Chapter 15 - Renewable and non-conventional energy sources

Small hydroelectric plants
Biomass energy
Solar energy
Wind energy
Conflicts and interactions between alternative energy use and other sectors
Bibliography

The energy crisis which began in 1973 caused petroleum supplies to decrease and prices to rise exorbitantly. This crisis forced developing countries to reduce or postpone important development programs, so they could purchase petroleum to keep their economies operating. It created the urgent necessity to find and develop alternative energy sources, such as other fossil fuels (coal, gas), nuclear energy, and renewable energy resources.

Coal is found primarily in industrialized countries, with Latin American and African reserves making up less than 1 percent of the world total. Thus, it is unlikely that this part of the Third World will be able to use large quantities of coal. The nuclear alternative is undesirable; the associated accident risks, waste disposal difficulties, nuclear terrorism, and nuclear weapon proliferation are dangerous in themselves, and make this form of energy excessively expensive (Brown et al, no date). Acquiring nuclear energy from the industrialized world could, moreover, result in greater technological and economic dependence on developed countries. A more feasible alternative to petroleum, coal, and nuclear reactors in developing countries is the direct and indirect use of solar energy, which is renewable, abundant, decentralized and non-polluting.

Each day, the sun sends to earth many thousands of times more energy than we attain from other sources (the equivalent of 200 times the energy consumed by the United States of America in one year). This energy can be captured directly as radiation or - even more significantly - indirectly in waterfalls, wind, and green plants. Countries in the humid tropics in particular contain enormous forest biomass resources, which, properly managed, could significantly contribute to the solution of their energy problems, as well as provide wood for other uses. Countries in the humid tropics also possess abundant water resources and high levels of solar radiation, which show promise in generating electrical and thermal energy.

Taking into account that the technology needed for exploiting renewable energy resources is simple and relatively economical, it is important from a strategic point of view that energy planning in Third World countries, particularly in the humid tropics, be oriented to developing the solar alternative. It offers them one of the few opportunities to develop independently of the industrialized countries. To this end, energy planning also must encourage energy conservation and optimize the use of organic by-products and residues generated by economic and domestic activities.

The National Energy Balance Study (MINEMIN, 1979) established the principal premises for the supply of primary conventional energy resources from 1960 to 2000 in Peru (it did not consider the significant introduction of renewable and non-conventional energy sources):

- Peru possesses a great hydroelectric potential, estimated to be 48,000 technically-exploitable MW, only 3 percent of which are being used at present.

- Peru apparently has more than 48 million metric tons of coal reserves, even though no significant production occurred between 1967-1977.

- Known petroleum and natural gas reserves do not support the optimistic predictions that hydrocarbons will maintain their present importance as energy sources in the Peruvian economy (Table 15-1).

- As petroleum presently represents the only raw material for fuel and lubricants, it should be used to satisfy internal consumption, not exported.

- It has been estimated that a gap will appear between supply and demand for petroleum products after 1988-1989, when it will be necessary, to meet internal consumption needs, to import 30-38 million barrels in 1990, 55-60 million barrels in 1995, and 100-105 million barrels in 2000.

- Firewood and plant residues will continue to be the principal combustible energy sources for most of the rural population.

- Considering the projections for electricity supply and demand (an increase from 484 KWH/inhab. in 1975 to 1,000 KWH/inhab. in the year 2000), it will be necessary to increase existing production capacity by 800 MW between 1980-1985,560 MW between 1985-1990, and 2,300 MW between 1990 and 2000.

Table 15-1
NATURAL GAS AND PETROLEUM PRODUCTION IN PERU

The major energy resources in the Central Selva are water and biomass which are renewable and do not generally require sophisticated technology. Furthermore, because it is near the equator, the Central Selva receives large amounts of solar radiation. The heat and radiation favor an intense evapotranspiration/precipitation cycle that generates the clouds which give the rain forest its name. This combination of rain, heat, and radiation, assures an unusual photosynthetic activity that potentially can generate large amounts of biomass. These conditions suggest that non-conventional energy sources such as waterfalls, the energy stored in green plants, organic residues, solar radiation, and wind can be viable alternatives to oil, gas or coal to satisfy rural demand for energy in the Central Selva, and, all are resources that can be exploited with presently available technologies, such as small hydroelectric plants.

