APES First Unit Test Review

Intro concepts and Energy

Test Make Up

• Commons 3• Nuclear 10• Fossil fuel 3• Biofuel 2• Solar 3• Geothermal 2• Hydro 1

• Science 2

• Wind 1

• Hydrogen 1

• General 3

What is the “Tragedy of the Commons”?

• ARTICLE: published in 1968 by Garrett Hardin.

• CONCEPT: a shared resource in which any given user reaps the full benefit of his/her personal use, while the losses are distributed amongst all users. Result? Tragedy all around.

What is the “Tragedy of the Commons”?

Belongs to a Class of Problems that have no Technical Solutions

The Nuclear Arms Race

Human Population Growth

What is the “Tragedy of the Commons”?

• CLASSIC EXAMPLE: cows on shared pasture.

• What are other examples of commons?

•Air

•Water

•Scenery

Could we think of EARTH as a commons?????

Would education help?One solution might be education. If everyone knew the best long-term strategy, would they act accordingly and “take 1 fish”?

Probably not.

More Conscious Farmers Get Less:

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1: Grass on Commons 4 2: F1 Cows Added 3: F2 Cows Added 2 4: F3 Cows Added 3 5: F4 Cows Added 4

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Graph 2: p1 (Untitled)

Farmer 3: 4.5 Cows

Farmer 2: 8 Cows

Farmer 4: 2 Cows

Farmer 1: 12 CowsIt’s just not fair!!!

Hardin’s Suggestion: Mutual Coercion, Mutually Agreed Upon

• A regulation accepted by the majority of those affected and imposed upon all involved.

• Examples?– Speed limits– Income tax– Aesthetic standards in

a gated community

Thomas Malthus:Unlimited Growth

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Unlimited Population Growth Based on the Exponential Equation

Hardin’s Suggestion: Mutual Coercion, Mutually Agreed Upon

• Hardin admits there are drawbacks to strict legislation, but believes:– There is no perfect solution.– Status quo is worse than a regulated situation– He writes: “Who enjoys taxes? We all grumble

about them. But we accept compulsory taxes because we recognize that voluntary taxes would favor the conscienceless.” (Hardin, 338)

USA Energy Flow, 1999

Nuclear Energy

AN INTRODUCTION TO

FISSION &(a bit on)

FUSION

AN INTRODUCTION TO

FISSION &(a bit on)

FUSION

• Nuclear reactions deal with Nuclear reactions deal with interactions between the nuclei of interactions between the nuclei of atomsatoms

• Both fission and fusion processes Both fission and fusion processes deal with matter and energydeal with matter and energy

Introduction

Matter and Energy

• We know that “matter and energy We know that “matter and energy cannot be created nor destroyed”cannot be created nor destroyed”

• We need to understand that Matter We need to understand that Matter and Energy are two forms of the and Energy are two forms of the same thingsame thing

MassMass

• Matter can be changed into EnergyMatter can be changed into Energy• Einstein’s formula above tells us how the Einstein’s formula above tells us how the

change occurschange occurs• In the equation above:In the equation above:

E = EnergyE = Energym = Massm = Massc = Speed of Light (Universal Constant)c = Speed of Light (Universal Constant)

EnergyEnergy LightSpeedLightSpeed

E = mc2

E = mc2

• The equation may be read as follows:The equation may be read as follows:

Energy (E) is equal to Mass (m) Energy (E) is equal to Mass (m) multiplied multiplied by the Speed of Light (c) by the Speed of Light (c) squaredsquared

• This tells us that a This tells us that a small amount of small amount of mass can be converted into a very largemass can be converted into a very large amount of energyamount of energy because the speed of because the speed of light (c) is an extremely large numberlight (c) is an extremely large number

FissionUsed in Nuclear Power

Plants

• Fission may be defined as the process of Fission may be defined as the process of splitting an atomic nucleussplitting an atomic nucleus into fission into fission fragmentsfragments

• The fission fragments are generally in the form The fission fragments are generally in the form of smaller atomic nuclei and neutronsof smaller atomic nuclei and neutrons

• Large amounts of energy are produced by the Large amounts of energy are produced by the fission processfission process

Fission

• Fissile nuclei are generally Fissile nuclei are generally heavy heavy atoms with large numbers of atoms with large numbers of nucleonsnucleons

• The nuclei of such heavy atoms The nuclei of such heavy atoms are struck by are struck by neutronsneutrons initiating the initiating the fission processfission process

• A classic example of a fission A classic example of a fission reaction is that of U-235:reaction is that of U-235:

U-235 + 1 Neutron U-235 + 1 Neutron

2 Neutrons + Kr-92 + Ba-142 + 2 Neutrons + Kr-92 + Ba-142 + EnergyEnergy

• In this example, a stray neutron strikes In this example, a stray neutron strikes an atom of U-235. It absorbs the neutron an atom of U-235. It absorbs the neutron and becomes an unstable atom of U-and becomes an unstable atom of U-236. It then undergoes fission. Notice 236. It then undergoes fission. Notice that more neutrons are released in the that more neutrons are released in the reaction. These neutrons can strike reaction. These neutrons can strike other U-235 atoms to initiate their fission.other U-235 atoms to initiate their fission.

