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Biobriquettes - a competitive fuel for cooking
[top] [end]BackgroundNepal has, in theory, a viable hydropower potential of 40 000 MW of energy, but to date it uses less than 1% of this potential because of the high cost of generation. From Table 1 it can be seen that most of the energy demand in Nepal is still met through traditional energy sources such as fuelwood - 67.9%, agricultural residues - 14.9%, and animal dung - 8.1%. If we look at the energy consumption per sector for the same year, 91.3% of the total energy is consumed by households, out of which 72.4% is met by fuelwood alone (Figure 1). Figure 2 shows the typical household energy end uses for the rural hill areas of the Western Development Region of the country. Most of the energy (about 80%) is used for cooking, including the preparation of animal feed.Table 1: Energy consumption by fuel type and sector
It is obvious that traditional sources, especially fuelwood, which form an important part of the energy supply, cause deforestation and serious ecological and environmental degradation in the country.
[top] [end]Alternatives to fuelwoodIn its search for alternatives, the country has introduced several alternative energy sources and technologies such as biogas, microhydro, kerosene, liquefied petroleum gas (LPG), improved cooking stoves, solar/wind technologies, briquettes, etc. An analysis of the alternatives (Elite Consultants) has shown that most of the technologies/energy sources:
This table clearly shows that efficiency is highest for electricity and gas, but (rice husk) briquettes are the most cost-effective fuel. Briquettes have some drawbacks such as increasing prices, combustion problems etc., but with some technical interventions, the modification of products, or by raw material substitution, they could provide an alternative to fuelwood for domestic cooking purposes. Most of the government and donor-led economic development plans have accorded priority and financial support to various alternatives such as biogas, cooking stoves, microhydro, etc., but promotion of briquettes and briquetting technologies is still lacking. Considering the technical and economical characteristics shown in Table 2, it can be seen that briquettes, with good government support, could very well serve as a possible alternative to fuelwood. Table 2: Cost comparison of different energy sources
Source: Water and Energy Commission report [top] [end]BiobriquettesBiomass briquettes of low density, manually prepared from animal dung and biomass (straw, jute sticks, etc.), have been used in rural Nepal for generations. With the introduction of densification technologies from Taiwan, biomass briquettes (rice husk and saw dust) have been produced using extrusion technology. They were a success when they were first introduced, as the raw materials - rice husk and sawdust -were cheap. However, more recently, these raw materials have found direct industrial use in boilers, causing a major price increase, making briquette production and briquettes expensive.A joint research project, the National Research and Development Centre for Alternate Energy (NRDCforAE) was initiated in 1992 with technical assistance from the Japan International Cooperation Agency (JICA) in the Royal Nepal Academy of Science and Technology (RONAST). The NRDCforAE addressed the problem of biobriquettes for the first time in the country, taking into consideration the cheaply available biomass materials such as sugarcane bagasse, banmara, pine needles, etc. Next, the project introduced the concept of biocoal, which is a composite fuel made of biomass and coal with an optimum composition of 25% biomass and 75% coal or lignite. [top] [end]Comparative tests of different biobriquettesDifferent biomass briquettes (EBB, EBM) and biocoal briquettes (BC), shown in Figure 3, produced experimentally at the NRDCforAE of RONAST and the Hokkaido Institute of Japan(HIRI), were tested in the laboratory and in field trials for cooking purposes. Some of the test results are given below.
[top] [end]Laboratory testsFuels used for testing:
Different fuels were used to boil water, using similar conditions for each test. Laboratory tests were conducted using an appropriate stove to boil water using a kilogram of each fuel. The amount of evaporated water and the corresponding calorific values of the different fuels are given in Figure 4. By measuring the amount of water which could be evaporated by each type of fuel it could be seen that different briquettes (BC-17, EBB-1, EBM-3) gave better results under the same conditions (evaporating more water) than could be achieved using the same amount of fuelwood (FW) as shown in Figure 4.
[top] [end]Field testsThe same fuels were used for field tests at Mugling, a road junction some 160 kms south west of Kathmandu Valley through which all road transport coming and going out of Kathmandu passes. Mugling and its surroundings has over 100 tea-stalls and restaurants and alone consumes about 16 tonnes of fuelwood daily.
The tests were performed at the Rupsi Hotel/restaurant (Figure 5) by cooking:
While cooking food for 5 persons almost all of the briquettes (BC-17, BC-19, EBB-1 AND EBM-9) show better results than fuel-wood: either in terms of the total cooking time (BC-17, EBM-9) or in terms of the amount of fuel consumed (BC-17, BC-19, EBM-9). The shortest total cooking time used BC-17 briquettes (64 minutes) and only 1.54 kg of the fuel was required, whereas for the same result, it took almost 3 kgs (double the amount) of fuelwood and 85 minute of cooking time. The time required to cook each individual item varies with the fuel used. A general observation is that, using briquettes, the cooking time for rice is always less than when using fuelwood. Furthermore, the combustion tests showed that the biobriquettes burn with a more uniform flame and at a higher temperature than fuelwood. The biobriquettes. particularly biocoal, were found to be easier to ignite, they lasted longer and burnt with very little smoke or harmful exhaust gases. The duration of combustion for all the biobriquettes - biomass, biocoal and even cowdung was longer than for fuelwood. [top] [end]Conclusions
[top] [end]References
[top] [end]AcknowledgmentsThe author would like to thank all the NRDCforAE team members, particularly Mr. Keiichi Yoshida, Mr. Toshino Chino, long term JICA experts and RONAST colleagues Mr. Rishi Shah, Mr. Gyani Ratna Shakya, Dr. Y.B. Chettri for their kind cooperation and assistance in making this publication possible.[top] [end]Contents: Boiling Point 41: Household energy: the urban dimension
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Page created:
01 August 2007; Last edited:
04 December 2008; Version: 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Pagename: Biobriquettes-ACompetitiveFuelForCooking @HEDON: KDGA | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
