Chapter 16 EnergyEfficiencyandRenewableEnergy. Chapter Overview Questions How can we improve energy efficiency and what are the advantages of doing

Chapter Chapter 1616

Energy Energy Efficiency Efficiency

and and Renewable Renewable

EnergyEnergy

Chapter Overview QuestionsChapter Overview Questions

How can we improve energy How can we improve energy efficiencyefficiency and and what are the what are the advantagesadvantages of doing so? of doing so?

What are the advantages and disadvantages What are the advantages and disadvantages of using of using solar energysolar energy to to heatheat buildings and buildings and water and to produce water and to produce electricityelectricity??

What are the advantages and disadvantages What are the advantages and disadvantages of using of using flowing waterflowing water to produce to produce electricity electricity??

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)

What are the advantages and disadvantages What are the advantages and disadvantages of using of using windwind to produce to produce electricityelectricity??

What are the advantages and disadvantages What are the advantages and disadvantages of burning plant material of burning plant material (biomass)(biomass) to to heatheat buildings and water, produce buildings and water, produce electricityelectricity, and , and propel vehiclespropel vehicles??

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)

What are the advantages and disadvantages What are the advantages and disadvantages of extracting heat from the earth’s “interior” of extracting heat from the earth’s “interior” (geothermal energy)(geothermal energy) and using it to heat and and using it to heat and cool cool buildingsbuildings, , heat waterheat water, and produce , and produce electricityelectricity??

What are the advantages and disadvantages What are the advantages and disadvantages of producing of producing hydrogen gashydrogen gas and using it in fuel and using it in fuel cells to produce cells to produce electricityelectricity, , heatheat buildings and buildings and water, and propel water, and propel vehiclesvehicles??

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d) How can we make a How can we make a transitiontransition to a more sustainable to a more sustainable

energy future?energy future?

Core Case Study: The Coming Energy-Core Case Study: The Coming Energy-Efficiency and Renewable-Energy Efficiency and Renewable-Energy

RevolutionRevolution It is possible to get It is possible to get

electricity from electricity from solar solar cellscells that convert that convert sunlight into electricity.sunlight into electricity. Can be attached like Can be attached like

shinglesshingles on a roof. on a roof. Can be applied to Can be applied to

window glasswindow glass as a as a coating.coating.

Can be mounted on Can be mounted on racks almost anywhereracks almost anywhere..

The Coming Energy-Efficiency and The Coming Energy-Efficiency and Renewable-Energy RevolutionRenewable-Energy Revolution

The heating bill for this energy-efficient passive The heating bill for this energy-efficient passive solar radiation office in Colorado is $50 a year (built solar radiation office in Colorado is $50 a year (built inin 1984 by energy analyst Amory Lovins)1984 by energy analyst Amory Lovins)

Core Case Study: The Coming Energy-Core Case Study: The Coming Energy-Efficiency and Renewable-Energy RevolutionEfficiency and Renewable-Energy Revolution

Australia will construct the world’s largest solar power plant, in Victoria state. It will have a capacity of 154 megawatts, with a completion date set for 2013. It will cost $320 million US dollars.

REDUCING ENERGY WASTE AND REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCYIMPROVING ENERGY EFFICIENCY 84%84% of all of all commercial energycommercial energy (energy (energy

“produced” by humans) used in the U.S. is “produced” by humans) used in the U.S. is wastedwasted.. Therefore we currently have an Therefore we currently have an overall energy overall energy

efficiency of 16%. efficiency of 16%.

41% will always be wasted due to 241% will always be wasted due to 2ndnd law of law of thermodynamics.thermodynamics. So we could So we could more than triplemore than triple our efficiency to our efficiency to

59%59%

International Energy EfficiencyInternational Energy Efficiency Unnecessary energy waste costs the Unnecessary energy waste costs the US US

$300 billion per year$300 billion per year.. $570,000 per minute$570,000 per minute

GloballyGlobally, $1 trillion per year is wasted, $1 trillion per year is wasted Canada is less efficient than the USCanada is less efficient than the US Developing nations are 3x less efficient than the Developing nations are 3x less efficient than the

US.US.

Japan, Germany, & FranceJapan, Germany, & France are 2-3x are 2-3x moremore energy efficient than the USenergy efficient than the US

International Energy EfficiencyInternational Energy Efficiency In 2004, In 2004, ChinaChina

announced an energy announced an energy strategy built around strategy built around using “leapfrog using “leapfrog technologies” to technologies” to improve the energy improve the energy efficiency of its cars, efficiency of its cars, factories, buildings, and factories, buildings, and consumer products.consumer products.

International Energy EfficiencyInternational Energy Efficiency ““Focusing the United States on greater Focusing the United States on greater

energy efficiency and conservation is the energy efficiency and conservation is the most tough-minded, geostrategic, pro-growth, most tough-minded, geostrategic, pro-growth, and patriotic thing we can do…Living green is and patriotic thing we can do…Living green is not just a personal virtue, it is a national not just a personal virtue, it is a national security imperative. Green is the new red, security imperative. Green is the new red, white, and blue.”white, and blue.”

-Thomas L. Friedman-Thomas L. Friedman

author, geopolitical expertauthor, geopolitical expert

Fig. 17-2, p. 385

Energy InputsSystem

Outputs

9%

7%

41%85% U.S.

economy and

lifestyles

8%

43%

4%

Nonrenewable nuclear Petrochemicals (plastics, etc.)