Small hydroelectric plants

Although this technology is not new, its wide application to small waterfalls and other potential sites is new. It is best suited to high falls with low volume, such as occur in high valleys in the mountains and in the High Selva. Thus ELECTROPERU (1979) conservatively estimates that at least 1,000,000 KW could be generated in hydroelectric plants producing 100 to 1,000 KW. The investment needed to provide this electricity to 1,186 isolated locations in Peru is high - approximately US$1,500 per KW. The ELECTROPERU 1979-1985 Program of Investment for Small Hydroelectric Plants has considered the construction of 14 plants in the high and low forest regions, which would consume 25 percent of the total investment for small hydroelectric plants during this period (Table 15-2). These plants are classified by power and size of waterfall in Table 15-3.

Table 15-2
INVESTMENT PROGRAM IN SMALL HYDROELECTRIC 1979-1985 (Peruvian Selva)

Many technological possibilities exist for exploiting the energy stored in green plants and organic wastes.

Direct Combustion

The combustion of firewood, forest residues, and other cellulose residues produced by urban and rural industry is the oldest process employed by man to provide energy for both domestic and industrial purposes (Table 15-4). Firewood and agriculture and livestock residues (husks and manure) contributed 33.8 percent of the primary energy consumed in Peru in 1976. This energy was not used commercially, but was almost entirely employed in domestic and cottage industries, where it would be more useful and efficient if first transformed to charcoal, a dry combustible material of higher calorific value (Table 15-5). As either wood or charcoal, it would be burned in the home in heat-efficient stoves which can be made in cottage industries or factory-made classic stoves of iron. Wood ovens can be used in small industries such as ceramics, brick-making, construction materials for bread making, smelting and others.

Table 15-4
NATIONAL ENERGY BALANCE AND PROJECTIONS TO THE YEAR 2000

Table 15-5
CALORIFIC POWER OF SELECTED COMBUSTIBLE SUBSTANCES

Scientifically managed forest plantations can annually produce approximately 70 steres per hectare. At a thermal conversion efficiency of 70 percent, it can be deduced that one plantation hectare is the equivalent of 45x10⁶ Kcal/hectare/year, or 28 barrels of petroleum per year. If the 141,764 hectares suitable for forest exploitation in the Perene river valley were to produce firewood the energy produced annually would be equivalent to 4,000,000 barrels of petroleum (ONERN, 1967).

Presently, however, the wood industry in the Central Selva is oriented to harvesting natural stands of trees and using them in construction and in furniture and paper production. Most sawmill wastes (wood chips, sawdust, and unusable pieces of wood) are burned or dumped into rivers. Data from ONERN and from the Subdirectorate of Statistics (Ministry of Agriculture), show that a total of 857,413 m³ of wood were cut in the Central Selva between 1974 and 1980, generating 257,224 m³ of cellulose wastes (factor=0.30). In other words, the equivalent of 102,890 barrels of petroleum was lost.

Thermo-conversion Processes

The thermal division of the components of wood and cellulose biomass in different oxidation, temperature, pressure, and catalysis conditions gives rise to a series of thermal conversion processes. Wood is most commonly converted to charcoal, while producing a poor wood gas (gazogene gas), but it is also possible to make combustible solids, liquids, and gases with different characteristics and applications, using various production technologies, including the pyrolosis and wood gasification for production of methanol and ethanol.

Pyrolysis, or dry distillation of wood, is a process in which wood and woody substances are heated in the absence of air. The process becomes exothermic and successively liberates gases, water vapor, and organic liquids. Residues, such as charcoal and heavy tar oil, remain. All of the products of the process except the water are combustible.

