Posted October 1997
by Alastair Hicks
Senior Regional Agricultural Engineering and Agro Industries Officer
FAO Regional Office for Asia and Pacific
This paper was delivered at the International Solar Energy Society (ISES) 1997 Solar World Congress, Taejon, Republic of Korea, 24-30 August 1997. See also: Report on Solar World Congress.
The world's oil reserves are estimated to be 1 trillion barrels. At the present rate of consumption it is estimated these reserves will be exhausted in 45 years. In relation to the 1992 Earth Summit in Rio de Janeiro, the mass consumption of oil and other fossil fuels is seen as aggravating global environmental problems, such as acid rain and the 'green house' effect.
Yet "all life processes involve energy" (D.M. Gates) and exchange of energy between plants, animals and environment takes place whenever the sun shines, the wind blows or the rain falls. The economic use and promotion of existing or new and renewable energy sources, is vital to ensure food security for future generations, as farmers in the future may increasingly be faced with difficult choices for example, energy cropping versus food production.
It is simply defined as the "ability of matter to work". It also includes capability, activity, energy, vigor, intensity and life. Power thus equates to energy and life, which latter is linked to food security.
Power consumption is linked historically with social progress and economic growth. The interdependence between energy producers, traders and users such as farmers, is vital to stable development and continued food security, in the Asian Pacific Region. Burning fossil fuels, formed from the remains of biological matter buried millennia ago, produces 90% of commercial power used in the world (Table 1).
|Global Ranking||Fossil fuel (%)||Change %|
|Reference: Asiaweek, NewWorld Order, The Fuel of Choice (December 1994); Source: Encyclopedia Britannica|
Two thirds of the world's population live in rural areas of developing countries; by the year 2000 there are expected to be about 3 billion rural people, over 2,300 million living in the Asia-Pacific Region. How will their energy needs be met? Rural energy needs are for cooking, lighting and water supply on the household level, much of which comes from fuel wood crop residues and dung. Modernization of agricultural cultivation, production and processing in rural areas, involves commercial energy such as coal, oil and gas, non-renewable fossil fuels.
Rural poverty leads to 'powerlessness' since commercial energy sources are ruled out in the absence of money or credit. Even modest investments in renewable energy sources are difficult to raise and as a result, these are failing to fulfill their promise and role in rural areas. Yet a number of renewable energy technologies have been successfully developed:
Among the rural poor New and Renewable Sources of Energy (NRSE) could provide non-commercial energy needs as high as:
New and Renewable Sources of Energy, (NRSE) from nuclear fission, hydro, wind, tidal, geothermal, solar, are however collectively still minor in the total commercial energy consumed. If food security is to be sustainable, it requires reliable, economic and efficient energy conversion technologies.
Yet an unquenchable thirst exists for non-renewable resources which is a development planners' bad dream. Asia's appetite for oil is expected to overtake North America's, as this Region becomes the world's biggest oil consuming region. New and renewable sources of energy still have not found their rightful place in national energy plans and strategies.
In 1980 the division of agricultural power in developing countries was 5% mechanical, 29% animal draft power, 60% hand labour. By the year 2000 FAO has estimated that global investment in agricultural mechanization of over $130 billion is needed, to raise mechanization to 13%, animal power lowering to 20% and human labour at around 67%.
Where will this investment come from? Yet food security nowadays hinges on the supply of not only high-yielding varieties but also irrigation, fertilizer and farm machinery. These inputs require power and credit to unleash their potential, both of which resources are difficult to obtain without substantial equity and proven output.
The consumption of energy is regarded as an indicator of the state of technology, production and material well-being of society. The search for New and Renewable Sources of Energy has in fact come down through the ages.
Animal draft power though domestication of cattle has existed for over eight thousand years, the water wheel is over two thousand years old, windmills were introduced over one thousand years ago. Direct solar energy, wind and wave power and biomass-derived fuels have always had their potential as energy sources, though these alternative energy systems, when developed, are relatively expensive in terms of cost per hour and unit of power produced.
Power and energy is needed in all stages of agriculture ranging from intensive power use in transport, water lifting and pumping, land preparation, primary and seedbed cultivation, through to weed control, planting, transplanting, and harvesting (Table 2).
