Mechanical Energy

Part 1 and 2 (Needs for Mechanical Energy & Meeting Mechanical Energy Need) of this article are based on the UNDP report on Mechanical Power from 2009.

Needs for Mechanical Energy

Needs for mechanical energy are often overlooked when rural energy demands are addressed by international donor organisations; one reason might be the fact that the most common applications of mechanical energy such as water-supply, agriculture, agro-processing, natural resource extraction, small scale manufacturing and mobility are often falling into the scope of programmes of other sectors such as water, agriculture, business development or transport. The energy needs, however, are real and providing mechanical energy can have highly-significant effects on income generation and poverty reduction. Mechanical power is today obtained from motorised equipment such as steam, diesel and gas engines/turbines, electrical and hydraulic motors. In spite of these technological improvements, the 2.5 billion people without access to modern energy services still depend on unimproved versions of mechanical power equipment that inefficiently use human or animal power to meet their energy needs. However, in spite of these technical challenges, motive power has remained an important driver of livelihood activities in impoverished regions of the world.

The most common needs for mechanical energy and technological options are presented in the following. Only static applications of mechanical power are covered, so applications to assist mobility are limited to lifting and crossing.

Water supply

Having a clean and reliable source of drinking water is essential in improving the health of a community. In rural areas, water collection often makes up a large part of a woman’s day, so a nearby water source allows her to focus more on other activities, such as spending time with her children and taking care of her own health.

Mechanical energy demands for water supply include pumping of drinking water, irrigation of field crops as well as livestock watering. Traditional and still widely utilized methods of water supply rely on manual lifting / carrying of water in containers.

Agriculture

The main energy needs for agricultural production occur during activities such as tillage/ploughing, harvesting, and seeding. Traditionally these activities are carried out with animal drawn tillers and hand hoes (tillage/ploughing), scythes, animal drawn mowers, and manual practices (harvesting), and hand planting (seeding).

Agro-processing

Post-harvest activity is arguably the main factor in helping farmers increase their income. Substantial time and resources are spent transporting crops to neighbouring mills if the services are not available in farmers’ own villages. Most processes can utilise energy derived from shaft power, with many alternatives for technologies powered by human, animal, water or a stationary engine. A huge demand for mechanical energy exists for milling and pressing, where typical manually-operated technologies in widespread use are hand grounds and flails. Cutting and shredding is conducted with the help of knives and saws, while winnowing bascets are used for winnowing and decorticating. Spinning with manual spins and sun drying or drying with hand-held fans are common in most developing countries.

Natural resource extraction

Small-scale mining is a labour intensive industry that often poses serious health hazards due to poor working conditions and lack of safety precautions. Artisanal and small-scale mining (ASM) may be the only livelihood opportunity for some people, or may be their source of income during the agricultural off-season. Small-scale forest harvesting has seen increased interest in recent years due to its relatively low environmental impacts. Most traditional methods of resource extraction involve hand tools, so there is significant room for some degree of mechanical power to increase efficiency and support related livelihoods. Traditional technologies for mineral resource extraction include shovels, chisels, hammers, and pick axes for drilling, crushing, and hole enlarging, while washing and grading is in most cases done by hand. The hand saw is the traditional technology for sawing in the context of timber extraction.

Small-scale manufacturing

Many people in developing countries rely on generating income through small-scale manufacturing of products. Due to the diversity of existing manufacturing processes mechanical energy needs are highly contextual. Some important examples of mechanical energy needs in the small-scale manufacturing sector shall be highlighted. Metal work with hammers, wood working/carpentry with hand saws, hand-weaving in textile making businesses, mould and deckle for papermaking, and hand powered potters wheels for pottery are wide-spread all over the developing world. Other processes do not involve any physical technology, but therefore high quality products cannot be produced, e.g. in packaging (unsealed packaging) or briquetting/brick pressing sector.

Lifting and crossing

Manual lifting of goods can be very taxing physically, but is sometimes necessary. Examples include natural resource extraction (such as mining), or crossing rivers to bring goods to market centres. Vehicular access in rural areas is usually very limited, and farmers or enterprise owners may need to employ couriers to transport goods on their behalf, placing an additional burden on their own savings, whilst the work itself is both physically challenging and often dangerous. Manual labour is widespread for many activities related to lifting (climbing, lifting) and crossing (swimming, walking).