Nonrenewable fossil fuels Useful energy

Hydropower, geothermal, wind, solar

Unavoidable energy waste

Unnecessary energy wasteBiomass

3%

REDUCING ENERGY WASTE AND REDUCING ENERGY WASTE AND IMPROVING ENERGY EFFICIENCYIMPROVING ENERGY EFFICIENCY

Four widely used devices waste large Four widely used devices waste large amounts of energy:amounts of energy: Incandescent light bulbIncandescent light bulb: : 95%95% is lost as is lost as heat.heat. Internal combustion engine (cars, etc.)Internal combustion engine (cars, etc.): :

94%94% of the energy in its fuel is wasted. of the energy in its fuel is wasted. Nuclear power plantNuclear power plant: : 92%92% of energy is wasted of energy is wasted

through the through the nuclear fuel cyclenuclear fuel cycle and energy and energy needed for needed for waste managementwaste management..

Coal-burning power plantCoal-burning power plant: : 66%66% of the energy of the energy released by burning coal is lost.released by burning coal is lost.

First Things FirstFirst Things First

To most energy analysts, To most energy analysts, reducing energy reducing energy wastewaste is the is the quickestquickest, , cheapestcheapest, , cleanestcleanest way way to:to: provide more energyprovide more energy reduce pollution reduce pollution reduce environmental degradationreduce environmental degradation slow global warming.slow global warming.

Fig. 17-3, p. 386

Solutions

Reducing Energy Waste

Prolongs fossil fuel supplies

Reduces oil imports

Very high net energy

Low cost

Reduces pollution and environmental degradation

Buys time to phase in renewable energy

Less need for military protection of Middle East oil resources

Creates local jobs

Net Energy Efficiency: Net Energy Efficiency: Honest AccountingHonest Accounting

Comparison of net Comparison of net energy efficiency for energy efficiency for two types of two types of space space heating.heating.

nextnext

Fig. 17-4, p. 387

Uranium mining (95%)

Uranium processing and transportation

(57%)

Power plant (31%)

Transmission of electricity (85%)

Resistance heating

(100%)

Uranium

100%

95% 54% 17% 14% 14%

Waste heat

Waste heat

Waste heat

Waste heat

Electricity from Nuclear Power PlantWindow transmission

(90%)Sunlight

100%

90%

Waste heat

Passive Solar Heat

WAYS TO IMPROVE ENERGY WAYS TO IMPROVE ENERGY EFFICIENCYEFFICIENCY

IndustryIndustry accounts for about 42% of U.S. accounts for about 42% of U.S. energy consumption.energy consumption.

Industry can greatly improve energy Industry can greatly improve energy efficiency by using efficiency by using cogeneration cogeneration more efficient electric motorsmore efficient electric motors


CogenerationCogeneration- combined heat and power - combined heat and power (CHP) systems.(CHP) systems. Steam used to produce electric power is used to Steam used to produce electric power is used to

heat the plant or nearby buildings rather than heat the plant or nearby buildings rather than wastedwasted

Efficiency is 80% instead of 20-40% for coal-fired Efficiency is 80% instead of 20-40% for coal-fired or nuclear power plants.or nuclear power plants.

Used in Western Europe for years, use is Used in Western Europe for years, use is growing rapidly in the US and China.growing rapidly in the US and China.

WAYS TO IMPROVE ENERGY EFFICIENCYWAYS TO IMPROVE ENERGY EFFICIENCY Energy wasting electric motorsEnergy wasting electric motors consume consume one one

fourthfourth of the electricity in the US. of the electricity in the US. Run only at Run only at full speedfull speed with their output with their output

mechanically throttledmechanically throttled to match the task. to match the task.• Like driving a car by always running the motor at top Like driving a car by always running the motor at top

speed and controlling the car’s speed with the brakes!speed and controlling the car’s speed with the brakes!

Each year a heavily used electric motor Each year a heavily used electric motor consumes 10xconsumes 10x it’s purchase cost in electricity. it’s purchase cost in electricity.• Like using $200,000 worth of gas in a $20,000 car.Like using $200,000 worth of gas in a $20,000 car.

The cost of replacing with adjustable speed The cost of replacing with adjustable speed motors would be motors would be paid back in 1 yearpaid back in 1 year in energy in energy savings.savings.

WAYS TO IMPROVE ENERGY EFFICIENCYWAYS TO IMPROVE ENERGY EFFICIENCY Transportation Transportation accounts for one fourth of US accounts for one fourth of US

energy consumption, 74% of this by motor energy consumption, 74% of this by motor vehicles.vehicles.

Between Between 1973 and 19851973 and 1985, average fuel , average fuel efficiency rose due to CAFE standards efficiency rose due to CAFE standards ((CCorporate orporate AAverage verage FFuel uel EEconomy).conomy).

Between Between 1988 and 20061988 and 2006, US vehicle fuel , US vehicle fuel efficiency efficiency droppeddropped 6%, due to SUVs and 6%, due to SUVs and trucks that do not have to meet CAFE trucks that do not have to meet CAFE standards.standards. A 2002 Roper poll showed that only 17% of Americans A 2002 Roper poll showed that only 17% of Americans

were aware of this, most thought that fuel economy had were aware of this, most thought that fuel economy had increasedincreased


Average fuel Average fuel economyeconomy of new of new vehicles sold in the vehicles sold in the U.S. between 1975-U.S. between 1975-2006.2006.

The governmentThe government Corporate Average Corporate Average Fuel EconomyFuel Economy (CAFE) has not (CAFE) has not increased after increased after 1985, until 2009.1985, until 2009.

nextnext

Fig. 17-5, p. 388

Cars

Both

Ave

rag

e fu

el e

con

om

y (m

iles

per

gal

lon

, o

r m

pg

)

Model year

Pickups, vans, and sport utility vehicles


Inflation adjusted Inflation adjusted priceprice of gasoline (in of gasoline (in 2006 dollars) in the 2006 dollars) in the U.S.U.S.

US gas is US gas is still cheapstill cheap compared to most of compared to most of the rest of the worldthe rest of the world

Motor vehicles in the Motor vehicles in the U.SU.S. use 40% of the . use 40% of the world’s gasoline.world’s gasoline.