Fission

What is a Breeder Reactor?

A breeder reactor IS a fission reactor. It is a much more efficient version of a fission reactor because it "breeds"new fuel while consuming the old fuel. This is possible because the fission reactions release lots of neutrons that can be used to transform certain non-useful isotopes of uranium(238) into useful isotopes (235. Plutonium is generally a product of breeder reactors. However, plutonium 239 (1/2 life of 24,000 years)is also rather hazardous and dangerous for reasons associated with proliferation of nuclear weapons, so breeder reactors have not been very popular in the U.S. They are widely used in other countries though

Pressurized Water Reactor

From: Joseph Gonyeau, P.E., Virtual Nuclear Touristhttp://www.nucleartourist.com/

• Fusion is a nuclear reaction Fusion is a nuclear reaction whereby whereby two light atomic nuclei two light atomic nuclei fuse or combinefuse or combine to form a single to form a single larger, heavier nucleuslarger, heavier nucleus

• The fusion process generates The fusion process generates tremendous amounts of energy; tremendous amounts of energy; refer back to Einstein’s equationrefer back to Einstein’s equation

• Fusion reactions do not occur Fusion reactions do not occur naturally on our planet but are the naturally on our planet but are the principal type of reaction found in principal type of reaction found in starsstars

Fusion

So Nuclear Energy is:

• Clean energy during production

• Seems to be unlimited

• Technology is mostly in place

• Then why is it not used more???

Three Mile Island

• Middletown, PA   1979• nuclear portion of plant had a pump

malfunction.• This caused pressure to build • valve was opened to release pressure and was

stuck open, allowing coolant to leak out.• Reactor core overheated, started meltdown,

but did not breach containment building.• HUGE SCARE..’cause this could have been…

ChernobylThe Chernobyl disaster was a nuclear reactor

accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine (then part of the Soviet Union). It is considered to be the worst nuclear power plant disaster in history and the only level 7 event on the International Nuclear Event Scale. It resulted in a severe release of radioactivity following a massive power excursion that destroyed the reactor. Most deaths from the accident were caused by radiation poisoning.

Chernobyl Pictures

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Fears of Nuclear Power Plants

• Possible meltdowns caused by human error such as Chernobyl

• Storage of Waste leaking dangerous radiation

• Use of “waste” product for nuclear bombs

USA Reaction to these Fears

• Strong laws governing building and regulating nuclear power plants have increased cost beyond profitability

• No new reactors have been ordered since 1978 and

all ordered after 1973 were cancelled.

fossil-fuel power plant

• is a power plant that burns fossil fuels such as coal natural gas or petroleum(oil) to produce electricity

• Net energy is the amount of energy gained from using the fuel minus what it takes to get it.

Coal = 22% Oil = 33% Natural gas = 21%

Crude Oil• Location (world): Middle East (OPEC 78%)• Location (US): Gulf of Mexico, Gulf Coast(3% of

world reserves)• Availability projections (US reserves): 10-48

years.• Availability projections (world): 42-93years• Advantages: Abundant, convenient, cheap• Disadvantages: Dependant on foreign oil,running

out, emissions, pollution, at current rate, we will run out in 53 years!

Crude Oil

• Conventional oil/light oil: what we use; pumped from ground

• Heavy crude oil: Oil that is difficult to pump out; currently not recovered

• Oil sand (tar sand): mixture of clay, sand, water and bitumen. Could be used, but has high sulfur content

• Shale oil: can be extracted from oil shale rock. Low quality oil

Natural Gas

• Location (world): Russia (31%), Middle East(36%)• Location (US): (3%) Gulf coast, above crude oil• Availability projections (US reserves): 55-80years• Availability projections (world): 62-125 (and upto 200 years

with unconventional)• Advantages: Can be transported easily, lower pollution than

other fossil fuels, high energy yield• Disadvantages: running out, greenhouse gas released, 

explosive (especially in liquid form)

Natural Gas• LPG: liquefied petroleum gas (LP). For

rural areas where natural gas lines aren’t run. Propane and Butane mixed

• LNG: liquefied natural gas.  For shipping across oceans

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COALLocation (world): China, Russia

Location (US): (25% of world supply) Eastern areas of US: Montana, Utah, Arizona and southern areas of midwest

Availability projections (US reserves): 300 years at current rates (64 years with 4% increase)

Availability projections (world):400+ years if new reserves are found and current rate of usage

Advantages: most abundant fossil fuel, high energy, US has large supply

Disadvantages: health concerns, high pollution when burned (CO2, high in sulfur, releases mercury

COAL

• Coal can be converted into synthetic natural gas (SNG), but the process releases more CO2 than burning coal does.

