There is limited information on environmental emissions in African grid electricity generation and transmission systems, especially from the sub-Saharan African countries. The developed parameters are useful for evaluating the extent to which grid electricity generation and transmission system drivers are designed and operated in the context of environmental governance (EG) factors. The environmental pressure caused by the studied power systems was evaluated in terms of carbon emission levels. To simplify the study, variable parameters were sampled from the national power grids of three sub-Saharan countries, namely: Kenya, Rwanda, and Tanzania. The developed inventory workbooks accounted for the residual carbon emissions related to the grid generation and transmission capacity survival lifetime, retired system capacity, and recycling rate, aiming to reduce the uncertainty in grid emissions in the study area. The obtained area of the curve for the business as usual and EG models reveals that Rwanda has the potential to contribute more emissions per unit power, followed by Tanzania and Kenya. The higher carbon emission uncertainty levels (65%–75%) obtained from the EG simuland and life cycle carbon emissions revealed that only limited EG factors were considered during the design and operation of the studied grid electricity generation and transmission systems. However, the possibility of significant lifetime decarbonisation performances from generation and transmission systems was also shown in the EG-modelled output, owing to its lower carbon emission uncertainty levels (15%–25%). The logarithmic regression trend lines presented by this research show a higher R² value for the EG modelled life cycle carbon emission (LCCE) output (R² = 0.8689) and EG simuland LCCE output (R² = 0.9209), compared to EG modelled LCCE output (R² = 0.7526) and EG simuland LCCE output (R² = 0.8223) obtained from the linear regression trend lines, implying a very good relationship between the structural assumptions and simplifications constituting the model itself for case studied by the year 2049. The study suggests monitoring of a wide range of environmental parameters (apart from carbon) and associated energy storage technologies, considering both cumulative data and expanded systems.
Aphrodis Nduwamungu, Godwin Norense Osarumwense Asemota
Solar PV research in East Africa has concentrated on solar home systems (SHS) in each country. However, several other fundamental advances in the solar photovoltaic (PV) industry have emerged, and the developments have seen the sector experienced significant growth and diversification of models, regulation, and financing. This paper begins with an extensive narrative on the solar PV outlook of each of the six countries studied. A solar PV minigrid was also simulated using HOMER software with a critical load of 2800.0?kWh/day in order to analyze the peak shaving capability and assess the affordability of the solar PV microgrid having commercial and industrial loads. The regional overview of the efforts was identified, followed by a description of the models, payment methods, and barriers encountered collectively. The lessons from this research suggest that there is a vast potential for solar PV micro and minigrid deployment in the region with a population of over 100 million people lacking access to electricity by the end of 2019. It shows that solar PV minigrid deployment in East Africa is still at a nascent phase. Also, minigrid developers face several challenges operating in rural areas. While solar PV minigrids remain fairly nascent in the East Africa region, the technology is gaining traction, a development that indicates budding confidence in the solar PV minigrid technology. This study identifies that (1) with large critical loads (industrial and commercial), solar PV minigrid can still contribute to affordable electricity through peak shaving, except Tanzania; (2) solar PV minigrid projects are largely dependent on donor financing, require vast financial diversity to get off the ground, and offer consistent service; (3) Governments support in the form of National electrification strategies, policies, and regulation are key ingredients for realizing the electrification of rural populations through minigrids; (4) hybrid minigrids and power demand creation have emerged as an approach that ensures sustainability or profitability for the operating solar minigrid firms. Overall, government policy and regulation, funding, and financial sustainability remain the major hurdles to minigrid uptake in the region.
Due to increase in integration of renewable energy into the grid and power quality issues arising from it, there is need for analysis and power improvement of such networks. This paper presents voltage profile, Q-V sensitivity analysis and Q-V curves analysis for a grid that is highly penetrated by renewable energy sources; solar PV, wind power and small hydro systems. Analysis is done on IEEE 39 bus test system with Wind power injection alone, PV power injection alone, with PV and wind power injection and with PV, wind and micro hydro power injection to the grid. The analysis is used to determine the buses where voltage stability improvement is needed. From the results, it was concluded that injection of the modeled wind power alone helped in stabilizing the voltage levels as determined from voltage profiles and reactive power margins. Replacing some of the conventional sources with PV power led to reduction of voltages for weak buses below the required standards. Injection of power from more than one renewable energy source helped in slightly improving the voltage levels. Distribution Static compensators (D-STATCOMs) were used to improve the voltage levels of the buses that were below the required standards.
Wind power penetration into the grid is increasing throughout the world due to centralized power generation constraints such as shortage of fossil fuel, need to reduce gas emissions, long transmission losses and need for more supply of electrical power. Connection of wind power into the grid results in power quality issues such as voltage profile changes and harmonics. This necessitates coming up with correction measures in order to meet power quality standards. This paper deals with the analysis of the effects of injecting wind power to the grid on voltage profile. Branch participation factors are used to analyze the sections of the grid where effects on voltage profile are highest due to wind power penetration. Reactive power-voltage sensitivity analysis is used to determine the buses that are more sensitive to the changes brought by the wind power injection. Two cases were considered for the injection of the wind power: IEEE 14 test bus system and IEEE 39 test bus system.