NextNext

Fig. 17-6, p. 388

Do

llars

per

gal

lon

(in

200

6 d

olla

rs)

Year

WAYS TO IMPROVE ENERGY EFFICIENCYWAYS TO IMPROVE ENERGY EFFICIENCY A possible (likely?) progression of vehicle A possible (likely?) progression of vehicle

technology:technology:hybrids hybrids 50 mpg-50 mpg- dominate by 2025dominate by 2025

plug-in hybrids plug-in hybrids 100 mpg, 1000 mpg short trips100 mpg, 1000 mpg short trips

→→eventually, most electricity from wind & solareventually, most electricity from wind & solar

ultralight, ultrastrong plug-in hybrids ultralight, ultrastrong plug-in hybrids 300-1000+ mpg300-1000+ mpg

→→nanotech materials for constructionnanotech materials for construction

hydrogen fuel-cellhydrogen fuel-cell zero emissionszero emissions if fueled with H if fueled with H22 instead instead of CHof CH4 4 →→some by 2020, could dominate by 2050some by 2020, could dominate by 2050


General features of a car General features of a car powered by a powered by a hybrid-hybrid-electricelectric engine. engine.

““Gas sipping”Gas sipping” cars cars account for less than 1% account for less than 1% of all new car sales in the of all new car sales in the U.S.U.S.

Current hybrids get Current hybrids get about about 50 MPG50 MPG

NextNext

Fig. 17-7, p. 389

Regulator: Controls flow of power between electric motor and battery bank.

Fuel tank: Liquid fuel such as gasoline, diesel, or ethanol runs small combustion engine.Transmission:

Efficient 5-speed automatic transmission.

Battery: High-density battery powers electric motor for increased power.

Combustion engine: Small, efficient internal combustion engine powers vehicle with low emmissions; shuts off at low speeds and stops.

Electric motor: Traction drive provides additional power for passing and acceleration; excess energy recovered during braking is used to help power motor.

Fuel Electricity

Fuel-Cell VehiclesFuel-Cell Vehicles

Hybrid Vehicles, Sustainable Wind Hybrid Vehicles, Sustainable Wind Power, and Oil importsPower, and Oil imports

Hybrid gasoline-electric engines with an Hybrid gasoline-electric engines with an extra plug-extra plug-in batteryin battery could be powered mostly by could be powered mostly by electricity electricity produced by windproduced by wind and get and get twice the mileagetwice the mileage of of current hybrid cars.current hybrid cars.

Currently plug-in batteries would be charged by coal and Currently plug-in batteries would be charged by coal and nuclear power plants…eventually wind and solar.nuclear power plants…eventually wind and solar.

According to U.S. Department of Energy, a network of According to U.S. Department of Energy, a network of wind farms in North Dakota, South Dakota, Texas, and wind farms in North Dakota, South Dakota, Texas, and Kansas could meet Kansas could meet all U.S. electricity demandsall U.S. electricity demands..

No more oil imports for transportation!No more oil imports for transportation!



Fuel-Cell VehiclesFuel-Cell Vehicles Fuel-efficient vehicles powered by a Fuel-efficient vehicles powered by a fuel cellfuel cell that runs that runs

on hydrogen gas are being developed.on hydrogen gas are being developed.

CombinesCombines hydrogen gas (H hydrogen gas (H22) and oxygen gas (O) and oxygen gas (O22) fuel ) fuel

to produce electricity and water vapor to produce electricity and water vapor

2H2H22+O+O22 2H 2H22OO

Emits no air pollution or COEmits no air pollution or CO22 if the hydrogen is if the hydrogen is

produced from renewable-energy sources such as produced from renewable-energy sources such as splitting water into H and O by using wind-generated splitting water into H and O by using wind-generated electricity. electricity. 2H2H22O O 2H 2H22+O+O22

Fuel-Cell BasicsFuel-Cell Basics

Protons “go through”, so electrons “flow around” (make electric current)

One hydrogen atom

Fig. 17-8, p. 390

Body attachments Body attachments Mechanical locks that secure the Mechanical locks that secure the body to the chassisbody to the chassis

Air system management

Universal docking connection Connects the chassis with the

drive-by-wire system in the bodyFuel-cell stack Converts hydrogen fuel into electricity

Rear crush zone Absorbs crash energy

Drive-by-wire system controls

Cabin heating unit

Side-mounted radiators Release heat generated by the fuel cell, vehicle electronics, and wheel motors

Hydrogen fuel tanks

Front crush zone Absorbs crash energy

Electric wheel motors Provide four-wheel drive; have built-in brakes


We can save energy in We can save energy in existing buildingsexisting buildings by by insulating theminsulating them

plugging leaksplugging leaks

using energy-efficient heating and cooling using energy-efficient heating and cooling systems, appliances, and lighting.systems, appliances, and lighting.


We can save energy in We can save energy in new buildingsnew buildings by by getting heat from the sungetting heat from the sun

superinsulating themsuperinsulating them

using plant covered green roofs.using plant covered green roofs.

using energy-efficient heating and cooling using energy-efficient heating and cooling systems, appliances, and lighting.systems, appliances, and lighting.

Strawbale HouseStrawbale House

StrawbaleStrawbale construction is a construction is a superinsulatorsuperinsulator that is that is made from bales of low-cost straw covered with made from bales of low-cost straw covered with plaster or adobeplaster or adobe. .

Insulation is measured in “R-values” (resistance to heat flow)Insulation is measured in “R-values” (resistance to heat flow) Standard home insulation is R-12 to R-19Standard home insulation is R-12 to R-19 Strawbale construction is R-35 to R-60.Strawbale construction is R-35 to R-60.

