ENERGY

Almost all energy we use comes originally from the sun.

We use energy sources to generate electricity.

There are two types of energy -- stored (potential) energy and working (kinetic) energy.

Radiation, conduction, convection

Conduction, convection and radiation are the three major methods of heat transfer.

They are the three different ways that heat can spread.

Conduction is the transfer of heat through an object.

When something is heated the atoms start to move faster.

As they move faster they collide with atoms next to them, which collide with atoms next to them.

This creates a chain reaction that actually moves the heat along a path, outward from the starting point where the heat was added.

This is what's happening if you've ever set a pan on the stove.

The handle gets warm even though only the bottom touches the burner because the metal conducts the heat.

heat travels from candle to metal rod to hand

Convection is the transfer of heat energy by movement of currents.

It causes currents of warm and cool air to move and occurs in liquids and gases.

You may have heard of the phrase “hot air rises”.

This is convection.

Heat leaves a coffee cup as the currents of steam and air rise.

The heat moves with the fluid.

Radiation has to do with light.

One of the most important types of radiation we receive on earth is from the sun.

The sun sends waves of heat through space to warm our planet.

Only about 51% of the sun’s rays are absorbed by the earth

The light that you see is actually made up of waves.

When something is hot, like the burner on your stove, it releases some of its energy in the form of waves.

The waves travel through the air until they hit something, which gets heated up.

This is why you can feel the heat from your stove even if your hand isn't actually touching it.

The burner literally 'radiates' heat.

The different forms of energy are stored in different ways.

Electrical energy cannot be stored directly.

Electrical energy can be indirectly stored by converting the electrical energy to some other form of energy ("storage" energy).

When a supply of electrical energy is required, the storage energy is reconverted back to electrical energy.

Large quantities of "storage" energy are difficult to store and reconvert.

Energy sources are divided into two groups –renewable (energy we can use over and over again) and nonrenewable (energy that we are using up and cannot recreate in a short period of time).

Renewable energy sources include solar wind, geothermal, biomass, and hydropower.

Another nonrenewable energy source is the element uranium, whose atoms we split (through a process called nuclear fission) to create nuclear energy.

Non- renewable Energy

Much of our current energy supply comes from coal, oil, natural gas, or radioactive elements.

They are considered non- renewable because once they are removed from the ground and used, they are not immediately replaced.

In fact, the world's natural gas, crude oil and coal deposits took millions of years to form

Petroleum Products Ink Crayons Bubble gum Dishwashing liquids Deodorant Eyeglasses CDs and DVDs Tires Ammonia Heart valves

RENEWABLEENERGY

Renewable energy refers to sources of energy that are always there.

You might think that we would be tapping these energy resources, but there is a catch.

While the energy is there, the cost of getting it is actually greater than using our more popular energy sources of fossil fuels and uranium.

An important advantage of renewable energy is that it produces much less pollution.

Renewable energy

Renewable sources of energy can be used over and over again

Renewable resources include solar energy, wind, geothermal energy, biomass and hydropower.

Solar energy comes from the sun.

Some people use solar panels on their homes to convert sunlight into electricity.

Wind turbines, which look like giant windmills, generate electricity.

Geothermal energy comes from the Earth's crust.

Engineers extract steam or very hot water from the Earth's crust and use the steam to generate electricity.

Biomass includes natural products such as wood, manure and corn.

These materials are burned and used for heat.

Dams and rivers generate hydropower.

When water flows through a dam it activates a turbine, which runs an electric generator.

GEOTHERMAL

Our earth's interior - like the sun - provides heat energy from nature.

This heat - geothermal energy - yields warmth and power that we can use without polluting the environment.

Geothermal energy is residual heat of the earth.

The heat from the earth's core continuously flows outward.

This natural energy heats water trapped under the ground and releases it as steam or hot water.

Today we drill wells into the geothermal reservoirs to bring this hot water to the surface.

heat of steam from geothermal sources

areas geothermal sources

The hot water or steam can be used directly to cook and warm homes or it can be changed into electricity.

Steam turns turbine, which turns generator that produces electricity

Nuclear Energy

Well-constructed nuclear power plants have an important advantage -- they are extremely clean.

There are, however, significant problems with nuclear power plants.

Mining and purifying uranium has not, historically, been a very clean process.

Improperly functioning nuclear power plants can create big problems.

Chernobyl scattered tons of radioactive dust into the atmosphere.

Spent fuel from nuclear power plants is toxic for centuries, and, as yet, there is no safe, permanent storage facility for it

Transporting nuclear fuel to and from plants poses some risk.

These problems have largely stopped the creation of new nuclear power plants in the United States.

BIOMASS

The term "biomass" refers to any form of plant or animal tissue.

In the energy industry, biomass refers to wood, straw, biological waste products such as manure, and other natural materials that contain stored energy.

The energy stored in biomass can be released by burning the material directly, or by feeding it to micro-organisms that use it to make biogas, a form of natural gas.

the energy from 2 tons of garbage = 500 lbs of coal

Hydropower

Hydro means water. So, hydropower is "water power."

Top hydroelectric plants

Hydroelectric power, a renewable resource, is generated when hydraulic turbines are turned by the force of moving water as it flows through a turbine.

The water typically flows from a higher to a lower elevation.

These turbines are connected to electrical generators, which produce the power.

Wave energy- water is sent through channels which makes the waves stronger. The water then turns a turbine.

Solar Thermal Energy

The sun's heat can be used in two ways

The sun can heat water for domestic hot water systems, or the sun's light can be concentrated and water temperatures increased to make steam and electricity.

These solar thermal power plants rely upon curved mirrored troughs that concentrate sunlight.

The sun heats a liquid that creates steam to turn a traditional turbine.

solar panels in space

WIND ENERGY

Wind is created because of different heating of land and water areas by the sun creating movement of air from one area to another.

Man has been using the wind to do work for thousands of years.

The kinetic energy of the wind can be changed into other forms of energy, either mechanical energy or electrical energy.

Wind energy has been used for many years to pump water from wells and grind grains to make flour.

Windmills can be connected to a shaft which in turn is connected to a generator to make electricity.

Tidal turbines are similar to wind machines except it is the tide not the wind which causes the blades to turn. They are used in Europe but are not economical in the U.S.

Nuclear Energy

Nuclear power plants provide about 17 percent of the world's electricity.

Nuclear power is generated using uranium, which is a metal mined in various parts of the world.

Nuclear power stations work in pretty much the same way as fossil fuel- burning stations, except that a "chain reaction" inside a nuclear reactor makes the heat instead.

The reactor uses uranium rods as fuel, and the heat is generated by nuclear fission.

Neutrons smash into the nucleus of the uranium atoms, which split roughly in half and release energy in the form of heat.

This heat turns the water into steam.

Then the steam drives turbines which drive generators and produces electricity.

Modern nuclear power stations use the same type of turbines and generators as conventional power stations.

If the rods become uncovered by water, deadly radiation is released into the air and contaminates the area surrounding the plants for miles.

Nuclear waste can be stored in caves or in above ground cement and metal canisters. The radiation will remain deadly for thousands of years.

Mechanical energy can be transformed into electrical energy or thermal energy.

Examples include wind turbines (electrical energy) and refrigerators (thermal energy).

Electrical energy can be transformed into mechanical energy (using an elevator) or thermal energy (by using a space heater).