Energy is defined as the ability or the capacity to do work.
The discovery of fire by humans led to the possibility of burning wood for cooking
and heating thereby using energy. For several thousand years human energy demands
were met only by renewable energy sources—sun, biomass (wood, leaves, twigs), water
and wind power.
As early as 4000–3500 BC, the first sailing ships and windmills were developed harnessing
wind energy. With the use of hydro power through water mills or irrigation systems,
things began to move faster. Fuelwood and dung cakes are even today a major source
of energy. Solar energy is used for drying and heating.
With the advent of the Industrial Revolution, the use of energy in the form of fossil
fuels began growing as more and more industries were set up. This occurred in stages,
from the exploitation of coal deposits to the exploitation of oil and natural
gas fields. More recently nuclear
power began being used as an energy source.
It has become evident that the consumption of non-renewable sources of energy causes
enviromental damage through human activity. Electricity generated from fossil fuels
such as coal and crude oil has led to high concentrations of harmful gases in the
atmosphere. This has in turn led to problems such as ozone depletion and global
warming. Vehicular pollution is also a grave problem.
There has been an enormous increase in the demand for energy since the middle of
the last century as a result of industrial development and population growth. World
population grew 3.2 times between 1850 and 1970, per capita use of industrial energy
increased about twentyfold forms combined increased more than twelvefold.
Due to the problems associated with the use of fossil fuels, alternative sources
of energy have become important and relevant in today’s world. These sources, such
as the sun and wind, can never be exhausted and are therefore called renewable.
Also known as non-conventional sources of energy, they cause less emission and are
available locally. Their use can significantly reduce chemical, radioactive, and
thermal pollution. They are viable sources of clean and limitless energy.
Most of the renewable sources of energy are fairly non-polluting and considered
clean. However, biomass is a major polluter indoors.
Renewable energy sources include the sun, wind, water, agricultural residue, fuelwood,
and animal dung. Fossil fuels are non-renewable sources. Energy generated from the
sun is known as solar energy. Hydro is the energy derived from water. Biomass –
firewood, animal dung, and biodegradable waste from cities and crop residues – is
a source of energy when it is burnt. Geothermal energy is derived from hot dry rocks,
magma, hot water springs, natural geysers, etc. Ocean thermal is energy derived
from waves and also from tidal waves.
Total commercial energy consumption has been growing tremendously since the last
decade. Per capita commercial energy consumption in low-income countries have more
than doubled. About 15% of the world's population living in the wealthy industrialized
nations consume over half the energy used in the world. The number of motor vehicles
in use worldwide has more than doubled since 1970.
In some respects, the global energy system has evolved in a cleaner direction in
the last 25 years. The share of world primary energy derived from natural gas –
the cleanest fossil fuel – has increased by more than 25%. So has the use and generation
of renewable energy sources.
Still, the overall efficiency of energy production remains extremely low: on average,
more than 90% of energy consumed is lost or wasted in the process of conversion
from raw materials such as coal to the final energy service such as the light to
read a book. The main problem isn’t that we use energy, but how we produce and consume
energy resources.
Source: Energy Quest
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