Figure 17-9Figure 17-9

Strawbale HouseStrawbale House Depending on the thickness of the bales, its Depending on the thickness of the bales, its

strength exceeds standard construction.strength exceeds standard construction.

Workshop in Eastern France

Living RoofsLiving Roofs


Roofs covered with plants have been Roofs covered with plants have been used for decadesused for decades in Europe and Iceland. in Europe and Iceland.

These roofs are built from a blend of light-These roofs are built from a blend of light-weight compost, mulch and sponge-like weight compost, mulch and sponge-like materials that hold water.materials that hold water.

They must first be They must first be carefully waterproofedcarefully waterproofed





“City of Living Roofs” proposed for London

(artist conception)

Saving Energy in Existing BuildingsSaving Energy in Existing Buildings

About About one-thirdone-third of the heated air in typical of the heated air in typical U.S. homes and buildings escapes through U.S. homes and buildings escapes through closed windows and holes and cracks.closed windows and holes and cracks. Thermal imaging “takes a picture” of heat lossThermal imaging “takes a picture” of heat loss

Why Are We Still Wasting So Much Why Are We Still Wasting So Much Energy?Energy?

Heavily subsidized, low-priced fossil fuels Heavily subsidized, low-priced fossil fuels and few government tax breaks or other and few government tax breaks or other financial incentives for saving energy financial incentives for saving energy promote energy waste.promote energy waste.

USING RENEWABLE SOLAR USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ENERGY TO PROVIDE HEAT AND

ELECTRICITYELECTRICITY

A variety of renewable-energy resources A variety of renewable-energy resources are are availableavailable but their but their use has been hindereduse has been hindered by by a lack of government support compared to a lack of government support compared to nonrenewable fossil fuels and nuclear power.nonrenewable fossil fuels and nuclear power. Solar Solar Moving water (hydropower) Moving water (hydropower) Wind Wind GeothermalGeothermal

USING RENEWABLE SOLAR ENERGY USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITYTO PROVIDE HEAT AND ELECTRICITY

The European UnionThe European Union aims to get 22% of its aims to get 22% of its electricity from renewable energy by 2010.electricity from renewable energy by 2010.

Costa RicaCosta Rica already gets 92% of its energy from already gets 92% of its energy from renewable resources.renewable resources.

ChinaChina aims to get 10% of its total energy from aims to get 10% of its total energy from renewable resources by 2020.renewable resources by 2020.

In 2004, CaliforniaIn 2004, California got about 12% of its electricity got about 12% of its electricity from wind and plans to increase this to 50% by from wind and plans to increase this to 50% by 2030.2030.

USING RENEWABLE SOLAR ENERGY USING RENEWABLE SOLAR ENERGY TO PROVIDE HEAT AND ELECTRICITYTO PROVIDE HEAT AND ELECTRICITY

DenmarkDenmark now gets 20% of its electricity from now gets 20% of its electricity from wind and plans to increase this to 50% by wind and plans to increase this to 50% by 2030.2030.

Brazil Brazil gets 20% of its gasoline from gets 20% of its gasoline from sugarcane residues called sugarcane residues called bagasse.bagasse.

In 2004, the world’s renewable-energy In 2004, the world’s renewable-energy industries provided 1.7 million jobs.industries provided 1.7 million jobs.

Heating Buildings and Water with Heating Buildings and Water with Solar EnergySolar Energy

We can heat buildings by We can heat buildings by orienting orienting them them toward the sun or by toward the sun or by pumpingpumping a liquid such a liquid such as water through rooftop collectors.as water through rooftop collectors.

NextNext

Fig. 17-12, p. 395

Summer sun

Heat to house (radiators or

forced air duct)

PumpHeavy

insulationSuperwindow

Hot water tank

Winter sun

Super windowSuperwindow

Heat exchanger

Stone floor and wall for heat storage

PASSIVESOLARHEAT

ACTIVESOLARHEAT

Passive Solar Passive Solar HeatingHeating

Passive solar heatingPassive solar heating system absorbs and system absorbs and stores heat from the stores heat from the sun directly within a sun directly within a structure structure withoutwithout the the need for need for pumpspumps to to distribute the heat.distribute the heat.

NextNext

Fig. 17-13, p. 396

Direct Gain

Summer sunHot air

Warm air

Super-insulated windows

Winter sun

Cool air

Earth tubes

Ceiling and north wall heavily insulated

Fig. 17-13, p. 396

Greenhouse, Sunspace, or Attached Solarium

Summer cooling vent

Warm air

Insulated windows

Cool air

Fig. 17-13, p. 396

Earth Sheltered

Reinforced concrete, carefully waterproofed walls and roof

Triple-paned or superwindowsEarth

Flagstone floor for heat storage

Fig. 17-14, p. 396

Trade-Offs

Passive or Active Solar Heating

Advantages Disadvantages

Energy is free Need access to sun 60% of time

Net energy is moderate (active) to high (passive)

Sun blocked by other structures

Need heat storage system

Quick installation

No CO2 emissions

Very low air and water pollution

High cost (active)

Very low land disturbance (built into roof or window)

Active system needs maintenance and repair

Moderate cost (passive)

Active collectors unattractive

Cooling Houses NaturallyCooling Houses Naturally

We can cool houses by:We can cool houses by: SuperinsulatingSuperinsulating them. them.

Taking advantages of breezes. Taking advantages of breezes.

Shading them.Shading them.

Having light colored or green roofs.Having light colored or green roofs.

Using Using geothermal coolinggeothermal cooling..

Cooling Houses Naturally:Cooling Houses Naturally:Geothermal CoolingGeothermal Cooling

Can also be reversed for heat in the winter.

