Developed countries are used to having a supply of fresh, clean water piped straight into their houses for their convenience. In some African countries, however, especially rural areas there isn't any provision for the supply of drinking water. Women and children take water from rivers or lakes and carry this back to their house, which is very labour-intensive.
I'm not dealing with the supply of fresh, clean water here – I am assuming that one of the other methods has been used where villagers have access to a central communal water tank. In a rural area, homes and farms tend to be spread out over longer distances than in cities. This makes running the infrastructure slow and expensive to connect all the rural households to the central water supply. My interim solution is to provide an electric tricyle that is capable of carrying up to 300 litres of water in the rear mounted water tank. The tricycle takes a 300 litre load of water from the main village water tank (assuming it is an above ground tank and this would be gravity fed). A submersible 24V pump would be mounted in the bottom of the tricycle water tank to pump the water through a hose. This hose would be attached to the water tank for each house that the tricycle visits, so each house has an agreed water allowance delivered to them.
The tricycle would use 6 120Ah 12V deep cycle lead acid batteries to provide the energy to drive two 500W 24V DC motors and to power the water pump. Each of these motors would be connected to one of the rear wheels via a chain. Electric motors have a high torque and the vehicle would be geared for low speed, high torque use and the maximum speed would be around 20km/h. The unloaded tricycle itself will weigh around 400kg and it is capable of carrying a 400kg load (including driver). The approximate dimensions of the tricycle will be:
The batteries would be configured to provide 24V – ie put 2 batteries in series and then have 3 sets of the 2 series batteries in parallel, to give a 360Ah 24V supply. This would give a maximum range of around 100km under ideal conditions (on level tarmac roads carrying no load). In day-to-day use carrying 300kg of water and using the on-board pump, a range of 40-50km is more realistic.
The tricycle would need to be recharged at the end of each day. Charging requires a 220V AC mains supply and would take around 7-9 hours for the batteries to fully charge. (Note: If there is no mains electricity to the village then a solar PV system can be designed to be mounted on the roof of a building. This would need an inverter to convert the DC voltage to 220V AC and also a battery bank to store the energy collected by the panels during the day, as the tricycle would be charged at night when a solar PV system would not be operating. While a hybrid solar PV system would be expensive to set-up initially, it would have very low running costs and the tricycles would be powered from energy collected from the sun!)
It is possible to have the tricycle make use of renewable energy, by adding an optional solar PV panel on the roof. The suggested panel size to use is 300W and this power of panel is available from a number of different manufacturers. A typical 300W Poly PV panel will weigh around 26-30kg and will be roughly 2m x 1m in size (they vary from manufacturer to manufacturer). This panel would be connected to a 24V 20A charge controller that would trickle charge the batteries during use as long as it was a sunny day. The panel would put back around 30% of the energy that would be drawn when the tricycle is moving along.
The approximate cost to buy a tricycle would be $700 to $800 if buying them from China. The optional 300W solar PV panel and 24V 20A charge controller would cost under $400 extra.
In a few years the tricycles could switch to using lithium ion battery technology once the price of these drop to a sensible level. Lithium ion batteries have a higher energy density than lead acid. The advantages is Li-ion is they would give a longer range and they would last longer than lead acid. Their disadvantage at the moment is they are much more expensive to buy initially.
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