1. Energy Sources and the Environment
Chapter 8
Energy Sources and the Environment

2. Section 1 – Fossil Fuels Energy Resources
Energy is used all the time in nature
Thermal energy – furnaces, stoves
Mechanical energy – cars, vehicles

3. Energy Transformation
The Laws of Conservation of Energy State:
Energy cannot be created or destroyed
To use energy, energy must be transformed into another form to perform a function
Energy can be transformed to forms that are not useful
Example: Electricity flowing through power lines
10% is lost to thermal energy

4. Energy Use in the United States
The US uses more energy than any other country in the world.
The US is an industrialized country
Example: graphs from 2008 show energy uses in the United States

5. Fossil Fuel Formation What are fossil fuels?
Coal
Natural gas
Petroleum (Crude oil)
How are fossil fuels formed?
Formed from the dead and buried remains of once living organisms over the course of many years

6. Combustion Reactions How do we use fossil fuels?
Fossil fuels contain energy in the form of chemical potential energy that is stored in fossil fuels
Fossil fuels’ stored energy is far higher than other organic substances
Example: burning 1kg of coal releases two to three times as much energy as burning 1kg of wood

7. Combustion Reactions

8. Formation and Obtaining Fossil Fuels
How do fossil fuels form and how do we get them?
Because they are formed from once living organisms, fossil fuels are stored naturally underground
Fossil fuels must be mined

9. Petroleum
Petroleum: a highly flammable liquid formed from the decay of organisms, such as plankton and algae
Humans pump millions of liters of petroleum every day
A mixture of many different unique chemical compounds
Most are hydrocarbons
Contain hydrogen and carbon
High energy bonds
Bonds are broken when burned

10. Fractional Distillation
Because petroleum contains many different types of hydrocarbons, they must be separated
Uses the process of fractional distillation

11. Fractional Distillation
This separation occurs in distillation towers at oil- refineries.
First, petroleum is pumped into the bottom of the tower and heated.
The chemical compounds in the petroleum boil at different temperatures.
Materials with the lowest boiling points rise to the top of the tower as vapor are collected.
Hydrocarbons with high boiling points, such as asphalt and some types of waxes, remain liquid and are drained off through the bottom of the tower.

12. Petroleum Use
About 15 percent of the petroleum-based materials that are used in the United States are not used for fuel
In addition to fuels, plastics and synthetic fabrics are made from the hydrocarbons petroleum.
Lubricants, such as grease and motor oil, as well as the asphalt used in surfacing roads, are made from petroleum.

13. Natural Gas
Natural gas: a fossil fuel composed mostly of methan, CH4, but it also contains other gases hydrocarbon such as propane, C3H8, and butane, C4H10.
¼ of energy consumed in the US comes from using natural gas
Contains more chemical potential energy per kg than petroleum or coal
The cleanest burning fossil fuel

14. Coal Coal: a solid fossil fuel that is found in mines
Forms from ancient swamps
Forms as plant material is buried beneath sediments, decays, and compacts
Before the 1900’s more than 90% of homes were heated by burning coal
Today, less than 25%
Coal is often burned in power plants to generate electricity

15. Origin of Coal
Coal is a mixture of hydrocarbons and other chemical compounds.
Compared to petroleum and natural gas, coal contains more impurities, such as sulfur and nitrogen-based compounds.
As a result, more pollutants, including sulfur dioxide and nitrogen oxides, are produced when coal is burned.

16. Electricity
Graph shows the percentages of energy that comes from different sources in the US

17. Electricity

18. Electricity

20. Power Plant Efficiency
Not all the chemical potential energy in the fuel is converted to electrical energy.
No stage is 100 percent efficient. Thermal energy is released into the environment.
The overall efficiency of a fossil fuel-burning power plant is about 35 percent.

21. The Cost of Fossil Fuels
Using fossil fuels has some negative side effects
When petroleum products and coal are burned, smoke is given off the pollutes the atmosphere with small particles
Releases carbon dioxide
Global warming can occur as a result

22. The Cost of Fossil Fuels
Most abundant fossil fuel is coal
Coal contains more impurities than oil or natural gas
Burning coal can release these impurities into air that is then breathed by organisms
Coal mining can also be dangerous
Inhalation
Risk of death or injury while mining

23. Nonrenewable Resources
Fossil fuels are nonrenewable resources
They are not regenerated in the earth as quickly as they are used
As human population increases, production of fossil fuel based products will continue to increase, reserves of fossil fuels will decrease
Fossil fuels will become more difficult to obtain
To meet demands, some are looking for alternatives such as shale deposits