Cooling Houses NaturallyCooling Houses Naturally

Cooling Houses NaturallyCooling Houses NaturallyGeothermal heat pumps cost $1000 to $2000 more than conventional heat pumps like many have in Georgia, but this cost is recovered in 1-2 years as energy bills can be cut in half.

Solar ThermalSolar Thermal

Solar thermal: Solar thermal: concentrating the concentrating the sun’s heatsun’s heat


Using Solar Energy to Generate High-Using Solar Energy to Generate High-Temperature Heat and ElectricityTemperature Heat and Electricity

Solar Thermal Systems:Solar Thermal Systems:

Large arrays of solar Large arrays of solar collectors in sunny collectors in sunny deserts can produce deserts can produce high-temperature heathigh-temperature heat to to spin turbines for spin turbines for electricityelectricity, but costs are , but costs are high.high.

Fig. 17-15, p. 397

Trade-Offs

Solar Thermal Systems:Solar Energy for High-Temperature

Heat and Electricity


Moderate net energy

Low efficiency

High costsModerate environmental impact

Needs backup or storage system

No CO2 emissionsNeed access to sun most of the timeFast construction

(1–2 years)High land use

Costs reduced with natural gas turbine backup

May disturb desert areas

Producing Electricity with Solar CellsProducing Electricity with Solar Cells

Solar cellsSolar cells convert convert sunlight to sunlight to electricity.electricity.

Their Their costs are costs are highhigh, but expected , but expected to fall.to fall.

We are just now We are just now reaching reaching 20% 20% efficiencyefficiency..



Photovoltaic (PV) cellsPhotovoltaic (PV) cells can provide electricity can provide electricity for a house of building using solar-cell roof for a house of building using solar-cell roof shingles.shingles. NextNext

Fig. 17-17, p. 398

Single solar cell Solar-cell roof

–

Boron enriched silicon

+

Junction

Phosphorus enriched silicon

Roof options

Panels of solar cells

Solar shingles


Solar cells can be Solar cells can be used in used in rural rural villagesvillages with ample with ample sunlight who are sunlight who are not connected to not connected to an electrical grid.an electrical grid.



Now that photovoltaic solar cells have Now that photovoltaic solar cells have reached reached 20% efficiency,20% efficiency, a sunny desert a sunny desert area equivalent to the states of area equivalent to the states of Connecticut and Rhode Island could Connecticut and Rhode Island could supply the US with supply the US with ALLALL of our of our electricity…electricity…


IF we could easily store and distribute all of that electric power!!

Fig. 17-19, p. 399

Trade-Offs

Solar Cells


Fairly high net energy Need access to sun

Work on cloudy daysLow efficiency

Quick installation

Need electricity storage system or backup

Easily expanded or moved

No CO2 emissions

High land use (solar-cell power plants) could disrupt desert areas

Low environmental impact

Last 20–40 years

Low land use (if on roof or built into walls or windows)

High costs (but should be competitive in 5–15 years)

Reduces dependence on fossil fuels DC current must be converted

to AC

PRODUCING ELECTRICITY FROM PRODUCING ELECTRICITY FROM THE WATER CYCLETHE WATER CYCLE

Water flowing in rivers and streams can be Water flowing in rivers and streams can be trapped in trapped in reservoirs behind damsreservoirs behind dams and and released as needed to spin turbines and released as needed to spin turbines and produce electricity.produce electricity.

There is There is little room for expansionlittle room for expansion in the U.S. in the U.S. – Dams and reservoirs have been created on – Dams and reservoirs have been created on 98% of suitable rivers.98% of suitable rivers. Provides Provides 7%7% of US electricity, 50% on the West of US electricity, 50% on the West

coastcoast

Trade-Offs

Large-Scale Hydropower


Moderate to high net energy High construction costs

Large untapped potential (global)

High environmental impact from flooding land to form a reservoir

High efficiency (80%)

High CO2 emissions from biomass decay in shallow tropical reservoirs

Low-cost electricity

Long life span (until dam silts up)

No CO2 emissions during operation in temperate areas

Floods natural areas behind dam

May provide flood control below dam

Converts land habitat to lake habitat

Danger of collapse

Provides water for year-round irrigation of cropland

Uproots people

Decreases fish harvest below dam

Reservoir is useful for fishing and recreation

Decreases flow of natural fertilizer (silt) to land below dam

PRODUCING ELECTRICITY FROM PRODUCING ELECTRICITY FROM THE WATER CYCLETHE WATER CYCLE

Ocean Ocean tides and wavestides and waves and and temperature temperature differencesdifferences between surface and bottom waters in between surface and bottom waters in tropical waters are tropical waters are not expected not expected to provide much of to provide much of the world’s electrical needs.the world’s electrical needs. High costs, storm damage, and salt water corrosion are High costs, storm damage, and salt water corrosion are

problemsproblems

Only Only two large tidal energy damstwo large tidal energy dams are currently are currently operating: one in La Rance, France and Nova operating: one in La Rance, France and Nova Scotia’s bay of Fundy where the tidal amplitude can Scotia’s bay of Fundy where the tidal amplitude can be as high as 16 meters (63 feet).be as high as 16 meters (63 feet).

ELECTRICITY FROM WINDELECTRICITY FROM WIND

One Blade

ELECTRICITY FROM WINDELECTRICITY FROM WIND Wind power is the world’s Wind power is the world’s most promising most promising

energy resourceenergy resource because it is abundant, because it is abundant, inexhaustible, widely distributed, cheap, inexhaustible, widely distributed, cheap, clean, and emits no greenhouse gases.clean, and emits no greenhouse gases.

Much of the world’s potential for wind power Much of the world’s potential for wind power remains untapped.remains untapped.

Capturing only 20%Capturing only 20% of the wind energy at the of the wind energy at the world’s best energy sites could meet world’s best energy sites could meet all the all the world’s energy demands.world’s energy demands.

