Scielo RSS <![CDATA[Journal of Energy in Southern Africa]]> http://www.scielo.org.za/rss.php?pid=1021-447X20210004&lang=es vol. 32 num. 4 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Outlook for the biomass energy sector in Mozambique: Policies and their challenges</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400001&lng=es&nrm=iso&tlng=es To overcome the negative impacts of unsustainable exploitation of forest resources, the Mozambican government has been trying to regulate the supply and demand of biomass, the main source of energy for the majo rity of the population. This paper reviews policies implemented in Mozambique aimed at increasing domestic energy production while promoting a sustainable use of biomass. Despite the efforts to reduce the level of biomass energy use, it remains the most attractive to local populations and, therefore, still has great importance in the national energy mix. Thus, rather than looking at woodfuels as an environmental problem, regulations should also recognise the dependence of local communities on these resources. Firewood remains the main energy source in rural areas, and approximately 0.36% of the forest in Mozambique is lost every year. The replacement of firewood and charcoal by other renewable sources of energy is still far from reality. Charcoal production continues to be carried out in traditional low-yield ovens and the levels of forest degradation are still alarming. As such, improvements to the existing regulation framework are still needed. HIGHLIGHTS: • Woody biomass remains the most attractive energy source in Mozambique. • The government implemented policies to address unsustainable use of biomass. • The policies did not lead to a sustainable use of biomass. • Policy design should consider both technical and socio-cultural aspects. <![CDATA[<b>Optimal sizing for a grid-connected hybrid renewable energy system: A case study of the residential sector in Durban, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400002&lng=es&nrm=iso&tlng=es Many countries, including South Africa, have introduced policies and incentives to increase their renewable energy capacities in order to address environmental concerns and reduce pollutant emissions into the atmosphere. In addition, consumers in South Africa have faced the ever-increasing price of electricity and unreliability of the grid since 2007 due to the lack of sufficient electricity production. As a result, employing hybrid renewable energy systems (HRESs) have gained popularity. This research focuses on grid-connected HRESs based on solar photovoltaic (PV) panels and wind turbines as a potential way of reducing the dependency of residential sector consumers on the grid. It aims to identify the optimal sizing of renewable energy sources to be cost-effective for consumers over a certain period of time, using Durban as a case study. Two artificial intelligence methods have been used to obtain the optimal sizing for the available PV panels, wind turbines and inverters. The results shown that the combination of PV panels and battery storage can be a profitable option. A system using higher rated power PV panels can start to become profitable in a shorter lifetime, but employing batteries can only be cost-effective if a long enough lifetime is considered.HIGHLIGHTS: • Modelling the load and a HRES based on the residential consumer needs and available products. • Defining the optimisation problem based on a cost evaluation indicator and identifying constraints. • Determining the optimum combination of renewable energy sources. • Assessing the cost of setting up a HRES for typical residential consumers. <![CDATA[<b>Effective selection of countries in sub-Saharan Africa for new market entry by independent wind power producers</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400003&lng=es&nrm=iso&tlng=es When independent power producers (IPPs) assess new market entry opportunities, subjective decision making can result in an unfavourable outcome. Multi-criteria decision analyses (MCDA) objectify the decision process and help to achieve better results. The aim of this study is to determine and rank the most important criteria for market entry and then determine which selected countries in sub-Saharan Africa are most favourable for wind IPPs. A combination of MCDA methods was used to rank seven countries. Nineteen criteria, identified in the literature reviewed, were included in the analyses. In the first phase of the study an industry expert survey was conducted and the analytical hierarchy process (AHP) was used to rank the criteria in order of importance. In the second phase, a preference ranking organization method for enrichment evaluation (PROME-THEE) was employed to rank the countries from most to least favourable for IPP market entry. The expert survey and AHP showed that political and economic criteria are more important than technical and social criteria. The PROMETHEE model ranked South Africa followed by Ethiopia as the most favourable markets for wind IPPs to enter. These countries have strong natural wind resources but only South Africa offers incentives specifically for on-grid renewable energy. The methods used in this study are not restricted to the wind industry and can be expanded to different technologies and industries to assist with decision making. <![CDATA[<b>Determining the causes of electricity losses and the role of management in curbing them: A case study of City of Tshwane Metropolitan Municipality, South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400004&lng=es&nrm=iso&tlng=es The problem of energy losses, both nationally and internationally, is a leading cause for the financial collapse of most utilities. A quantitative research approach was adopted for this study where a questionnaire was used to collect information from the participants. A total of 113 City of Tshwane (CoT) employees within the electricity division participated in the study. Descriptive sta tistics and inferential statistical methods were used to analyse the outcome of the survey. The study found that technical and non-technical losses are the major cause of revenue loss. Non-technical losses are caused either by inefficiencies in managing losses or by end-users being unwilling to pay for electricity. The study found that power theft through meter tampering, incorrect billing by employees, and cable theft were also major causes of energy losses. Illegal connections were found to be the major cause of energy losses, along with power theft and lack of resources. Deficiencies in infrastructure maintenance were found to be the main cause of technical losses. The study found that management of CoT is committed to managing energy losses, being aware of their impact on the financial well-being of the municipality. There is an established policy of managing energy losses and there is a plan to replace ageing infrastructure. Employees are continuously trained in accurate billing and metering as part of efforts to curb energy losses. The municipality is also engaged in efforts to put educational programmes in place to inform communities about electricity theft.HIGHLIGHTS: • Technical losses are a major cause for utilities 'financial losses. • Utilities must have a long-term loss management plan. • Illegal connections are the leading cause of electricity losses. • Energy losses impact negatively on service delivery. • Management impacts