Chapter 15: Nonrenewable Energy and Electricity

Primary Energy

• Energy contained in natural resources
>> Coal, oil, sunlight, wind, uranium

Secondary Energy

• When primary energy is converted into another form
>> Electricity

End Use

• Final application of energy
• Running a car or computer

Second Law of Thermodynamics

• Energy is lost in each conversion

Energy Conversion Efficiency

• Percentage of primary source energy that is captured in secondary form

Energy End-Use Efficiency

• Product of all of the energy conversions and end use
• 100 units of coal powers a lightbulb that produces 1.2 units of light energy, 1.3% efficiency

Renewable Primary Energy

• Sources that are not depleted when used or can be replenished quickly
>> Solar, wind, wood

Nonrenewable Primary Energy

• Derived from sources that exist in limited quantities
>> Fossil fuels, nuclear

Energy Production and Consumption

• Future patterns depend on four factors
>> Size of reserves
>> Extraction rates
>> Market price
>> Environmental impacts

Generating Electricity

• Electric current flow of electrons through a wire
• Measured in amperes
• Electric potential measured in volts
• Electric power measured in kilowatt hours (kWh)
• Electricity generated in power plants using turbines to drive electric generators

Transformers

• Reduce amperage and increase voltage to facilitate transmission

Electric Power Grid

• Network of transmission lines and transformers

Base Load

• Minimum amount of electricity for consumer needs

Peak Load

• Maximum amount of electricity for consumer demand

Electric Power

• Electromagnetic field produced by transmission lines
• Polychlorinated biphenyls (PCBs) in transformers
• Chemicals from batteries
>> Lead, heavy metals

Coal

• Formed from plants hundreds of millions of years ago
• Deposited in layers of sediment called coal seams

Types of Coal

• Lignite
• Sub-bituminous
• Bituminous
• Anthracite

Coal Extraction and Processing

• Removed from sediments by underground and surface mining
• Cleaned to remove dirt and other impurities
• Globally, 67% used for electricity generation (90% in US)

Coal Environmental Impacts

• Mining destroys habitats
>> Mountaintop removal
• Mine tailings are acidic
• Exhaust from coal fires
>> Numerous toxins (mercury, CO2)

Oil

• Forms under specific geological conditions
>> Found only in a few places
• Formed from remains of microorganisms millions of years ago
• Became trapped beneath impermeable rock
>> Oil reservoirs

Oil Extraction and Processing

• Crude oil is pumped from reservoirs and sent to refineries

Primary Oil Recovery

• Original flow (first 20%)

Secondary Oil Recovery

• Additional methods, injecting water

Tertiary Oil Recovery

• Injection of CO2 stream
• Fracking

Natural Gas

• Formed in the same way as oil
• Usually found in association with crude oil deposits
• Also found with coal seams
• 65-year supply exists at current consumption rate

Natural Gas Extraction and Processing

• Sent by pipeline to refinery
• Converted to liquefied natural gas (LNG)
• Largest use is industrial and power generation
• Some used for production of plastics, fertilizers, and synthetic fibers
• 31% used to generate electricity

Natural Gas Environmental Impacts

• Has fewer effects than coal or oil
• Fracking for natural gas may contaminate aquifers
• Burning releases CO2
>> Half as much as coal

Uranium Extraction and Processing

• Extracted by open pit mines
• Uranium ore crushed into fine powder and processed into yellowcake
• Yellowcake converted to gas and centrifuged to produce uranium fuel pellets
• Fuel pellets packed into rocks
• 100-300 fuel rods packed into assemblies
• 3,000 assemblies make a reactor core

Nuclear Power Environmental Impacts

• Large open pit mines
• Thermal discharge
• Meltdown
• Radiation leak
• Nuclear waste
• Does not release greenhouse gases