Wind Wind TurbineTurbine

PRODUCING ELECTRICITY PRODUCING ELECTRICITY FROM WINDFROM WIND

Wind turbines can be used iWind turbines can be used individuallyndividually to to produce electricity. They are also used produce electricity. They are also used interconnected in arrays on interconnected in arrays on wind farmswind farms..


Fig. 17-21, p. 402

Gearbox

Electrical generator

Power cable

Wind turbine Wind farm

PRODUCING ELECTRICITY FROM PRODUCING ELECTRICITY FROM WINDWIND

The United States The United States once ledonce led the wind power the wind power industry, but Europe now leads this rapidly industry, but Europe now leads this rapidly growing business.growing business. The U.S. government lacked subsidies, tax The U.S. government lacked subsidies, tax

breaks and other financial incentives.breaks and other financial incentives.

European companiesEuropean companies manufacture 80% of manufacture 80% of the wind turbines sold in the global marketthe wind turbines sold in the global market The success has been aided by strong The success has been aided by strong

government subsidiesgovernment subsidies..

Wind Turbine Bird MortalityWind Turbine Bird Mortality Wind turbines kill about Wind turbines kill about 40,000 birds40,000 birds per year in the per year in the

USUS

Other sources of US bird mortality Other sources of US bird mortality per yearper year:: Cars & trucksCars & trucks: 50-100 million: 50-100 million

HuntersHunters: 100 million: 100 million

Electric transmission Electric transmission lineslines: 175 million: 175 million

Glass windows, buildings, & electric transmission Glass windows, buildings, & electric transmission towerstowers: 100-900 million: 100-900 million

Trade-Offs

Wind Power


Moderate to high net energy Steady winds needed

Backup systems needed when winds are low

High efficiency

Moderate capital cost

Low electricity cost (and falling)High land use for wind farm

Very low environmental impact

No CO2 emissions Visual pollution

Quick constructionNoise when located near populated areasEasily expanded

Can be located at sea

Land below turbines can be used to grow crops or graze livestock

May interfere in flights of migratory birds and kill birds of prey

PRODUCING PRODUCING ENERGY FROM ENERGY FROM

BIOMASSBIOMASS Plant materialsPlant materials and and

animal wastesanimal wastes can be can be

burnedburned to provide heat to provide heat or electricity or electricity

converted into converted into gaseousgaseous or or liquidliquid biofuels. biofuels.

NextNext

Solid Biomass FuelsWood logs and pellets

CharcoalAgricultural waste

(stalks and other plant debris)Timbering wastes

(branches, treetops, and wood chips)Animal wastes (dung)

Aquatic plants (kelp and water hyacinths)Urban wastes (paper, cardboard),And other combustible materials

Direct burningConversion to gaseous

and liquid biofuels

Gaseous Biofuels

Synthetic natural gas(biogas)

Wood gas

Liquid Biofuels

EthanolMethanolGasonolBiodiesel

Stepped Art

PRODUCING ENERGY FROM PRODUCING ENERGY FROM BIOMASSBIOMASS

The The scarcity of scarcity of fuelwoodfuelwood causes causes people to make people to make fuel briquettes fuel briquettes from cow dung in from cow dung in India. India.

This This deprives soildeprives soil of plant nutrients.of plant nutrients.


Trade-Offs

Solid Biomass


Large potential supply in some areas

Nonrenewable if harvested unsustainably

Moderate costsModerate to high environmental impact

No net CO2 increase if harvested and burned sustainably

CO2 emissions if harvested and burned unsustainably

Low photosynthetic efficiencyPlantation can be located on semiarid land not needed for crops

Soil erosion, water pollution, and loss of wildlife habitat

Plantation can help restore degraded lands

Plantations could compete with cropland

Often burned in inefficient and polluting open fires and stoves

Can make use of agricultural, timber, and urban wastes

Converting Plants and Plant Wastes Converting Plants and Plant Wastes to to Liquid BiofuelsLiquid Biofuels: An Overview: An Overview

Motor vehiclesMotor vehicles can run on can run on ethanolethanol, , biodieselbiodiesel, , and and methanolmethanol produced from plants and plant produced from plants and plant wastes.wastes.

The major The major advantagesadvantages of biofuels are: of biofuels are: Crops used for production can be grown almost Crops used for production can be grown almost

anywhere.anywhere. There is no net increase in COThere is no net increase in CO22 emissions (why?) emissions (why?) Widely available and easy to store and transport.Widely available and easy to store and transport.

Case Study: Producing EthanolCase Study: Producing Ethanol CropsCrops such as such as

sugarcane, corn, sugarcane, corn, and switchgrass and and switchgrass and agricultural, forestry agricultural, forestry and and municipal municipal wasteswastes can be can be converted to converted to ethanol.ethanol. SwitchgrassSwitchgrass can can

remove COremove CO22 from the from the

troposphere and store troposphere and store it in the soil.it in the soil.


Disadvantages of BiofuelsDisadvantages of Biofuels Sustainable?Sustainable?...industrialized agriculture has a larger ...industrialized agriculture has a larger

harmful environmental impact than any other harmful environmental impact than any other industry.industry.

