Chapter 2.5Chapter 2.5

Population, Energy, and Population, Energy, and Climate ChangeClimate Change

What are the Major Air Pollution Problems?What are the Major Air Pollution Problems?

TroposphereTroposphere The atmospheric The atmospheric

layer closet to layer closet to earthearth’’s surfaces surface

A dynamic system A dynamic system involved in the involved in the chemical cycling of chemical cycling of the earth vital the earth vital nutrientsnutrients

StratosphereStratosphere 17 to 48 kilometers 17 to 48 kilometers

above the earthabove the earth’’s s surfacesurface

Ozone layerOzone layer

Air pollutionAir pollution Primary pollutantsPrimary pollutants Secondary pollutantsSecondary pollutants Carbon OxidesCarbon Oxides

Carbon monoxide (CO)Carbon monoxide (CO) A colorless, odorless, A colorless, odorless,

highly toxic gas highly toxic gas Carbon dioxide (CO2)Carbon dioxide (CO2)

Colorless, odorless gasColorless, odorless gas 93% found in the 93% found in the

atmosphere is caused by atmosphere is caused by the natural carbon cyclethe natural carbon cycle

What are the Major Air Pollution Problems?What are the Major Air Pollution Problems?

ParticlesParticles A variety of solid A variety of solid

particles and liquid particles and liquid droplets that droplets that remain suspended remain suspended in the air for long in the air for long periods.periods.

OzoneOzone O3 is the major O3 is the major

component of smogcomponent of smog

Volatile Organic Volatile Organic Compounds (VOCs)Compounds (VOCs) Organic compounds Organic compounds

that exist as gases in that exist as gases in the atmospherethe atmosphere

Radioactive Radon Radioactive Radon (Rn)(Rn) A naturally occurring A naturally occurring

colorless & odorless colorless & odorless radioactive gas found radioactive gas found in rocks and soilin rocks and soil

What are the Major Air Pollution Problems?What are the Major Air Pollution Problems?

Temperature Temperature InversionInversion The layer of warm The layer of warm

air that lie atop of air that lie atop of cooler air near the cooler air near the groundground

Due to cooler air Due to cooler air being denser than being denser than warmer air above, warmer air above, the result is the air the result is the air near the surface near the surface

How Might the EarthHow Might the Earth’’s Temperature and s Temperature and Climate Change in the Future?Climate Change in the Future?

Enhanced Enhanced Greenhouse EffectGreenhouse Effect Global WarmingGlobal Warming

Scientists warn that Scientists warn that the concern is not the concern is not just above how just above how much the much the temperature temperature changes but also changes but also how rapidly it how rapidly it occurs. occurs.

How can technology help?How can technology help?

Economies are powered by fossil Economies are powered by fossil fuelsfuels

80% of our energy 80% of our energy comes from oil, coal, comes from oil, coal, and natural gasand natural gas

Nations vary in the renewables Nations vary in the renewables they usethey use

In the U.S., most In the U.S., most renewable energy renewable energy comes from hydropower comes from hydropower and biomass.and biomass.

The new renewables are growing fast

• They are growing at much faster rates than conventional sources.

• Wind power is the fastest growing.

• However, since these sources began at low levels, it will take time to build them up.

• Due to: population and consumption growth, Due to: population and consumption growth, increased energy demand, declining fossil fuel increased energy demand, declining fossil fuel supplies, and the demand for a cleaner environmentsupplies, and the demand for a cleaner environment

• Technological and economic barriers prevent a quick Technological and economic barriers prevent a quick switch to renewables.switch to renewables.• Renewables receive little government help.Renewables receive little government help.

Rapid growth in renewables will Rapid growth in renewables will continuecontinue

The 2007 energy bill passed only after Congress dropped requirements to shift subsidies from non-renewables to renewables and for utilities to increase using renewables.

Biofuels can power Biofuels can power automobilesautomobiles

EthanolEthanol: produced as a : produced as a biofuel by fermenting biofuel by fermenting carbohydrate-rich cropscarbohydrate-rich crops Ethanol is widely added to Ethanol is widely added to

U.S. gasoline to reduce U.S. gasoline to reduce emissions.emissions.

Any vehicle will run well Any vehicle will run well on a 10% ethanol mix.on a 10% ethanol mix.

In 2007, the U.S. produced 30 billion L (6.5 million gal) of ethanol in 100 ethanol plants.

Cars can run on ethanolCars can run on ethanol Flexible fuel vehiclesFlexible fuel vehicles: :

run on 85% ethanolrun on 85% ethanol But very few gas stations But very few gas stations

offer this fueloffer this fuel BiodieselBiodiesel: a fuel : a fuel

produced from vegetable produced from vegetable oil, used cooking grease oil, used cooking grease or animal fator animal fat

Some people use straight Some people use straight vegetable oil in their vegetable oil in their diesel engines.diesel engines.

