SERC Scholarly Articles

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A heuristic model for planning of single wire earth return power distribution systems
(Power and Energy Systems and Applications, PESA, ) Da Silva, Izael; Da Silva, I. P; Bakkabulindi, G.; Mohammad, R. H.; Amelin, M.; Lugujjo, E.
The planning of distribution networks with earth return is highly dependent on the ground's electrical properties. This study incorporates a load flow algorithm for Single Wire Earth Return (SWER) networks into the planning of such systems. The earth's variable conductive properties are modelled into the load flow algorithm and the model considers load growth over different time periods. It includes optimal conductor selection for the SWER system and can also be used to forecast when an initially selected conductor will need to be upgraded. The planning procedure is based on indices derived through an iterative heuristic process that aims to minimize losses and investment costs subject to load flow constraints. A case study in Uganda is used to test the model's practical application.
An M&E mobile based application for Pico PV lighting solutions for the “Kerosene Free Kenya” project
(Small PV-Applications Rural, ) Da Silva, Izael; Da Silva, I. P; Ronoh, G.; Maina, D. N
This paper describes the use of a mobile based application used as a Monitoring and Evaluation (M&E) tool to a pilot project supported by the National Council for Science and Technology of Kenya (NCST) which seeks to research best practices and lessons learned in the dissemination of Pico PV systems to rural households in Kenya. In order to overcome the affordability barrier a microfinance institution (MFI) was brought into the system, to properly handle the challenge of access to finance while Lighting Africa will provide standards for the products to be distributed. Many of such pilot system have been used in practically all countries of East Africa. The novelty of the present one is the use of an Unstructured Supplementary Service Data (USSD) mobile based tool to collect and transmit data. This will make the analysis of the product quality, user experience and faults much simpler and given the two ways relationship between the researchers and the users, consumer satisfaction and product improvement is envisaged to happen in a to date unprecedented manner. As the clients are distributed in a known geographical region, the researchers have provided for the training of technicians to handle repairs and battery replacement locally. As the duration of the project is 2 years, it is expected that the follow up of product performance and life span will be measured way beyond its payback period.
Analysis of induction generator controller techniques for Pico hydropower - a case study of a 3kW Pico hydropower scheme in Kasese, Western Uganda
(2014) Izael Da Silva; Teddy Nalubega; Okou Richard; Mary Suzan Abbo; Da Silva, Izael
This paper presents a comparative analysis of control techniques used on induction generators for stand-alone Pico hydropower schemes. The techniques were tested on a prototype Pico hydropower system modeled for the site developed in western Uganda by the Centre for Research in Energy and Energy Conservation. The case study scheme to date is manually operated, a process that requires constant attention due to variations in load. This demonstrated the need for an automatic load controller. The site specifications were considered when designing models using Matlab simulink employing the automatic load control techniques. These model designs are simple so that it is affordable for local practical application. The proposed designed control techniques presented in this paper are composed of logic gates, IGBT switch, uncontrolled diode rectifier, the PID controller and other semiconductor devices supplying an electrical load and a ballast load. In addition, the response of the case study site and the Matlab model to load variations is presented.
Analysis of induction generator controller techniques for Pico hydropower a case study of A 3kW Pico hydropower scheme in Kasese, Western Uganda
(IEEE, 2014) Nalubega, Teddy; Da Silva, Izael Pereira; Okou, Richard; Abbo, Mary S.; Da Silva, Izael
This paper presents a comparative analysis of control techniques used on induction generators for stand-alone Pico hydropower schemes. The techniques were tested on a prototype Pico hydropower system modeled for the site developed in western Uganda by the Centre for Research in Energy and Energy Conservation. The case study scheme to date is manually operated, a process that requires constant attention due to variations in load. This demonstrated the need for an automatic load controller. The site specifications were considered when designing models using Matlab simulink employing the automatic load control techniques. These model designs are simple so that it is affordable for local practical application. The proposed designed control techniques presented in this paper are composed of logic gates, IGBT switch, uncontrolled diode rectifier, the PID controller and other semiconductor devices supplying an electrical load and a ballast load. In addition, the response of the case study site and the Matlab model to load variations is presented.
