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Chapter 13

Achieving Energy Sustainability

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What is renewable energy?

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What is Renewable Energy?

Renewable energy sources can berapidly regenerated, and some can

never be depleted, no matter how

much we use them.

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What is Renewable Energy?

Nonrenewable sources: exist in finite

amounts (fossil fuels, uranium)

Potentially renewable sources: must notbe consumed more quickly than they

are replenished (biomass)

Nondepletable sources: cannot bedepleted in the span of human time

(solar, wind)

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What is Renewable Energy?

Using any form of energy (renewable or

nonrenewable) will have an impact onthe environment.

Overharvestingof woode.g., to obtain

biomasscan lead to deforestationand land degradation.

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How can we use less energy?

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How Can We Use Less Energy?

Energy conservation: finding ways to

use less energy.For instance, lower your thermostat

during the winter, or walk instead of

driving, and do laundry using coldwater.

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How Can We Use Less Energy?

Energy efficiency: getting the same

result from using a smaller amount of

energy.

Examples include using energy-efficient

(EPA Energy Star) appliances, and

switching to compact fluorescent or

LED lighting.

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Benefits of Conservation and

Efficiency

Energy companies periodically needbackup energy sources available to

meet thepeak demand, the greatest

quantity of energy used at any one

time.

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Benefits of Conservation and

Efficiency

Often thesepeak demandsources are

natural gas-fired generators.

Reducing peak demand reduces theneed to build extra generating

capacity.

Some utilities give away free compactfluorescent light bulbs or help pay for

house insulation in order to reduce

peak demand.

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Benefits of Conservation and

Efficiency

Variable price structure: utility customerscan pay less to use energy at times

when demand is lowest and pay more

during peak demand.

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Sustainable Design

Sustainable design improves theefficiency of the buildings in which we

live and work.

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Passive Solar Energy

Passive solar energycan lower your

electricity bill without the need for

pumps or other mechanical devices.

For example, building a house with

windows along a south-facing wall,

allowing the Suns rays to warm the

house.

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Sustainable Design

The California Academy of Sciences

building embodies many sustainable-

design elements:

Natural lighting and ventilation

Rooftop solar panels

Rooftop garden to collect rainwater

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Biomass is energy from thesun.

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Biomass Is Energy from the Sun

The Sun is the ultimate source of almost

all types of energy, including

Biomass

Hydroelectric

Wind

Solar

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Modern Carbon vs. Fossil Carbon

Why is it better to burn biomass suchas wood than a fossil fuel such as

coal?

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Modern Carbon vs. Fossil Carbon

The carbon found in biomass:

Existed in the atmosphere as carbon dioxide

Was taken in by the tree through photosynthesis

By burning it, was put back into the atmosphere

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Modern Carbon vs. Fossil Carbon

Coal contains carbon:

That has been buried for millions of years and was out ofcirculation until we began to use it

Now it is being returned to the atmosphere at a rapid rate

This results in a rapid increase in the concentration of carbondioxide in the atmosphere

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Biomass

Wood, charcoal, and manure: used to heat

homes throughout the world

Ethanoland biodiesel(biofuels): used as

substitutes for gasoline and diesel fuel

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Charcoal

Land denuded for

charcoal

production

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The kinetic energy of watercan generate electricity.

The Kinetic Energy of Water Can

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The Kinetic Energy of Water Can

Generate Electricity

Hydroelectricity: electricity generated by

the kinetic energy of moving water

The second most common form of

renewable energy in the world

Creates 7% of electricity used in theUnited States

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T pes of H droelectric Po er

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Types of Hydroelectric Power

Systems

Run-of-the-river systems: water is held behind a

low dam and runs through a channel to return

to the riverThese do not store water

Are generally small

Can be affected by droughts

Types of Hydroelectric Power

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Types of Hydroelectric Power

Systems

Water impoundment: water is storedbehind adam and the gates of the dam are opened and

closed controlling the flow of water.

Types of Hydroelectric Power

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Types of Hydroelectric Power

Systems

Tidal systems: the movement of water is driven

by the gravitational pull of the Moon.

Gates and turbines are used to generate

electricity.

Limited application depending on difference

between heights of low and high tides.

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The suns energy can becaptured directly.

The Suns Energy Can Be

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The Sun s Energy Can Be

Captured Directly

Passive solar energy: can be used in homes,

buildings, and ovens

Active solar energy: capturing the energy of

sunlight with the use of a pump or

photovoltaic celland generating hot water orelectricity

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The Suns Energy Can Be

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The Sun s Energy Can Be

Captured Directly

Solar energyhas certain drawbacks:

Photovoltaic cells are expensive

Requires longer sunlight days to decrease

payback period

Solar cell manufacture requires energy and

creates toxic wastes

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Earths internal heat is a

source of nondepletableenergy.

Earths Internal Heat Produces

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Earth s Internal Heat Produces

Geothermal Energy

Geothermal energy: using the heat from natural

radioactive decay of elements deep within the Earth.

Does not use sunlight as a source of energy.

Iceland now heats 87% of their homes geothermally, and

also creates 20% of their electricity in this way.

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Wind energy is the most

rapidly growing source ofelectricity.

Wind Energy Is the Most Rapidly

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Wind Energy Is the Most Rapidly

Growing Source of Electricity

Wind energy: uses a wind turbine to convert

kinetic energy into electrical energy

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Wind Energy Is the Most Rapidly

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Wind Energy Is the Most Rapidly

Growing Source of Electricity

Wind energyis the fastest-growing majorsource of electricity in the world, but not

without problems:

Most off-grid wind systems must rely onbattery-storage.

Wind Energy Is the Most Rapidly

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Wind Energy Is the Most Rapidly

Growing Source of Electricity

Wind turbines are highly visible.

Placement is suited only to certain areas,

and it does not supply a constantsource of power.

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Hydrogen fuel cells havemany potential applications.

Hydrogen Fuel Cells Have Many

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y g y

Potential Applications

Fuel cell: a device that operates like a common

battery where electricity is generated by a

reaction between two chemicals.Potential problems include the expense

involved in making hydrogen and its

explosive nature.

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How can we plan our energyfuture?

Our Energy Future

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gy

A varied strategy will be required to meet future

energy challenges, including:

Conservation

Increased energy efficiency

Greater use of renewable sources

New technology to improve energy storage anddistribution

Review Questions

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List some common forms ofnondepletable,potentially renewable, and nonrenewable energy

sources.

Why is energy conservation important?

What is meant by energy efficiency as opposed to

energy conservation?

Which government agency established the EnergyStarprogram?

Review Questions

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What ispeak demand?

How can peak demand be managed and reduced?

What are some characteristics ofsustainably

designedhomes?

What ispassive solar design?

What produces the energy found in biomass?

Review Questions

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Distinguish between modern carbon and fossilcarbon sources of energy.

What are three examples ofsolid biomass?

What is biodiesel?

What is the ultimate energy source for

hydroelectric energy?

How does a run-of-the-river system differ from a

water impoundmentsystem?

Review Questions

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15. What are some advantages and disadvantagesof hydroelectric power?

16. How can solar energybe captured directly?

17. What are some drawbacks to active solar

systems?

18. How can the Earths internal heat be used for

energy?

Review Questions

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19. Where does the Earths heat come from?

20. What is the most rapidly growing source ofelectricity?

21. What is a fuel cell?