chapter 10

Chapter 10Structure of the Utility Industry

Managing Energy Demand

Electrical Charges and Currents

Batteries and Electric Vehicles

Hybrid Vehicles

Ohms Law

Energy in the News

Electrical Generation vs Time

Sources and amount of electricity generation in the UnitedStates from 1950 to 2000 (for units see figure 10.1 in yourBook. Purple (top): coal Green: Petroleum and natural gasAqua: Hydroelectric power Blue: Nuclear power.

General Trends

Coal provides most of the power for electrical generation

Need for electrical power in the 1970s, doubled every 10 years

Rate of growth in demand has slowed to about 2% per year(implied doubling time??)

Energy use overall: largest rate of growth is in electrical consumption

Use of Coal, Natural Gas and Petroleum by Utilities

Nonutility producers ofEnergy: use proportionatelymore renewable energy,Don’t use nuclear at all.Do use some fossil fuels.

Restructuring of the Utilities

Deregulation of the utilities: Goals: 1) To make electricity cheaper by promoting competition2) Promote increased efficiency of power plants3) Allow consumers choice of renewable energy sources

Historical Perspective: Why a utility monopoly?

1) Smoothing of demand: promotes efficiency2) Power plants are expensive

Utilities: Why Change?

1) Facilities already built

2) Profit guaranteed: no incentive for change

3) Power plant efficiencies: historical trends

4) Renewable energy sources (other than hydro)

Deregulation History

PURPA: Public Utility Regulatory Policy Act: 1978

1) Must buy power from independent producers at avoided cost(about 6 cents per kWH), typical cost of electricity from existingPower plants (about 3.5 cents per kWH).Avoided cost: cost of constructing new power plants

Cost of wind generated power: about 5.5 cents per kWhCogeneration: typically cheaper than wind power

Result: promotion of cogeneration and wind power: Increased energy efficiency and renewable power.

Problems with Deregulation

Stranded costs

Utilities divided up: Generation, transmission and distribution all separate

If a utility sells a power plant: who should get the profits?

California: regulated charges from utilities to consumersBut not charges from fossil fuel brokers to utilities

Transmission lines: incentive to modernize?

Good Aspects of Deregulation

Number of independent power producers increased,Therefore more power generated from renewables

Efficiency of power plants now increasing ratherThan stalling; newer plants 40% efficientCould be 60% efficient with best technology

Consumers in some states can choose to pay moreTo buy power generated from renewables: Increases the market for renewables

Energy Trends

Times of high demand: electrical costs $10 per KWHVs typical price?

Peak power use closer and closer to total capacity

Big plants no longer most efficient power generators:New technologies like microturbines important

Transmission lines: need modernization(What happened in California power crisis?)

Times of high demand: utilities pay big energy usersTo shut down. (What types of companies use the most power?)

Electrical Charges and Currents

Electricity= moving electrons

Conductors: metals with electrons able to move easily(outer shell of electrons in the atom)

Electron: negative chargeProton: positive charge

Unit of Charge: coulomb

6.25E18 electrons = 1 Coulomb

Like charges repel: unlike charges attract

Semi-Conductors and Insulators

Semi-conductors: electricity is conducted but lessEasily than in conductors (What uses semi-conductors?)

Insulators: don’t conduct electricity. PCBs are insulatorsPCB = polychlorinated biphenols Hudson river and PCBsWhy did General Electric manufacture PCBs in large amounts?

Electrical ForcePotential Energy: Applies to electrical force

Electrical Potential= Potential energy embodiedIn electrical charges: unit of potential = voltOne volt = 1 Joule per Coulomb

Potential Difference: Electrical potential energyDerived from difference in energy between positivelyAnd negatively charged parts of electrical device

Electrical current flows from negative to positiveWhy??