The most simple pyrolysis produces only charcoal in batch furnaces constructed in cottage industries; neither liquids nor gases are recovered. Charcoal-makers along the north coast in Peru (Piura, Lambayeque) use another primitive technology, making charcoal from mesquite trees that are stacked and covered with mud in ovens used only for this purpose. However, in Brazil and in northern Argentina cylindrical ovens covered with a roof of bricks (media naranja ovens) can be used to obtain charcoal in the forest or to produce it in foundries for industrial and domestic uses.

Making charcoal in these batch furnaces consists of filling them with dried wood, then completely closing the doors except for an orifice in the upper part to allow ignition and a series of other orifices at ground level to permit air to enter. After ignition, air intake is controlled by closing the lateral openings so that combustion proceeds slowly, without enough air to burn the formed charcoal. One successful operation should produce some 40 kg of charcoal from 100 kg of dried wood. A media naranja oven produces 150 tons of charcoal a year, lasts five years, and costs US$800.

Other raw materials that can be pyrolyzed are the husks of coconuts and nuts, which, because of their high density and quantities of lignin, can produce high quality charcoal for foundries and other applications. Wood residues from sawmills and paper mills are still other potential raw materials.

Biomass gasification is a thermal process that transforms vegetal material (wood, charcoal, cellulose residues) into combustible gas containing carbon monoxide and hydrogen. The wood is burned in controlled conditions in oxygen and water vapor in a gasogene oven.

In practice, gasification is a continuation or natural complement of wood pyrolysis, but in gasification wood dries, becomes charcoal, and then gasifies in the same equipment, thus improving efficiency and reducing cost. For this reason, present-day research is investigating wood gasification as a replacement for coal.

The gas produced contains varied proportions of carbon monoxide, carbon dioxide, hydrogen, and methane, as well as several minor substances that vary according to the chemical composition of the wood or charcoal used and the gasification technology employed. The gas has basically two uses: as a substitute for petroleum in industry and in generating power; and as a component in the production of methanol and ammonia. Wood gasification in the Peruvian Central Selva is a promising alternative for small-scale thermal applications such as for vehicles, boilers and ovens.

Methanol and Ethanol are popular sources of alternative energy that may be synthesized from plant matter. Methanol (methyl alcohol or wood alcohol) is a chemical product now manufactured world-wide by processing natural gas. It is used principally as a raw material for the production of formaldehyde (40-50% of production), industrial solvents, dimethyl-sulfoxide (DMSO), and others. After the 1973 petroleum crisis, methanol began to be considered one of the more promising combustible alternatives to liquid fossil fuels, because it is easily synthesized from wood gas. Today, numerous investigations into methanol use are being carried out in developed countries.

Ethanol, also called ethyl alcohol or alcohol, is either synthesized from ethylene, or it is fermented from amylaceous and glucidic substances. The use of alcohol today has spread from the distillation of spirits to the chemical, pharmaceutical and cosmetic industries. Pure alcohol is produced throughout the world by fermenting molasses (made from sugar cane and sugar beets) with Sachoromices cerevisae, a yeast that segregates specific enzymes that break down hexose and other simple sugars. The resulting substance is then distilled, producing pure ethanol and a form of wine as a residue.

Ethanol is most commonly made from sugar cane, sucrose and glucose, but can also be made from manioc, wood, and other substances. Sugar cane needs only a physical treatment; manioc, on the other hand, requires a thermal and enzymatic treatment, while wood requires a thermoacid treatment and hydrolized neutralization.

Manioc alcohol has been investigated in several pilot programs in Brazil and industrial projects are now being developed. Its alcohol yield is compared with that of sugar cane in Table 15-6.

