Renewable Energy Week

Renewable Energy Week

¡Discover how renewable energy systems workand craft your own prototypes!

From water to the lamp

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The force of wind

Crafting an electric engine

Sun provides light and... electricity!

TIMETABLE AND GROUP ORGANIZATION

Session S1

Session S2

Session S3

Session S4

Sustainable Development Goals (SDG) are comprised of 17 goals proposed by the United Nations for achieving a better and more sustainable future for all. You can find more about them by clicking here.

WORK TEAMS

4 PEOPLE GROUPSCHOOSE A NAME

THE ROLES:2 Engineers: Craft the project1 Scientist: Write the ''scientific sheet''1 Reporter: Search for relevant information

Alternative enrgy sourcesHoy do they work?

Two types

Photovoltaic

Thermosolar

Electricity is directly generated, when sun beams impinge

Electricity is generated indirectly. Sun beams are concentrated Heat Electricity

Wind moves the propeller Turbine moves Electricity is generated

Onshore (“on land”) Offshore (“out of land”, over the sea)

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Rotative shaft propeller-multiplicator.

Rotative shaftmultiplied-generator

Rotor blade, generally built with fibreglass. Wind drives the blades, so that, mechanical energy is produced. Fibreglass is made of numerous fibres randomly arranged and composed of silicon dioxide (SiO2).

This is the multiplier. It contains gears that speed up the rotational speed. Thus, more electricity is prpoduced within the electric generator. Gears: The small wheel speed is faster than the big wheel speed.

This is the electric generator. It transforms mechanical energy into electricity. The loop wire placed within a magnetic field, creates an induced electric current

Sea waves move the turbineElectricity

Waterfalls move the turbineElectricity

Subsoil heat is taken

Electricity

Farming and forest waste is processed at high temperatures

Gas with high methane content (CH4)

Electricity

Crafting an electric engine

Experiment: Low-cost compass

Socrative

Project: Electromagnetic engine

Scientific sheet

Experiment: Potato battery

Experiment: Potato battery

This basically consist on building a battery by using potatoes and wires for turning on a LED. Electric current generated comes from chemical reactions produced at the electrodes, as a consequence of the potential difference between zinc and copper metals.Anode (Zinc plated nail) ---------> Oxidation reaction Cathode (Copper coin) ----------> Reduction reaction

Scientific basis

Material

- 4 coins- 1 m of copper wire- 1 LED of 3V- 4 zinc plated nail- 4 potatoes

For each potato, hit a zinc plated nail on one end and a coin on the other. The coin and the nail of the next potato must be connected by a wire (repeat for all potatoes).Finally, connecting the nail of the first potato to one LED extreme, and the coin of the last potato to the other extreme.

Experimental method

Experiment: Low-cost compass

Due to the Earth's magnetic field, our planet behaves as a giant magnet. Thus, it will influence any compass, including a hand-made on.When a magnet is passed near a metal, its magnetic domains get reorganized, turning into another magnet.

Scientific basis

Material

- 1 tray - 1 or 2 needles- 1 cork bung/porexpan- A cup of water

Pass the magnet near the needle, always in the same direction. Pass the needle though a cork bung and let it float over a tray filled with water. Check if it points to the North, comparing its direction with a commercial compass.

Experimental method

N

MAGNETIZED

NON-MAGNETIZED

Experiment: Oersted experience

Ørsted’s law, or Oersted’s Law states that when a steady electric current passes through a wire it creates a magnetic field around it.

Scientific basis

Material

- 3 or 4 neodimium cylinder shaped magnets- Metal bar- Support - A piece o thread for the magnets- 5V battery- 2 alligator clip wires

Fix the magnets to the thread, and held it by a support.Put the metak bar (conductor) parallel and near the magnets. Connect the aligator clip wires to the battery and to the conductor. Check how the magnets move when electricity passes through the conductor.

Experimental method

Project: Electromagnetic engine

- Neodimium magnets (5-10 mm diameter aprox.)- Cooper wire- Foundation for the cooper loop (plastic cup, piece of wood, etc.)- Battery or power supply

Material

Experimental method

Roll cooper wire around a marker for the loop. One of the loop ends has to be completely sanded, while only a half of the other should get sanded. This will allow to keep the loop movement. Another two pieces of copper wire must be sanded to be the loop support. One of the extremes will be rolled as a hook, and the others will be connected to a battery. This supports should be assembled to a foundation. Finally, two magnets must be positioned at the foundation bottom. Then, loop is placed over the "hookes'' and battery terminals are connected. Propell the loop with your hands, and it will keep in movement.