Benefits of using biogas in households experience from a user in Uganda
Da Silva, Izael; Sendegeya , Al-Mas; Ssebuwufu , Pancras John; Da Silva, Izael Pereira
This paper discusses the socio-economic benefits of using biogas based on the experience of a long term user as a typical example. A floating drum type of digester was installed with a capacity of 6.5 m3 in the year 2000 at a total cost of US$ 1,830. The gas generated is used exclusively for cooking. For the user, his typical kitchen day consists of three meals for a household of 8 people. Prior to the installation of the biogas plant, the user was using liquefied petroleum gas (LPG) supplied in 15 kg cylinders at an average cost of US$ 23 per cylinder and used to consume an average of 3 cylinders in 2 months bringing a monthly expenditure on the kitchen fuel of US$ 35 including transport costs for the cylinder. The user has now totally substituted LPG with biogas which translates into an annual average saving of US$ 420. At this rate of saving, the break-even point for the full recovery of the installation costs is about five years. Since installation the digester has not had any significant breakdown, so no major maintenance has been required. The water used for mixing the cow dung into slurry is harvested rainwater. Thus according to his experience it indicates that the use of biogas offers a substantial cost saving on domestic energy. In addition to the economic benefits, other benefits include increased organic agricultural production when the sludge is used as fertiliser. The use of the slurry as bio-fertiliser on his small vegetable farm (about 0.5 ha), has helped him to save money that would have been used to buy the imported artificial fertilisers. Fermenting the cow dung in a biogas digester instead of composting it in open air provides several other advantages, ranging from a foul odour-free environment to improvements in the general health conditions in the home. Thus, a reduction in the unhealthy smell from the compost dumps where the cow dung used to be deposited, as well as a reduction in free methane gas (one of the green house gases, GHG) which used to be emitted direct into the atmosphere by the decomposing dung.
Book review : Renewable Energy for Residential Heating and Cooling Policy Handbook
(ICE Publishing, 2012-08) Da Silva, I. P.; Da Silva, Izael
The scope of this book, as far as REHC projects are concerned, covers programme phases: portfolio planning, programme design, implementation and evaluation. It also covers market maturity stages from initial deployment to full market. It considers instruments such as: economic incentives, regulations, information and market activities. As the title mentions, the content is applicable to the residential sector only: new and existing buildings, including single and multi-family dwellings. As far as technology is concerned, it covers active solar thermal systems for air and water heating; biomass (pellets, wood and wood waste); geothermal (ground source and heat-pump) and finally heat-pump technologies based on ambient air heat (air-to-air and air-to-liquid)
Comparative performane analysis of a solar box cooker and improved charcoal stoves in Mozambique
(International Solar Energy Society, 2014-09) Da Silva, I. P.; Cuamba, B. C; Nhabetse, M. T.; Da Silva, Izael
With exception of South Africa, where only 16% of the population depends on traditional biomass energy, almost 80% of the population in the sub-Saharan Africa depends on biomass resources for cooking and heating. The burning of traditional biomass in the so-called three stones stove puts pressure on biomass resources because of its inefficiency. Besides, fumes and soot are related to respiratory diseases that are the common cause for deaths among women and children in Africa. The shortage of fire wood makes women and girls to walk in search of fuel for cooking. Solar cooking is one of the possible solutions for this poignant problem. Yet another partial solution is the use of improved biomass stoves. This paper presents a comparative analysis of the performance of solar box cooker and improved charcoal stove in Mozambique, in its technical and economic aspects.
Consumer price sensitivity impact on tariff level in isolated rural power systems
(2006-09) Silva I.P; Sendegeya, A; Amelin,A; Soder, L; Lugujjo, E
Uncertainties in demand and supply are among the challenging aspects when planning isolated power systems as well as one of the reasons why plans are not as optimal as expected. Most consumers in these areas are price sensitive and their sensitivity may change over time. To be able to estimate the outcome of certain investments in such markets with uncertainties, it is important to have a realistic modelling of the market. The modelling of markets can be performed using probability methods. This paper presents a methodology using Monte Carlo simulation to analyze the impact of price sensitivity of consumers on the probability distribution of tariff as a basis for making decision during planning. The stochastic nature of the market due to uncertainties in sensitivity, demand and supply has been modelled explicitly by random variables of given distributions. The developed model has been demonstrated on a small test system. The results include probability distributions showing the impact on the tariff levels for various system configurations.