24. Nonrenewable Resources

25. Section 2 – Nuclear Energy
Nuclear Fusion
Fusion: when atomic nuclei combine at very high temperatures
The Sun is a giant nuclear reactor
This process takes a small amount of mass and converts it into huge amounts of thermal energy
Fusion is the most concentrated energy source known
Fusion-based power plants are not practical because the reaction occurs at millions of degrees Celsius

26. Fission
Fission: energy released when the nucleus of an atom splits apart
Extremely small amounts of mass are converted to huge amounts of energy
9% of US electricity is made using fission
Nuclear power plants use thermal energy to generate electricity

27. Nuclear Reactors
Nuclear reactor: uses the energy from controlled nuclear reaction to generate electricity
All reactors share common parts
They will contain:
Fuel for fission
Control rods
Cooling system

28. Nuclear Reactors
The core of a reactor is the small part where fission occurs
The core contains fuel rods and control rods
Control rods absorb neutrons from radioactive decay
Water acts as a coolant to remove heat

29. Nuclear Fuel
Only certain elements have nuclei that can undergo fission.
Naturally occurring uranium contains an isotope, U-235, whose nucleus can be split apart.
As a result, the fuel that is used in a nuclear reactor is usually uranium dioxide.

30. Fuel Rods
The core of a reactor contains about 100,000 kg of uranium in hundreds of fuel rods
Cores contain pellets of uranium dioxide
Tubes of fuel rods are bundled and covered in alloys
For every kg of uranium that undergoes fission, 1g of matter is converted to energy
1g of matter converted to energy = energy generated by burning 3 million kg of coal

31. Fuel Rods

32. The Nuclear Chain Reaction
Uranium atoms split to release neutrons which causes other atoms to split apart. This causes a chain reaction
When an atom of Uranium-235 (U-235) is hit by a neutron it splits into two smaller nuclei
This causes two or three more neutrons to be emitted
Causes a large chain reaction

33. The Nuclear Chain Reaction

34. A Constant Rate As the nuclear chain reaction occurs heat is produced
Sometimes this can occur too fast creating too much heat
In this case, cooling rods are used to absorb some of the neutrons and prevent them from striking other U- 235 atoms
By raising or lowering the cooling rods, the reaction can be sped up or slowed
This can allow for a constant rate to be found

35. Benefits and Risks of Nuclear Power
Nuclear power is used to generate electricity in a similar way to burning fossil fuels
Nuclear power plants to do not produce the same pollutants as fossil fuels and are cleaner

36. Benefits and Risks of Nuclear Power
Mining uranium can cause environmental damage
They do risk a nuclear meltdown
Coolant from the core must be cooled before returned to streams or rivers

37. The Release of Radioactivity
One of the most serious risks of nuclear power is the release of harmful radiation from power plants.
The fuel rods contain radioactive elements with various half-lives.
Some of these elements could harm living organisms if they were released from the reactor core of a nuclear power plant

38. The Disposal of Nuclear Waste
Nuclear waste: any radioactive material that results when radioactive materials are used.
After about three years, not enough fissionable U- 235 is left in the fuel pellets in the reactor core to sustain the chain reaction.
The spent fuel contains radioactive fission products in addition to the remaining uranium.

39. Low-Level Waste Contain small amounts of radioactive material
Have short half lives
By product of electricity generation, medical research and treatments, pharmaceutical industry, and food preparation
Low-level wastes are usually buried in trenches about 30m deep in special locations
If dilute, some waste is released into air or water where it will dissipate

40. High-Level Waste
Generated by nuclear power plants and nuclear weapons programs
After a fuel rod is spent, it is stored in a deep pool of water
Many high-level wastes have long half-lives
High-level wastes remain radioactive for tens of thousands of years
Must be stored in extremely stable containers

41. High-Level Waste
One method of long-term waste storage incases radioactive wastes in glass and ceramic then placed in protective metal containers
Containers are then buried hundreds of meters below ground in stable rock formations or salt deposits

42. Section 3 – Renewable Energy Resources
Energy Options
Renewable Resources: an energy source that is replaced by natural processes faster than humans can consume the resource
Demand for energy increases as Earth’s population increases
Other sources must be used to meet the demand
Some alternatives are renewable

43. Energy From the Sun
Photovoltaic cells: convert radiant energy from the sun directly into electrical energy
About 1 billionth of the suns energy strikes earth
The suns energy should last for billions of years – it’s inexhaustible
Solar energy is a renewable resource
Many devices use photovoltaic cells
Example: cars

44. How Solar Cells Work
Two layers of semiconducting material between two layers of conducting metal
One layer of semiconductor is rich in electrons; one is poor in electrons

45. How Solar Cells Work
When sunlight strikes a solar cell, electrons are ejected from the electron-rich semiconductor. These electrons can travel in a closed circuit back to the electron-poor semiconductor

