Energy and Energy SourcesEnergy and Energy Sources

IPCIPC

I. The Nature of EnergyI. The Nature of Energy

A. Energy is the ability to cause change.A. Energy is the ability to cause change.1. 1. Kinetic energyKinetic energy – energy in the form of motion. – energy in the form of motion.

a. The amount of kinetic energy an a. The amount of kinetic energy an object has depends on its mass and its object has depends on its mass and its velocity.velocity.

b. Kinetic Energy = b. Kinetic Energy = mvmv22

22

c. Joules- the SI unit to measure energy.c. Joules- the SI unit to measure energy.

2. 2. Potential EnergyPotential Energy - energy stored in a - energy stored in a motionless object, giving it the potential to motionless object, giving it the potential to cause change.cause change.

I. The Nature of EnergyI. The Nature of Energy

A. Energy is the ability to cause A. Energy is the ability to cause change.change.

3. 3. Elastic potential energyElastic potential energy - energy - energy stored by things that stretch or stored by things that stretch or compress.compress.

4. Chemical potential energy – energy 4. Chemical potential energy – energy stored in chemical bonds between stored in chemical bonds between atomsatoms

I. The Nature of EnergyI. The Nature of EnergyA. Energy is the ability to cause A. Energy is the ability to cause change.change.5. Gravitational potential energy – energy 5. Gravitational potential energy – energy

stored by things that are above the Earth.stored by things that are above the Earth.

a. the amount of GPE and object has a. the amount of GPE and object has depends on its mass, the acceleration due depends on its mass, the acceleration due to gravity, and its height above ground.to gravity, and its height above ground.

b. GPE= mass(kg) x 9.8 m/sb. GPE= mass(kg) x 9.8 m/s22 x x height(m)height(m)

II. Conservation of EnergyII. Conservation of Energy

A. Energy Conversions – energy A. Energy Conversions – energy changing from one form to another.changing from one form to another.1. Fuel store energy in the form of 1. Fuel store energy in the form of

chemical potential energy.chemical potential energy.

2. Mechanical energy – the total amount 2. Mechanical energy – the total amount of potential and kinetic energy in a of potential and kinetic energy in a system.system.

II. Conservation of EnergyII. Conservation of EnergyB. Law of Conservation of Energy – Energy B. Law of Conservation of Energy – Energy may change from one form to another, but may change from one form to another, but the total amount of energy never changes.the total amount of energy never changes.1. Example – as a swing moves back and forth, 1. Example – as a swing moves back and forth,

its energy continually converts from kinetic to its energy continually converts from kinetic to potential and back.potential and back.

2. If the energy of the swing decreases, then the 2. If the energy of the swing decreases, then the energy of some other object must increase by energy of some other object must increase by an equal amount.an equal amount.

3. Friction converts on the mechanical energy 3. Friction converts on the mechanical energy into thermal energy.into thermal energy.

II. Conservation of EnergyII. Conservation of Energy

C. Converting mass to energy – you C. Converting mass to energy – you must think of mass as energy when must think of mass as energy when discussing nuclear reactions. The discussing nuclear reactions. The total amount of mass and energy is total amount of mass and energy is conserved.conserved.1. Nuclear fusion – two nuclei are fused 1. Nuclear fusion – two nuclei are fused

together – takes place in the sun.together – takes place in the sun.

2. Nuclear fission – two nuclei are broken 2. Nuclear fission – two nuclei are broken apart. apart.

II. Conservation of EnergyII. Conservation of Energy

D. Conservation of Energy in your D. Conservation of Energy in your body.body.1. Chemical potential energy from food 1. Chemical potential energy from food

that is stored in your body is used to that is stored in your body is used to fuel the processes that keep you alive.fuel the processes that keep you alive.

2. The food calorie is used to measure 2. The food calorie is used to measure how much energy you get from various how much energy you get from various foods. foods.

3. One calorie is equal to 4,180 J.3. One calorie is equal to 4,180 J.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

A. Energy can not be created nor A. Energy can not be created nor destroyed according to the law of destroyed according to the law of conservation of energy, but energy can be conservation of energy, but energy can be converted from one form to another.converted from one form to another.

B. Fossil fuels – formed from decaying B. Fossil fuels – formed from decaying remains of ancient plants and animals.remains of ancient plants and animals.1. Burning fossil fuels converts energy from 1. Burning fossil fuels converts energy from

chemical bonds to light and heat.chemical bonds to light and heat.

2. Chemical energy in fossil fuels is more 2. Chemical energy in fossil fuels is more concentrated than in other fuels such as wood.concentrated than in other fuels such as wood.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

C. Petroleum- thick, greenish-brown, C. Petroleum- thick, greenish-brown, highly flammable liquid formed by highly flammable liquid formed by decayed ancient organismsdecayed ancient organisms1. A process called fractional distillation 1. A process called fractional distillation

separates the compounds in petroleum.separates the compounds in petroleum.

2. Petroleum is used for plastics, synthetic 2. Petroleum is used for plastics, synthetic fabrics, and other products in addition to fabrics, and other products in addition to its use as a fuel.its use as a fuel.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

D. Natural gas is also a product of D. Natural gas is also a product of ancient organisms.ancient organisms.1. It contains more energy per kilogram 1. It contains more energy per kilogram

than petroleum or coal.than petroleum or coal.

2. It burns more cleanly than other fossil 2. It burns more cleanly than other fossil fuels.fuels.

3. It provides about one-fourth of the 3. It provides about one-fourth of the energy consumed in the United States.energy consumed in the United States.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

E. Coal – a solid fossil fuel found E. Coal – a solid fossil fuel found underground.underground.1. It produces more pollution when 1. It produces more pollution when

burned than natural gas or petroleum.burned than natural gas or petroleum.

