about energy; various information about energy. source, uses,types and so on. mainly for electrical and mechanical engineering student.

1. Thermal Engineering
ME-1105
Energy
Dr. Sobahan Mia
Professor
Department of Mechanical Engineering
Khulna University of Engineering & Technology

2. Energy
• In physics, energy is a property of objects, transferable among
them via fundamental interactions, which can be converted in
form but not created or destroyed.
• The joule is the SI unit of energy, based on the amount
transferred to an object by the mechanical work of moving it 1
meter against a force of 1 Newton.

3. Forms of energy
Type of energy Description
Kinetic that of the motion of a body
Potential A category comprising many forms in this list
Mechanical the sum of (usually macroscopic) kinetic and potential energies
Mechanical wave a form of mechanical energy propagated by a material's oscillations
Chemical that contained in molecules
Electric that from electric fields
Magnetic that from magnetic fields
Radiant that of electromagnetic radiation including light
Nuclear that of binding nucleons to form the atomic nucleus
Ionization that of binding an electron to its atom or molecule
Elastic that of deformation of a material (or its container) exhibiting a restorative force
Gravitational that from gravitational fields
the rest energy that equivalent to an object's rest mass
Thermal A microscopic, disordered equivalent of mechanical energy
Heat
an amount of thermal energy being transferred (in a given process) in the direction of decreasing
temperature
Mechanical work
an amount of energy being transferred in a given process due to displacement in the direction of an
applied force

4. World Energy Situation

6. Energy Situation
The world uses a lot of energy –
-Average power consumption = 17 TW (2.5 KW per person)
-World energy market ~ $3 trillion / yr (electricity $1 trillion / yr)
The world energy use is growing
– To lift people out of poverty, to improve standard of living, and to meet
population growth
Climate change and debilitating pollution concerns are on the rise
– 80% of energy is generated by fossil fuels
– CO2 emission is increasing at an alarming rate
Oil supplies are dwindling
– Special problem for transportation sector (need alternative fuel)

7. Conventional Sources of Energy
I. The sources of energy which have been in use for a long time, e.g., coal,
petroleum, natural gas and water power.
II. They are exhaust able except water.
III. They cause pollution when used, as they emit smoke and ash.
IV. They are very expensive to be maintained, stored and transmitted as they
are carried over long distance through transmission grid and lines.
Non-Conventional Sources of Energy
I. The resources which are yet in the process of development over the past few
years. It includes solar, wind, tidal, biogas, and biomass, geothermal.
II. They are inexhaustible.
III. They are generally pollution free.
IV. Less expensive due to local use and easy to maintain.
Difference Conventional and Non-conventional energy

8. Mainly coal, oil, and natural gas are used as energy. Fossil fuels are non-
renewable. In contrast, the many types of renewable energy resources-such
as wind and solar energy-are constantly replenished and will never run out.
• Solar energy
• Wind energy
• Hydro energy
• Bioenergy
• Geothermal Energy
• Ocean Energy
Most renewable energy comes either directly or indirectly from the sun.
Sunlight, or solar energy, can be used directly for heating and lighting
homes and other buildings, for generating electricity, and for hot water
heating, solar cooling, and a variety of commercial and industrial uses.
The sun's heat also drives the winds, whose energy, is captured with wind
turbines. Then, the winds and the sun's heat cause water to evaporate.
When this water vapor turns into rain or snow and flows downhill into
rivers or streams, its energy can be captured using hydroelectric power.
Renewable Energy

9. Along with the rain and snow, sunlight causes plants to grow. The organic
matter that makes up those plants is known as biomass. Biomass can be used to
produce electricity, transportation fuels, or chemicals. The use of biomass for
any of these purposes is called bioenergy.
Hydrogen also can be found in many organic compounds, as well as water. It's
the most abundant element on the Earth. But it doesn't occur naturally as a gas.
It's always combined with other elements, such as with oxygen to make water.
Once separated from another element, hydrogen can be burned as a fuel or
converted into electricity.
Not all renewable energy resources come from the sun. Geothermal energy taps
the Earth's internal heat for a variety of uses, including electric power
production, and the heating and cooling of buildings. And the energy of the
ocean's tides come from the gravitational pull of the moon and the sun upon the
Earth.
In fact, ocean energy comes from a number of sources. In addition to tidal energy, there's
the energy of the ocean's waves, which are driven by both the tides and the winds. The
sun also warms the surface of the ocean more than the ocean depths, creating a
temperature difference that can be used as an energy source. All these forms of ocean
energy can be used to produce electricity.

10. Real problems: Alternatives to conventional fossil fuels all have liabilities
& limitations
• Traditional biofuels (fuelwood, charcoal, crop wastes, dung) create huge
indoor air-pollution hazard
• Industrial biofuels (ethanol, biodiesel) can take land from forests & food
production, increase food prices
• Hydropower and wind are limited by availability of suitable locations,
conflicts over siting
• Solar energy is costly and intermittent
• Nuclear fission has large requirements for capital & highly trained
personnel, currently lacks agreed solutions for radioactive waste & links to
nuclear weaponry
• Nuclear fusion doesn’t work yet
• Coal-to-gas and coal-to-liquids to reduce oil & gas imports doubles CO2
emissions per GJ of delivered fuel
• Increasing end-use efficiency needs consumer education.