Expanding agricultural lands for biofuel crops Expanding agricultural lands for biofuel crops degrades landdegrades land and and decreases biodiversitydecreases biodiversity

Competition with crops grown for food.Competition with crops grown for food. In 2007-2008, global food prices have increased 40%In 2007-2008, global food prices have increased 40% There have been food riots in Haiti and Egypt There have been food riots in Haiti and Egypt

Corn vs SugarcaneCorn vs Sugarcane

Net energy efficiency Net energy efficiency = energy out = energy out / energy in/ energy in

Brazilian sugarcane “bagasse” = 8.3Brazilian sugarcane “bagasse” = 8.3

US corn = 1.5 (maximum)US corn = 1.5 (maximum)

Switchgrass = 4Switchgrass = 4

Case Study: Producing EthanolCase Study: Producing Ethanol 10-23% pure ethanol makes gasohol which 10-23% pure ethanol makes gasohol which

can be run in can be run in conventional motorsconventional motors.. 85% ethanol (E85) must be burned in 85% ethanol (E85) must be burned in flex-flex-

fuel cars.fuel cars. Processing all corn grown in the U.S. into Processing all corn grown in the U.S. into

ethanol would cover only about 55 days of ethanol would cover only about 55 days of current driving.current driving.

BiodieselBiodiesel is made by combining alcohol with is made by combining alcohol with vegetable oil made from a variety of different vegetable oil made from a variety of different plants such as plants such as soybeanssoybeans and and palm oilspalm oils

Fig. 17-27, p. 407

Trade-Offs

Ethanol Fuel


High octane Large fuel tank needed

Some reduction in CO2 emissions

Lower driving range

Low net energy (corn)

High net energy (bagasse and switchgrass)

Much higher cost

Corn supply limited

Reduced CO emissions

May compete with growing food on cropland

Can be sold as gasohol

Higher NO emissions

Corrosive

Potentially renewable Hard to start in cold weather

Case Study: Producing BiodieselCase Study: Producing Biodiesel

Biodiesel has the potential to supply about Biodiesel has the potential to supply about 10% of the country’s diesel fuel needs.10% of the country’s diesel fuel needs.


Trade-Offs

Biodiesel


Slightly increased emissions of nitrogen oxides

Reduced CO2 emissions (78%)

Higher cost than regular diesel

Reduced hydrocarbon emissions

Low yield for soybean crops

Better gas mileage (40%)May compete with growing food on cropland

Loss and degradation of biodiversity from crop plantations

High yield for oil palm crops

Moderate yield for rapeseed crops

Hard to start in cold weatherPotentially renewable

Case Study: Biodiesel and MethanolCase Study: Biodiesel and Methanol

Growing crops for biodiesel could potentially Growing crops for biodiesel could potentially promote promote deforestation.deforestation.

Methanol Methanol is made mostly from is made mostly from natural gasnatural gas but but can also be produced at a higher cost can also be produced at a higher cost from COfrom CO22 from the atmosphere which could from the atmosphere which could

help slow global warming.help slow global warming. Can also be converted to other hydrocarbons to Can also be converted to other hydrocarbons to

produce chemicals that are now made from produce chemicals that are now made from petroleum and natural gas petroleum and natural gas (petrochemicals)(petrochemicals)

Fig. 17-30, p. 408

Trade-Offs

Methanol Fuel


High octane Large fuel tank needed

Some reduction in CO2 emissions Half the driving

rangeLower total air pollution (30–40%) Corrodes metal,

rubber, plasticCan be made from natural gas, agricultural wastes, sewage sludge, garbage, and CO2

High CO2 emissions if made from coal

Expensive to produce

Can be used to produce H2 for fuel cells

Hard to start in cold weather

GEOTHERMAL ENERGYGEOTHERMAL ENERGY Geothermal energyGeothermal energy consists of heat stored in consists of heat stored in

soil, underground rocks, and fluids in the earth’s soil, underground rocks, and fluids in the earth’s mantle.mantle. HydrothermalHydrothermal energy (hot water/steam from energy (hot water/steam from

underground) is underground) is one type of geothermalone type of geothermal

We can use geothermal energy stored in the We can use geothermal energy stored in the earth’s mantle to earth’s mantle to heat and coolheat and cool buildings and to buildings and to produce electricityproduce electricity..

A A geothermal heat pumpgeothermal heat pump (GHP) can heat and cool a (GHP) can heat and cool a house by exploiting the difference between the house by exploiting the difference between the earth’s surface and underground temperatures.earth’s surface and underground temperatures.

Geothermal Heat PumpGeothermal Heat Pump

The house is The house is heatedheated in the in the winter by winter by transferring heat transferring heat from the ground from the ground into the house.into the house.

The process is The process is reversedreversed in the in the summer to cool summer to cool the house.the house.


Fig. 17-31, p. 409

Basementheat pump

GEOTHERMAL ENERGYGEOTHERMAL ENERGY

Deeper more concentrated Deeper more concentrated hydrothermal hydrothermal reservoirsreservoirs can be used to heat homes and can be used to heat homes and buildings and spin turbines:buildings and spin turbines: Dry steamDry steam: water vapor with no water droplets.: water vapor with no water droplets.

Wet steamWet steam: a mixture of steam and water : a mixture of steam and water

droplets.droplets.

Hot waterHot water: is trapped in fractured or porous rock.: is trapped in fractured or porous rock.

Fig. 17-32, p. 410

Trade-Offs

Hydrothermal Energy


Very high efficiency

Scarcity of suitable sites

Moderate net energy at accessible sites

Depleted if used too rapidly

Lower CO2 emissions than fossil fuels Moderate to high

local air pollutionLow cost at favorable sites

CO2 emissions

Noise and odor (H2S)Low land use

Low land disturbance Cost too high

except at the most concentrated and accessible sources

Moderate environmental impact

HYDROGENHYDROGEN

Some energy expertsSome energy experts view hydrogen gas as view hydrogen gas as the the best fuel to replace oil during the last half best fuel to replace oil during the last half of the century,of the century, but there are but there are several hurdlesseveral hurdles to overcome:to overcome: Hydrogen is Hydrogen is chemically lockedchemically locked up in water an up in water an

organic compounds.organic compounds. It takes It takes energy and moneyenergy and money to produce it (net to produce it (net

energy is low).energy is low). Fuel cells areFuel cells are expensive expensive.. Hydrogen may be produced by using Hydrogen may be produced by using fossil fuelsfossil fuels..