46. Parabolic Troughs
Focuses sunlight on a tube containing heat- absorbing fluid such as synthetic oil or liquid salt
Used in remote areas where electricity is hard to get
Best forms focus solar power into a receiver
Heated fluid is circulated through a boiler to make steam
Used in turbines

47. Energy from Water Steam can move a turbine
Running water can be used the same way
GPE of water is increased if a dam is used
GPE is released when water flows through tunnels at the base

48. Energy from Water
Rushing water spins a turbine, which rotates the shaft of an electric generator to produce electricity

49. Hydroelectricity Electricity produced from moving water
8% of electrical energy in the US made by hydroelectric power plants
Very efficient with little pollution
Reservoirs created by dams for hydroelectric power can be used for drinking water and crops
Electricity is cheap after initial setup costs

50. Energy from Oceans Every day ocean levels rise and fall
These tides can be used for hydroelectric power
Water is trapped behind a dam
At low tide, water flows back out to sea using turbines to generate electricity
Tide differences are limiting, only a few places on earth have large enough tidal differences
Waves and ocean currents can also be used

51. Wind Energy Windmills convert wind energy into electrical energy
Wind spins a propeller connected to a generator
Disadvantages are that few places on earth have enough wind to meet needs
Renewable resource

52. Energy from Inside Earth
The thermal energy that is contained in hot magma is called geothermal energy.
Heat is generated within Earth by the decay of radioactive elements.
This heat is called geothermal heat.
Geothermal heat causes the rock beneath Earth’s crust to melt.
This hot molten rock beneath Earth’s surface is called magma

53. Alternative Fuels
The use of fossil fuels would be greatly reduced if cars could run on other fuels or sources of energy.
Cars have been developed that use electrical energy supplied by batteries as a power source.
Hydrogen gas is another possible alternative fuel. It produces only water vapor when it burns and creates no pollution

54. Biomass Fuels
Biomass is renewable organic matter, such as wood, sugarcane fibers, rice hulls, and animal manure.
Biomass can be burned in the presence of oxygen to convert the stored chemical energy to thermal energy.
Converting biomass is probably the oldest use of natural resources for meeting human energy needs.

55. Section 4 – Population and Carrying Capacity
Population: all the individuals of one species living in a particular area
Carrying Capacity: the largest number of individuals of a particular species that the environment can support
Since the mid-1800s human population has increased at a rapid rate
Causes: advances in medicine, better nutrition, and availability of clean water

56. Population and Carrying Capacity
If natural resources are used too quickly, the environment is threatened and populations suffer
Irresponsible usage of earth’s resources could result in us reaching our carrying capacity

57. People and the Environment
Pollutants: any substance that contaminates the environment
You have an impact
Electricity you use comes from fossil fuels. This can affect the air you breath
Water you use must be treated

58. Impact on Land
Land is affected when fossil fuels are extracted from earth
Land: used for agriculture, forests, urban development, and waste management
Deforestation: the clearing of forest land for agriculture, urban development, or logging
Increases the amount of carbon dioxide in the atmosphere
Can cause increases in atmospheric temperatures

59. Urban Development
Over time as population grows, urban development increases
Highways, office buildings, parking lots
Some communities, states, countries, and private businesses try to preserve natural areas by designating them as historic sites or national parks

60. Waste
Hazardous Wastes: wastes that are poisonous, causes cancer, or can catch fire
Garbage affects the amount of hazardous waste
About 55% of garbage is disposed of in sanitary landfills
The rest is recycled or burned

61. National and State Parks
National and state parks are areas of land protected and preserved by the government.
The forests, wetlands and grasslands, and parks in the United States are safe from urban development, waste disposal, and extensive deforestation

62. Impact on Water Life on Earth would not be possible without water.
Plants need water to convert radiant energy into food energy.
Some animals make water their homes.
Sixty percent of the human body is composed of water

63. Sources of Water Pollution
Polluted water contains chemicals and organisms that cause disease
Sediments can be pollutants
Mining can release metals into water
Examples: mercury, lead, nickel, and cadmium
Oil and gas can run off
Wastewater (sewage) contains human waste, household detergents, and soaps

64. Impact on Air Harms humans, plants, and animals
Dust from construction contributes
Volcanoes and forest fires are natural sources of air pollution

65. Types of Air Pollution
Photochemical smog: the pollution that results from the reaction between sunlight and vehicle or factory exhaust
Acid precipitation: sulfur-, nitrogen-, and carbon- based compounds released with moisture in the air

66. Types of Air Pollution

67. Reducing Pollution Ways to conserve resources
Composting yard and kitchen waste
Low-flush toilets and leak-free faucets will help reduce water impact
Bicycling or using buses can help reduce impact on the air