Designing decentralized small-scale bioenergy systems based on short rotation coppice for rural poverty alleviation
Da Silva, Izael; Buchholz, T; Volk, T; Tennigkeitb, T; Da Silva, I. P
Access to electricity is crucial for the attainment of the Millennium Development Goals of poverty reduction and environmental sustainability. In East Africa, increasing environmental degradation and modern energy supply are a major obstacle to sustainable rural development. Small-scale bioenergy systems can supply clean, renewable and affordable energy to rural communities while at the same time creating new job opportunities and having beneficial impacts on natural resources especially when fed from Short Rotation Coppice (SRC). However, bioenergy systems are complex because their three components feedstock supply, conversion technology and energy allocation are influenced by environmental factors simultaneously with economic and social factors. Assessing these factors and their interdependence is essential to determine the project’s contribution to sustainable development as failure of one component can lead to failure of the entire system. Decision Support Tools (DST) structure the collection and evaluation of quantitative and qualitative information about social, economic and environmental impacts at scales ranging from local to national level. DSTs enable transparent and informed decisions even when limited information is available and many participants with different expertise and interests are involved to consider all relevant criteria. This paper introduces an approach to develop a DST assessing sustainability of bioenergy systems.
Diffusion of solar energy technologies in rural Africa: Trends in Kenya and the LUAV experience in Uganda
Da Silva, I.P.; Batte, G; Ondraczek, J; Ronoh, G.; Ouma, C.A. ; Da Silva, Izael
The diffusion of Modern Energy Technologies Africa has been found to be very low especially for solar energy systems. The installed solar PV capacity in Africa is a major issue of concern globally. This low trend in technology adoption is of interest because Africa enjoys some of the best solar radiation levels in the world averaging between 4 – 6 kWh/m2/day for most of the year. It was initially speculated that the low uptake of solar technology was associated with the continent’s high poverty levels and limitations in technical capacity as well as awareness; nevertheless, the introduction of Mobile Telephony Technology (MTT) has cast some doubt on those speculations due to the rapid assimilation and diffusion of the technology in several African countries. The paper elaborates on the approach taken by a successful MET business model known as the Lighting-up-a-village (LUAV), designed by an energy company, Barefoot Power (BFP), in Uganda. This model has been used to distribute micro solar home systems in rural Uganda and exhibited a rapid uptake rate that resulted in the establishment of 18 LUAV projects in a span of 12 months. Through the LUAV program, more than 3000 households took up the technology securing their own independent power generation hub. The success factors noted in the LUAV business model were identified and highlighted so as to present recommendations on the key factors that can possibly drive a rapid adoption of METs.
Economics of a Gasification Based Mini Grid - a case study of a 10 kW Unit in Uganda
(2007-01) Da Silva, I. P.; Buchholz, T.; Volk, T; Tennigkeit, T; Da Silva, Izael
Small-scale wood gasification systems have the potential to contribute to the rural electrification in Uganda. This paper presents an economic analysis of a 10 kW gasifier unit and its minigrid installed on a Ugandan farm. The bioenergy system has been running stable on a six hour daily base for seven months. When the gasifier is operated close to the rated capacity, the gasifier system is economically attractive compared to diesel generated electricity Results indicate that replicating successful wood gasification systems stipulates integration of sustainable fuelwood supply and viable business models.
Electricity from wood-fired gasification in Uganda - a 250 and 10kW case study
(IEEE, 2016-06) Buchholz, T.; Da Silva, I. P.; Furtado, J.; Da Silva, Izael
Wood gasification systems have the potential to contribute to the rural electrification in Sub-Saharan Africa. This paper presents an operational and economic analysis of two wood-based gasification systems (250 and 10 kW) installed in Uganda in 2007. Both systems proved their potential to compete economically with diesel generated electricity when operating close to the rated capacity. At an output of 150 kW running for ~12 h/day and 8 kW running for ~8h/day, the systems produced electricity at US$ 0.18 and 0.34/kWh, respectively. A stable electricity demand close to the rated capacity proved to be a challenge for both systems. Fuelwood costs accounted for ~US$0.03/kWh for both systems. Recovery of even a small fraction of the excess heat (22%) already resulted in substantial profitability gains for the 250 kW system. Results indicate that replicating successful wood gasification systems stipulates integration of sustainable fuelwood supply and viable business models.
