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Phuket DIY bicycle generator alternative energy project for a rainy day

Happy Habitat: For those of you who’ve followed this column, you’ll know how enthusiastic I am about alternative energy, particularly solar power, for which I’ve highlighted in a number of previous editions just how cheap, easy and practical it can be in Phuket. If you missed those articles, search the Happy Habitat archive in thephuketnews.com Environment section.


By Steven Layne

Sunday 21 February 2016, 02:12PM


As abundant as the sun is in Phuket, one obvious challenge is that it’s not always shining on our side of the planet; even on a good day, you’re lucky to get more than eight hours of direct sunlight. So the next obvious alternative energy solution that comes to mind is wind power – particularly if you live on a boat, on the coast, or high up on a hill – which has the advantage over solar in that you can generate electricity any time of day or night given that there is sufficient wind blowing.

But I live in the city, where there is not sufficient wind to justify buying or building a wind turbine.


This brings us to the next practical alternative energy solution, which I’ve long wanted to experiment with, and only recently got around to it: a bicycle generator. 

Like wind and hydro power, a bicycle generator utilizes simple 19th century technology: magnets spinning around coils (or vice versa) in constant revolutions, resulting in an electromagnetic charge, AKA electricity.

But instead of relying on the force of wind or water to create this force of revolutions, a bicycle generator utilizes human pedal power. In simple terms, it’s nothing more than a re-purposed bicycle with a motor, which are both found in abundance in Thailand.

 

                                                           Pilot Peddler

This project is essentially a special bicycle trainer, like those static bicycles found in workout gyms, but instead of requiring electricity to operate, one generates electricity during their workout, and thus can recover and store that energy for other uses, be it charging your multimedia devices, operating your computer or watching TV, for example. While it is possible to use the energy real time as you generate it (watch the tube while you work out, for example) it’s just as practical to store the energy by channeling it to charge a battery. Depending on the power of your motor/generator, you could theoretically generate enough electricity to watch TV and still have excess to store in a battery.

                                                     Motor-Generator

EPL Prediction Competition 2018-2019

Motors are found in all types of electrical appliances – fans, drills, pumps, blenders and then some. Not to complicate things too much with technical specs here, I opted on using a DC (direct current) motor for my pilot. While you can use ordinary AC (alternating current) motors, such as the one in your typical house fan, this requires an additional step of rectifying and converting the energy generated into DC if you wish to store the electricity in a battery, for example.

For my pilot, I took apart a 15 Watt DC fan that I had lying around, disconnected the speed controls, and re-purposed the motor, removing the propeller from the shaft and replacing it with a belt drive pulley (designed for a washing machine motor), which would be driven by a rubber automotive drive belt. (After the initial pilot, I finally ordered a more powerful 24-volt 250W DC motor, which turned out to be much more efficient, though pending pulley tweaks)

                                                             Bicycle

The bicycle I used was a five-year-old Turbo bicycle that needed new wheel bearings anyway if it were to be street-worthy. So, I simply removed the back 26-inch Shimano gear equipped tyre and replaced it with a single gear, 20-inch rim without a tyre or innertube. I could have used the original 26-inch rim, however, the largest drive belt I could find in Phuket had a 26-inch circumference, and the tyre rim needs to be smaller than the drive belt so there is enough slack to drive the motor (See image).

Finally, you need to build a trainer stand to mount the bicycle and generator on. I simply bought some lumber, screws and braces, and made two, sturdy upright posts. Ideally, you should reinforce the posts so that it can comfortably support your weight. There is no one way to build this stand and if you have a bicycle trainer already, this can be re-purposed pretty easily. The idea is to simply mount the back tyre’s axle at least 20 centimetres from the ground so that you can pedal freely, and the back rim drives or spins the smaller pulley on the motor via the belt.

                                                           Regulation

One final component is a charge controller, or at minimal a blocking diode, to ensure that electricity can flow in only one direction, in this case from the generator to the battery, and not the other way around. I had an extra solar charge controller, with built in blocking diode lying around, which worked perfectly. Another purpose of the charge controller is to regulate the electricity to a constant charge (roughly 13-14 volts is needed to charge a 12 volt battery). Otherwise, you end up getting erratic and spiked charges which will easily damage your battery. That’s it really. Study the pictures and the video demonstration that I’ll embed on the online version, and in the future, I’ll look to follow up again on the performance and specs.

Materials List

  • Old bicycle with back wheel’s tyre and intertube removed, leaving only the rim
  • Large enough rubber drive belt
  • DC motor repurposed as a generator affixed with a drive-belt pulley
  • Bicycle trainer stand (can be built from scratch or re-purposed from a ready-made trainer)
  • Charge controller and battery

 

 

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