Biot-Savart Law: It states that an electric current passing through a conductor generates a magnetic field around it. Concretely, the magnetic field created at the centre of a circular loop, can be expressed as: B (magnetic field); μ0 , vaccum magnetic permeability; I, current intensity passing through the loop; R, loop radius.The induced magnetic field tends to align with the magnetic field created by magnets placed near the loop. If the loop magnetic field induced is constantly changing, it keeps in movement.

Scientific basis

The force of wind

Experiment: Paper propeller

Experiment: Hand-made dynamo

Project: Wind propeller

Socrative

Scientific sheet

Experiment: Hand-made dynamo

- 2 Neodimium magnets (5-10mm diameter aprox.)- Cooper wire- Cardboard, plastic or PVC (for shaping the coil)- LED - Sand paper- Wood or metal shaft- Foam

Material

Experimental method

Roll enameled cooper wire around of a cylindrical surface. This must be wide enough to introduce magnets inside. The coil may have 400 loops, approx. The more loops it has, the higher current will be induced!Two holes must be previously done aiming to place a metal or wood stick, acting as a shaft and supporting the "inductor'' magnets. It is convenient that those magnet are well fixed to the shaft by means of a piece of wood or foam.Finally, the enamel of the coil extremes must be removed. A LED will be connected to the coil terminals, thus the current induced could be directly visualized.

The operation of a dynamo is based on electromagnetic induction. Concretely, Faraday's Law of induction, which states that the voltage or electromotive force (EMF), induced on a loop of wire is directly proportional to the magnetic flux (φ) variation which pass through the loop per unit of time (t). The mathematical expression that describes this phenomena is:This is essentially the basis of all the power plants electric generators.

Scientific basis

Experiment: Paper propeller

- Paper and propeller template- Wood or metal stick- 1 or 2 beads- Glue or silicon- Clay or plastic bottle (foundation)- 4 candles- Lighter or matches

Material

Experimental method

Create the paper propeller itself, by means of a template. The center of the propeller must be correctly defined, other way it is not stableChoose a stick for supporting the propeller. With the purpose of maintain the height of the propeller, it can be placed over a bead fixed to the stick.Finally, the propeller should have an enough resistant foundation such as piece of clay or a half filled bottle with a hole on the cover.Fire the candles and the paper propeller will start to move due to the convection phenomena.

Convection is one of the three mechanisms through which heat can be transferred. It requires a material media, and it is produced heat transfer between zones at different temperatures.Some examples are boiling water or home heating. The warmer fluid posses low density, thus it rises until getting colder and falling again. Newton's law of cooling mathematically describes such phenomena Q Heat T Temperature K Cooling parameter

Scientific basis

This experiment implies the use of FIRE.The TEACHER will perform itCAUTION

Project: Wind propeller

Material

Experimental method

Scientific basis

Experimental method depends on the wind propeller design, as well as material proposed.Generally, a wind propeller must count with blades, which can be crafted, for example, with plastic spoons or ice cream sticks. A support for that blades and a shaft are also necessary. It can be build on cardoard, CD's, etc. Depending on the design, the support and the shaft may be the same piece.The wind propeller can be crafted within a vertical or horizontal concept, like depicted in the images.

- Plastic spoons - Soda covers or ice cream sticks and pen- PVC or/and carboards or similar- Silicon gun

The scientific basis is the same as the one seen at "Hand-made dynamo" experiment, since a dynamo is used for switching on the LED. Click here for returnning back.Within this project, the mechanical energy provided by the wind turns into electricity at the dynamo output.

From water to the lamp

Experiment: Protoboard

Project: Small hydroelectric system

Socrative

Scientific sheet

Experiment: Protoboard

Material

Experimental method

Scientific basis

The scientific basis concerning this experience is Ohm’s law, which states that the relationship of electric potential difference (∆V), intensity of current (I) and resistance(R) can be described as follows:

∆V = I · R

- Protoboard itself- Wires- Resistors (at least two: 330 Ω and 1kΩ )- LED's (at least 1)- 5 V Power supply

First, assemble circuit a), the resistors and the LED are in series. Take the multimeter and place the terminals in points A and B, respectively. If measure is negative, change terminals position. Take note of potential difference, electric current (ask the teacher or search for information about how to connect the multimeter), and electric resistance of the resistors and LED. Then, verify Ohm's law. Assemble circuit b) and repeat the process with A-B and A'-B' points. Now resistors are in parallel and one resistor is in series with the LED. Which magnitudes have changed?