Meeting Mechanical Energy Needs

Water Supply

Water supply services for drinking water, irrigation and livestock watering can be met by introducing technologies such as diesel pumps, treadle pumps, rope pumps, ram pumps, Persian wheels, hand pumps, river turbines, solar pumps, and wind pumps.

For some technologies, such as wind pumps, options are available in different sizes – ranging from household (e.g. wind/rope pump) to village scale, where wind speeds are sufficient for economic operation. The treadle pump, a human powered technology, can be advantageous because it can accommodate a wide range of weather conditions and is only used when needed. A simple irrigation system, like a drip system, can also reduce water consumption for a crop by 50%, compared with conventional irrigation practices, and increase the yield by 30–40%. It should be used in tandem with a water pumping device in dry areas.

Agriculture

Agriculture in developing countries relies heavily on the physical capability of the farmers. The introduction of mechanical power machinery such as power tillers/two-wheel tractors, harvesters, bed planters, row planters, and seed drills can greatly improve productivity and hence livelihoods. In Bangladesh, power tillers (12–15hp) are used for about 70% of farm work because of their versatility; they can be used for tilling, irrigation pumping, threshing, husking and transporting. Locally made attachments to the tiller, such as a bed planter with a seeder, allow bed formation and seeding to be done in one pass. A study has shown that the yield of wheat, maize and mungbean on beds was around 19–23% higher than on beds using conventional systems. In one year, the total cost of planting in a bed system can be reduced by 59% compared to that of conventional methods. Research has found that by using this system, the irrigation method can be changed, and this can lead to a reduction of the demand for water by 30%.

Agro-processing

Post-harvest activity is arguably the main factor in helping farmers increase their income. Substantial time and resources are spent transporting crops to neighbouring mills if the services are not available in farmers’ own villages. Most processes can utilise energy derived from shaft power, with many alternatives for technologies powered by human, animal, water or a stationary engine. This includes powered mills and oil expellers, saw mills, powered shredders, powered shakers and grinders, powered spinners and fans. Diesel powered mills, for example, can easily be adapted to power other machines such as oil presses. This opens up the possibility of self-sustaining community systems, where machine fuel will be obtained from the crops processed, and maintenance costs will be paid for through a charge for the services. This framework has been successfully used, for example, by the Multifunctional Platform (MFP) project in Mali.

Natural resource extraction

The suitability of mechanical tools for small-scale mining, and their use, has been well documented, and there are many technologies that can reduce the effort needed for mining. Small-scale forest harvesting has seen increased interest in recent years due to its relatively low environmental impacts. Without access to large machines, these enterprises are limited in the size of trees that they can harvest, and this means that extracting them from the forest does not create the wide pathways that unnecessarily destroy vegetation. Improvements in the use of mining and forestry methods and technologies can help save lives by reducing human error, and can enable access to previously inaccessible resources. Improved technogies are e.g. manual percussion drills, petrol powered drills, expandable tubes with hydraulic pumps, powered water jets and shakers, as well as powered saws (sawmills, chainsaws).

Small-scale manufacturing

Mechanical power technologies allow micro-enterprises to produce goods consistently at the same quality and at a faster production rate. This, in turn, will directly affect their income for the same time spent on labour. In some cases, new products can be manufactured, for example, setting up a metal workshop, where previously people did not have the means to produce replacement engine parts. Once they can manufacture their own products, entrepreneurs can ensure that local demands are met.
Examples for improved technologies for small-scale manufacturing include sheet metal/pipe benders, hole punchers, saw mills, treadle lathes, hand/foot powered pressers, treadle looms, paper presses, pulp mills, treadle pottery wheels, bottle cappers.

Lifting and crossing

Accidents, loss of goods, and human power for lifting can be reduced with technologies such as gravity ropeways. This can help improve health and save time that can be spent on other more productive activities. In addition to transporting goods, lifting and crossing mechanical power technologies, such as gravity ropeways, can be more flexible, and provide low cost alternatives to bridges in remote areas. These can form vital connections, enabling people as well as goods, to travel far more quickly from remote villages separated by rivers, ravines or cliffs from centres where medical or educational resources or markets may be found.

Further Reading

• Productive Use of Electricity
• GTZ Approaches for Promoting Productive Use of Energy