Table15-6
ETHANOL PRODUCTION FROM SUGAR CANE AND MANIOC

The Central Selva has several features, especially optimal climatic conditions, that favor producing alcohol from sugar cane and manioc. The region produces more manioc than it can use for food because of the difficulties of transporting it to processing centers. From a global point of view, therefore, producing combustible ethanol from saccharides and amylaceous products can be a viable alternative in solving the Central Selva's energy problems in the near future, even though it is currently unprofitable. This process can also generate by-products that can prove useful as food and as raw material in industry and agriculture. Such products include:

husks, which can be a useful raw material in the pulp, paper, and particleboard industry; a combustible solid for boilers; a cellulose substance that can produce alcohol through hydrolysis; and a nutritious food for animals;

non-hydrolizable residues, (from manioc or from amylaceous substances), which can be a nutritionally-balanced food and a raw material for producing biogas;

carbon dioxide, which can be used to produce solid carbon dioxide (dry ice) and unicellular protein (microalgae, filamentous fungi, etc.);

fuel oil, which can be used to make industrial solvents, aromatic esters, and various chemical products; and

wine. which can be used to recover and produce yeast, fertilize soil, make firm airstrips, and, as a liquid substrate, produce biogas.

The Anaerobic Fermentation Process

Research into anaerobic fermentation has achieved some spectacular results, and the process now appears to have several uses that can contribute to rural development: it can provide energy, boost agricultural productivity, and aid in environmental sanitation. The anaerobic fermentation process converts the complex organic material in agricultural, livestock, and human wastes into combustible gas with high methane content and leaves a highly nutritious and harmless by-product. The process is carried out in easily constructed and operated biogas digesters, which use all types of wastes as raw material, including agricultural wastes (straw, leaves); animal wastes (manure, rumenal fluids, viscera); urban organic wastes (garbage, sewage); and industrial organic wastes (from food, fish, fruit, and vegetable processing plants).

The process depends on various factors, such as pH (between 7.0 and 7.2), temperature (the mesophyllic range being 10°C-40°C and the thermophyllic range being 40°C-60°C), digester hermeticity (absence of O₂), and the carbon/nitrogen ratio of the raw material. Also important are operating parameters such as flow, percentage of solids, and processing time. In hot climates like the Central Selva, external heat sources are not required. Assuming an average biogas calorific power of 4,767 Kcal per m³, Table 15-7 presents the biogas and energy production of different resources.

The presence of such resources as plant stems, leaves, wood residues, and wastes from coffee, manioc, banana, and aquatic plant production, combined with the optimal environmental conditions, can make biogas production a significant industry in the Peruvian forest region. Biogas can be an economical source of domestic and semi-industrial energy, useful for cooking food, lighting, warming chicks, refrigeration, and operating motors and pumps (Table 15-8).

Table 15-7
THE BIOGAS AND ENERGY PRODUCTION OF DIFFERENT RESOURCES

At present, ITINTEC, in an agreement with the Special Project for Madre de Dios, is constructing four demonstration digesters in Iberia, la Cachuela, Puerto Maldonado, and Fundo Ganadero Amazona. ITINTEC has also been investigating the agriculture and aquacultural uses of biofertilizer. Greatly increased yields of potatoes, lettuce, corn, onions, and other crops have been obtained by using fresh manure. The yields are as high as those obtained with chemical fertilizers. In no case were pathogenic parasites detected in the biofertilizer. Another interesting application of biofertilizer (the effluent of digesters) is its use as animal food. Excellent results have been obtained in Mexico feeding cattle with silage containing biofertilizer.

Plant Oils

For the last several years, efforts have been made to develop diesel fuel substitutes made from plant oils obtained from oleaginous seeds (sunflowers, cotton, peanuts, and others).

The Brazilian PROOLEO Program is considering increasing the production of colza, sunflower and almond oils to 1,000,000 liters for the short-term, and, at the same time, stimulating the planting and cultivation of oil palm (Elaeis guineensis) in order to significantly increase plant oil production by 1986-87.

Table 15-8
QUANTITIES OF BIOGAS REQUIRED FOR DIFFERENT USES

The Peruvian Central Selva and the Amazonian humid tropics in general receive high amounts of solar radiation. There are so many trees hiding the sun, however, that it was once thought too difficult to directly exploit solar energy. Today, however, it is understood that such endeavors could enhance integrated development in Central Selva.

Solar energy can be used in low potency thermal generation. For example:

Heating of water is necessary for industrial and cottage industry requirements, such as making cheese and preserves. Flat collector technology is widely known, with many brands existing in the national marketplace. One of these is made in Peru, licensed by ITINTEC which has been conducting research in this field since 1975.

