torsdag 4. september 2014

How to light up rural Bangladesh: Renewable energy mini-grid solution for villages

Katherine Inzani, PhD student, Department of Materials Science and Engineering, Norwegian University of Science and Technology

Ershad Ullah Khan, PhD student, Department of Energy Technology, KTH Royal Institute of Technology, Sweden
Duong Le, Postdoctoral Researcher, Department of Energy, Politecnico di Milano, Italy​ 
Nhi Nguyen, PhD student, Department of Energy, Politecnico di Milano, Italy
Livingstone Senyonga, PhD student, NMBU School of Economics and Business, Norwegian University of Life Sciences

Bangladesh in 2014: three quarters of rural villages are in darkness with no clean fuel for cooking. Kerosene lanterns and hurricane lamps light up the darkening sky and generate black carbon. People cook their meals by firewood in open traditional stoves. Women and children face dangerous health problems. Business and studies end at dusk. Sustainable access to electricity for the 100 million of the population that are not connected to the national grid is a huge challenge but will give widespread benefits. Here we present a model for electrification of a typical village in Bangladesh, and show that it is feasible, with some initial funding, to utilize local resources for electricity and clean cooking fuel in a sustainable way. This in turn will support social services such as healthcare and schools, and encourage development of local businesses and entrepreneurship.

Mini-grid configuration

Electricity is a pre-requisite for technological development and economic growth of a nation. Around 30% of people in Bangladesh earn below $2 per day. Countries that are lower in per capita energy consumption have low adult literacy rates, life expectancies and education index. In remote areas of Bangladesh especially in the rural and hilly regions, the health, education and communication system are in deteriorating condition because of the unavailability of electricity. In this context, energy deficiency is one of the main barriers to poverty alleviation, industrial and economic advancement, empowerment, and rural development. 

A typical village is Sherpur, located on the bank of the river Jamuna. The village consists of 219 households with an average of five family members. It is unlikely that the village will be connected to the national grid in the next 25 years. The main livelihood is agriculture and the lifestyle is simple, not requiring large amounts of electricity for dramatic improvement. Electricity for lighting, cooling, TV, radio and IT alone would bring enormous benefits, facilitating better learning conditions in schools, with longer study hours and PC-based learning made possible, as well as benefiting business and improving communication and healthcare. TV, lighting and productive uses in community centers enhances social life and may foster community based development. Risk of fire from kerosene lamps and candles would be significantly reduced. Energy security would no longer be related to the availability of diesel and kerosene.

Energy resources from a hybrid system

The electricity and cooking fuel needs of the village can be provided by a hybrid system of photovoltaics, an anaerobic biomass digester and a small-scale gas engine.

Solar PV systems utilize semiconductor-based materials (solar cells) which directly convert solar energy into electricity. Solar PV systems have many attractive features, including modularity, no fuel requirements, zero emissions, no noise and no need for national grid connection.

In a biomass digester, agricultural residues (biomass) are converted into a combustible gas in a high temperature digester, and the gas is cleaned to remove tars and particulates before being stored in a large tank. From the storage tank, clean gas is partly provided through a piping network to the individual households in the village for cooking using gas stoves. Reduced deforestation, health benefits and hygiene improvement through waste disposal are considerable benefits of using the anaerobic digester. This gas is also provided to an internal combustion engine-generator to generate electricity along with the PV solar.

Needs assessment

The load estimation takes into account the needs of different households and public buildings in nine months of summer and three months of winter. Load profiles also vary throughout the day, and peak load is estimated at 22.37 kW, with average load demand 291.48 kWh/day in summer and 153.45 kWh/day in winter. Gas needs per day are estimated at 0.4 m3/ person, with a total of 238 m3/day for the village.

Load estimation

Daily load profiles

System design

Based on these estimations, a small 20kW solar PV power plant will be sufficient, with a 25 year lifespan of modules and 10 year lifespan of batteries. A capacity factor of 20 % of the solar PV is assumed based on 4.8 hours daily of peak power output. Sizing of system components follows the above analysed load profile. 

System components

Grid structure will be an AC grid with voltage level of 380/220 V. Electricity and gas are supplied from solar PV and a biogas digester located at the centre of the village. During the day, primary electricity is supplied by solar PV and the biomass digester. Extra energy from the solar PV will be stored in the battery bank. During night time, when solar radiation is not available, electricity is supplied by the biomass digester and the battery bank. Part of the gas from the biomass digester will be supplied to each household for cooking. 

Operation, management and sustainable financing 

An estimation of costs for set-up of the hybrid mini-grid is given below, totaling approximating 130,000 USD. A rural community cannot cover this high cost, hence outside funding must be gathered. Government and non-governmental organization grants can be used as a funding source. However, in order to include the community in participation and ownership of the system, land and labor should be contributed by the participants. This will encourage acceptance of electrification and a responsibility to not misuse the grid. The company used for providing the grid should provide after-sales services.

Initial cost of the hybrid mini-grid. 1 USD = 80 taka

Management of the electricity and gas supply should be done by a local committee. This should be set-up in accordance with the power structure in the particular region. Management tasks include formulation of policy, collection of revenue, security, discipline for misuse, recruitment of new users and management of operators. Operators will be recruited from members, with the criteria of secondary education and a commitment to stay in the village. Operators chosen by the committee will be trained in general running and maintenance of the equipment, and will be tasked in security and safety. When more technical repairs are necessary, external technicians can be brought in. Regular servicing can also be done by technicians from the equipment provider. Additional support for maintenance and repairs can be provided by government, energy companies and perhaps mobile phone companies, who should all benefit in the success of rural electrification.

Education will be vital to the success of the project. This can be provided in the form of group training and workshops by operators or technicians. Topics to cover are operation and equipment maintenance at home, responsibilities of being connected to the grid, hazards and safety and energy efficiency. Customers who rent equipment can be informed of proper use at the point of rental. Publicity of the benefits of the project will be needed to foster initial and further participation.
The cost of electricity is based on usage, with tariffs set at an affordable percentage of income and comparable to prices on the heavily subsidized national grid. The tariffs are detailed below. 
The cost of biogas will be a flat rate of 800 taka per month, affordable for middle and higher income households. Rental of lamps and batteries will incur a fee.

Tariffs and ongoing costs

These estimations show that the combined revenue of tariffs and rent of equipment is enough to cover operation and maintenance costs and the project is sustainable. The net revenue of approximately 700 USD per month can be used to add solar panels and batteries in accordance with growing needs. There is also the potential for income generating activities to grow from the project. Local businesses, sale of bulbs and appliances and community owned projects utilizing excess energy are all possible sources of revenue. Another option is loans and micro-finance, especially loan of equipment to the surrounding area. Funds provided by these activities could be used to extend the grid further from the power source, enabling a subsidy for new customers with a higher connection cost due to location. 

This study has shown that electrification and provision of clean cooking fuel on the local scale is feasible for rural Bangladesh with the use of local renewable energy sources. The biggest hurdle is obtaining the funds for start-up of the project, for which government and international agencies must be relied upon. Once this investment is obtained, the above model proves the potential for sustainability of the hybrid mini-grid solution. Considering the benefits to health, education, economy and the environment for those out of reach of the national grid the investment seems a modest cost.

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