Hydroelectric powerHydroelectric power

Hydroelectric (hydro) powerHydroelectric (hydro) power: uses : uses the kinetic energy of moving water to the kinetic energy of moving water to turn turbines and generate electricityturn turbines and generate electricity

TheThe storage technique storage technique: : impoundments harness energy by impoundments harness energy by storing water in reservoirs behind storing water in reservoirs behind damsdams Water passing through the dam Water passing through the dam

turns turbines.turns turbines. The The run-of-riverrun-of-river approach approach

generates energy without greatly generates energy without greatly disrupting the flow of river water.disrupting the flow of river water.

A typical damA typical dam

Hydropower is clean and Hydropower is clean and renewablerenewable

Hydropower has two clear advantages Hydropower has two clear advantages over fossil fuels for producing electricity:over fossil fuels for producing electricity: It is renewable: as long as precipitation fills It is renewable: as long as precipitation fills

rivers, we can use water to turn turbines.rivers, we can use water to turn turbines. It is clean: no carbon dioxide is emitted.It is clean: no carbon dioxide is emitted.

Hydropower is efficient.Hydropower is efficient. It has an EROI of 10:1, as high as any modern-It has an EROI of 10:1, as high as any modern-

day energy source.day energy source.

Hydropower has negative Hydropower has negative impactsimpacts

Damming rivers destroys riverine Damming rivers destroys riverine habitats.habitats.

Natural flooding cycles are disrupted.Natural flooding cycles are disrupted. Sediment depositionSediment deposition Thermal pollution of downstream Thermal pollution of downstream

waterwater Reducing fish populations and Reducing fish populations and

aquatic biodiversityaquatic biodiversity

Hydroelectric power is widely Hydroelectric power is widely usedused

Nations with large rivers and economic Nations with large rivers and economic resources have used dams.resources have used dams.

But hydropower is not likely to expand.But hydropower is not likely to expand. Most of the worldMost of the world’’s large rivers have already s large rivers have already

been dammed.been dammed. People have grown aware of the ecological People have grown aware of the ecological

impact of dams.impact of dams.

Solar energy

• The sun provides energy for almost all biological activity on Earth.

• There is great potential in solar energy, but we are still developing technologies to efficiently use it.

• Passive solar energy: the most common way to harness solar energy

• Buildings are designed to maximize direct absorption of sunlight in winter and keep cool in summer.

• Active solar energy collection: uses technology to focus, move, or store solar energy

Passive solar heating is Passive solar heating is simple and effective simple and effective

Low south-facing windows maximize heat Low south-facing windows maximize heat in the winter.in the winter. Overhangs shade windows in the summer.Overhangs shade windows in the summer.

Thermal massThermal mass: construction materials : construction materials that absorb, store, and release heatthat absorb, store, and release heat

By heating buildings in winter and cooling By heating buildings in winter and cooling them in summer, passive solar methods them in summer, passive solar methods conserve energy and reduce costs.conserve energy and reduce costs.

Active solar energy collection Active solar energy collection Flat plate solar collectors (solar Flat plate solar collectors (solar

panels)panels): one active method for : one active method for harnessing solar energyharnessing solar energy Installed on rooftops Installed on rooftops Dark-colored, heat-absorbing metal Dark-colored, heat-absorbing metal

plates plates Water, air, or antifreeze pass through the Water, air, or antifreeze pass through the

collectors, transferring heat throughout collectors, transferring heat throughout the building.the building.

Heated water is stored and used later.Heated water is stored and used later. Effective for heating water for homesEffective for heating water for homes

Focusing solar rays magnifies Focusing solar rays magnifies energyenergy

Focusing solar energy on a single point intensifies its Focusing solar energy on a single point intensifies its strength.strength.

Solar cookersSolar cookers: simple, portable ovens that use reflectors : simple, portable ovens that use reflectors to focus sunlight onto food to focus sunlight onto food

Power towerPower tower: mirrors concentrate sunlight onto receivers : mirrors concentrate sunlight onto receivers to create electricityto create electricity

In southern California, a power tower produces power for 10,000 households.

Solar power is little used but Solar power is little used but fast growingfast growing

Solar energy was pushed to the sidelines by fossil fuels.Solar energy was pushed to the sidelines by fossil fuels. Because of a lack of investment, solar energy Because of a lack of investment, solar energy

contributes only a miniscule amount of energy.contributes only a miniscule amount of energy. But solar energy use has grown 25%/year since But solar energy use has grown 25%/year since

1971.1971. Solar energy is attractive in developing nations.Solar energy is attractive in developing nations.

Where hundreds of millions donWhere hundreds of millions don ’’t have electricityt have electricity The U.S. may recover its leadership, given a 2005 The U.S. may recover its leadership, given a 2005

federal tax credit and some state initiatives.federal tax credit and some state initiatives. Solar energy use should increase as prices fall, Solar energy use should increase as prices fall,

technologies improve, and governments enact technologies improve, and governments enact economic incentives.economic incentives.