Solar dehydration of agricultural products is the most promising solar energy option for the Central Selva, considering the enormous difficulties that confront small farmers when preparing such products as rice, bananas, and manioc for the market. A program to distribute appropriate solar dehydration techniques to farmers can use equipment that optimizes the use of transparent plastic in place of glass and that also dries products (rice) by creating forced air convection that is heated by solar radiation of the product stored in vertical silos. Industrial concerns in Brazil can provide and install such operations. Solar heating, on the other hand, is not practical in households, but can be used for some production and livestock purposes.

Potent thermal generation also is possible using solar energy. Techniques exist to focus solar radiation on a single point, which can transform the latent heat of liquid vaporization into closed primary circuits. The absorbed heat is transferred to secondary circuits in series with mechanical works (turbines), eventually generating electric energy (helioelectric plants). At present, these techniques are in the experimental phase and are not yet competitive because of the very high cost of their sophisticated mirror systems that move synchronously by computer to derive maximum benefit from solar energy.

Photovoltaic generation is a technology that directly converts solar energy to electric energy through the use of cells with monosilica and polycrystalline surfaces that act as semi-conductors. It can probably supply the limited energy demands of remote and rural areas in the near future. The technological advances appearing day after day in developed countries have reduced the cost of energy produced by photovoltaic panels by five times since 1976; therefore, production has increased, the products are of better quality, and their manufacture is now automated and uses less expensive materials. Photovoltaic generation has its place in the integrated development of the Central Selva, particularly in providing energy for telecommunications and television and for water pumps and electrical service to homes in remote areas.

Wind energy

There is little potential for wind energy in Peru. Although no map exists that illustrates wind patterns in the Peruvian forest, recent reconnaissance of the High Selva in San Martin, Pucallpa, and Satipo did not detect winds with energy-producing potential. Nevertheless, before discarding this option, and taking into account its unpredictability, wind velocity should be evaluated where wind is being considered a potential energy-producer.

Wind's application for mechanical (mills) or electrical (aerogenerators) purposes would depend on the presence of continual wind; the demand (water to be pumped or KW required); the design and dimensions of the equipment and; whether equipment is produced nationally or locally.

Table 15-9 summarizes non-conventional energy alternatives.

Conflicts and interactions between alternative energy use and other sectors

Conflicts and Interactions with the Livestock Sector

The livestock sector can only benefit from biogas techniques which, among other things, use animal wastes. Because Central Selva soils are poor in phosphorus, phosphate needs to be imported and applied for good grass growth. One way to provide phosphates is to use the livestock manure that now is dumped into water courses and lost.

Table 15-9
SUMMARY OF NON-CONVENTIONAL ENERGY ALTERNATIVES

Brown, L.S., Me Cracken, D. Hayes and R. Rovere. No date. "Diálogo sobre la energía ¿Energía solar o energía nuclear?" FACETAS, International Communication Agency.

CETEC. 1980. Uso de Madeira para Fins Energéticos. Fundación Centre Tecnológico de Minas Gerais, Belo Horizonte, Brasil.

(ELECTROPERU) Compañía Nacional de Electricidad. Perú. 1979. "Fuentes de energía para la electrificación rural en el Perú." VIII Conferencia Latinoamericana de Electrificación Rural. Lima, Peru.

Klinge, S.H, 1980. Etanol a partir de la madera. CETEC, Belo Horizonte, Brasil.

(MINEMIM) Ministerio de Energía y Minas. 1979. Balance Nacional de Energía. INP/MINEMIN/PNUD, Oficina Sectorial de Planificación. Lima, Peru.

(ONERN) Oficina Nacional de Evaluación de Recursos Naturales. 1967. Los suelos y su capacidad de uso en la zona del Río Perené. Lima, Perú,

Verástegui, J. and y M. Matero. 1979. Producción de biogas a partir de desechos orgánicos. Investigación Tecnológica Industrial y de Normas Técnicas (ITINTEC). Lima, Peru.