The Concept of Energy
Energy is the ability or capacity to do work. Its unit is Joules.
 
Types of Energy
Energy exists in various forms some of which are;
Mechanical energy
Chemical energy
Solar energy
Heat energy
Sound energy
Electrical energy
Nuclear energy
Mechanical Energy
Kinetic energy and potential energy constitutes mechanical energy. Kinetic energy is the energy a body possesses as a result of its motion. Potential energy on the other hand, is the energy possessed by a body because of its position. A body can also possess potential energy as a result of its nature. For example, an elastic material when stretched stores up energy (potential energy) which is given as ½ k e2 where k is what we call the elastic constant and e is extension in metres. Another form of potential energy is chemical potential energy which is energy stored up in a substance because of its chemical composition. Examples are; energy in the food we eat, electrolytes in cells or batteries.
Mathematically, Kinetic energy K.E=12(mv2).
M is mass in kilogram, v is velocity in m/s.
Examples of bodies that possess kinetic energy are
A rolling ball
An object falling under gravity
wind or air in motion
An athlete running a race
A bullet movement
A plane flying.
If a body  is raised to a height  h, its potential energy is given as
P.E = mgh. Where m is mass in kilogram, h is height in metres and g is acceleration due to gravity.
EVALUATION
Differentiate between potential energy and kinetic energy
What is the formula for calculating kinetic energy and potential energy
 The Law of Conservation of Energy
Energy as we have treated earlier exists in various forms. Although energy can be converted from one form to the other, the total energy remains conserved.
This is the law of conservation of energy. It states that energy can neither be created nor destroyed but can be converted from one form to the other.

Sources of Energy
The following are the sources of energy:
Energy from the sun (solar energy)
Wood (fire wood)
Coal
Electricity
Fossil fuels
Chemicals as in cells and batteries.
 
Classification of the Sources of Energy
Sources of energy can be classified into:
Renewable sources of energy: These sources are not usually depleted as a result of usage. e.g, solar energy, tidal waves, wind, waterfalls and dams.
Non renewable sources of energy: These sources are usually reduced as they are being used. E.g, fossil fuels-coal, oil, natural gas and wood.
 
Uses of Energy
Solar energy is a universal source of light to planet earth. The plants also use it to manufacture their own food through photosynthesis.
Fire wood gives heat for cooking our food.
Energy from coal is used to boil water, then, produce steam used in steam engines.
Energy from waterfalls is used in hydro-electric power stations like kanji dam to produce electricity.
Natural gas, petroleum, diesel oil, etc are all derived from fossil fuels.
Chemical energy from cells and batteries are used to power our electronics and phones.
EVALUATION
State five source of energy discussed.
What fuel can we derive from fossil fuels?
State three uses of energy.
 
Energy and Social Environment
The availability of electricity and petrol is very essential to every society. In fact, all lives on earth depend on the availability of energy. This is because all our electrical gadgets at home and in offices, big machines and engines in the factories and manufacturing industries, our day to day activities, all depend on the availability of energy.
In advanced countries like the USA, Japan, Canada, Russia, etc, the availability of electricity is everywhere. This has enhanced the economy of the countries and thus having a better Gross Domestic Products (GDP). The reverse is the case in the under-developing world like Nigeria, Liberia, Togo, etc where the availability of electricity is nothing to write home about. This has therefore jeopardized the economy, thus, giving rise to low GDP.
Energy is indeed needed in every society for the production of food, efficient transport system, good health programmes, good educational system, etc.
The need for energy availability in every society can never be over emphasized. In short, energy is a major factor to societal development.
 
The Impact of Energy Usage on the Environment
The impact of energy usage on the environment could be friendly or unfriendly.
The friendly impact is the display of light to give beauty to cities, at night and other significances; while the unfriendly impact include the hazardous radiations from nuclear reactors, gases from industries, etc which could be detrimental to human health.
Global Warming
Global warming is the rise in the average temperature of Earth’s atmosphere and oceans.Since the early 20th century, Earth’s mean surface temperature has increased by about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980.
Warming of the climate system is unequivocal, and scientists are more than 90% certain that it is primarily caused by increasing concentrations of greenhouse gases( like carbon (iv) oxide, methane, etc) produced by human activities such as the burning of fossil fuels and deforestation.
The Greenhouse Effect
The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in the atmosphere warm a planet‘s lower atmosphere and surface. It was proposed by Joseph Fourier in 1824, discovered in 1860 by John Tyndall,was first investigated quantitatively by Svante Arrhenius in 1896,and was developed in the 1930s through 1960s by Guy Stewart Callendar.
Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiation from CO2, methane, tropospheric ozone, CFCs and nitrous oxide. According to work published in 2007, the concentrations of CO2 and methane have increased by 36% and 148% respectively since 1750.
EVALUATION
What is green house effect?
The concept of green house effect was developed by who?
Mention any four countries of the world that has high GDP
Why do you think that the mentioned countries above have high GDP?
 Energy Crises
Meaning of Energy Crisis
An energy crisis is any great bottleneck (or price rise) in the supply of energy resources to an economy. It often refers to one of the energy sources used at a certain time and place, particularly those that supply national electricity grids or serve as fuel for vehicles.
There has been an enormous increase in the global demand for energy in recent years as a result of industrial development and population growth. Since the early 2000s the demand for energy, especially from liquid fuels, and limits on the rate of fuel production has created such a bottleneck leading to the current energy crisis.
Causes of Energy Crises
Market failure is possible when monopoly manipulation of markets occurs.
Large fluctuations and manipulations in future derivatives can have a substantial impact on price.
Pipeline failures and other accidents may cause minor interruptions to energy supplies
Oil Spillage

Meaning of Oil Spillage
Oil spillage is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is usually applied to marine oil spills, where oil is released into the ocean or coastal waters, but spills may also occur on land. Oil spills may be due to releases of crude oil from tankers, offshore platforms, drilling rigs and wells, as well as spills of refined petroleum products (such as gasoline, diesel) and their by-products, heavier fuels used by large ships such as bunker fuel, or the spill of any oily refuse or waste oil.
Spilled oil penetrates into the structure of the plumage of birds and the fur of mammals, reducing its insulating ability, and making them more vulnerable to temperature fluctuations and much less buoyant in the water. Cleanup and recovery from an oil spill is difficult and depends upon many factors, including the type of oil spilled, the temperature of the water (affecting evaporation and biodegradation), and the types of shorelines and beaches involved.Spills may take weeks, months or even years to clean up.
Causes of Oil Spillage
When oil tankers have equipment faults.
From nature and human activities on land.
Water Sports.
Drilling works carried out in sea.
 
EVALUATION
What are the causes of energy crises?
Define oil spill.
State two causes of oil spillage.
Define the concept of energy.
Why do you think that energy is one of the vital factors to societal existence?
Discuss the impact of energy use on environment.
Discuss the concept of global warming and the green house effect.
Enumerate the factors to be considered in cleaning up the water bodies as a result of oil spillage.