Renewable EnergyRenewable Energy

What is the meaning of renewable What is the meaning of renewable energy?energy?

Why is there a need for alternative Why is there a need for alternative sources of energy?sources of energy?

Renewable EnergyRenewable Energy

Renewable energyRenewable energy is energy which is energy which comes from natural resources such as comes from natural resources such as sunlight, wind, rain, tides, and sunlight, wind, rain, tides, and geothermal heat, which are renewable geothermal heat, which are renewable (naturally replenished).(naturally replenished).

Renewable EnergyRenewable Energy

Wind powerWind power HydropowerHydropower Solar energySolar energy BiomassBiomass BiofuelBiofuel Geothermal energyGeothermal energy

How can one of this source of energy How can one of this source of energy be employed in one area of your life?be employed in one area of your life?

Future of Future of TransportationTransportation

In the coming decades, transportation is expected to change radically in response to environmental constraints, fluctuating oil availability and economic factors.

Future Decision-Future Decision-MakersMakers

The transportation systems that emerge in the 21st century will be defined largely by the choices, skills and imaginations of today’s youth.

Solar Car CIDSolar Car CID

Generate Generate enthusiasm for science and engineering enthusiasm for science and engineering at a crucial stage in the educational development of at a crucial stage in the educational development of young people. young people.

Improve students' Improve students' understanding of scientific understanding of scientific concepts and renewable energy technologiesconcepts and renewable energy technologies; and ; and

Encourage young people to Encourage young people to consider technical consider technical careerscareers at an early age. at an early age.

Solar Car CIDSolar Car CID Students use Students use mathematics and science mathematics and science

principles together with their principles together with their creativitycreativity in in a fun, a fun, hands-onhands-on educational program educational program

Using Using engineering principlesengineering principles, students , students get excited about generating ideas in a get excited about generating ideas in a group and then building and modifying group and then building and modifying models based on these ideasmodels based on these ideas

Students can see for themselves Students can see for themselves

how changes in design are how changes in design are

reflected in car performancereflected in car performance

Solar Car CIDSolar Car CID

This CID challenges students to use scientific know-how, creative thinking, experimentation, and teamwork to design and build high-performance model solar vehicles.

Solar Car CIDSolar Car CIDWhat is involved in this CID:What is involved in this CID:Understanding of world issues: Understanding of world issues:

Alternative energy sourcesAlternative energy sourcesApplication of Physics:Application of Physics:

AerodynamicsAerodynamics ForceForce MotionMotion

TeamworkTeamworkHow design effects functionHow design effects functionProblem solvingProblem solving

What Teachers are What Teachers are looking out forlooking out forHighly motivated students Highly motivated students who accepts who accepts

and works on the challenge with excitementand works on the challenge with excitementStudents Students thinking on their feet and thinking on their feet and reacting quicklyreacting quickly

PerseverancePerseverance to complete the task and to complete the task and improve on their carimprove on their car

Active participation Active participation in a competitive in a competitive situationsituation

MissionMission

Construct a car from Construct a car from raw materials raw materials that that can run on solar energy. can run on solar energy.

Your car should Your car should resemble an animalresemble an animal..

Mission TaskMission Task

To build a solar car that To build a solar car that resembles an resembles an animalanimal and can and can

race in the shortest time to complete a 2.0 m race in the shortest time to complete a 2.0 m horizontal track,horizontal track,

race the greatest height up a small inclined of race the greatest height up a small inclined of 303000..

Some solar cars

4 Assessments4 Assessments

Group reportGroup report Individual reportIndividual report Oral PresentationOral Presentation Mission Task AssessmentMission Task Assessment

First TaskFirst Task

Get into groups of 3.Get into groups of 3. Elect a leader amongst you.Elect a leader amongst you. Submit the names of group members Submit the names of group members

(and class) to me – indicate the leader. (and class) to me – indicate the leader.

End

Accomplish MissionsAccomplish Missions

The faster it moves the more kinetic The faster it moves the more kinetic energy the shorter it the time taken to energy the shorter it the time taken to travel the specified distance.travel the specified distance.

The faster it moves the more kinetic The faster it moves the more kinetic energy it has the further is will rise up the energy it has the further is will rise up the incline as the kinetic energy is converted to incline as the kinetic energy is converted to gravitational potential energy.gravitational potential energy.

