Self-Contained Very Low Power Mini Hydroelectric Generator
Identifying the Need & Defining the Problem
In every country there is a need for electricity in remote areas not otherwise supplied by mains power, or where generators and fuels are unavailable or too expensive.
Sometimes this need can be met with solar power, wind power or another form of renewable energy. However, in many areas of the world; fuel, generators, solar panels and other standard technologies are too expensive for local people to afford, or are simply unavailable.
I've always been very interested in electricity generation, since my experiments with wind, wave, clockwork (wind-up), chemical and water power when I was a child. I always imagined how useful it would be to have a renewable but relatively portable power source which could be constructed and used locally in remote areas of the world, where people live in, or are bordering on poverty. Where resources such as fuel are hard to come by.
Since everyday perpetual motion doesn't exist (yet), any locally based power source would have to be practical and must be capable of being recharged fairly easily. It would also need to be easily transportable, with the potential to be built using locally available, recycled parts.
If fuels and renewable energy sources are not an option, an alternative power source could utilise people-power in order to obtain a charge. However, the effort/sweat required would have to be realistic for the amount of energy produced.
A good example of a people-powered energy source is the wind-up spring mechanism. This has been used for over 500 years of course and one of the earliest experimenters was Leonardo da Vinci. More recently it has been used in alarm clocks and wind-up toys, and even more recently in wind-up radios and torches etc. The point is that clockwork is a relatively efficient way of storing energy.
Meeting the Need & Providing a Solution
I've experimented with many forms of electricity generation over the years and have come up with quite a few novel ways to achieve it. I will include all my ideas here in my invention blog, but this time I want to describe a simple idea which might provide a low cost source of very low-energy power for charging mobile phones etc.
I must stress that this is only an idea at this stage, I haven't had time to experiment or check the practicality of it, or even carry out a basic analysis. My initial thoughts are that this idea/system/device would work to some small extent, and with proper design & development, may be turned into a modest, practical but very low power generator.
At the very least, I think this idea might make an interesting project for a student or group of students to pursue as part of some experimental coursework :-) The idea could be tested and assessed on a tiny budget with minimal equipment.
My idea (which I have only given a couple of hours thought to at this stage) is based loosely on a sand/egg timer. It would consist of two large water barrels/tubs diametrically opposed to each other mounted on a steel, wood or preferably aluminium frame. The two containers would be connected by a plastic tube (a piece of old drainpipe would do nicely) into which would be mounted an electric motor (the generator) or a permanent magnet alternator/rectifier, with a water-wheel (a Pelton wheel) mounted on its drive-shaft. The electric motor would need to be fairly small, and capable of producing a usable voltage at low RPM.
When the unit is vertical and charged (250 litres of water or similar fluid in the top barrel) it will have some potential energy. When a valve/tap is opened in the connecting pipe, the flow of water becomes kinetic energy which is then converted to electric power as it passes across the generator Pelton wheel blades.
(n.b. I wonder if in a desert environment, dry sand could be used as the charge instead of water, just as in a sand/egg timer! :-) In theory it would work since sand flows very well, it has a substantial mass, and if I'm not mistaken, its exit pressure wouldn't depend on the height of the sand above it in the charge.)
The flow could be adjusted using the valve/tap (one at each end of the pipe - the lower one would always open fully and automatically using some sort of butterfly valve maybe), to provide more power/less time or more time/less power. It may also be possible to rig up a method of increasing the flow automatically as the level drops in the charge/top barrel, to compensate for the reduction in water pressure.
In my basic scribble of the design, I have included the notion of water guide flaps, these would divert the falling water flow onto the 'cup' side of the generator Pelton wheel blades, which would improve efficiency. When the unit is rotated/recharged, the flaps would automatically cross over to the correct side under the action of counterweights.
To recharge the unit, it would 'simply' have to be rotated 180 degrees after first closing the connection pipe valve/tap. The previously filled barrel will then be at the top of the frame ready to discharge again across the generator. The unit could be fitted with a gearbox and crank handle to allow a single person to rotate and recharge the unit. Alternatively, if there are three or four people available, the unit could be rotated manually within a few seconds, to the fully charged position.
The main advantage is that the unit is self-contained and does not require natural resources or fuel as such - other than people power (or possibly animal power), and it can be used in almost any location (since it would be fairly lightweight when empty).
Another advantage is that it could be filled with any kind of water, for example waste water or water that would not be fit for any other purpose. In the locations in which I anticipate this unit may have some potential uses, drinking water would be far too valuable to use as the charge.
One final advantage is the long life and low cost of the unit. If the bearings, generator shaft, and gearbox are maintained occasionally, the unit could last for many years or even decades. The whole device could be made from scrap parts; maybe a motor from an old cassette player, an impeller (Pelton wheel) from an old hairdryer, etc., along with a couple of old oil drums, beer barrels or other commercial containers (since only basic cleaning would be required).
The main disadvantages would be the very low power output and the effort required to rotate/recharge the unit. However, I believe there may be just enough power output to make the device useful, and in order to increase the capacity, several units could be strung together and used in parallel or sequentially to produce either more current or a longer operational time.
A smaller version which could be easily rotated by hand might also be interesting, something with maybe 20 or 30 litres of water as a charge. The operating time would be much lower of course, but since it could be recharged/rotated in a couple of seconds, it may still be of some use and it would be completely portable too :-)
Also, the unit could be used to charge a bank of recycled nickel-cadmium or lithium mobile phone batteries over the length of a day for example, then the substantially greater battery power would be available for use during the evening or kept in reserve for emergency use.
I've drawn a diagram of the basic design features (click on the diagram at the beginning of this post for a larger view) including pressure equalisation/breather pipes, and this should provide enough information to produce a small scale model which could be used to carry out some basic tests and calculations. These results could then be extrapolated to determine if a full scale version would have any small merit.
Uses / Applications
I've listed below a few of the potential applications for this device but please bear in mind, I am thinking about its use in remote locations; the edge of deserts, small islands, wilderness areas, villages too distant from towns to have mains electricity etc. Also, coupled with a lack of financial resources, i.e. solar panels, wind turbines etc., would not be affordable to the local population.
- Charging mobile device batteries. With the flow control valve/tap in a restrictive position, the unit would only generate a few tens of milliamps, but the operating time would increase substantially. A single charge/rotation might be able to provide a couple of hours worth of charging to a mobile phone for example.
- Direct operation of mobile phones - for short periods with the valve/tap fully open.
- Providing power to small pocket radios, possibly up to a couple of hours usage.
- Powering LED lighting or possibly very low power fluorescent lighting.
- As I mentioned above, trickle charging a bank of recycled nickel-cadmium or lithium mobile phone batteries which could subsequently provide power for much larger items of equipment.
Ultimately, the number of applications will depend upon the practicability of the device. At the very least it could be used as a demonstration tool to help explain and teach the principles of hydroelectric power generation in a classroom environment.
Please feel free to test my idea and if it has any small merit that would warrant further development, then I wish you every success - have fun! :-)
Usually I provide some further resources for my products/ideas but in this case, the idea represents a couple of hours thought and scribbling, so I haven't had time to test it further or produce any more material. However, I have provided a few links below which may be of some help or further interest.