Techno-economic analysis of microgrid for universal electricity access in Eastern Cape, South Africa

Introduction

The importance of electricity access to socioeconomic development  cannot be over-emphasized. Yet there are about 1.4 billion people around the world who lack access to electricity. Some 85% of them are rural dwellers and the majority live in sub-Saharan Africa [1]. Most rural areas in sub-Saharan Africa are in off-grid locations and can be powered through microgrids using renewable sources such as wind, solar, biomass, and water. A microgrid can be defined as a regional or communal energy system comprising distributed energy sources (renewable and/or non-renewable) often in order to optimize power quality, reliability, efficiency, and sustainability. Microgrids also have accompanying economic benefits (cheaper cost of energy, local employment generation and economic development), and environmental friendliness (if renewable energy sources are used). Microgrids can be operated in off-grid, on-grid, or dual-mode depending on factors such as capacity, availability of energy sources, and the required load to be met. In South Africa, 20% of urban dwellers and 55% of rural dwellers lack access to electricity. Eastern Cape Province is the least electrified province in the country with 75% of  households using electricity for lighting. Ntabankulu Local Municipality (NLM), with a 20% electrification rate, is the least electrified municipality in Eastern Cape [2] and is used here as a case study to investigate the implementation of a microgrid compared to grid extension in NLM. In the literature are studies [3] on the possibility and challenges of using a modular form of electrification for rural areas in South Africa, but with inconclusive result and incomplete simulations.

Methodology

The proposed Ntabankulu microgrid design comprises a Fuhrlander 100 wind turbine, Photovoltaic (PV) array, 6V Surrette 6CS 25P battery, diesel generator, and AC/DC converter. Hourly electrical load profiles were generated and simulated according to the income level of NLM residents. Time series (8,760 hours) wind speed data obtained from Wind Association of South Africa (WASA) and solar irradiation data obtained from Council for Scientific and Industrial Research (CSIR) were used for NLM with average annual wind speed of 6.383 m/s and average annual solar radiation of 5900 kWh/m²/day, respectively. HOMER software, developed by the National Renewable Energy Laboratory (NREL), USA [4] was used for the simulation, optimization, and sensitivity analyses of the design because it displays a ranked tabular result from least total Net Present Cost (NPC), limits the input complexity, and performs fast enough computation - although it is less detailed than  other micropower time-series simulation models like Hybrid2, PV-DesignPro and PV*SOL and non-time series simulators like RETScreen.

Results

The optimal microgrid design for the proposed Ntabankulu microgrid was a Wind/PV/Battery/Diesel Generator with least total NPC at $0.321/kWh cost of electricity, 0.084 kg/person CO₂ emission and 0.97 renewable fraction compared to $0.328/kWh cost of grid extension electricity, 8.9 kg/person CO₂ emission from grid extension and 0% renewable penetration in South Africa. The microgrid as a standalone has breakeven grid extension distance of -0.296 km compared to 104 km grid extension proposed by the utility provider. We hereby propose this microgrid design as a solution to electricity access in unelectrified areas of NLM.

Conclusion

The proposed renewable energy sources (RES) microgrid has shown that a standalone microgrid can be used to achieve electricity access in rural off-grid areas of developing countries like NLM.

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Last edited: 23 March 2015