What is a solar panel made What is a solar panel made of ?of ? Solar panels are composed of and can be made of Solar panels are composed of and can be made of

various semi conducting materials, especially Silicon. various semi conducting materials, especially Silicon. These are in layers which consist of different types of These are in layers which consist of different types of

Silicon – mono crystalline Silicon, Polycrystalline Silicon – mono crystalline Silicon, Polycrystalline Silicon and Amorphous Silicon – and there is a Silicon and Amorphous Silicon – and there is a transparent anti-reflection film that protects the cell transparent anti-reflection film that protects the cell and decreases the reflective loss on the surface of and decreases the reflective loss on the surface of the cell and panel. the cell and panel.

The different types of Silicon increase the efficiency The different types of Silicon increase the efficiency of the solar cell and they are more cost efficient of the solar cell and they are more cost efficient compared to using pure Silicon.compared to using pure Silicon.

How does Solar Cell work?How does Solar Cell work?

Semi-conductors like silicon and germanium are not Semi-conductors like silicon and germanium are not very conducting in its pure form.very conducting in its pure form.

Doping is a process of adding impurities into the Doping is a process of adding impurities into the semi-conductors semi-conductors

The solar cells are produced by “doping” and when The solar cells are produced by “doping” and when the different layers of the silicon or other semi the different layers of the silicon or other semi conductors are combined, a so called p-n-junction conductors are combined, a so called p-n-junction will be formed on the boundary of the layers. will be formed on the boundary of the layers.

At these junctions, an interior electric field is built up At these junctions, an interior electric field is built up which causes the charge carriers that are released which causes the charge carriers that are released by light to be separated. And when an electrical load by light to be separated. And when an electrical load is connected, an electric current will flow.is connected, an electric current will flow.

Doping Semi-conductors

Doping • In doping, the electrical properties of the semiconductors are

permanently modified by introducing impurities. Usually, it is sufficient to approximate that each impurity atom adds one electron or one "hole" that may flow freely.

• Upon the addition of a sufficiently large proportion of impurity dopants, semiconductors will conduct electricity nearly as well as metals.

• Depending on the kind of impurity, a doped region of semiconductor can have more electrons or holes, and is named N-type or P-type semiconductor material, respectively.

• As mentioned before, the junctions between regions of N- and P-type semiconductors create electric fields, which cause electrons and holes to be available to move away from them, and this effect is critical to semiconductor device operation.

• Also, a density difference in the amount of impurities produces a small electric field in the region which is used to accelerate non-equilibrium electrons or holes.

A solar panel

Photovoltaic effect• The solar cells works in what is known as the photovoltaic effect. • The photovoltaic effect is the basic physical process through

which a PV cell converts sunlight into electricity. • Sunlight is composed of photons--packets of solar energy. • When photons strike a PV cell, they are either reflected or

absorbed, or they may just pass right through. • The absorbed photons generate electricity. Their energy is

transferred to an electron in an atom of the semiconductor device.

• With its newfound energy, the electron is able to escape from its normal position associated with a single atom in the semiconductor to become part of the current in an electrical circuit.

• Special electrical properties of the PV cell have a built-in electric field that provides the potential different to drive the current through an external load.

Photovoltaic Effect

Factors that affect the efficiency of the Solar Panels

• Factors that can affect current output which will then determine how fast a car runs are light intensity, temperature and surface area of exposure and angle of incidence of the sun’s rays.

• While light intensity is one of the factors which affect current output, the dominant factor which greatly increased the current output is temperature.

• However, there is also an optimum range of temperature for each solar cell and an increase surface area of exposure can increase the power output of the solar cells.

Power output against temperature of the solar cells

Power Output against temperature• The amount of output (product of current and

voltage) of a solar cell is determined by two main factors, mainly light intensity and temperature.

• However, temperature affects the output more, compared to light intensity.

• The hotter the solar panel, the lower the power output.

• In other words, higher cell temperatures lead to lower output, and hence to lower efficiency.

• The optimum temperature that achieves the maximum output is 30 0C to 43 0C for this particular solar panel.

Power output against light intensity

• As for light intensity, the higher the light intensity, the larger the output. However, the output obtained is a lot lesser than the output obtained from higher temperatures. Therefore, the dominant factor for the efficiency of the solar panel is temperature and not so much of light intensity.

Parallel connection of Solar Panels•In parallel arrangement, the current output is equal to current in the branches while the voltage is constant.  For example, if we have cells that are 0.5 V each and 0.1 A each then:Atotal = A1 + A2

= 0.1 A + 0.1 A

= 0.2 A Power = 0.5 V x 0.2

A = 0.1 Watt

Series ConnectionHowever, if the arrangement is in series, the voltage is sum of the voltage of each cell while the current is constant. This can be shown through this:Vtotal = V1 + V2

Vtotal = 0.5 V + 0.5 V

= 1.0 VPower = 1.0 V x 0.1 A = 0.1 Watts