Power intensive: viable mechanization at an early stage
Control intensive: viable for mechanization at a later stage
Source: Tools for Agriculture, 1992
Human power has a limited output, but humans are versatile, dexterous and can make judgments as they work. This gives humans an advantage in skilled operations such as transplanting, weeding, harvesting of fruits and vegetables at maturity, also working with fibers (jute, silk). Water lifting and soil preparation need less skill and far more energy. A sustainable rate at which the body can use up energy is about 250-300 watts for a fit person, depending on climate, needing between 10-30 minutes per hour rest. Efficiency of energy conversion is only about 25%. This means the maximum sustainable power output is only 75W, which translated means pedaling at 30-40 r.p.m. or simulated walking as on treadle-pumps (Table 3).
|Activity||Gross power consumed (Watts)|
|Clearing bush and scrub||400-600|
|Ridging, deep digging||400-1000|
|Ploughing with animal draught||350-550|
single axle tractor
|Driving car on-farm||150|
|Reference: Tools for Agriculture, 1992. Source: Extracted from Durnin and Passmore, 1967, "Energy, work and leisure". Heinemann|
Animals are found to be working in
The working speed for most draught animals is about 1 metre/second, lower for cattle and buffalo. A Brahman bull consumes about 3.3 Joules for each Newton of pull in one metre. Power output in Watts ranges from 200 W for a donkey, to 650 W for a camel, with buffalo at 520 W. Working hours per day range from 4 hours for a donkey to up to 10 hours for a horse. There are limitations on the performance of animals, especially when they are needed most, that is in the dry season when feed, grazing and even water are in short supply. The types of implements can be 'pole-pull' 'chain-pull' or 'wheeled carriers' for implements, used for breaking, ploughing, ridging, weeding, planting and harvesting for various crops (Table 4).
|Animal||Typical weight kN (kgf)||Pull-weight ratio||Typical pull N (kgf)||Typical working speed m/s||Power output W||Working hours per day||Energy output per day MJ|
|Buffalo||5.5 (50)||0.12||650 (65)||0.8||520||5||9.5|
|Horse||4.0 (400)||0.13||500 (50)||1.0||500||10||18|
|Donkey||1.5 (150)||0.13||200 (20)||1.0||200||4||3|
|Mule||3.0 (300)||0.13||400 (40)||1.0||400||6||8.5|
|Camel||5.0 (500)||0.13||650 (65)||1.0||650||6||14|
| Note: For animals of different weight the power
output and energy output per day may be adjusted proportionately |
Source: Tools for Agriculture, 1992
Low power tractors produce around 25 Kilowatts (kW) and are intended for pulling, but with a power take-off can operate rotary hoes, pumps and threshing machines.
In Asia the single axle (two-wheel) tractor predominates, for irrigated rice and horticultural crops in the tropics. Traction is limited, as well as ground clearance. The power take-off can be used for threshing, transporting and even spraying, when pulling a tank.
The additional energy available with machine power over animal and human power, needs to be put to the best use. The experience, judgment and skill of humans needs to be applied in balance with power - intensive operations and above all the power used should be:
The cost of tractor operations is such that FAO has calculated about 40 Ha of good arable land is needed to support the costs of a 20kW tractor, the minimum viable size.
Many alternative power sources are proposed for the replacement of fossil fuels in food production agriculture. Many are essentially incompatible with the main power needs, but can be adapted to supplementary power needs.
Considerable effort has been used to promote alternative energy in rural areas. Most have failed miserably because they do not fit the rural socio-political or economic constraints, or take into account gender issues.
Many energy sources in the countryside have been essentially non-commercial, though they too are rapidly gaining value.
The rural sector is generally overlooked in national energy plans policies and programmes - e.g. the improvement of agricultural activities through energy availability, in the right form, cost and quantity, in the rural area.
A number of countries in the region are able to fulfill the energy needs of their population whereas some have deficiencies in some areas. In small scale food cooking and production, the problem of fuel and energy consumption is highlighted, as many wood stoves are only between 8-15% efficient. A serious decrease in available firewood, and the poor financial situation of marginal rural populations make the problem of food security even more severe.
Power sources from fuels, whether conventional, fossil, new or renewable, are required to supply energy for these preservation operations, as well as their packaging, distribution and consumption. Food products available to today's consumers have an energy price tag and the relative cost of cooking, preserving and packaging needs to be considered when developing food products for market. The extended shelf life and storage capability of modern food products is a source of food security particularly to urban communities at a distance from the farm.
Many food crops when harvested cannot be consumed directly but must pass through several stages of processing as well as cooking in order to be palatable. Raw meats, uncooked grains, vegetables and even fruits, require preparation and often heating to enhance their flavour, rendering their components edible and digestible. The processing and cooking stages also reduce harmful organisms and parasites of public health significance.
The Food Security issues in relation to food preservation are clear when one considers that poorly handled and stored food becomes spoiled and contaminated easily thus lost. The causes of this are microbiological, through the actions of bacteria, yeast and mould; physiological by self-destruction effected by built in enzymes and chemicals in the foods; environmental through the effects of moisture, light, oxygen, unwanted radiation. The main technology used is the destruction by heat and other agents. To inhibit or slow down microbial or enzyme spoilage other preservation techniques are ued.
