| Local Experience With Micro-Hydro Technology |
Countries that depend on imports of energy are compelled to step up domestic energy production due to the sharp rise (see fig. 1) in the cost of imported energy (mainly oil). This is particularly so for developing countries, where the oil import bill adds every year to the problem of financing an already large external deficit.
Source: World Sank 1980, Energy in the developing countries
Today, energy should rank in importance with the classical factors of production -land, labour and capital - in economic activities and general development efforts. This not only applies for imported energy but also for energy produced domestjca11y. Now and in the future, questions of energy supply can no longer be treated as a second priority because conventional resources are depletable and the switch away from such resources is inevitable.
There is no single resource or technology that could replace oil in the near future. Conservation of energy and the development of all new and renewable resources are necessary to reduce dependence on oil. Many developing countries possess considerable potentials that have remained unexploited while oil was cheap. Their development is quickly becoming economically viable now, but not all resources lend themselves to quick and easy exploitation. A number of relevant technologies are in the research or experimental stage, others have long gestation times due to their size and sophistication, on still others, environmental constraints limit political acceptability.
A second energy crisis, coming from diminishing supplies of biomass energy, traditionally used in most rural areas (wood, dung, agricultural residues), is emerging simultaneously. Population growth, deforestation and diversion of fuelwood and charcoal to cities, where more expensive kerosene is replaced, endanger the ecosystem which supported village life . The system of traditional energy supply always was and remains very much an integral part of village life. Any change in energy use (e.g. increased consumption) has far reaching consequences on other aspects of life and the rural environment. Energy consumption levels of the majority of the rural population in developing countries are sufficient only to satisfy subsistence requirements according to a study commissioned by U.S. A.I.D.. An approximate figure of the amount of energy consumed is 300 to 400 kilograms of coal equivalent per capita per year (kg ce/cy). This figure seems appropriate for reference purposes although conditions in different countries and areas vary widely and data are available only from a few specific cases.
Most of the rural requirements are met with traditional energy resources. Percentage points of traditional energy use in relation to total energy vary in different environments and can be summarised as follows:
-800 Million people use 50 %
-160 Million people use 70 %
-270 Million people use 90 %
-The remaining people in developing countries use around or less than 40 %.
The figures given are based on national averages , and for rural areas the share of traditional energy is even higher.
Commercial energy used in rural areas is mainly in the form of oil-derivates such as petrol, high speed diesel and kerosene. Much of it goes to the transport and agricultural traction sector. Other important uses are lighting (kerosene lamps), cooking (kerosene, LNG, LPG)(LNG = Liquid Natural Gas, LPG = Liquid Petroleum Gas ) and provision of motive power to produce electricity for isolated rural communities and individual farms and plantations, small agro-based industries and cottage industry. Very often such motive power is used directly in its mechanical form, to run all kinds of machinery, typically water pumps, grain-and saw-mills.
Attempts to substitute petroleum products for traditional forms of energy have been dramatically undermined by todays cost of oil. Transport and traction by animal and human energy, for which petroleum products had been substituted to a much greater extent, are suffering a reversal in many regions, and rural electrification -if based on oil-derivate fuel -also has to deal with increasing costs of supply.
a) Liquid Fuel from Biomass
b) Gaseous Fuel from Biomass
c) Direct use of Sun and Windpower
d) Water-Power Resources
Energy problems are manifold indeed, and a unique solution - consisting of a variable mix of resources and technologies for each case - seems to be called for. There is scope for improving the balance of rural ecosystems through conservation, reforestation and effective wood lot management, and the use of traditional energy may be enhanced with better devices such as more efficient cooking-stoves and charcoal-kilns. Various new technologies have emerged in the past that can meet a number of needs and it is perhaps worthwhile to give a short summary of the state of the art of the major possibilities:
a) Liquid fuel from biomass:
The conversion of biomass to liquid fuel is not new. It was used during the Second World-War as a substitute for scarce fuel. It holds considerable promise for application in the developing countries. The production of alcohol, particularly ethanol (ethyl-alcohol), from certain types of biomass, is a commercially well established technology. Ethanol is produced by fermentation and distillation of carbohydrate materials such as sugar cane, sugar beet, molasses and cassava. It can be used to power vehicles either by itself or blended with petrol. Within limits, ethanol can substitute for an equal volume of petrol with only minor engine modifications. It could thus help to reduce the consumption of petroleum in the transport sector. Methyl alcohol, produced from wood, is more difficult to use as a vehicle fuel, and does not hold promise for the near future.
