By: Sahibullah Nassery
Energy has an important role in overall social and economic developments. However, most energy providers are reluctant to venture into rural regions of developing countries. These regions are generally characterized by remoteness, poverty, low-income population, and minimum access to electricity. In this paper, I present the potential of rice husk for rural electrification in Afghanistan. The conversion of rice husk into electricity through gasification and thermally is a well-known technology. Rice husk or commonly renewable energy can contribute in a sustainable manner to grant access to electricity in rural areas in Afghanistan. The present investigation focuses on the study of self-sustaining energy services to provide grid quality power to the rural populations without the need for subsidies. In Afghanistan, many rice mills are operating in rural and urban areas. All of them are using oil fuel for electricity production for their mills. I believe that power systems focusing on power requirement for industries such as rice mills and power requirement for the people living in the neighboring rural areas at affordable tariff could become the most appropriate solution for sustainable rural electrification
1 – Introduction
About 2.4 billion people around the world are dependent on traditional bioenergy (wood, agricultural residues and animal dung) as their primary source of cooking and heating energy fuels . About 1.6 billion people around the world do not access to regular electricity . Amongst these 1.105 billion people with no access to electricity that are live in rural, semi-urban or remote rural areas of sub-Saharan Africa and South Asia . Big conventional energy providers are reluctant to venture in rural areas that are characterized as low income group category populations with low energy demand. Therefor the present paper is focused on to study the self-sustaining energy service to provide the grid quality power to rural areas without any grant subsidies. The grid expansion is a vital objective for several developing countries in the rural areas and the Afghanistan as well. However, major hurdles for the electrification of many rural areas are: poverty, remoteness, low population, and low electricity demand, high operational and maintenance cost of grid power and unwillingness to invest in rural areas. Since grid extension is not a feasible solution the decentralized renewable technology seem to be the batter option to electrify the rural areas. Recent investigation also indicate that the renewable energy sources are the best choice especially in areas far from the grid connections.
More developing countries pursuing various policies for development of new renewable sources. Although solar, wind and micro hydro power technologies. But they face strict limitation imposed by the site specificity and seasonally of resources. Furthermore, intermittency of wind and solar energies lead to the technical problems such as generation imbalance. Solar and wind energy energies are subject to weather conditions and wind speed .The biomass energy (gasification or thermally electricity), develop and widely used in developing countries, has proven to be a reliable and competitive option to the other renewable energy technologies. In the lower and medal range of power, biomass gasification is emerging as a promising technology in many develop and developing countries. The produced gas can be for operation of machines in industries and for electric power generation to households lighting. The block diagram of gasification process is displayed in figure (1).
The bioenergy, based on direct combustion boiler and steam turbine system at a small and large-scale for residential and industrial is mature and commercially available technology .
Lim el al, have reported that the rice husk and rice straw biomasses have great potential to be converted into energy in order to meet the energy demands in rice producing countries. The Islamic republic of Afghanistan a land locked country having a total landmasses of 652,230 km2, and a population of 32,564,342 (July 2015) . With 23.5% of urban population  that 16% of them are have access to energy . Agriculture is the primary source of income in Afghanistan . The ministry of energy and water is responsible to providing the basic electricity service to the rural areas. The ministry of energy and water is now working on some renewable energy projects to electrify rural areas in Afghanistan.
Since rice husk and straw is locally abundant in rural areas. Afghanistan is a good candidate to study the self-sustaining power system which is focusing on both power requirement for rice mills and power requirement for the people living in the rural urban, semi-urban areas. Therefor the study of rice mills generating power using rice husk biomass for their own use as well as for the rural electrification are presented her. Such an energy service model of rural electrification could become financially viable business model to electrify rural areas at an affordable tariff. Her I present a self-sustaining business model to provide the grid quality power to rural population without any grant or subsidy. Rice husk gasification technology could be an attractive solution for the sustainable and affordable rural electrification where the energy demand is low and rice production provinces in Afghanistan.
The first section of this paper is devoted to the introduction of the topic discussed in the present investigation. The second section deals with the current energy situation. The third section discussed on rural electrification in Afghanistan. While the rice production, rice husk gasification, rice husk power plant in Afghanistan, self-sustaining business model, conclusion and recommendation are discussed in the fourth, fifth, sixth, seventh, eighth and ninth sections respectively.
2 – Energy situation of Afghanistan
Afghanistan has a low level of electrification in 2012. The electricity consumption was reached 3.893 billion KWh, or 120 KWh per capita . About 28% of Afghan peoples have access to electricity . Since about 5% to 9% rural people have access to grid electricity . The total energy production in 2012 was 884.1 KWh, 35.4% of this is produce from fossil fuels, 64.4% is from hydroelectric power plants and 0.2% is produce from renewable energy. And the total traditional energy imports from central Asian countries was 3.071 billion KWh in (2012) . The price per kW power of each technology is in the table (1).
