Browsing by Author "Da Silva, Izael Pereira"
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- PublicationAnalysis 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, IzaelThis 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.
- PublicationBenefits of using biogas in households experience from a user in UgandaDa Silva, Izael; Sendegeya , Al-Mas; Ssebuwufu , Pancras John; Da Silva, Izael PereiraThis 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.
- PublicationCurriculum Vitae(Izael Pereira Da Silva, 2015) Da Silva, Izael Pereira; Da Silva, Izael
- PublicationProspects of the use of solar water heaters in demand side management in UgandaDa Silva, Izael; Da Silva, Izael Pereira; Mugisha, PatrickThe commercial sector in Uganda accounts for about 20% of the total electrical energy consumed in the country, with about 50% consumed in the domestic sector and the remaining 30% to the industrial sector. As the economy continues to grow due to attraction of foreign investment and improvement in local production, more challenges now come up in terms of sustaining the already-attained levels of development and social transformation. It is known that Uganda has only 300 MW of installed electric power capacity. This power is insufficient and could be used better - it is estimated that about 40 MW of the total load is allocated to water heaters. Among the energy-saving schemes being implemented in the commercial sector to avoid or reduce load shedding and to reduce the use of costly generators is the use of Solar Water Heaters (SWHs). A case study on the use of solar water heating in a three-star hotel as a means of implementing an energy saving scheme is presented and an economic analysis of the project is given. Finally, future prospects of use of solar thermal technologies in the commercial sector as a means of energy conservation and as a solution to some of the environmental concerns under Clean Development Mechanisms (CDM) are presented.
- PublicationReducing carbon emissions in a third level educational institution in Sub-Sahara AfricaDa Silva, Izael; Da Silva, Izael Pereira; Ronoh, Geoffrey; Ouma, Clint; Jerono, CarenThe effort to reduce carbon emissions as the arguably most prevalent cause of global warming has been a positive trend in most African countries. One of the most successful strategies towards reaching that goal is the shift from fossil fuel power generation to renewable sources of energy such as wind, hydro, geothermal and solar. As Kenya sits on the equator it enjoys an all year round insolation between 5 to 6 kW/m2/day which is more than double of the average insulation in Germany, a country where solar energy is widely used. Taking advantage of a green line of financial support created by the French Government, Strathmore University embarked in a project to install a 600kW roof-top, grid connected solar PV system to cater for its electricity needs. Having as a background of the newly instituted Feed-in- Tariff regulation, the system is designed to produce more than the required self-consumption such that the extra power can be sold to the utility via a PPA (power purchase agreement) and the revenue used to pay for the electricity used by the university at night. This paper describes the whole process from the technical, regulatory, educational and financial aspect highlighting the positive and negative events along the path such that it can be useful for other private sector institutions interested in greening their sources of energy, invest in renewable energy and thus reduce their operation costs. The authors have written this work having in mind not only countries in Africa but all other countries which sit in the so called "solar belt".
- PublicationStandalone small level power systems based on utilization of agricultural residue (Benecke System)(Domestic use of energy conference, ) Da Silva, Izael; Da Silva, Izael Pereira; Krishnan, C. Kutty; Baker , Samuel Kucel; Nturanabo, FrancisStand alone small level power systems as a route to low investment decentralized systems with low gestation period is a worthwhile proposition which is being considered and implemented in many third world countries. When the concept of mini-grid is associated with renewable sources of energy such as solar, wind, hydro and biomass, small-decentralized power generation systems lessen the often over-dependence on fossil fuels. Fossil fuel are used at excessively and lead to warming problem due to net carbon-dioxide transfer into the atmosphere besides being a cause of unhealthy trade balance for developing countries. This paper describes a stand alone 0.5 MVA steam powered generator system, which utilizes agricultural residues as fuel. A complete technical description of the system is given. The economic and social impact of such a set-up is also given.
- PublicationWood Gasification in Uganda – Is this a solution for the Energy Crisis? Hard facts from installed unitsDa Silva, Izael; Da Silva, Izael Pereira; Buchholz, Thomas; Okure, Mackay; Kjellström, T.