The economics of alcohol production are not very well established and depend greatly on the cost of biomass material. R + D is being done to improve the efficiency of production and to reduce costs, but it is still too early to assess the prospects for a breakthrough. The biggest constraint of using biomass-derived alcohol on a large scale is the direct competition with food production for arable land. Great care must be taken not to upset an already precarious balance.
b) Gaseous fuel from biomass:
Biogas, a mixture containing 55 -65 % methane (CH4) can be produced from the anaerobic (in the absence of oxygen) decomposition of animal, plant and human wastes. It can be used directly in cooking, reducing the demand for firewood. Also, combustion engines may be run on biogas with little adaptation of the engine only. Moreover, the material from which biogas is produced retains its value as a fertilizer and can be returned to the soil. Millions of small plants exist worldwide (China, India, South Korea, Nepal). Their operation has met with varying levels of success. In cold climates, prospects for the application are reduced since economics are best in the temperature range 25 -35° C. The poorer part of a population often has no access to the necessary feedstock. Although there is a big potential in aquatic weeds (water hyacinth) and other vegetable waste, its use as a "free" feedstock is not developed to any extent. More research and funds are required to make biogas a viable alternative in many more situations.
Partial combustion of wood or materials such as straw, nutshells, bark or rice hulls, produces a gaseous mixture (wood-gas, producer-gas) with a low calorific value. It can be burned for thermal energy applications, or if filtered, for use in combustion engines. The production and use of both biogas and producer gas could be viable much more widely in rural areas, given funds for research and development, incentives for experimentation and effective dissemination mechanisms.
c) Direct use of sun and windpower
Solar and windpower technologies are a third source of renewable energy for developing countries. A firm technical basis exists for windpower projects. Particularly water pumping is a simple and effective technology for rural areas. Machines that produce electricity are highly optimised for small outputs (up to 5 kW) and may be the best alternative for remote and isolated small consumers. Windpower tends to be an erratic resource and care must be taken to assess the wind regime properly and to choose a suitable machine that has been designed for the kind of existing wind regime.
Water heating by flat plate collectors is the solar technology most ready technically, economically and commercially - for widespread application. Some developing countries have begun to manufacture their own solar water heaters and many others could do so. Solar water heaters are often an economical source of hot water for domestic and industrial purposes. Solar dryers that basically heat air, can provide heat for drying crops in agriculture and are already in use in a number of countries.
Photovoltaic cells, which convert solar energy directly into electricity, appear well suited to many applications in developing countries because they promise long life and trouble-free operation. Solar electricity is still at price levels on the order of $ 2 per kWh. Costs of photovoltaic cells are falling but it is still difficult to say when the big cost breakthrough will happen. For its high costs it has good prospects only in applications where relatively low power needs exist in remote locations. The use of photovoltaic electricity for water pumping (drinking water, irrigation) appears -at prices of early 1981 - to be viable only where no other alternative exists.
d) Water power resources:
For many developing countries, unused water power resources constitute a very considerable potential. The technology is well developed and plays an important role worldwide. Geographically it is limited to suitable sites along rivers and other sources of flowing water.
"The historical approach to energy planning stresses the expansion of conventional energy sources and, generally, large-scale centralised systems. Thus, many countries face the problem of unequal internal growth, and also, a disintegration of the rural and non-commercial sectors." On the other hand, small potentials may be a very useful resource mainly in the field of providing motive power to stationary users -either direct or through electricity - and lighting. Considerable recent experience exists from a number of developing countries. The rest of this paper is devoted to this and to the elaboration of a practicable approach to harness water power on a small scale (in relation to installation size), but widely applied wherever potential exists and where it appears to be a viable or often superior alternative to other energy sources.