3 – Rural electrification
About 70% of Afghan population lives in rural areas . And around 5% to 9% of them have access to electricity .
The government of Afghanistan has investigate the ambitious plan for rural electrification . Time horizon for this power sector master plan is 20 years up to 2032.
• The connection rate in rural area will reach 65% of the households.
• For urban areas the high level of near 100% will be reached.
• 95% of electric power generation will be from renewable energy.
The summery of renewable energy implementation is shows in the table (2).
The primary energy in rural household depend on traditional fuel (wood, crop residues and animal dung) for cooking and heating, and kerosene for lighting . The share of this sources shown in figure (2). Afghanistan can produce around 318GW of electricity utilizing available renewable energy in the country . The share of all of them is shown in figure (3).
3.1 – Solar Energy
Solar energy is energy directly from the Sun. This energy drives the climate and weather and supports virtually all life on Earth. Solar energy is considered the most abundant renewable energy source. Estimates indicate that in Afghanistan, solar radiation averages about 6.5 kilowatt-hours per square meter per day, and the skies are sunny for about 300 days a year. Consequently, the potential for solar energy development is huge, not only for solar water heaters for homes, hospitals, and other buildings, but also for generating electricity .
The potential of solar energy in Afghanistan is 222 GW . And the solar radiation assessment is shown in figure (4). The renewable energy projects in Afghanistan have so far been supported extensively by the donor community. Some of the recent initiatives include 1 MW off-grid solar plant in Bamyan, and 2.2 MW of solar and MHP projects are in Takhar and Badakhshan provinces .
3.2 – Wind energy
Wind energy is plentiful in Afghanistan and wind turbines capture the energy of the wind and convert it directly to electricity. This can displace fossil-fuel derived electricity . The potential of wind energy in Afghanistan is 67 GW . And the site of wind potential assessment is shown in figure (5).
3.3 – Hydro (mini, micro) power
Some 125 sites have been identified in Afghanistan for micro hydro resources, with the potential to generate about 100 megawatts of electricity. Hydro power captures the energy from flowing water to power machinery and produce electricity .
3.4 – Biomass gasification
Afghanistan has significant biomass energy resources (4000MW) . Rice husk and straw offers an immense potential to create bioenergy in Afghanistan. Biomass energy is the least cost source for mini-grid in rural areas with greater than 200 households where power is needed for more than three hours in a day . But the ministry of energy and water dose not has any policy to use this.
4 – Rice production in Afghanistan rice husk and straw
Afghanistan is an agricultural based country. And after wheat rice is the second most important staple crop in Afghanistan. In 2011-2012 around 210,000 hectares of paddy rice were planted in Afghanistan and the total production was 449,400 ton . In 2014-15 the production reach up to 520,000 tons from a harvested area of 205,000 hectares . Table (3), shows the production of rice in the different provinces of Afghanistan . The paddy rice production in 2014-15 is expected to be 205,000 tons, generating 106,260 tons of rice husk.
4.1 – Rice husk and straw
Rice husk is the most prolific agricultural residue in rice producing countries around the world. The rice husk (or hull or chaff) is the outermost layer of the paddy grain that is separated from the rice grains during the milling process and constitutes about 20% of paddy by weight. Paddy straw is generated as biomass residue during harvesting process. Both are largely considered a waste product that are often burned or dumped on landfills. Only in recent years, some amount of the rice husk is used to produce power and other applications such as silica production and composting. The importance of rice husk and rice straw as an attractive source of energy can be understood from the statistic presented in table (4) .
5 – Rice husk gasification
Biomass or rice husk gasification is a thermo-chemical process in which the solid biomass is converted to a combustible gas. This gas can be used in a generator set for production electricity. Gasification is one of the renewable energy technologies suitable for rural electrification. As it can be applied on a small scale (from several KWe upward) with a reasonable efficiency typically more than 15%. Energy content of each biomass is important in order to use as energy resource. Heating value is often used as an indicator of the energy content of that biomass. To burn 1kg of rice husk we need to 4.7kg of air. Burning in reduced air atmosphere (30%-40%) gasifies rice husk by combustion process. Approximately 2kg rice husk is need to generate about 1KWh of electricity .