This paper analyses the current energy access rate situation in Burundi, which is relatively low compared to other countries. The paper aims to identify the key gaps in improving the electrical energy access in Burundi and proposes a solution to overcome these gaps. It is shown that the electrical power grid is old and concentrated in the north-western Burundi and in Bujumbura while other regions lack access to national grids. Next to that, the link between electricity access and sustainable development in Burundi is clarified. Further, some solutions are suggested to solve energy access problems such as the electricity transmission lines extension and renovation, diversification of energy sources.
In Rwanda, most small-scale hydropower systems are connected to the national grid to supply additional generation capacity. The Rwandan rivers are characterized by low flow-rates and a majority of plants are below 5 MW generation capacity. The purpose of this study is to provide a scientific overview of positive and negative factors affecting the sustainability of small-scale hydropower plants in Rwanda. Based on interviews, field observation, and secondary data for 17 plants, we found that the factors contributing to small-scale hydropower plant sustainability are; favorable regulations and policies supporting sale of electricity to the national grid, sufficient annual rainfall, and suitable topography for run-of-river hydropower plants construction. However, a decrease in river discharge during the dry season affects electricity production while the rainy season is characterized by high levels of sediment and soil erosion. This shortens turbine lifetime, causes unplanned outages, and increases maintenance costs. Further, there is a need to increase local expertise to reduce maintenance cost. Our analysis identifies environmental factors related to the amount and quality of water as the main current problem and potential future threat to the sustainability of small-scale hydropower. The findings are relevant for energy developers, scholars, and policy-makers in Rwanda and East Africa.
Uganda is endowed with a number of energy generation sources, however; these sources are spread out or scattered throughout the country. This makes transmission of power from the generating stations expensive. This paper aims at assessing the possibility of reduced cost through increasing substations instead of electricity generation plants through use of Geo pandas and spatial informatics techniques. Power substation data that included coordinates and power ratings, data for Uganda districts, major roads and towns together with population were imported in the jupyter notebook using python and plotting was done to generate a map of power stations in Uganda. The power generating plants, substation, district and population stored data in jupter notebook was retrieved and visualised in GIS where buffering was done in order to determine the area covered by the substations. The point layer of current power substations and plants was buffered at a defined radius to get the current unserved area scenario map for Uganda. As a result of this preliminary work, specific areas were targeted for investment and optimized supply systems was established, which included proposed new power substations. Four power substations were proposed to serve areas without access to the grid and a map showing new sited power stations in unserved areas (densely populated) was generated. Net present worth method was used in the economic analysis to determine whether it makes economic sense in extending transmission lines to serve places without access to electricity vis a vis constructing more power plants. It was observed that extending the grid to selected substations was relatively cheaper as compared to constructing power plants since the economic analysis showed a positive net present worth of USD 63.6 million. Since Uganda has surplus electricity generated, it is better to invest in the transmission lines to serve areas without electricity.
The purpose of this study is to make a preliminary assessment of the wind resource in South Sudan. This is mainly to get data on the quality of the wind resource at different locations in the country and investigate its suitability for the development of wind power generation projects of all sizes. Wind data for 33 locations, covering the period from 1981 to 2019, were requested from Modern-Era Retrospective analysis for Research and Applications version 2 or MERRA-2. The data were then analysed to produce a variety of statistics that describe the quality of the wind resource in each location. Long-term monthly and annual averages together with wind direction were computed for each location at a height of 10 m above ground level. Wind speeds were extrapolated to hub heights of 30 and 50 m above ground level and fitted to five different distribution functions to get the parameters for estimating wind power density. Results show that at 10 m above ground level, the long-term annual average wind speeds range between 5.08 m/s and 2.36 m/s while wind power density range between 128.36 W/m2and 14.39 W/m2. Development of utility-scale wind power plants is marginal in two locations while small-wind turbines development may be possible in the north-north eastern locations. Further research is proposed to explore the possibility of deployment of large-scale wind turbines at locations north-north east. Investigating the wind resource in other locations using alternative methods as well as possibility of development of small wind turbines is suggested.
Enhancing solar photovoltaic and thermal conversion performances may help develop more environmentally friendly hybrid photovoltaic/thermal (PV/T) systems that can be used in applications ranging from household to industrial scales. Owing to their enhanced thermal and optical properties, nanofluids have proven to be good candidates for designing PV/T systems with superior performances. As smart nanofluids, magnetic nanofluids (MNFs) can further enhance the performances of PV/T systems under external magnetic fields. This paper reviews recent developments in enhancing the electrical and thermal performances of PV/T systems using magnetic nanofluids. Various parameters affecting the performances are highlighted, and some areas for further investigations are discussed. The reviewed literature shows that PV/T systems with MNFs are promising. However, their performances need further investigation before they can be used in applications.
The potential for mining companies to contribute to sustainable energy development is characterized in terms of opportunities for energy efficiency and support of electricity access in mining-intensive developing countries. Through a case study of the Central African Copperbelt countries of Zambia and the Democratic Republic of Congo, energy efficiency opportunities in copper operations and environmental impact of metal extraction are evaluated qualitatively, characterized, and quantified using principles of industrial ecology, life cycle assessment, and engineering economics. In these countries the mining sector is the greatest consumer of electricity, accounting for about 53.6% in the region. Energy efficiency improvements in the refinery processes is shown to have a factor of two improvement potential. Further, four strategies are identified by which the mining and technology industries can enhance sustainable electricity generation capacity: energy efficiency; use of solar and other renewable resources; share expertise from the mining and technology industries within the region; and take advantage of the abundant cobalt and other raw materials to initiate value-added manufacturing.