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The watermill battery charger
Throughout the Himalayas, many people living in remote areas use water-powered mills on a seasonal basis to grind wheat, corn, millet, and other grains into flour. It is estimated that there are 25 000 water mills operating in Nepal (referred to as ghattas), over 200 000 in India (referred to as gharats or panchakis), and many more in the mountainous regions of China, Pakistan, and Turkey. Each traditional mill has a power output of 200 to 500 W (Figure 1). Today, much of these mountainous regions remains non-electrified, despite the interest in and demand for basic electricity. The aim is to create an opportunity for an individual entrepreneur to provide electricity to his immediate community by using part of the indigenous infrastructure: the water mill.
Just as in the industrialized world, entrepreneurship can be an excellent way to introduce and disseminate technology in developing nations. When engineering a product for the individual entrepreneur quickly in the Himalayan region, low cost becomes the dominant criteria. For a mill owner (Figure 2), expensive induction generators and transmission lines may be simply out of the question. A battery charger is a much more viable solution. The mill owner bears the cost of the inexpensive charging system, while the individual households bear the cost of batteries, as they are able. Even the more remote and isolated homes are able to participate in this scheme, as long as they are within walking distance of a mill. Although issues of transportation and disposal remain, battery use seems the quickest and most economic path to bring basic electrical lighting to the mountains.
Batteries simply can go where a transmission grid cannot. Indeed, the precedent has already been established; villagers in parts of eastern Nepal are currently carrying 12V car batteries into gridconnected towns for recharging. A battery-charging extension to the mill could both alleviate the need for these long trips and make such a strategy available to other, more remote areas of the mountains. The mill is also an ideal site for a battery-charger. During much of the year, a steady stream of people arrive at their local mill with grain and leave with flour, as has been done for centuries. It will not be a dramatic change of routine for rural villagers to bring their batteries to the mill as well (Figure 4). They can have a battery charged and their grain ground in the same trip. The battery charger extension can also be operated during the currently non-utilized time of the mill, which varies by season. The availability of a battery-powered light also allows the mill to operate at night, either for grinding or battery charging.
A car alternator is an excellent choice for a battery charger as is it has been specifically engineered to provide a regulated voltage ideal for recharging 12V batteries. It can supply up to 500W of power, which is conveniently the maximum estimated power output of most traditional water mills. Although the alternator needs a fairly high rotational speed (rpm) to generate electricity, it can be run below car idle speeds. The bicycle rim and alternator pulley provide enough of a ratio to allow the alternator to produce power at water mill speeds (60-90 rpm). For the rural regions of Nepal and surrounding countries, the cost of an alternator may still seem prohibitively high. Although it does account for much of the total cost (US$50), there is evidence that this is affordable. Nepal’s Center for Rural Technology has successfully launched a programme to sell higher efficiency mill turbines for approximately US$80 to rural water mill owners. Over 600 new turbines have already been purchased and installed; sales are currently averaging over 250 per year. There should be a considerable market for a battery charger in a similar cost range. The initial low cost of the battery charger is not the only advantage of the simple design. With the device’s removable shaft, the mill owner can quickly switch between battery charging and the traditional grinding operation. With the bicycle wheel removed, the mill looks and operates exactly as it always has for centuries. The only permanent modification to the mill itself is the addition of the small square post on its key. This post does not interfere with grain being fed in between the grinding stones, and is completely out of sight.
The most significant advantage of using an inexpensive mill addon to bring electricity to the mountains is sustainable maintenance. Maintenance is always a large concern when introducing new energy technology to remote areas of the world. Typically it cannot be maintained without additional infrastructure and technical expertise. The Himalayan water mill, however, has been built and repaired locally by the mill owner and his family for centuries. They are already technical experts for most of the battery charging system. The electrical portion, the alternator, cannot be repaired by the mill owner, but it can be repaired by any auto garage shop in the country. There is no need for assistance outside the country, and no need for a major centralized repair centre. All parts of the system come from locally available, offthe-shelf components. Renewable energy projects can be costly in the developing world. A considerable amount of time and capital is needed to create local expertise and manufactured parts. The Himalayan region, however, does not need to wait for such assistance. The technology infrastructure already exists to support basic power generation. [top] [end]Download the original article The watermill battery charger by Nathan Eagle and Ben Olding (117 KB)[top] [end]Contents: Boiling Point 46 - Household energy and the vulnerable
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Page created:
10 July 2007; Last edited:
10 July 2007; Version: 1 | |||||||||||||||
Pagename: TheWatermillBatteryCharger @HEDON: DRFA | |||||||||||||||
