Unit 6 Test

Largest user of energy

The United States is one of the largest consumers of energy, primarily from fossil fuels.

2nd Law of Thermodynamics

Energy transfer is inefficient; some energy is always lost as heat during conversion.

Cogeneration

The process of using waste heat from electricity generation to heat buildings or water, improving efficiency.

Hybrid-electric car

Uses both a gasoline engine and an electric motor, switching between them for fuel efficiency.

Mass transit efficiency

Moves many people using less energy per person compared to individual cars.

Solid biomass

Examples include wood and charcoal.

Liquid biomass

Examples include ethanol and biodiesel.

Advantages of biomass

Biomass is renewable and reduces waste.

Disadvantages of biomass

Biomass can cause deforestation and air pollution.

Cow manure as fuel

Burns away nutrients needed for soil fertility.

Common biofuels

Ethanol, biodiesel, and methanol.

Carbon neutral biofuels

The CO₂ released is reabsorbed by plants during photosynthesis.

Ethanol source

Common sources of ethanol include corn and sugarcane.

Gasohol

A blend of gasoline and ethanol, usually containing 10% ethanol.

Flex-fuel E85

An ethanol blend containing 85% ethanol and 15% gasoline for flex-fuel vehicles.

Ethanol advantages

Ethanol is renewable and reduces fossil fuel use.

Ethanol disadvantages

Ethanol has lower energy content than gasoline and competes with food supply.

Biodiesel source

Biodiesel can be made from vegetable oils, animal fats, or algae.

Palm oil and deforestation

Replacing forests with palm plantations destroys biodiversity and increases CO₂ emissions.

Biodiesel advantages

Biodegradable with lower emissions.

Biodiesel disadvantages

High production costs and risk of deforestation.

Methanol sources

Common sources include wood, coal, natural gas, and municipal waste.

Methanol advantages

Methanol can be produced from waste and burns cleaner.

Methanol disadvantages

Methanol is toxic and less energy-dense than gasoline.

Passive solar energy

An example is using south-facing windows for heating without mechanical systems.

Active solar energy

An example is the use of solar panels (photovoltaic cells) to convert sunlight into electricity.

Photovoltaic cells

Devices that convert sunlight into electricity.

Advantages of solar panels

Solar panels are renewable and produce no emissions.

Disadvantages of solar panels

Solar panels have high initial costs and their effectiveness is dependent on sunlight.

Solar thermal system

Uses mirrors or lenses to concentrate sunlight and generate heat for electricity.

Hydroelectric system

Utilizes water to turn turbines and generate electricity.

Reservoir and dam

A reservoir stores water; a dam controls the flow to generate electricity.

Tidal dam

Uses ocean tides to spin turbines and produce electricity.

Dam advantages

Dams provide renewable energy and flood control.

Dam disadvantages

Dams can disrupt ecosystems and cause silt buildup.

Salmon fish ladders

Structures that help fish migrate past dams.

Geothermal advantages

Geothermal energy is renewable and has low emissions.

Geothermal disadvantages

Geothermal energy production is expensive and location-dependent.

Hydrogen fuel cells

Devices that generate electricity through the reaction of hydrogen and oxygen.

Electrolysis

The process of splitting water into hydrogen and oxygen using electricity.

Wind turbines

Devices that convert wind energy into electricity.

Energy efficiency examples

Improving building efficiency includes better insulation and using energy-efficient appliances.

Phantom loads

Energy consumed by electronics that are turned off but still plugged in.

Smart grid

An electricity network that adjusts power supply based on real-time demand, reducing waste.

Nuclear Fusion

A process where two light atomic nuclei combine to form a heavier nucleus, releasing energy.

Nuclear Fission

The process of splitting a heavy atomic nucleus into lighter nuclei, releasing energy.

Hybrid Cars

Vehicles that use both an internal combustion engine and an electric motor to improve fuel efficiency.

Three Gorges Dam

A large dam on the Yangtze River in China, used for hydroelectric power, flood control, and river navigation.

Siltation

The accumulation of silt, sand, and sediment in waterways, which can reduce water flow and affect ecosystems.

Uranium

A heavy metal used as fuel in nuclear reactors for both fission and fusion processes.

Petroleum

A liquid fossil fuel formed from the remains of ancient marine organisms, used for energy and as a chemical feedstock.

Plutonium

A radioactive chemical element used as fuel in nuclear reactors and in the production of nuclear weapons.

Control Rods

Materials used in nuclear reactors to absorb neutrons and regulate the fission process.

Fuel Rods

Cylindrical tubes that contain nuclear fuel for reactors, usually made from uranium or plutonium.

Methane

A colorless, odorless gas that is the main component of natural gas, produced from decomposed organic material.

Fracking

A method of extracting oil and gas by injecting high-pressure fluid into underground rock formations.

Crude Oil

Unrefined petroleum extracted from the earth, consisting of hydrocarbons and other organic materials.

Tar/Oil Sands

A mixture of sand, clay, water, and bitumen, used as a source of crude oil.

Natural Gas

A fossil fuel composed mostly of methane, used for heating, electricity generation, and as a chemical feedstock.

Forms of Coal

Different types of coal include lignite, peat, bituminous, and anthracite, varying in carbon content and energy output.

Dry Steam

Steam produced without the presence of water droplets, typically used in geothermal power plants.

Wet Steam

Steam that contains water droplets, typically used in various heating applications.

Hot Water

Water heated to above its normal temperature, often used in heating systems or power generation.

Heater Pumps

Devices that transfer heat from one place to another, often used for heating and cooling buildings.