7%

21.9%

16.4%

10.8%

6.0%

4.5%

1.9%

1.5%

0.2%

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

Gas

Imports

Hydroelectric

Nuclear

Coal

Geothermal

BioMass

Wind

Solar

Ele

ctri

cal

Po

wer

So

urc

e

Fraction of Total Electrical GenerationCA_Electricity_Mix-0711.xls



Electric Cars?Electric Cars?

The USA consumes about 140 BILLION Gallons of Gasoline per year• As discussed by Dr. Mike Carnall in his

Ethanol presentation

Lets make an estimate of how much electricity would be needed to replace the amount of gasoline used by on-road vehicles



Electricity Estimate AssumptionsElectricity Estimate Assumptions

95% of Gasoline is used in Cars/Trucks Gasoline heat of combustion = 45 MJ/kg Gasoline Density = 737 kg/cu-m Piston Engine Thermal efficiency = 25% Electricity Transmission Efficiency = 96% Battery charging efficiency = 80% Battery discharging efficiency = 80% Electric Motor efficiency = 90% 1 cubic meter = 264.2 gallon [US, liquid]



Electricity EstimateElectricity Estimate

95% of Gasoline used by Vehicles

Gal 13395.0Gal 140 BB

133B gallons to Cu-m

33

m 503.0264.2Gal

m 1Gal 133 BB




Mass of 503M cu-m

kg 37195.0m

kg737m 503

33 BM

Thermal Energy in 371B kg of Gasoline

TJ 000,695,16kg

MJ 54kg 371 B




Energy delivered to DriveShaft using 25% Engine Efficiency

TJ 174000,425.0TJ 16695000

This is the amount of Mechanical Energy that must be delivered to the DriveShaft by the electric motor that REPLACES the gasoline engine• Now Work BACKwards




Electrical Energy applied to the motor using motor efficiency

TJ 000,797,58.0TJ 000,638,4 Electrical Energy applied to Battery Charger

using charger efficiency

TJ 000,246,78.0TJ 7970005

Energy stored in Batteries to Power the motor using Battery efficiency

TJ 000,638,49.0TJ 4174000




Electrical Energy produced at the PowerPlant using Transmission Efficiency

TJ 000,548,796.0TJ 000,246,7 Thus the ADDITIONAL electric energy that power plants must

produce to run vehicles is about 7 550 000 TeraJoules in a year




Convert TeraJoules per year into MegaWatts-Electric (MWe)

s

TJ

s

hr

hr

day

day

yr

yr 2393.0

3600

1

24

1

365

1TJ 000,548,7

And a J/s is a watt, so the MWe equivalent:

MWe 300,239TW

MW 000,000 1,TW 2393.0 MWe




Now a BIG nuclear PowerPlant such as Diablo Canyon is rated at about 2000 MWe – Use this to Calc the NEW Power Plants needed run vehicles

PlantsPwr 120MWe 2000

PwrPlant 1MWe 300,239




Thus to Run our vehicles on Electricity we would need to open a NEW Nuclear PowerPlant EVERY MONTH for TEN YEARS



New Electricity for Cars ComparedNew Electricity for Cars Compared

The TOTAL generating Capacity in the USA is about 1 070 000 MWe• The Electricity for Cars would add about

25% to the USA total

The Total generating Capacity in the CALIFORNIA is about 56 000 MWe• The Electricity for Cars would require

about 4 NEW Californias



Energy SummaryEnergy Summary In My Humble Opinion ENERGY

PRODUCTION is the SINGLE MOST IMPORTANT Technology Issue Facing Human Kind• A Low-Cost, Low-Environmental-Impact

Energy Source GREATLY Facilitates The Solution of All Technical Problems– Food Production

– Medical Advances

– Water Production

– Housing & Shelter



All Done for TodayAll Done for Today

NationalIgnitionFacility

Fusion in LIVERMORE

Cool Videos

https://lasers.llnl.gov/multimedia/video_gallery/




Engery delivered to DriveShaft using 25% Engine Efficiency

TJ 174000,425.0TJ 16695000 Electrical Energy applied to the motor using

motor efficiency

TJ 000,638,49.0TJ 14174000



DT ReactionDT Reaction

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Bruce Mayer, PE Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege

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