• Low quality coal is often burnt with high emissions: mercury, sulfur, CO2

• Different types of coal: Lignite, Bituminous,Anthracite, Peat

Coal Types

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Heat Heat Heat

Peat(not a coal)

Lignite(brown coal)

Bituminous(soft coal)

Anthracite(hard coal)

Pressure Pressure Pressure

Partially decayed plant matter in swamps and bogs; low heat content

Low heat content; low sulfur content; limited supplies in most areas

Extensively used as a fuel because of its high heat content and large supplies;normally has a high sulfur content

Highly desirable fuel because of its high heat content and low sulfur content;supplies are limited in most areas

U.S. Energy Consumption by Source, 1998

Renewable Energy Sources

• Wind

• Solar photovoltaics

• Solar thermal power

• Passive solar air and water heating

• Hydropower

• Biomass

• Ocean energy

• Geothermal

• Waste to Energy

How Wind Turbines WorkOverview – Like a windmill, the wind turns the blades of the wind turbines. This generates electricity which is then stored for later use. More in detail – At the top of a wind turbine is a rotor. This rotor is made up of 2 or 3 blades. These blades turn when the wind blows. The entire top swivels to face the changing direction of the wind. Wind is stronger at higher altitudes, so the wind turbines are built at least 30 meters above the ground. As the rotor spins, it powers a generator, which makes electricity that can be stored.

Diagram

Controller – The controller turns the turbine on and off depending on the wind speed. For example, it turns on when the wind is blowing 8 mph or faster. It turns it off when the wind is blowing 65 mph or faster, because the machine would overheat.

Nacelle – Holder of important parts of the turbine including the generator.

Rotor – This is the hub (tip) and the blades.

Wind Vane – This detects the direction of the wind and communicates this information to the yaw drive.

Yaw Drive – This ensures that the rotor is always facing the wind.

Additional:

Produced domestically

Doesn’t augment greenhouse effect

Doesn’t cause acid rain

Renewable energy source

One of the cheapest renewable energy sources – 4 to 6 cents per kilowatt-hour

They benefit rural farms in the Midwest (where the wind is greatest) by helping the rural economy

Additional:

Higher initial cost (compared to fossil fuel)

Located in areas at a distance from cities where electricity is in highest demand

Photovoltaics

Using the sun to generate electricity

Photovoltaic (PV) systems convert sunlight directly into electricity, and are potentially one of the most useful of the renewable energy technologies.

The heart of a photovoltaic system is a solid-state device called a solar cell.

Groups of solar cells can be packaged into modules, panels and arrays to provide useful

output voltages and currents to provide a specific power output.

PV applications

include lighting for remote signs like this outdoor board along a U.S. highway.

Many utility companies in the U.S. are turning to large PV systems to help meet peak power demand and

reduce the need for building new power plants.

Maybe no uses are as dramatic and important as the portable PV panels and small refrigerators carried around Africa on the backs of camels.

Solar Thermal Power Uses the same technology but uses the sun’s energy to hear water to generate electricity that would flow to the grid

Geothermal Energy can be spectacular!

Geysirs and volcanoes show the earth heat

Photos of US Geological Survey

Geothermal Energy

Graph from Geothermal Education Office, California

Definition:

Geothermal Energy is energy stored in the form of heat beneath the surface of thesolid earth

High-Enthalpy Geothermal Energy world-wide

Graph from Geothermal Education Office, California

Water generated - HydroelectricShasta Dam In California

-Conversion from potential energy of water to electric energy is at 80 – 90% efficiency

-Hydroelectric projects in the United States have rated capacities from950 – 6480 MW

-The use of Water Power is much greater in some other countries. Norway obtains 99% of its electricity from water power. Nepal, Brazil, and New Zealand are close seconds.

-About 50% of the United States potential for hydroelectric energy has been tapped. However, further advances are unlikely.

-The Wild and Scenic River Act and the Endangered Species Act have inhibited development of some sites

-Silt collection in hydroelectric Dam storage volumes over time causes maintenance issues, as well as environmental concerns

-The loss of free flowing streams and land due to flooding behind the dam disturbs the life of species: eg – Salmon

- Possibility of dam failure

-Solar Power – uses the sun energy to either boil water or directly converts solar energy to electrical energy

-Ocean Thermal Energy Conversion – uses temperature differences between different depths of ocean water to drive a heat engine. Working fluid is ammonia which is gas at room temperature.

-Biomass Energy: Municipal Solid Waste – burning wastes to drive heat engines

-Geothermal Energy – based on naturally occurring heat in the Earth in the Earth due to radioactive decay

-Tidal Energy – uses the gravitational pull of the moon on our oceans to drive turbines