on the ability of a municipality to reduce losses. <![CDATA[<b>International procurement policies influencing renewable energy siting - implications for South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400005&lng=es&nrm=iso&tlng=es The South African Renewable Independent Power Producer Procurement Programme selects bid winners based on bid tariff (70% weighting) and various economic development criteria (30% weighting). Locating renewable energy (RE) projects in areas with better resources increases their cost competitiveness. As a result, most successful bids for wind and solar photovoltaic (PV) systems to date have been concentrated in the Eastern Cape and Northern Cape provinces, respectively. Studies have shown that a wider geographic distribution of wind and solar PV projects mitigates the impacts of the variability of wind and solar PV resources, eases grid congestion and generally improves the power system's operation. This paper conducts a literature review to investigate the procurement methods used in different regions of the world to influence the placement of RE plants, the results of which then inform proposals on adjustments to the current REI4P. The study finds that, after congestion incidents due to concentration of RE plants, some regions implement location-based tariff, where high-resource areas receive the lowest tariff and vice versa. Other regions prioritise on building transmission infrastructure in high-resource areas, while others limit the size of RE installations in one area. Given the current generation and transmission constraints in South Africa, it is important to encourage geographical dispersion of RE plants and avoid RE curtailment, since this can escalate the cost of RE integration significantly. <![CDATA[<b>Electric energy planning in Namibe, Angola: Inserting renewable energies in search of a sustainable energy mix</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400006&lng=es&nrm=iso&tlng=es The socioeconomic development of any region requires electricity for operating the various sectors of the economy. Sometimes energy is scarce, not only because of the lack of energy resources, but also because energy policy is inadequate or non-existent. This paper examines the situation in the province of Namibe, Angola, characterising the energy sector, and proposing an energy mix for the security of electricity supply, environmental protection and sustainable economic development. Using the Long -range Energy Alternative and Planning System, energy scenarios were simulated and the greenhouse gas emissions (GHGs) for the period 2014-2040 calculated and analysed. The most sustainable scenario, in terms of energy mix diversification and GHG reduction, as well as the least costly (considering electricity production and carbon costs), has an increase of hydro capacity and the insertion of wind, solar photovoltaic, thermoelectric sources and natural gas. Given the intermittency of photovoltaic and wind systems, natural gas appears in this scenario as a way to avoid interruptions in the electricity supply. This scenario is the one with the largest production reserve margin of 24.47 %, and emissions are avoided at 386 550 tCO2eq compared to the base scenario in 2040. Energy policymakers can take this scenario as a model to assist in making decisions on how power capacities can be installed over the planned time for the desired energy output. <![CDATA[<b>Improving reliability of the power distribution system in Goma (DRC) using solar distributed generation</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400007&lng=es&nrm=iso&tlng=es The existing power distribution system of the city of Goma in the Democratic Republic of the Congo has many problems, including the scarcity of electric energy, power unreliability, the low access rate of electrification, poor flexibility in the network topology, and lack of demand response, which lead to shedding of load, unbalancing and overloading the system. The reliability of the Goma power distribution system is very poor by international standards. The major cause of this is the lack of adequate energy supply to meet demand. To mitigate the power reliability problem, a solar-based distributed generation (DG) is modelled and evaluated in this study. Each feeder has been considered separately with an appropriately designed DG. The work has evaluated initial investment cost and life cycle cost of the investment to assess the feasibility of the proposed solution. Based on the unserved energy and electricity tariff, an economic analysis was conducted. The reliability indices are computed and the modelled solution is designed for each feeder in PV syst software and simulated using ETAP, whose simulation results show that the reliability can be improved by up to 76%. Highlights • Reliability analysis and determination for Goma. • Reliability indices are mathematically calculated using IEEE 1366 standard. • The distribution system reliability will improve by up to 76%. • Solar distributed generation can greatly improve the reliability of electricity supply in Goma. <![CDATA[<b>Design and development of a low-cost system to convert solar thermal energy into electricity for households in South Africa using solar concentrators</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-447X2021000400008&lng=es&nrm=iso&tlng=es South Africa is, due its specific latitude location in the southern hemisphere, exposed to high solar irradiation levels. Black thermal absorbers have a high absorbance for solar incident radiation, while commercial photovoltaic technology only converts about 10% of energy available in the solar spectrum. In this article, low-cost Peltier conversion cells, that are normally used for cooling purposes, and that are freely available in supply stores in South Africa, were identified as suitable conversion cells for converting thermal energy into electricity. Two prototypes of thermal-to-electricity energy conversion systems were subsequently designed and developed. Particularly, advanced pulse mode DC- to- DC conversion technology, a special electronic control system, was developed, that could extract high amounts of electrical energy from the cells and could store the energy in standard storage batteries. A 3 W and a 30 Woutput continuous conversion capacity system were developed. A power conversion of up to 2 W capacity per individual cell was achieved. The systems used no movable parts, and the lifespan of the systems is projected to be at least twenty years. Cost and viability analyses of the systems were performed and the results were compared to existing solar photovoltaic energy conversion systems. Combining the 30 W capacity system with a black body and reflector plate absorber system revealed a cost structure of only ZAR 0.8 per kWh, as compared with a derived ZAR 3 per kWh for a combined photovoltaic and solar geyser combination, as calculated for a ten-year term. The technology as developed is suitable to be incorporated in South African households and rural Africa applications.HIGHLIGHTS: • Extremely cost-effective harvesting and storage of solar energy in household context. • Development of novel low-cost thermal energy to electricity conversion systems. • Conversion to electricity at ZAR 0.80 per kWh. • Household applications and labour-intensive job creation possibilities. • Business creation possibilities under established intellectual property.