Electrical CurrentElectrical current: movement of electrons from Area of electron excess (negative charge) to Area of electron deficit (positive charge)

Unit of current= amp or ampere

Types of current: direct current (DC)Alternating current (AC)

Alternating current: has a frequency in hertz (Hz)USA: 60 HzEurope: 50 HzMost devices run on AC because generators produce ACSolar homes run on DC (why?)

Battery Driven Electrical Motor

Where is the circuitIn this picture?

What do you need to Know to determineThe direction of Current flow?

Batteries

Inside of a flashlight with two batteries:Where is current flowing in this device?In what part is current flowing to the right?In what part is current flowing to the left?

Components of a Battery

1)Two electrodes (or terminals) 2) Submerged in an electrolyte

Electrolytes allow a chemicalReaction to occur. This chemical energy is convertedInto electrical energy by theBattery

Do batteries get warmer when they operate: why or why not?

Pb-acid Dry Cell

Pb-acid batteriesChemical reactions:Negative electrode Pb= Pb 2+ +2e-

Pb2+ +SO4

2- = PbSO4

Positive electrode: PbO2PbO2 + SO4

2- , 4H+ + 2e- = PbSO4 + 2H20

Electrolyte is providing H+ and SO4 2-

Both are needed for the chemical reaction

Where does PbSO4 end up?

Pb acid battery: car battery stores about 2% of the energy in 1 gallonOf gasoline (seismometers in Iceland)

Important Battery Characteristics

Overall voltage

Battery Life

Rechargable?

Energy Density (Watt hours per kilogram)

Toxicity of components

Battery Design

First battery: invented by Volta

Zinc and Silver platesBlotting paper moistened withSalt water.

What are the electrodes?What is the electrolyte?What compounds are being formed?(Make an educated guess)

Lemon Power Runs a Calculator

Why does this work?What part of the battery areThe lemons functioning as?

What else needs to be Present?

Battery Characteristics (for electric cars)

What is the range derived from? Why don’t the batteries withThe highest energy density always have the greatest range?

Types of Batteries

Range is for an electrical car with that battery. Why doesn’t theBattery with the highest energy density have the largest range?

Electrical Vehicles

Not new: first speeding ticket for a car-given toAn electrical car(how fast was it going?)

Electric powered vehicles (Evs) Mostly powered by Pb acid batteriesBatteries take 6 to 8 hours to rechargeRange of 60 to 160 miles between charges

(sound too short a distance? 75% of private carsAre driven less than 50 miles per day)

How an Electrical Vehicle Works

Electrical Vehicles:Why?Big incentive: California law requiring that 10% of all new cars sold in California be zero emission vehicles (ZEVs) by 2003.

Only two types of zero emissions vehicles: bicycles and electrical cars

Are there zero emissions of CO2 when an electricalCar is used? Why or why not?

Electrical Cars: Pros and Cons

Against: are not truly zero emissions vehiclesEmissions are just moved to the power plant

Pb acid batteries: production and use generate PbPollution-so far other batteries much too expensive

At present power plant efficiencies overall level of pollutionProduced by electrical cars: more than by hybrid cars

Pro: as power plant efficiencies improve (60% possible)Electrical vehicles will outperform present hybridsIn terms of overall emissions

Reduce urban air pollution

Hybrid Vehicles

Hybrids are not just cars: a hybrid is any vehicleThat uses two forms of energy for propulsion

Name three types of hybrid vehicle.

Two Hybrids on the Market

Toyotas Prius: 52 mpg city, 45 mpg highway

Hondas Insight: 61 mpg city, 70 mpg highway

How Insight gets 70 mpg!!This is a new record!!

Combination of electrical motor and gasoline engine: thus gasoline engine smaller, runs at maximum efficiency

Gasoline engine shuts off at a stoplight

Energy from braking used to charge the battery that runs the electrical motor.

Unique aerodynamic design of car

Emissions Reduction

Insight emits 84% fewer hydrocarbons and50% less NOx than a typical car.

Note that the Prius gets better mileage in the City than on the highway. Why?