Electricity production from energy plantations : results from a feasibility and impact scoping study in Northern Uganda for a 50 MWe grid model
(European Biomass Conference, 2007) DaSilva, Izael; Buchholz, Thomas; Tennigkeit, Timm; Timothy A., Volk; Da Silva, Izael
Uganda currently faces an electricity crisis due to high fossil fuel prices and falling levels of lake Victoria affecting hydro power capacities. In this paper, we introduce a feasibility study for a 50 MW biomass fired power plant covering plantation design, conversion technology, environmental and social impacts, anticipated problems, overall economics, project status, and benefits of the project. The 30,000 ha project area consists mainly of Eucalyptus and native Markhamia lutea stands. Results indicate that this project can provide electricity to a competitive price which is considerably lower than generated by fossil fuel powered generators.
Energy efficient building envelope designs for institutional buildings in East Africa
(Domestic use of energy conference, ) Da Silva, Izael; Da Silva, I. P.; Ssekulima , E. B.
To date, insufficient attention has been afforded to the design and energy performance of Institutional buildings in East Africa. As a result, most Institutional buildings in the region do not incorporate the issue of energy efficiency at the design, construction and utilization stages. Institutions are amongst the major consumers of energy in any country most of which is utilized within buildings, thus a thorough critique of the building envelope is necessary to reduce energy wastage within them. The aim of this paper is to present findings of the comparative study carried out on Institutional buildings at Strathmore University Nairobi, Kenya and Makerere University-Kampala, Uganda. The study mainly considered the effect of building envelope designs and orientation to the energy consumption of the buildings. ECOTECT, a Building energy performance analysis tool was employed to quantify the effect of both the conventional and Energy Efficient Building Envelopes to the overall energy consumption of the buildings. The research findings show that the overall energy consumption of Institutional buildings could easily be reduced by about 40% through the design of envelopes suited to the micro-climate of the particular site, proper selection of construction materials vis-a-vis their thermal performance, extensive use of daylighting, wise utilization of water and good building waste management systems as well as utilization of Energy Efficient Appliances within the building. The study also revealed that integration of a Building Management System would significantly reduce resource utilization within the building.
Energy for social transformation : a study of the West Nile region of Uganda
(Domestic use of energy conference, ) Da Silva, Izael; Tickodri-Togboa, S.S; Da Silva, I. P
This Paper presents the results of technical, financial, environmental and management feasibility studies into the provision of reliable, sustainable and environmentally-friendly supply of electricity to the north-west corner of Uganda, called the West Nile Region – a region that is highly populated by comparison with the average population densities of the country and whose location is of both strategic and economic importance in that it serves as a gateway to the Democratic Republic of Congo and the Central African Republic in the west and to the south of Sudan in the north. The study examines various possible options for supply of electricity to the region and concludes that the optimal mode is through micro/mini-hydro power plants to be built on the 19 potential sites along nine principal rivers that drain the five districts comprising the region. It presents the current situation of supply of electricity in the region. This is followed with a detailed study for the implementation of the site at Olewa – the site nearest and with sufficient capacity to supply the current largest load centre in the area, which are the Arua Municipality and its environs. Due to the close similarities amongst those sites, it is argued that the data and findings pertaining to the Olewa one can easily be extended to the others, which thus makes this study beneficial and of direct relevance for the whole region. The paper then proceeds to discuss some of the foreseeable transformations that are likely to emanate from availability of adequate and reliable electricity supply in the region and ends with concluding remarks and recommendations.
Entrepreneurial capacity, government intervention and diffusion of technologies in Uganda: Comparing the supply side of modern types of energy and mobile telephony technologies
George Bill Batte; Izael Pereira Da Silva; Da Silva, Izael
The diffusion of modern technologies plays a critical role in job creation. Mobile Telephony Technology (MTT) has been successfully diffused in Uganda, within a short time, and with minimal government intervention. However, despite heavy government interventions, Modern Energy Technology (MET) remains outside the reach of most Ugandans. Low access to MET seems to be contributing to Uganda’s under-development and unemployment. Projects initiated to spur MET diffusion haven’t been very successful, and METs widely used in other developing countries and successfully piloted in Uganda have found minimal diffusion and failed to up-scale. Although policy makers are quick to blame poverty and ignorance for the slow diffusion of MET, the rapid diffusion of MTT in similar environments have put to doubt most these arguments. This study explored the diffusion of technologies in Uganda, using entrepreneurial capacity as an independent variable. By comparing the fast diffusing MTT with the slow diffusing MET, this study helps to provide a better understanding of the dynamics of technology diffusion in Uganda. Using government documents and a questionnaire survey targeting employees of MTT and MET vending firms, the study identifies differences in intervention related to governance, regulation and funding between MTT and MET vendors, which significantly affect some aspects of Entrepreneurial capacity. The study also found evidence of significant differences in the constructs of Entrepreneurial Capacity measured for MET and MTT vending firms that affect technology diffusion.