Project: Small hydroelectric system

Material

Experimental method

Scientific basis

The scientific basis is the same as the one seen at "Hand-made dynamo" experiment, since a dynamo is used for switching on the LED. Click here for returnning back to the explanation.Within this project, some energy transformations are involved, and they can be summarized as follows: Potential energy Kinetic energy Electric energy (water dammed) (water falling, shaft moving) (engine output)

- Plastic spoons or bottle covers and wood sticks- CD’s or plastic circles- Pulley system- Metal or wood stick for the shaft- 12 V engine- Tray to collect the water- Silicon gun

Experimental method depends on the waterwheel design, as well as material proposed.Basically, a waterwheel must count with blades, which can be crafted, for example, with plastic spoons or ice cream sticks. A support for that blades and a shaft are also necessary. It can be built with wood, CD's, etc. The shaft can be a metal or a wood stick. Finally, the waterwheel should be connected to an engine trough a pulley system or by directly linking the engine with the shaft. Remember to place the system into a tray and reuse the water.

Experiment: Magnifying glass

Experiment: Photovoltaic energy

Sun provides light and... electricity!

Berta needs your help!

Experiment: Stirling engine

Project: Solar oven

Socrative

Scientific sheet

Final Socrative

Bertha needs your help!

Experiment: Magnifying glass

Material

Experimental method

Scientific basis

Convex lenses are used in glasses for farsighted people. They can converge a beam of parallel rays to a point called "focus'' or "focal point'', placed on the other side of the lens.At this point, all the energy is concentrated, thus high temperatures are achieved when solar beams pass though the lens.

- Black cardboard or paper painted with a black pen- Magnifying glass- Sunlight

For finding the focal point, the magnifying glass must be zoomed in and out until a small and intense point appears. It is recommended to point over a black paper or cardboard, which absorbs more radiation and reaches high temperatures quickly. This experience should be performed by a teacher, or in a minutely controlled environment, since fire could appear and get out of control.

This experiment may implies FIRE.CAUTION

Experiment: Photovoltaic energy

Material

Experimental method

Scientific basis

When sunlight (electromagnetic radiation) hits the photovoltaic plate, electrons are pulled or emitted by the silicon plate. Then, the electrons are driven into a circuit for power supply. The work function , W, (minimum energy necessary for emitting electrons) can be written as follows:

- Photovoltaic "Solar kit"-Sunlight

Direct the "Solar kit'' photovoltaic plate towards the Sun, and check how the engine starts to move.

W = h · ν0

Where h is Plank constant and ν0 is the minimum frequency needed to pull the electrons out of the plate

Experiment: Stirling engine

Material

Experimental method

Scientific basis

- Stirling engine- Burner (heat source)

Fire the burner and give the first impulse to the piston. The engine will keep in movement

Ideal Stirling cycle is a thermodynamic cycle comprised of two isothermal (temperature remains constant) processes (compression and expansion) and an isochoric (constant volume) and isobaric (constant pressure) processes.First, the piston is ideally compressed while the temperature remains constant. Then it is produced a pressure rise at constant volume. That pressure rise drives the expansion phase, where the piston goes back at constant temperature. Finally a pressure drop ocurrs, turning back to the first stage.This process is the basis of some thermosolar systems, where there is a movement (a piston or a shaft rotation) which is transformed into electricity, and the heat source is the Sun.

Project: Solar oven

Material

Experimental method

Scientific basis

- Shoe box (or similar)- Aluminium foil- Cling film- Black cardboard- Chocolate (or something similar that could get melted or cooked).

Crop a flap on a shoe box cover (this will serve as a reflector) and coat it with aluminium foil. Cover the hollow with cling film.Finally, coat the inside of the box with aluminium foil and put a black cardboard on the base, so as to reach higher temperatures.Put a piece of chocolate (for example) in the interior and direct the flap to the Sun, ensuring that radiation is reflected inside. After some minutes, the chocolate will be melted.

Solar oven working can be explained through two physical phenomena:- Laws of reflection: Second law states that the angle of reflection is equal to the angle of incidence.- Greenhouse effect: Sunlight crosses plastic or glass heating the object inside the solar oven. However, the radiation reflected by the object is in the infrared bandwidth, thus the temperature of the inside air rises.

Sunlight reflected

Chocolate melted by the solar oven