Converting to a Hydrogen EconomyConverting to a Hydrogen Economy

IcelandIceland plans to run its economy mostly on plans to run its economy mostly on hydrogen (produced via hydropower, hydrogen (produced via hydropower, geothermal, and wind energy), but doing this geothermal, and wind energy), but doing this in large industrialized nations is more difficult.in large industrialized nations is more difficult. Must convert economy to Must convert economy to energy farmingenergy farming (e.g. (e.g.

solar, wind) from solar, wind) from energy hunter-gatherersenergy hunter-gatherers seeking new fossil fuels.seeking new fossil fuels.

No infrastructureNo infrastructure for hydrogen-fueling stations for hydrogen-fueling stations (12,000 needed nationwide at $1 million apiece).(12,000 needed nationwide at $1 million apiece).

High costHigh cost of fuel cells. of fuel cells.

Trade-Offs

Hydrogen


Not found in nature

Energy is needed to produce fuel

Negative net energy (so far)Renewable if from renewable resources CO2 emissions if produced from

carbon-containing compoundsNo CO2 emissions if produced from water Nonrenewable if generated by fossil

fuels or nuclear powerGood substitute for oil

Competitive price if environmental & social costs are included in cost comparisons

High costs (but may eventually come down)

Will take 25 to 50 years to phase in

Easier to store than electricity Short driving range for current fuel-cell cars

Safer than gasoline and natural gasNo fuel distribution system in place

Nontoxic

High efficiency (45–65%) in fuel cells

Excessive H2 leaks may deplete ozone in the atmosphere

Can be produced from plentiful water

Low environmental impact

A SUSTAINABLE ENERGY A SUSTAINABLE ENERGY STRATEGYSTRATEGY

Shifts in the use of commercial energy Shifts in the use of commercial energy resources in the U.S. since 1800, with resources in the U.S. since 1800, with projected changes to 2100.projected changes to 2100.

NextNext

Fig. 17-34, p. 413

Wood

Coal

Natural gas

Oil

Hydrogen Solar

NuclearCo

ntr

ibu

tio

n t

o t

ota

l en

erg

y co

nsu

mp

tio

n (

per

cen

t)

Year


A more A more sustainable energy policysustainable energy policy would: would:

improve improve energy efficiencyenergy efficiency

rely more on rely more on renewable energyrenewable energy

reduce the harmful effectsreduce the harmful effects of using fossil fuels of using fossil fuels and nuclear energy (our current strategy)and nuclear energy (our current strategy)


There will be a There will be a gradual shiftgradual shift

from:from: large, centralized large, centralized macropowermacropower systems systems

• coal & nuclear power plantscoal & nuclear power plants• huge refinerieshuge refineries

to:to: smaller, decentralized smaller, decentralized micropowermicropower systems systems

• See next slideSee next slide

Fig. 17-35, p. 414

Small solar-cell power plantsBioenergy power

plantsWind farm

Rooftop solar cell arrays

Fuel cells

Solar-cell rooftop

systems

Transmission and distribution system

Commercial

Small wind

turbineResidential

Industrial Microturbines

Fuel cells

Fig. 17-36, p. 415

More Renewable Energy

Increase renewable energy to 20% by 2020 and 50% by 2050

Provide large subsidies and tax credits for renewable energy

Use full-cost accounting and life-cycle cost for comparing all energy alternatives

Encourage government purchase of renewable energy devices

Greatly increase renewable energy R&D

Reduce Pollution and Health Risk

Cut coal use 50% by 2020

Phase out coal subsidies

Levy taxes on coal and oil use

Phase out nuclear power or put it on hold until 2020

Phase out nuclear power subsidies

Improve Energy Efficiency

Increase fuel-efficiency standards for vehicles, buildings, and appliances

Mandate govern-ment purchases of efficient vehicles and other devices

Provide large tax credits for buying efficient cars, houses, and appliances

Offer large tax credits for invest-ments in energy efficiency

Reward utilities for reducing demand for electricity Encourage indepen-dent power producers Greatly increase energyefficiency research and development

Economics, Politics, Education, and Economics, Politics, Education, and Energy ResourcesEnergy Resources

Governments can use a combination of Governments can use a combination of subsidiessubsidies, , tax breakstax breaks, , rebatesrebates, , taxestaxes and and public educationpublic education to promote or discourage to promote or discourage use of various energy alternatives:use of various energy alternatives: Can keep Can keep prices artificially lowprices artificially low to encourage to encourage

renewable energy resources.renewable energy resources.

Can keep Can keep prices artificially highprices artificially high to discourage to discourage nonrenewable energy resources.nonrenewable energy resources.

Emphasize consumer Emphasize consumer education.education.

Fig. 17-37, p. 416

What Can You Do?

Energy Use and Waste

• Get an energy audit at your house or office.

• Drive a car that gets at least 15 kilometers per liter (35 miles per gallon) and join a carpool.

• Use mass transit, walking, and bicycling.

• Superinsulate your house and plug all air leaks.

• Turn off lights, TV sets, computers, and other electronic equipment when they are not in use.

• Wash laundry in warm or cold water.

• Use passive solar heating.

• For cooling, open windows and use ceiling fans or whole-house attic or window fans and geothermal heat pumps

• Turn thermostats down in winter, up in summer.

• Buy the most energy-efficient homes, lights, cars, and appliances available.

• Turn down the thermostat on water heaters to 43–49°C (110–120°F) and insulate hot water heaters and pipes.

Documents

Chapter 16 EnergyEfficiencyandRenewableEnergy. Chapter Overview Questions How can we improve energy efficiency and what are the advantages of doing