2. It provides about one-fourth of the 2. It provides about one-fourth of the energy produced in the United States.energy produced in the United States.

3. About 90 percent of coal burned in the 3. About 90 percent of coal burned in the United States is used to produce United States is used to produce electricity.electricity.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

F. Electricity is generated when fossil fuels F. Electricity is generated when fossil fuels are burned.are burned.1. The burned fuel releases thermal energy.1. The burned fuel releases thermal energy.

2. The thermal energy produces high pressure 2. The thermal energy produces high pressure steam.steam.

3. The steam spins a turbine.3. The steam spins a turbine.

4. The spinning turbine produces an electric 4. The spinning turbine produces an electric current.current.

5. The electric current is transmitted through 5. The electric current is transmitted through power lines to consumers.power lines to consumers.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

G. Only about 35% of the energy in G. Only about 35% of the energy in fossil fuel reaches consumers since fossil fuel reaches consumers since some energy is lost in every stage of some energy is lost in every stage of the process.the process.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

H. Fossil fuel have some undesirable H. Fossil fuel have some undesirable side effects.side effects.1. Fossil fuel pollute the environment and 1. Fossil fuel pollute the environment and

increase carbon monoxide in the increase carbon monoxide in the atmosphere.atmosphere.

2. Mining coal can cause health problems 2. Mining coal can cause health problems for miners.for miners.

III. Energy Sources – Fossil FuelsIII. Energy Sources – Fossil Fuels

I. Fossil fuels are nonrenewable I. Fossil fuels are nonrenewable resources, so it is important to not resources, so it is important to not waste energy.waste energy.

IV. Nuclear EnergyIV. Nuclear Energy

A. About 20% of the electricity in the U.S. A. About 20% of the electricity in the U.S. come from nuclear power plants.come from nuclear power plants.

B. Nuclear reactors contain a fuel, rods to B. Nuclear reactors contain a fuel, rods to control nuclear reactions, and a cooling control nuclear reactions, and a cooling system.system.1. Heat is produced by nuclear fission – energy is 1. Heat is produced by nuclear fission – energy is

released when U-235 nuclei split in two after released when U-235 nuclei split in two after being struck by a neutron.being struck by a neutron.

2. Special rods absorb excess neutrons to 2. Special rods absorb excess neutrons to prevent dangerous chain reactionsprevent dangerous chain reactions

IV. Nuclear EnergyIV. Nuclear Energy

C. Nuclear Power plants use the heat C. Nuclear Power plants use the heat of nuclear fission to produce steam.of nuclear fission to produce steam.

1. The steam drives a turbine.1. The steam drives a turbine.

2. The Turbine rotates an 2. The Turbine rotates an electric electric generator. generator.

IV. Nuclear EnergyIV. Nuclear Energy

D. Nuclear power plants produce D. Nuclear power plants produce nuclear waste—radioactive by-nuclear waste—radioactive by-products from radioactive materials.products from radioactive materials.

1. Low-level wastes contain only a small 1. Low-level wastes contain only a small amount of radioactive material.amount of radioactive material.

2.High-level wastes must be disposed of 2.High-level wastes must be disposed of extremely carefully because they will extremely carefully because they will remain radioactive for tens of thousands remain radioactive for tens of thousands of years.of years.

IV. Nuclear EnergyIV. Nuclear Energy

E. Nuclear Fusion—the joining E. Nuclear Fusion—the joining together of nuclei—is not a practical together of nuclei—is not a practical energy source due to the high energy source due to the high temperature fusion requires.temperature fusion requires.

V. Renewable Energy SourcesV. Renewable Energy Sources

A. A renewable resource can be A. A renewable resource can be replaced as quickly as it is used. replaced as quickly as it is used.

V. Renewable Energy SourcesV. Renewable Energy SourcesB. Solar energy is converted into electricity B. Solar energy is converted into electricity by a photovoltaic cell or solar cell.by a photovoltaic cell or solar cell.

1. A solar cell converts only 15 to 20 percent of 1. A solar cell converts only 15 to 20 percent of the sun’s energy into electricity.the sun’s energy into electricity.

2. Energy produced by solar cells is more 2. Energy produced by solar cells is more expensive than energy produced with fossil expensive than energy produced with fossil fuels.fuels.

3. Energy from solar cells must be stored in 3. Energy from solar cells must be stored in batteries when the Sun is not shining.batteries when the Sun is not shining.

V. Renewable Energy SourcesV. Renewable Energy Sources

C. Hydroelectricity is produced by C. Hydroelectricity is produced by moving water; it is about twice as moving water; it is about twice as efficient as fossil fuels or nuclear efficient as fossil fuels or nuclear power.power.

V. Renewable Energy SourcesV. Renewable Energy Sources

D. Tidal energy uses moving water, D. Tidal energy uses moving water, but it can only be used in places but it can only be used in places where high and low tides are where high and low tides are different enough.different enough.

V. Renewable Energy SourcesV. Renewable Energy Sources

E. Windmills can be used to generate E. Windmills can be used to generate electricity, but are useful only when electricity, but are useful only when the wind blows consistently.the wind blows consistently.

V. Renewable Energy SourcesV. Renewable Energy Sources

F. Geothermal energy—thermal F. Geothermal energy—thermal energy contained in hot magma; energy contained in hot magma; limited to areas where magma is limited to areas where magma is close to the surface.close to the surface.

V. Renewable Energy SourcesV. Renewable Energy Sources

G. Alternative fuels include hydrogen G. Alternative fuels include hydrogen gas and biomass—renewable organic gas and biomass—renewable organic matter such as wood or animal matter such as wood or animal manure.manure.