Government policies and grid extension as solutions for availing energy services for the urban poor
Da Silva, Izael; Da Silva, I.P; Kyokutamba , J
Urban poor households face challenges of meeting energy needs within their economic resources and established infrastructure. Previous Government efforts to meet this need by subsidizing modern energy supply were poorly designed and ill targeted. Despite those initiatives, the eventual energy sold was not used for income generation activities. This study analyses the impact of government policies and available technologies to improve the percentage of poor households using electricity in the urban areas of Uganda.
Implementation of a solar test laboratory in sub-Sahara Africa
Da Silva, Izael; Da Silva, I.P.; Wassler, S.
Penetration of decentralized power supply for households and commercial enterprises is low in Sub-Sahara Africa. Solar Home Systems (SHS), despite their widespread use in other continents have failed to attain much success in Africa. One of the reasons is the high rate of failure of existing implementations. Data shows earlier failure rates of 50 [1]. This is largely attributed to poor quality of products used, inefficient installation, mismanagement and lack of maintenance. To address this problem, the Centre for Research in Energy and Energy Conservation (CREEC) has set up a Solar PV test laboratory in Uganda. This paper describes the process used and how to sustain the laboratory after implementation. The lab is intended to provide a forum for training, research and consultancy under CREEC. It is intended as a tool to implement the triple helix and clusters procedure in the PV industry. This paper offers detail covering the current situation of the energy sector in Uganda and how the lab helps capacity building in the University to support the upcoming demand.
Implementation of triple helix clusters procedure in the Sub-Sahara Africa energy sector
(Universitätsbibliothek Fasanenstr, ) Da Silva, Izael; Da Silva, I. P.; Wassler, S.
Penetration of decentralized power supply for households and commercial enterprises is low in Sub-Sahara Africa. Solar Home Systems (SHS), despite their widespread use in other continents have failed to attain much success in Africa. One of the reasons is the high rate of failure of existing implementations. Data shows earlier failure rates of 50%.1 This is largely attributed to poor quality of products used, inefficient installation, mismanagement and lack of maintenance. To address this problem, the Centre for Research in Energy and Energy Conservation (CREEC) is setting up a Solar PV test laboratory in Uganda. This paper describes the installation process and how to sustain the laboratory after implementation. The lab is intended to provide a forum for training, research and consultancy under CREEC. It is intended as a tool to implement the triple helix and clusters procedure in the PV industry in particular and the energy sector in a more general scope. This paper offers details covering the current situation of the energy sector in Uganda and how the lab supports capacity building in the university to support the upcoming demand.
Inductive Voltage Transformers Calibration by the Parameters
(WSEAS, 2010) Brandao, F.A; Da Silva, I. P.; Demetri, I.; De Silos, A. C.; Diaz, E. M; Da Silva, Izael
The accuracy class of an IVT - Inductive Voltage Transformer - is typically assessed in laboratory installations either by comparing with another IVT presenting greater accuracy and traceable to a national laboratory or by using a capacitive divider. Calibration in the field using internal parameters is considered herein, using results obtained from typical open and short circuit tests and winding resistances, performed with common meters. A Möllinger & Gewecke graphic diagram is employed together with the results of an accuracy test previously carried out to determine the exact value of the winding turn relation and of the primary winding dispersion reactance. These values are used to calculate the phase and ratio errors, which must lie between definite limits, defined by the accuracy class of the instrument. Four commercial IVTs were tested to determine the validity of the procedure. The errors are compared with those obtained with the Schering-Alberti method (AC Bridge and comparison with standard IVT).

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