5.1 – Gasification technology
Gasification is a process that converts organic or fossil fuel based carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam. The resulting gas mixture is called syngas (from synthesis gas or synthetic gas) or producer gas and is itself a fuel. The power derived from gasification and combustion of the resultant gas is considered to be a source of renewable energy if the gasified compounds were obtained from biomass. The advantage of gasification is that using the syngas is potentially more efficient than direct combustion of the original fuel because it can be combusted at higher temperatures or even in fuel cells, so that the thermodynamic upper limit to the efficiency defined by Carnot’s rule is higher or (in case of fuel cells) not applicable. Syngas may be burned directly in gas engines, used to produce methanol and hydrogen, or converted via the Fischer– Tropic process into synthetic fuel. Gasification can also begin with material which would otherwise have been disposed of such as biodegradable waste. In addition, the high-temperature process refines out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic fuels. Gasification of fossil fuels is currently widely used on industrial scales to generate electricity .
5.1.1 – Fixed bed
The fixed bed gasification system consists of a reactor/gasifier with a gas cooling and cleaning system. The fixed bed gasifier has a bed of solid fuel particles through which the gasifying media and gas move either up or down. It is the simplest type of gasifier consisting of usually a cylindrical space for fuel feeding unit, an ash removal unit and a gas exit . It is a specially designed reactor that con heat biomass in low oxygen environment to produce a fuel gas. This gasifier is a suitable option to flexible production of gas loud and has low sensitivity to tar content of fuel, but not feasible for very small size particles of fuel .
5.1.2 – Gasification agent
In other to convert solid biomass into inflammable gas, a gasification agent is required which promotes the necessary chemical reaction. Especially air, oxygen, water or carbon dioxide are used as gasification agent. In this process the gasification is carried out in amount of inflammable gas .
5.1.3 – Carbonization
It is the technology or method where in rice husk or other biomass such as wood, bark, bamboo, etc. are heated 400-600 C in the almost absence of air or oxygen .
5.1.4 – Composition of the gas
The combustible gas produced from rice husk contents CO2 (12.6%), CO (17.9%), N2 (57%), H2 (8.8%) CH4 (1.9%) and others (1.8%). The produced gas can be used to generate electricity or heat or both of them using combined heat and power system .
5.1.5 – Fluidized bed
In rice husk gasification rice husk burns in a controlled amount of oxygen to produce gas that powers the internal combustion engine and produce electricity. The fluidized bed gasifier are more complex, more expansive and produce a gas with a higher heating value . Figure (7) shows a type of circulating fluidized bed gasifier .
6 – Rice husk biomass power plants in Afghanistan
Afghanistan has the potential to produce 106,260 tons of rice husk that could equivalent to the production of energy from 15,026 tons of oil. The conversion rate of rice husk to power is 1.6-1.8 kg of rice husk per KWh electricity . But unfortunately there in no any rice husk or biomass power plant to produce electricity for rural areas especially for those areas that there is rice fields. It is mentionable to say rice husk is not an abundant resource of energy in all provinces of Afghanistan. Figure (8) shows the rice producer provinces in Afghanistan.
7 – Self-sustainable business model for rural electrification
Solution to provide the grid quality electricity without grant or government subsidy has a niche in the marginal income group sector in rural areas that are off-grid and for most part have no available electricity. The vast majority of rural electrification projects in many developing countries have not been financially viable and failed to scale since they are grant or subsidy-based and
not self-sustaining. Therefore, the focus should be on a self-sustainable business model of power system and to provide the sustainable and affordable clean energy to rural consumers. The success of any new enterprise depends on the financially viable business model and potential demand by consumers. The business model to power the rice mills machinery and rural communities through fully managed by the rice mills owners is shown in figure (9).
The success of the self-sustainable business model of power system for rural electrification depends on, adequate financing infrastructure, accurate knowledge of the generation capacity versus consumption requirements, proper design of entire power system to operate successfully in rural markets, affordable pricing model and the responsive after sales support to fulfill the needs of the end users .
Afghanistan has significant renewable energy resources including biomass energy in the form of agricultural and potential energy crop, rice husk is forming a part of agricultural residues. However it has a huge potential of energy but it found in some finite provinces in Afghanistan and we can electrify rural areas in that provinces using rice husk, not in all rural areas in Afghanistan. But the other renewable energy resources such as solar, wind, micro hydro power are abundant at almost whole of Afghanistan. Since the energy requirement in rural areas is very low rural electrification will be realized in many villages of Afghanistan by a small integrated or hybrid (solar-biomass, solar-biomass-wind or wind-biomass) power plant. Unfortunately there is not any rice husk biomass power plant in Afghanistan. Some of rural areas are electrified using solar and wind energy technologies.
In conclusion the power system such as rice husk power plant is not a feasible solution to electrify all rural household in Afghanistan. But an integrated power system can overcome in an affordable tariff to this problem in rural households.
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