Quick view about energy scources and these types, Solar System and its problems By: Ali Reda

1. Environmental Physics
Lecture 5
Prepared by: Ali Reda
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2. Solar Energy
The Renewable Energy Resources
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But,What’s the energy?

3. Forms of Energy
• Energy has a number of different forms, all of which measure the ability
of an object or system to do work on another object or system. Here are
the different basic forms:
Kinetic Energy.
Heat energy.
Chemical Energy.
Electrical Energy.
Sound Energy.
Nuclear Energy. 3

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Energy cannot be destroyed or created.
Energy can be changed from one form to another.
 Burning match: chemical to heat and light.
 Portable torch: chemical to heat and light.
 Microphone: sound to electrical.
 Radio: electrical to sound and heat.
 Television: electrical to sound and light and heat.
 Catapult: elastic to kinetic and heat.
 Mobile phone: chemical to sound and microwaves
(EM radiation) and heat.
 Car: chemical to kinetic and sound and heat.

5. In every transformation from a form to
another, there is a lose in the energy.
• Energy is measured in (The unit of energy) Joules (J).
• We define term “Efficiency” as
Useful energy transferred by a device
Total energy supplied to a device
× 100
• Also, we define term “Power” as the energy (work) per unit time.
• Power is measured in Walt (W).
1 Walt means 1J per 1 sec
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6. Inside a fossil fuel power station
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The national grid
How do we get the electricity?

7. We can get the energy from
• Coal (The most unfriendly-enviro resource)
• Earth (From hot rocks deep inside the Earth)
• Water (Generating energy by waves)
• Sun (Using solar cells; our lecture )
• Wind (The amount of energy depends on the amount of
wind, using an electricity generator on top of a tall tower).
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8. Energy
Resources
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9. There are two types of energy resources
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10. The Sun
•The Sun is the original source of most energy
resources.
•Plants store the Sun’s energy through
photosynthesis. Animals then eat the plants.
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11. Light to Electricity ... How?
In 1905, Albert Einstein solved this
apparent paradox by describing light as
composed of discrete quanta, now called
photons. A photon above a threshold
frequency has the required energy to
eject a single electron, creating the
observed effect.This discovery led to the
quantum revolution in physics and
earned Einstein the Nobel Prize in
Physics in 1921.
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12. Scientists used the
idea of photoelectric
effect to make
electrons emitted
from the surface of
the materials.
Using the waves that
come from the sun,
we can generate
current.
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13. Why Sun?!
• Solar energy is the radiation from the Sun that reaches Earth. It powers
photosynthesis in green plants and is ultimately the source of all food and
fuel.
• The amount of solar energy that strikes the Earth each day is 10,000 to
15,000 times greater than our daily energy needs.
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14. For hundreds of years, people have wanted to harness
the sun’s power for weapons, heating, and many other
uses to make their lives more comfortable.
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15. Meanwhile, there is one energy source that is free and
inexhaustible. It’s like a giant nuclear reactor – only this
one is located 93 million miles away. It is calledThe Sun
• The first solar water heating collector appears to have been built in the 18th
Century by a Swiss scientist who constructed a simple wooden box with a
glass top and a black base. It trapped solar energy, and the collector
reached a temperature of 190 degrees Fahrenheit
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16. Types of solar cells
1.Solar-
generated
electricity -
Photovoltaics
(PV)
• First is solar-generated electricity.
• Photovoltaics are solar cells that convert sunlight to
D.C. electricity.
• The solar cells in a PV module are made from
semiconductor materials.
• Electrical conductors attached to the positive and
negative sides of the material allow the electrons to be
captured in the form of a D.C. current.
• This electricity can then be used to power a load, such
as a water pump, or it can be stored in a battery.
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17. Uses of PV
• In fact, water pumping is one of
the simplest and most appropriate
uses for photovoltaics. From crop
irrigation to stock watering to
domestic uses, photovoltaic-
powered pumping systems meet a
broad range of water needs. Most
of these systems have the added
advantage of storing water for use
when the sun isn’t shining,
eliminating the need for batteries,
enhancing simplicity and reducing
overall system costs. 17

18. Types of solar cells
2. Getting heat
from the sun
• Drying crops and grains by simply exposing them to
the heat of the sun is one of the oldest and most widely
used applications of solar energy. But allowing crops to
dry naturally in the field exposes them to the elements
and contamination as well as birds and insects.
• Another use of solar energy for higher agricultural
productivity is water heating particularly in livestock
operations.
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20. How do solar cells work?
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21. Efficiency
of a solar
cell
• Solar cells suffer from a low efficiency.This is
because only light with enough energy causes
an electron to be released which is only about
25% of all sunlight.
• The amount of electricity a solar panel can
produce depends on two factors: its surface
area and the light intensity.
• Producing enough electricity to power a town
would require a very large area of solar panels
but covering the roof of a house can meet the
annual electricity needs of the household.
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22. Problems of solar cells
Simply, the is no sun at
night
Then, they do not produce
electricity at night.
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23. Solar Power station
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© Sandia National Laboratory/NREL
© Bill Timmerman/NREL
© Warren Gretz/NREL

24. ThankYou
08 Nov. 2016
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