Solar power offers many Solar power offers many benefits benefits

The sun will burn for 4The sun will burn for 4––5 billion more years.5 billion more years. Solar technologies use no fuels, are quiet, safe, contain Solar technologies use no fuels, are quiet, safe, contain

no moving parts, and require little maintenance.no moving parts, and require little maintenance. They allow local, decentralized control over power.They allow local, decentralized control over power. Developing nations can use solar cookers and Developing nations can use solar cookers and

photovoltaics.photovoltaics. Net meteringNet metering: PV owners can sell excess electricity to : PV owners can sell excess electricity to

their local power utilitytheir local power utility New jobs are being created.New jobs are being created. Solar power does not emit greenhouse gases and air Solar power does not emit greenhouse gases and air

pollution.pollution. Manufacturing units currently require fossil fuels.Manufacturing units currently require fossil fuels.

Location is a drawbackLocation is a drawback Not all regions are sunny Not all regions are sunny

enough to provide enough enough to provide enough power, with current power, with current technology.technology. Daily and seasonal variation Daily and seasonal variation

also poses problems.also poses problems.

• Up-front costs are high and solar power remains the most expensive way to produce electricity.- Future technologies will be much more

efficient and have lower costs.

Modern wind turbines convert Modern wind turbines convert kinetic energykinetic energy Wind turbinesWind turbines: devices that turn wind energy into : devices that turn wind energy into

electricityelectricity Wind blowing into a turbine turns the blades of the Wind blowing into a turbine turns the blades of the

rotor, which rotate machinery inside a compartment rotor, which rotate machinery inside a compartment ((nacellenacelle) on top of a tall tower.) on top of a tall tower.

Towers are 40Towers are 40––100 m (131100 m (131––328 ft) tall.328 ft) tall. Higher is better to minimize turbulence and maximize Higher is better to minimize turbulence and maximize

wind speed.wind speed.

Wind is the fastest-growing Wind is the fastest-growing energy sectorenergy sector Wind farmsWind farms: turbines : turbines

erected in groups of up to erected in groups of up to hundreds of turbineshundreds of turbines

Wind power grew 26% Wind power grew 26% per year globally between per year globally between 2000 and 2005.2000 and 2005. Five nations account Five nations account

for 80% of the worldfor 80% of the world’’s s wind power.wind power.

California and Texas California and Texas produce the most wind produce the most wind power in the U.S.power in the U.S. Wind power could be Wind power could be

expanded to meet 30% expanded to meet 30% of the U.S. electrical of the U.S. electrical needs by 2030.needs by 2030.

Wind power has many benefitsWind power has many benefits Wind produces no emissions once installed.Wind produces no emissions once installed. It prevents the release of COIt prevents the release of CO2,2,, SO, SO22, NO, NOxx, ,

mercury.mercury. It is more efficient than conventional power It is more efficient than conventional power

sources.sources. Turbines also use less water than conventional Turbines also use less water than conventional

power plants.power plants. It can be used on many scales, from one turbine It can be used on many scales, from one turbine

to hundreds.to hundreds. Farmers and ranchers can lease their land.Farmers and ranchers can lease their land.

Produces extra revenue Produces extra revenue Landowners can still use their land for other Landowners can still use their land for other

uses.uses.

Wind power has some Wind power has some downsidesdownsides

We have no control over when wind We have no control over when wind blows.blows.

This poses little problem if wind is one of This poses little problem if wind is one of several sources of electricity.several sources of electricity.

Good wind sources are not always Good wind sources are not always near population centers that need near population centers that need energy.energy.

Residents often oppose wind farms Residents often oppose wind farms near population centers.near population centers.

Wind turbines also kill birds and bats Wind turbines also kill birds and bats when they fly into rotating blades.when they fly into rotating blades.

U.S. wind-generating capacityU.S. wind-generating capacity

Mountainous regions have the most wind capacity.Mountainous regions have the most wind capacity.

ConclusionConclusion More people are becoming convinced that we need to shift More people are becoming convinced that we need to shift

to renewable energy sources.to renewable energy sources. Biomass and hydropower already play important roles.Biomass and hydropower already play important roles. Renewable sources include solar, wind, geothermal, Renewable sources include solar, wind, geothermal,

and ocean energies.and ocean energies. Hydrogen fuel may produce electricity.Hydrogen fuel may produce electricity.

Most renewable sources have been hampered by Most renewable sources have been hampered by inadequate funding for research and by artificially cheap inadequate funding for research and by artificially cheap fossil fuels.fossil fuels. But there is hope that we can shift to renewables with But there is hope that we can shift to renewables with

minimal disruption.minimal disruption.

What do you know?What do you know?

QUESTION: ReviewQUESTION: Review

We can harness power from wind by using We can harness power from wind by using devices called:devices called:

a)a) Wind turbinesWind turbines

b)b) Wind parksWind parks

c)c) Wind farmsWind farms

d)d) Solar cellsSolar cells

e)e) Nacelles     Nacelles     

QUESTION: Interpreting QUESTION: Interpreting Graphs and DataGraphs and Data

_____ is the best state for producing solar energy, while _____ is best for wind energy.

a)a) Maine, FloridaMaine, Floridab)b) Texas, KentuckyTexas, Kentuckyc)c) Arizona, IdahoArizona, Idahod)d) North Dakota, OhioNorth Dakota, Ohioe)e) Louisiana, OklahomaLouisiana, Oklahoma

Solar

Wind