In physics, energy is an indirectly observed quantity
that is often understood as the ability of a physical
system to do work on other physical systems.
Since work is defined as a force acting through a distance
(a length of space), energy is always equivalent to the
ability to apply pulls or pushes against the basic forces
of nature, along a path of a certain length.
Sun is only one source of energy for the planet: Earth.
The radiant energy of sun in the form of
electromagnetic waves are released from the sun
during the transmutation of hydrogen to helium and
are converted in to chemical energy. This energy
required by all living organisms.
This chemical energy stored in the food of living
organisms is converted in to potential energy by the
arrangement of the constituent atoms of food in a
Energy exists in two forms:
1. Potential energy is energy stored in matter.
i.e. stored energy
2. kinetic energy is motion energy
i.e. free energy.
Law of Thermodynamics
The first law of Thermodynamics:
It states that the amount of energy in the universe is
constant. It may change from one form to another, but it
can neither be created nor destroyed.
Light energy can be neither created nor destroyed as it passes
through the atmosphere.
Law of Thermodynamics
The second law of Thermodynamics:
It states that non-random energy (mechanical, chemical,
radiant energy) cannot be changed without some
degradation into heat energy.
The change of energy from one from to another takes place
in such a way that a part of energy assumes waste form. In
this way, after transformation the capacity of energy to
perform work is decreased. Thus energy flows from higher
to lower level.
Types of Energy
Nonrenewable energy is energy that
comes from the ground and is not
replaced in a relatively short period of
Non-renewable sources of energy can be
divided into two types:
1. Fossil fuels: Fossil fuels include; coal, oil
and natural gas. These resources come
from animals and plants that have died
millions of years ago and then
decomposed to create a useable source of
energy for humans.
2. Nuclear fuel: Nuclear fuel makes use of
the radioactivity of some elements.
Fossil fuels are fuels formed by natural processes such
as anaerobic decomposition of buried dead organisms.
The age of the organisms and their resulting fossil
fuels is typically millions of years, and sometimes
exceeds 650 million years.
Coal, oil and natural gas are fossil fuels.
Coal: Total Global Coal Production (including hard
coal and lignite):
- 7678 Mt (2011)
- 7201 Mt (2010)
- 4677 Mt (1990)
Oil: Oil is any neutral chemical substance that is a
viscous liquid at underground temperatures,
is immiscible with water but soluble in
alcohols or ethers.
Oils have a high carbon and hydrogen content and are
usually flammable and slippery . Oils may be
originated from animal, vegetable, or petrochemical .
It can be volatile or non-volatile.
The use of nuclear technology requires
a radioactive fuel. Uranium ore is present in the ground at
relatively low concentrations and mined in 19 countries.
This mined uranium is used to fuel energy-generating
nuclear reactors with fissionable uranium-238 which
generates heat that is ultimately used to power turbines to
Nuclear power provides about 6% of the world's energy and
13–14% of the world's electricity
Nuclear energy is produced in two different ways:
Nuclear Fission: In nuclear fission, the nuclei of atoms are
split, causing energy to be released. The atomic bomb and
nuclear reactors work by fission. The element uranium is
the main fuel used to undergo nuclear fission to produce
energy since it has many favorable properties.
Uranium nuclei can be easily split by shooting neutrons at
them. Also, once a uranium nucleus is split, multiple
neutrons are released which are used to split other uranium
nuclei. This phenomenon is known as a chain reaction.
Nuclear Fusion: In nuclear fusion, the nuclei of
atoms are joined together, or fused. This happens only
under very hot conditions. The Sun, like all other
stars, creates heat and light through nuclear fusion. In
the Sun, hydrogen nuclei fuse to make helium.
The hydrogen bomb, humanity's most powerful and
destructive weapon, also works by fusion. The heat
required to start the fusion reaction is so great that
an atomic bomb is used to provide it. Hydrogen nuclei
fuse to form helium and in the process release huge
amounts of energy thus producing a huge explosion.
Renewable energy is energy that comes from resources
which are continually restocked by natural process.
Types of renewable energy:
Water (tides, waves, hydropower)
Sunlight (solar energy): Solar power is the conversion
of sunlight into electricity, either directly by using
photovoltaics (PV) cell, or indirectly by using concentrated
solar power (CSP).
PV convert light into electric current using the photoelectric
effect. The world largest PV plants are Agua Caliente Solar
Project(over 200 MW) in the United States, and Charanka
Solar Park (214 MW) in India.
CSP use lenses or mirrors and tracking systems to focus a
large area of sunlight into a small beam.
Largest CSP is located in ‘Mojave Desert’ of California which
has capacity to produce 354 MW electricity.
Wind: Wind power is the conversion of wind energy into a
useful form of energy, such as using –
Wind turbines to make electrical power,
Wind mills for mechanical power,
Wind pumps for water pumping or drainage,
Sails to propel ships.
Wind turbines: A wind farm is a group of wind
turbines in the same location used to produce electric
Largest operational on shore wind farms are located in
the United States and China. The Gansu Wind Farm in
China has over 5,000 MW capacity which has installed
with a goal of 20,000 MW by 2020.
Windmill: windmill is a machine that converts
the energy of wind into rotational energy.
This mills are used for milling grain, pump water for
land drainage etc.
Water: Hydropower or water power is power derived
from the energy of falling water, which may be exploited
for useful purposes.
Hydroelectricity is the term referring
to electricity generated by hydropower.
The production of electrical power through the use of the
gravitational force of falling or flowing water. It is the
most widely used form of renewable energy.
Geothermal: Geothermal energy is the heat from the Earth (fig
1). Resources of geothermal energy range from the shallow ground
to hot water and hot rock found a few
miles beneath the Earth's surface, and
down even deeper to the extremely
high temperatures of molten rock called
magma. Earth's geothermal energy
originates from the original formation of
the planet (20%) and from radioactive
decay of minerals (80%).
Tire rubber from plant
Wageningen UR Food &
Biobased Research, developed
a rubber extraction process
from the roots of Russian
Dandelions (Taraxacum koksghyz).
Analysis showed that pure rubber with good quality was
obtained. With this rubber, Apollo Vredestein has produced the
first tires that contain natural rubber from Europe. The tires will
undergo extensive testing over the coming months.
Pork meat grown in the laboratory
The scientists, led by Professor of
Physiology Dr. Mark Post, made pork meat
in his laboratory. The meat, grown from
bovine stem cells into strips of muscle,
is the first made from a petri dish and
costs around $393,000.
The meat muscle grown in a lab in the Netherlands, then mixed with
layers of fat, also grown in the lab, to make the burger.
Dr Mark Post, of the Maastricht University in the Netherlands, said his
objective is to recreate meat but with a more resource-friendly approach.
It can also reduce animal suffering and can provide food safely.