Unit 6 Flashcards

1
Q

What is the major source of energy on earth?

A

the sun

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2
Q

What is mechanical energy?

A

energy of moving objects; potential and kinetic energy

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3
Q

What is radiant energy?

A

light energy; travels in waves and a straight path

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4
Q

What is chemical energy?

A

stored in the bonds of molecules; brought about in a chemical reaction

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5
Q

What is electrical energy?

A

the movement of electrons or electronic charges

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6
Q

What is nuclear energy?

A

energy locked in the nucleus of an atom

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7
Q

What is nuclear fission?

A

the process of splitting and atom

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8
Q

What is nuclear fusion?

A

joining two or more atoms, which creates a larger atom

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9
Q

What is thermal energy?

A

the energy of heat; hot has more energy than cool

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10
Q

What is sound energy?

A

energy from vibrations in matter; can travel through solids, liquids, and gasses

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11
Q

What is cogeneration?

A

process in which excess heat produced during the generation of electricity is captured and used to heat nearby workplaces and homes and to produce other kinds of power

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12
Q

How can we harness nuclear energy?

A
  1. During fission, the nucleus emits energy in the form of heat, light, radiation, and neutrons. The neutrons can in turn bombard other nearby atoms, resulting in a self-sustaining chain reaction. The chain reaction maintains energy at a controlled rate by moving control rods into and out of water to maintain the fission reaction at the desired rate.
  2. Control rods are moved into and out of the reactor core, absorbing excess neutrons to regulate the chain reaction. Water heated by fission circulates through the primary loop.
  3. In the secondary loop, the heated water turns to steam.
  4. Steam drives turbines, which generate electricity.
  5. The steam is later cooled in the cooling tower by water from an adjacent river or lake and returns to the containment building, to be heated again by heat from the primary loop.
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13
Q

What are the benefits of nuclear energy?

A

-Nuclear power delivers energy more cleanly than fossil fuels.
-Less air pollution from stack emissions.
-Poses far fewer chronic health risks from pollution.
-No CO2 is released from a nuclear power plant

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14
Q

What are the negatives of nuclear energy?

A

-Nuclear energy is non-renewable
-Produces radioactive waste; safe disposal of this waste has proven challenging.
-A large amount of thermal pollution (heat) is produced.
-Heated water is often released into nearby bodies of water causing decreased oxygen levels.
-Water vapor is released from the cooling towers
-If an accident occurs at a power plant, or if a plant is sabotaged, the consequences can potentially be catastrophic.

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15
Q

What atom is used in nuclear fission?

A

Uranium-235

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16
Q

What is half life?

A

the time it takes for half of a radioactive nucleus to decay; never really reaches 0; usually 10 half life’s indicate safety

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17
Q

What is used for biomass energy?

A

Wood
Peat
Charcoal
Crop Residue
Manure

18
Q

What are the benefits of biomass?

A

Easily accessible
Inexpensive
Used for heating and cooking

19
Q

What are the negatives of biomass?

A

Air pollutants; carbon dioxide, carbon monoxide, particulates, nitrous oxides (NOx), and volatile organic compounds (VOX)
Typically burned intensifying human health effects from pollutants
Over harvesting of trees for wood causes deforestation

20
Q

What are biofuels?

A

Liquid fuels made from plant matter that can be used as substitutes for conventional petroleum products (gasoline and diesel)

21
Q

What is ethanol?

A

Made by fermenting plant products to change carbohydrates to sugars and eventually alcohol.

22
Q

What are the sources of ethanol?

A

United States- Corn
Brazil- Sugar Cane
United States and Brazil- Sugar Beet

23
Q

What is biodiesel?

A

extracted and chemically modified oil from plants

24
Q

What are the sources of biodiesel?

A

United States and Brazil- Soybeans
Southeast Asia- Oil Palms
Europe- Grapeseed

25
What are the benefits of biofuels?
Existing infrastructure, such as gas pumps, can be utilized Combustion is carbon neutral (Modern carbon vs. fossil carbon Potentially renewable Can be produced domestically
26
What are the negatives of biofuels?
Net energy is low More gasohol is needed to drive the same distance Increased use of fossil fuels to harvest Increased deforestation Reduction of fertility of agricultural lands
27
What are some other solutions being researched for biofuels?
Switchgrass- perennial grass that can be grown and harvested year after year SVO- straight vegetable oil- filtering used vegetable oil from restaurants to power vehicles Algae- NASA in the Omega Project, is growing algae in plastic pouches in the sea. This solution reduces impact on habitats.
28
What are the three forms of solar power?
Photovoltaic Transforms sunlight directly into electricity Active Solar Uses mechanical and electric equipment to create solar heated liquid to transfer heat or to create electricity Passive Solar Heat is directly absorbed from the sun without the use of mechanical or electrical equipment
29
What are Photovoltic cells?
When sunlight strikes the components, electrons are released. As the electrons flow we get electricity.
30
What are the pros and cons of PV cells?
Pros Generates electricity Reduces habitat destruction depending on installation location (top of buildings, parking lots) Large and small scale applications Cons Use is limited by availability of sunlight Limited lifespan of nonrenewable PV cells Expensive Solar Farms may negatively impact fragile desert ecosystems
31
What is active solar power?
the use of concentrated sunlight to heat a liquid contained in troughs. The liquid then heats water, which creates steam to turn a turbine activating a generator to create electricity. Similar to the process of coal fired and nuclear power plants.
32
What are the pros and cons of active solar power?
Pros Generates electricity or heat Large and small scale applications Cons Expensive Requires maintenance Solar farms may negatively impact fragile desert ecosystems Solar farms require high solar intensity to maximize efficiency
33
What is passive solar power?
Sunlight entering home through windows; Requires good insulation and high thermal mass in the flooring. This allows heat to collect in the floor to be re-radiated later in the evening.
34
What are pros and cons of passive solar energy?
Pros Relatively inexpensive and low maintenance Cons Some elements are difficult to implement retroactively Energy cannot be collected or stored
35
How is dam power used?
Water is stored behind the dam in a reservoir. When gates of the dam are opened, water flows create kinetic energy. Kinetic energy spins a turbine which is connected to a generator. The turning generator creates electricity which is transferred to power lines.
36
What is tidal power?
Turbines are set in the ocean. Current created from moving water and tides creates kinetic energy which turns the turbine.
37
What are pros and cons of hydroelectric power?
Pros Does not generate air pollution or waste Relatively inexpensive generation of electricity Additional services provided by the reservoir Cons Flooding of land for reservoir Construction is very expensive High maintenance for tidal systems Loss or change of habitats following the construction of dams. Most viable sites are already used
38
What is geothermal energy?
Geothermal energy is obtained by using heat stored in earth’s interior to heat up water, which is brought back to the surface as steam. The steam is used to drive an electric generator.
39
How does geothermal plants work?
Water is pumped down an injection well. Stored heat in the earth’s interior heats the water producing steam Steam rises in a production well Kinetic energy of steam turns a turbine Turbine turns a generator Generator produces electricity
40
What are the pros and cons of geothermal energy?
Pros No combustion No CO2 emissions Not dependent on weather factors such as solar and wind Cons Accessibility at reasonable cost is limited Release of hydrogen sulfide gas during drilling and processing- “rotten egg smell”. While unpleasant, not as harmful as greenhouse gases. Short term depletion of heat is possible if water is added too quickly Impacts groundwater
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