The Hidden Power of Sewage

St. Paul’s Co-educational College Lo Ka Shun, Parco

Tsang Tin Ki, AngelaWong Ho Gan, Albert

Poon Wing Yiu, Sarah

How much sewage we Hong Kong people produce each

day?

2.6 million cubic metres!!

X 1400

Working Principle

.• Utilize kinetic energy of running sewage

Sewage rushes down along the pipes outside buildings

Large kinetic energy spin a watermill

A dynamo changes kinetic energy to electricity

Preliminary Model

1.5 metres long plastic PVC water pipe

plastic box with a watermill

Preliminary Model

Drawbacks• Some water escapes

without spinning watermill

• Some water rebounds back onto the watermill– hinder the rotation.

Advanced Model

1.top and bottom each have a hole for the entry and exit of water

2.Slightly tilted plane

3.An arc is craved for the watermill to tuck in

4.space below the watermill is enlarged

Advanced Model

Output Power• Measuring Setup:

– An electronic water pump – Amount of water pumped

to our model is kept at a constant

• Water velocity

=0.4516 m/s²

– AC-DC transformer in our advanced model

• Procedures:– Substituted the resistor and

– re-measure the current and voltages

– calculate output power

• Output voltage is very stable

• ~5 batteriesX 5

Output Power

Applications

• Widely used, especially in big cities like Hong Kong

• modified and installed in underground pipes to generate electricity

Further Improvement

• Further Investigation on – How many of our device is to be installed in a

pipe outside a building– What interval between devices can achieve

the maximum electrical output

• Further develop:– Use lighter material to make the watermill– Use a more corrosion resistance material

Conclusion• clean, inexpensive energy resource.

• easy to build

• applying this alternative energy resource in a large scale,

• the reliance on burning fossil fuels for energy

• environmental damage, e.g. global warming

Thank You!