ENERGY

EnergyEnergy is the mysterious force that travels through the universe making things happen.

The scientific definition is the ability to do work.

Types of EnergyThere are many types of energy, in fact new types are still being discovered from time to time. The main ones we understand today are:■Electromagnetic■Thermal■Mechanical■Chemical■Electrical■Nuclear

ElectromagneticElectromagnetic energy travels in waves.

Thermal

■Thermal energy is the total energy of all of the molecules in a substance.

■Temperature is the measure of thermal energy!

Mechanical

■Mechanical energy is the energy of motion.■Potential energy is the energy a body has from

its position.■Kinetic energy is the energy it has when it is

actually in motion.

Chemical

■Chemical energy is released when chemical bonds are broken and reformed...in other words during a chemical reaction.

Electrical

■Electrical energy is energy created by flowing electrons moving from one atom to the next.

■ It travels through wires and we use it…a lot!

Nuclear■Protons and neutrons in

an atom’s nucleus are held there by nuclear forces.

■When these forces are overcome and neutrons and/or protons are removed from an atom nuclear energy is released.

Energy Transformations

Just like the other main component of the universe, matter, energy is also conserved. Energy can be neither created nor destroyed.It does, however, get transformed from one form of energy to another all the time.

What if I told you most of this energy come from the sun?

Here is an example:

Energy UseHow do we humans use energy?

Transportation

Electricity Where does our

electricity come from?From Duke Energy/Progress: 58,200 megawatts of generating capacity from a diverse mix of coal, nuclear, natural gas, oil and renewable resources

Non-renewable resources cannot be replenished at the rate at which they are being used.Also referred to as fossil fuels because they were created by the Earth over millions of years from decomposing organisms.

Examples:▪ Coal ▪ Petroleum

NON-RENEWABLE

▪ Natural Gas ▪ Nuclear

Advantages of Coal

Coal provides:■ Jobs■ Income from exports(US holds majority of the world’s reserves)■Taxes to government used in essential services

including schools, hospitals, roads and police■cheap & reliable infrastructure

▪It is non-renewable!▪Mining creates environmental & human

problems▪On combustion, emits air pollutants such as

carbon dioxide, and nitrogen oxides▪Creates waste in the form of ash which needs to

be stored ▪Uses large amounts of water in the electricity

generation process

Disadvantages of Coal

■Produces half the greenhouse gas emissions of coal and oil

■High heating value (more energy released)■ Is accessible from a number of areas■Can be transported easily by pipes to homes

and businesses■Plants can be started up quickly & easily...can

be a great backup for unreliable renewables

Advantages of Natural Gas

■ It is non-renewable!■On combustion produces greenhouse gases;

mainly carbon dioxide■Costs involved in exploration, infrastructure

e.g. plants and pipelines

Disadvantages of Natural Gas

Natural Gas Plant

Advantages of Nuclear

■Uses a smaller amount of fuel■No greenhouse gas emissions!Yearly fuel of a nuclear

power plant (NPP)

Disadvantages of Nuclear

■ It is non-renewable!■ Toxic waste - can be toxic for 1000’s of years■Waste storage locations - NIMBY■ Possible use in nuclear weapons – “Dirty bombs”■ Possible accidental radiation release - like Fukushima

1. In a nuclear reactor, fuel rods full of uranium pellets are placed in water.

2. Inside the fuel rods, uranium atoms split, releasing energy.

3. This energy heats water, creating steam.

4. The steam moves through a turbine, which turns a generator to create electricity.

5. The steam cools back into water, which can then be used over again. At some nuclear power plants, extra heat is released from a cooling tower.

■Combusts (burns) easily■Has a high heating value■Relatively easy to

transport■Can be made into a

variety of useful products

Advantages of Petroleum

Petroleum – Crude Oil

■ It is non-renewable!■Combustion of oil

produces greenhouse gases

■ Sources of oil are becoming more difficult to find

Disadvantages of Petroleum

■Cost of oil can be high ■ Political & human problems – WAR!

Environmental Impact

Non-Renewable Resources are Finite Folks!

RENEWABLE ENERGY Sources of energy that will not run out!

Examples:■ Solar■Wind■Hydroelectric■Geothermal

Advantages of Solar

Source: United States Department of Energy

■Renewable!■Limited CO2 emissions■The source of energy

(sun) is free!■Costs associated with

solar are going down as cost of fossil fuels are going up

Disadvantages of Solar■The technology is

expensive■Not reliable (not

always sunny)■Equipment can be

damaged easily■Dust/dirt can impact

effectiveness

1. Sunlight hits the surface of the photovoltaic cell.• A material called a semi-conductor converts the light into electricity.

1. Mirrors or reflectors concentrate the sun's rays to heat a special kind of liquid.

2. The heat from this liquid boils water to create steam.

3. Steam spins a turbine that is connected to a generator, which creates electricity.

4. The steam cools and condenses back to water, which is recycled, reheated, and converted into steam again.

■ Renewable energy from the wind has been used for centuries to power windmills to mill wheat or pump water

■ It is free other than the cost to produce & maintain the equipment

■ No emissions except in the production of equipment

Advantages of Wind

■Unpredictable wind speeds■Can be unsightly depending on where they are

located■ Impacts on habitat (especially for birds & bats)■Noise & shadows

Disadvantages of Wind

1. As the wind blows over the blades of a wind turbine, it causes the blades to lift and rotate.

2. The rotating blades turn a shaft that is connected to a generator.

3. The generator creates electricity as it turns.

Advantages of Hydroelectric

■Renewable form of energy■ Low emissions except in construction of

equipment & if coal fired power is used to pump water back up to a higher dam

Disadvantages of Hydroelectric

■ The building of large dams floods large areas and causes damage to existing habitats (for humans & wildlife)

■Changing the flow of a river can affect the water supply to other areas

■A suitable site is not always near where energy is being used

Three Gorges Dam in China

1. Flowing water turns a waterwheel or turbine.

2. A generator attached to the turbine produces electricity.

■Renewable!■Less expensive■Becoming more

and more accessible with new technology

Advantages of Geothermal

■Sometimes hot water pumped to the surface contains pollutants (stinky sulfur)

■Location restricted: Must be at convergence of tectonic plates.

Disadvantages of Geothermal■Earth’s crust must be

thin■Hot rocks and water

must be close to earth’s surface.

1. Hot water is pumped from deep underground through a well under high pressure.

2. When the water reaches the surface, the pressure is dropped, which causes the water to turn into steam.

3. The steam spins a turbine, which is connected to a generator that produces electricity.

4. The steam cools off in a cooling tower and condenses back to water.

5. The cooled water is pumped back into the Earth to begin the process again.

1. Water or a refrigerant moves through a loop of pipes.

2. When the weather is cold, the water or refrigerant heats up as it travels through the part of the loop that's buried underground.

3. Once it gets back above ground, the warmed water or refrigerant transfers heat into the building.

4. The water or refrigerant cools down after its heat is transferred. It is pumped back underground where it heats up once more, starting the process again.

5. On a hot day, the system can run in reverse. The water or refrigerant cools the building and then is pumped underground where extra heat is transferred to the ground around the pipes.