Pharos University
Faculty of Engineering
Petrochemical Department
‫جامعه فاروس‬
‫كلية اهلندسة‬
‫قسم البرتوكيماوايت‬
PE 330 ENERGY CONSERVATION
LECTURE (10)
Renewable Energy Sources
Renewable energy sources also called non-conventional
energy, are sources that replenish themselves, and are
continuously present. A renewable energy system converts
the energy found in sunlight, wind, falling-water, seawaves, geothermal heat, or biomass into a form, we can
use such as heat or electricity.
 However, most of the world's energy sources are derived from
conventional sources-fossil fuels such as coal, oil, and natural
gases. These fuels are often termed non-renewable energy
sources. Although, the available quantity of these fuels are
extremely large, they are nevertheless finite and so will in
principle ‘run out’ at some time in the future
 Renewable energy sources are essentially flows of energy,
whereas the fossil and nuclear fuels are, in essence, stocks of
energy .
 They supply about 3% of worlds energy, on the other hand,
fossil fuels supply 90%, and nuclear 7%.
2-Various forms of renewable energy
 Solar energy
 Wind energy
 Biomass energy
 Hydroelectric energy
 Geothermal energy
 Tidal/Oceanic energy
 Waste to energy
2.1 Solar energy
 Sunlight is the most abundant energy source on the earth
 On average, the earth's surface receives about 1.2 x 1017 W
of solar power.
 Solar energy is utilized in three ways:
Passive heating
Active heating
Solar generated electricity
2.1.1 Solar passive heating
Suns energy is converted directly to heat energy when it is
absorbed by a surface based on design, construction
materials, energy is captured and used on site.
No moving parts
No energy is used to transfer heat within system.
No operating costs.
Practical only in new constructions.
2.1.2 Solar Active Heating:
Suns energy is converted into heat, but transported
elsewhere to be used.
It requires the following:
Solar collector
Pump
System of pipes
Operation and maintenance costs are high.
 Solar collectors transfers suns energy to liquid filled
tubes.
Tubes carry warm liquid to area to be heated.
Heat from liquid filled tubes is transferred to areas to
be heated or transferred to water that needs to be
heated.
Heat developed liquid in liquid-filled tubes is recirculated to solar collectors.
2.1.3 Solar generated electricity:
Process of converting solar energy directly into
electrical energy by use of photovoltaic (PV) cell.
Sunlight energizes electrons, in a transparent wafer
containing a semi conductor material, causing the
electrons to flow, creating electrical current that
produces tiny amount of energy.
To produce significant amount of electricity, many
semi conductors must be wired together in modular
panels.
2.2 Hydro-electric Energy
 Using flowing water to generate electricity.
 It is used widely nowadays.
 It was used before to power some machines as:
Grain mills
Saw mills
Machines for textile industry
2.3 Tidal and Ocean Energy:
 Tidal energy:
The head of water is then used to drive turbines to generate electricity
from the elevated water in the basin as in hydroelectric dams.
Ocean Energy :
 Oceans cover more than 70% of Earth’s surface, making them the
world’s largest solar collectors. Ocean energy draws on the energy of
ocean waves, tides, or on the thermal energy (heat) stored in the
ocean. The sun warms the surface water a lot more than the deep
ocean water, and this temperature difference stores thermal energy.
 The ocean contains two types of energy: thermal energy from the
sun’s heat, and mechanical energy from the tides and waves.
 Ocean thermal energy is used for many applications, including
electricity generation.
2.4 Wind Energy:
 Wind contains kinetic energy
 The higher the wind speed ,the higher the kinetic
energy
 Kinetic energy of the wind→ rotor( blades with an
aerodynamic profile) → transmits the rotational
motion via a gear set to the generator → power
2.5 Geothermal energy
 Earths core temperature is about 4400 ºC
 Natural heat extracted from the earth's crust ,which
originates deep in the earth's molten interior ,
responsible for volcanoes and earthquakes in some
areas is close to the surface .
 This heat could heat underground water and form
steam used to generate electricity.
2.6 Biomass Energy:
 Biomass is any accumulation of organic material produced
by living organisms.
 Utilization of organic waste to produce energy
 Chemical energy stored in plants and animals or in the
animal waste is called bio-energy
 Burning of the biomass will release the energy which can
be used as:
Source of heat
Produce electricity
Converted to alcohol
Used to produce methane.
2.7 waste to energy:
 It is defined as the use of municipal waste as a source
of energy.
 Waste energy concerns with:
Air pollution
Formation of toxic compounds such as toxins.