Building a turbine: Starting inquiry into hydroelectricity

 - Schoolgen Sister School Activity -

 Outline-  Students have 20-30 minutes to assemble a water-powered turbine (Pelton wheel)  from pre-prepared items that could be used to drive a small electric generator.

Suggested background to this activity-

1)     Bring in partially disassembled F&P smart-drive washing machine- show the motor, remove the permanent magnet rotor, show the rotor and magnets, show the copper wire coils arranged around the stator, show the three phase wires- explain how instead of putting electricity IN to make the rotor turn, you can make the rotor turn using some mechanical force such as water, wind or a combustion engine (biomass powered of course) and get electricity OUT!

2)     Show a reconstructed smart-drive motor combined with a Pelton wheel turbine that can be used as a hydro electric generator for a house.

Aim- To learn in a hands-on activity:

1. How a turbine harnesses the motion of a moving fluid.
2. How the energy in moving water can be transformed into electricity through the rotation of a turbine.
3. How electricity is generated using a renewable energy source.

 Equipment-

• Plastic teaspoons (8 per turbine).
• Plastic milk bottle tops (1 per turbine)
• Craft knife
• Hot glue gun.
• Piece of 6mm wooden dowel (10-15 cm long)
• Drill (hand or electric drill).
• Pliers/ strong scissors to cut plastic spoons.

Optional-

• Small electric motor/generator, tiny straw light (from Surplustronics).
• 4L plastic container to make into a permanent housing for the turbine.
• Voltmeter/multi-meter to measure output of generator.

 Method-

1)     Cut off the handle of 8 plastic teaspoons (preferably recycled) 1cm above the spoon (I used Home Brand plastic teaspoons and cut the teaspoons just past the dot on the handle).

2)     Cut 8 equally spaced slots around the plastic milk bottle top- this can be done quite accurately by carefully counting the number of ribs around the side of the cap and then dividing that number by 8.

3)     Drill a hole of diameter just slightly less than the dowel through the exact centre of the plastic milk bottle cap.

4)     Arrange the spoons around the cap by pushing the cut-off handle end through the slots – the spoons should protrude an equal distance around the perimeter, and also leave room for the dowel to be inserted through the hole

5)     Glue the spoons into the edge of the cap using the hot glue-gun.

6)     Leave to cool for a minute or so- the spoons should be firmly set into the cap.

7)     Insert the dowel and centre the turbine.

8)     Balance the turbine if need be so that the turbine is at right angles to the dowel and doesn’t wobble when spun.

9)     Glue the turbine onto its shaft.

10)  Once cool, test the turbine by lightly holding both ends of the dowel and holding it under a stream of water from a tap or hose. The turbine should spin at high speed!

 Optional 1- For a more permanent mounting the ends of the shaft need to be supported so that they can spin freely with as little friction as possible. Large rectangular shaped plastic bottles (say 4L) can be modified so that they support the spinning rotor and optional generator.

Optional 2- Attach the turbine shaft to a small electric generator.

 Optional 3- A gearing or pulley system could be used to increase the revs of the motor and its electric output.

 Web links-

For further ideas see the link below which includes instructions on how to build your own generator from copper wire and magnets:

http://www.re-energy.ca/hydro-generator

 Building a turbine: Starting inquiry into hydroelectricity

- possible links to the NZ Curriculum with ideas for extension. 

• Suggested Principles

 Future Focus

“Encourage the making of connections across the learning areas, values and key competencies … relevant to students’ futures

Sustainability-

 Long term impacts on environment/society.

Enterprise-

 Innovation through working effectively with the forces of nature.

Coherence

“… makes links within and across learning areas, … and opens up pathways to further learning.”

• Suggested Values

Innovation, inquiry, and curiosity

Thinking “critically, creatively, and reflectively”. 

Ecological sustainability

Key Competencies 

Managing self- manage time frames, reflect/respond to ideas encountered

Relating to others-     work in pairs/small groups, share ideas

Thinking- consider …applications of the turbine to generate electricity.

 Learning Areas

Science

Physical World-

 Part 1 – Making & testing the turbine:

Motion (linear to rotational), energy (PE to KE & friction).

 Part 2 – Using the turbine to drive a generator and light a very small bulb:

Electricity/magnetism (transformation of energy- rotational KE to electrical to light).

 See Mathematics section below.

 Planet Earth & Beyond-

 Sun- the source of energy for hydro/wind power.

 Geosphere/Hydrosphere/Atmosphere- Interactions control rainfall, run-off, river flow and lake storage. Ability to dam river valleys and create artificial lakes.

 Nature of Science-

Study the scientists who discovered electricity & magnetism- Michael Faraday, Allesandro Volta, etc

Investigate how the new discoveries were turned into useful technologies by inventors such as Tesla, Edison.

 Technology

 Technological Practice-

“Students examine the practice of others and undertake their own”.

 Technological Knowledge-

“Students develop knowledge particular to technological enterprises and environments and understandings of how and why things work.”

 Nature of Technology-

“ …learn to critique the impact of technology on societies” – See Social Science below.

 Further possible areas to extend investigation of hydroelectric generation:

 Social Sciences

Impacts on communities/environment of large scale hydro, contrast with remote communities using small-scale hydro.

Resource Management consents process in NZ. Compare with say China, Brazil etc.

Mathematics

Collect data/graph data on say how long turbine spins for when 1 litre of water falls onto the turbine from different heights.

How many times does it spin? (Could use cotton thread to wind onto spool, but see if students can come up with a creative method first).

Future Focus

“Encourage the making of connections across the learning areas, values and key competencies … relevant to students’ futures.”

Sustainability-

 Long term impacts on environment/society.

Enterprise-

Innovation through working effectively with the forces of nature.

Advertisement