Pasteurization causes the inactivation of spoilage enzymes and reduction of bacteria, with temperatures around 80-90°C. Heat sterilization can use atmospheric steam at 100°C for high-acid foods, pressurised steam at around 120°C for low acid foods. Irradiation is used to destroy micro-organisms by the destruction of DNA in the living organisms, through ionizing radiation. These techniques use increasing amounts of energy depending on the level of preservation required.
Unfavourable conditions can be created for microbes by:
|dehydration||reduction of available moisture to between 8-12%|
|freezing||removal of energy and moisture immobilization, to reduce microbe and enzyme mobility|
|salting/syruping||osmotic removal of moisture required for life processes|
|fermentation||inhibition of growth and numbers of microbes by means of alcohol, acid, sugar/salt concentrations|
|pickling/smoking||combinations of salt, acid, smoke pasteurization to reduce microbes|
|combination methods||using two or more of the methods, in conjunction with irradiation, to inhibit microbes, e.g. freeze-drying|
Dr. Gustavo Best, Senior Coordinator of the Environment and Energy Programmes Centre, FAO Rome, takes the following line in an occasional paper on "Food Security from an Energy Standpoint".
"Most aspects controlling, guiding and ascertaining food security are energy-dependent. It is impossible to envisage an effective food production system, or an efficient food processing and distribution chain without the necessary energy inputs which makes them operate. There is a close correlation between the quality and quantity of food produced, transformed and consumed and the quality and quantity of energy used to "turn the wheels": of food security. In many cases, it is precisely the low quality and the meagre amounts of energy available for the food chain, which are at the base of unattainable food security.
"The situation in many areas of developing countries is characterized by that lack of sufficient energy inputs to satisfy a minimum of the requirements of the potential food security level. Agricultural practices continue to be based to a large extent on animal and human power; little, if any indirect energy inputs such as irrigation or fertilization are at hand; food losses are very high due to the lack of energy for processing or storing, or for transportation to markets; the use of locally available energy sources, such as solar, wind, biomass or hydropower is minimal, as is the access to conventional energy sources such as hydrocarbons or electricity.
"FAO faces these challenges through a programme which comprises both policy and technology issues. The main policy problem addressed is the general lack of rural energy development policies; most energy policies are designed for the needs of the more 'modern': sectors of society, i.e., industry, transport and urban infrastructure. Rarely are policies in place to deal effectively with the needs of rural populations and of their energy-demanding activities. Not even the 'fuelwood problem', critical in many areas of Africa, Asia and in arid and semi-arid areas of many developing countries, is policy framed and confronted. From the food security standpoint, rarely are the energy requirements identified within policy considerations. In most instances, a 'bridge': is required between the energy and agricultural authorities, so as to effectively incorporate rural energy needs into overall energy planning and policy formulation efforts, and to make sure that agricultural porgrammes explicitly identify their energy needs. The promotion of this policy, planning and institutional is a major part of FAO's energy activities.
"A large number of energy technologies useful in rural areas are mature. Others still require further research or demonstration. FAO is active in both these fronts, and has activities in fields such as biomass conversion (liquid fuels; biogas; gasification; pyrolysis; combustion), solar energy (thermal and electricity), wind energy, energy efficiency (cooking stoves; mechanization; fishing vessels), and geothermal energy (greenhouses). If food security is to be sustainable, it requires reliable, economic and efficient energy conversion technologies. FAO's activities include field projects, technical studies and meetings, promotion of the transfer of technology, and information diffusion.
"Because of the close energy and environment linkages, efforts to attain food security necessarily face the challenge of a proper developmental and environmental balance. In both FAO's energy policy and technology work, this balance is critical, and it is sought through the guidance of an Interdepartmental Working Group on Energy, which has members from all relevant FAO services. A multidisciplinary approach is at the base of FAO's energy workplan."
1. Gates D.M. "Energy exchange and ecology" Bioscience, 1968, in CERES, No. 133 (Vol. 24, No. 1) January - February, 1992.
2. FAO "Multi farm use of agricultural machinery' FAO Agriculture Series No. 17, 1985.
3. Carruthers, I. Rodriquez, M., Tools for Agriculture, a guide to appropriate equipment for small holder farmers. I.T., C.T.A., Intermediate Technology Publication, U.K. 1992.
4. Rural Energy Bulletin issue 1994/1, FAO Regional Office for Asia and the Pacific, Bangkok, 1994.
5. Pimentel, D. and M., Energy Use in Food Processing for Nutrition and Development, Food and Nutrition Bulletin, V.7, No 2, 1985.
6. CERES - The FAO Review No. 133 (Vol. 24, No 1) Jan-Feb 1992.
7. Woods, J. and Hall, D.O., Bioenergy for Development Technical and Environment Dimensions, FAO Environment and Energy Paper, No 13, Rome 1994.