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Report 2 of 5: The River Runs Through It - Peru
Introduction
At present, in Peru, the energy supply to the rural areas of the jungle is almost negligible. Most of the rural population (about 1,500,000 people) in the jungle areas of Peru are settled along the banks of the largest rivers, such as the Amazon, Mara?on, Ucayali and Napo, etc. because the rivers are the natural means of transport and communication, as well as a source of food. In fact in the Peruvian jungle there are hundreds of small communities who live mainly settled in the river banks, where the river is one of the most important means of life for them. They fish in the rivers, move through the rivers etc.
Energy use in small and isolated communities
Isolated communities or villages like those existing along the river banks in the Peruvian Jungle require small quantities of energy to satisfy essential needs, such as lighting, vaccine preservation, refrigeration, communications equipment and others. Small kerosene lamps or burning wood are used for lighting. Those villages which are closer to towns like Iquitos and Pucallpa, etc. have found an appropriate way of providing lighting and power for radios by using vehicle batteries. These batteries have to be recharged regularly in towns which involves an expensive journey of perhaps one day, plus the charging cost of US$2 to US$3 each time.
Unfortunately, the usual sources of energy are not readily available in this area. Conventional hydro is not practical due to the topography; diesel engines require fuel, oil, spare parts and specialised maintenance; solar energy is still expensive and the radiation is weak due to cloud cover; and wind speeds are too low to generate power. The one energy source which is present in abundance is the rivers themselves which, in most cases, have speeds high enough to generate power.
In this situation, river current turbines become a very interesting option which should be tested, transferred and promoted strongly in that area in order to benefit as many settlements as possible. Once the introduction of the small units proves to be successful, it would be possible to extend the range of power capacity not only by adding units but by designing and building larger sizes of machines.
Water current turbines
In jungle areas, where conventional hydro power is not an option, the kinetic energy in river or canal currents is an alternative renewable energy resource. The idea of using the kinetic energy of water in large rivers to generate energy started in the late 1970s. A current speed of 1m/s represents an energy density of 500 Watts per square metre of cross section. Water current turbines extract some of this energy and convert it to electricity or mechanical shaft power to drive a pump. These turbines are quiet and non polluting in use.
The power output from a turbine depends on its efficiency at converting the available energy, its size and the river velocity at the turbine site. The velocity is particularly important because a doubling of water velocity gives an eight fold increase in energy density.
Battery charging water current turbines
Marlec Engineering, leading wind charger manufacturers, and Thropton Energy Services, water turbine specialists, have joined forces to develop a revolutionary new battery charging water current turbine.
The 1.8m diameter turbine has been designed to generate free power when moored on any river or canal deeper than 1.75m and flowing at between 0.45m/s (1 mph or 0.87 knots) and 1.5m/s. The turbine can be mounted onto the back of an ordinary open boat, providing it is more than 5 metres in length. It starts charging batteries at 0.5m/s and can charge up to five 12 or 24 volt batteries simultaneously at 1.5m/s. The exceptionally low water current speed required to start the battery charging generator has been achieved through aerodynamic blade design and the use of a high efficiency low friction alternator.
Power from the turbine is stored in the batteries and between ten and twenty car batteries can be recharged every day at a good site. This power is then available for running 12V appliances such as lighting, vaccine refrigerators, portable TVs, radio communications equipment and inverters to operate 240V a.c. appliances. Larger machines can also be supplied with a generator suitable for battery charging.
The battery charging turbine needs at least 1.75m of water depth. A site survey is not necessary before installing this machine as the rotor is protected against hitting the bottom and the machine automatically tips out of the water if the current is faster than 1.5m/s.
Battery charging water current turbine © ITDG - Saul Ramirez
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Specifications of the water current turbine
The water current turbine uses a large, three blade turbine which is rotated by the force of a free stream of water. The turbine is installed over a floating base and tied to the river bank through cables which anchor it. It also has a long piece of wood attached, which gives access to the floating base and stability to the system.
The shaft of the turbine is coupled either to an electrical generator or to a small pump if it is to be used to raise water onto the river bank for irrigation. The amount of energy available in the flowing water depends on the area swept by the turbine and on the cube of the water speed. In the Nile, for example, turbines with a swept area of 10m2 operating in a river speed of 1metre/second generate about 3 kW of power per unit. In places where the river speed is higher, the energy available increases greatly and, with 1.2 metre/second flow, the same machine can produce up to 5kWatts of power.
The Peruvian turbines are stand-alone units and have a maximum power output of about 2kW. The size of the machines, hence generation capacity, can be higher if suitable river conditions exist, that is depth, width and speed of the flow. However, it is also possible to get larger power capacities by installing various units in parallel. To keep the capital cost down the turbines have been designed for local manufacture.
Safety measures
The system incorporates a furling device that lifts the turbine out of the river if the water current speed exceeds the preset maximum. As the unit furls the turbine is electrically braked to avoid the blades freewheeling, reducing unnecessary wear and tear. The rotor is also protected against grounding or damage from floating debris. Should sudden flood conditions occur (water speeds above 1 .5m/s) the automatic furling system will activate, allowing the boat to be moved safely closer to the bank and the turbine manually reset. The turbine can be furled manually and the whole unit can be easily dismantled and transported to alternative sites with the minimum of labour and effort.
The charge controller included senses the battery terminal voltage and automatically stops the turbine rotation when full charge is achieved, it continues to monitor the battery voltage state and restarts the turbine as the charge level decreases.
Cost
This cost effective solution is ideal for rural communities, health centres, schools, missions, battery charging stations, tourist lodges, border posts, radio communication sites, research stations, etc. The cost of the battery charging water current turbine will be approximately GBP£1,850, excluding installation work.
Advantages of the battery charging water current turbine
- Affordable power to isolated areas
- Easily transportable so many users can benefit
- Completely independent operation
- Continuous power generated 24 hours/day
- Non polluting
- Simple to install, operate and maintain
For further information, please contact:
Intermediate Technology Development Group would like to thank ITDG Peru, in particular Saul Ramirez, and Thropton Energy Services for providing the original information on river turbines for battery charging.
This document is an output from a project funded by the UK Department for International Development (DFID) for the benefit of developing countries. The views expressed are not necessarily those of the DFID.
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