Browsing by Author "Madhlopa, Amos"

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    Open Access
    An analysis of institutional structures, organisational culture and decision-making processes that affect the sustainability of buildings at the University of Cape Town
    (2018) Mandalia, Jigisha; Marquard, Andrew; Madhlopa, Amos
    Universities globally are realising the potential they have in shaping the future workforce to deal with a variety of environmental issues, such as efficient resource use and sustainable development. The University of Cape Town (UCT) has committed to a number of environmental sustainability goals and is a signatory to international sustainable campus charters. This dissertation analyses the progress of sustainability levels of buildings on campus. A case study of three recently built buildings was undertaken, the last of which attained a 4-star green rating by the Green Building Council of South Africa. A detailed analysis was conducted through semi-structured interviews with key stakeholders at the university and others, including architects and sustainability experts. This study specifically evaluates the institutional structures, organisational culture and decision-making processes that have enabled, promoted or hindered sustainable buildings at UCT. One key policy was established in 2012, which stated that all new buildings at UCT will be constructed to be 4-star rated at a minimum. The decisions leading up to this policy were analysed and they highlight the enabling mechanisms within the university. However, a number of barriers and challenges were found that hindered progress. Many challenges are not unique given the similarity of university structures and governance globally, such as lack of: resources, awareness, motivation and coordination. However, there are local and contextual challenges, especially lack of funding and competing priorities, that need to be addressed before sustainability is fully integrated into UCT. Moreover, inertia of large institutions, difficulty in shifting organisational culture, and complex and lengthy decision-making processes make change difficult at a university. Nevertheless, some strategies are explored that are likely to be effective in promoting increased sustainability levels, especially of buildings on campus.
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    Assessing the potential for urban wind energy in Cape Town
    (2018) Gough, Matthew Brian; Madhlopa, Amos; Khan, Mohamed Azeem
    As the demand for alternative and renewable sources of energy grows worldwide, it has been argued that small-scale Urban Wind Energy (UWE) could have the potential to provide a significant portion of the electricity demand for urban areas. However there is currently a lack of knowledge surrounding the realisable potential for UWE, especially in the South African context. In order to gain a better understanding of the potential for UWE and the barriers acting against its widespread uptake, it is essential to first quantify the resource potential. This study appraise and evaluate the UWE resource potential at six locations in Cape Town, South Africa in order to gain a solid understanding of the UWE resource potential and thus begin to build the knowledge base around UWE. In order to meet the research objectives, wind data was obtained from the South African Weather Service for six locations in Cape Town at five minute recording intervals for a period of two years. These locations were: The Royal Cape Yacht Club located in the Table Bay harbour, the Astronomical Observatory located in Observatory, and the Kirstenbosch Botanical Gardens located in Kirstenbosch, the Molteno reservoir located in Oranjezicht, the Automatic Weather station located near the Cape Town International Airport as well as the Cape Town Weather Office (WO) station which is also located at the Cape Town International Airport. The data sets are then analysed using a script written in the programming language R in order to quantify the wind energy resource potential of the chosen locations. The wind energy resource potential of each site was combined with four commercially available wind turbines power curves in order to calculate the expected annual energy production values of the various turbines at the each of the locations. Results from this study highlight the significant variability resource potential of the wind regime that occurs between the six locations. The lowest yearly average wind speed was 2.044m/s which was recorded at the Kirstenbosch recording station, while the highest average wind speed was 5.06m/s which was recorded at the WO station. The average of all six stations for the two year period was 3.24m/s. Therefore the WO station had the highest energy potential with a value of 1474 kWh/m²/year and the station with the lowest energy potential was the Kirstenbosch station with a value of 80 kWh/m²/year. Combining these resource potential values with power cures from four commercially available wind turbines yields the Annual Energy Production (AEP) values for the chosen site and wind turbine. These AEP values also varied drastically with the high of 4304 kWh/year being calculated for the SkyStream turbine at the WO station and a low of just 0.66 kWh/year being calculated at the Kirstenbosch station with the Turby turbine. This variability hampers the wide spread uptake of small scale wind power as the results from one area cannot be reliably used to infer the wind resource potential at another nearby site. Out of the six chosen locations in the Cape Town area, three of the locations (Royal Cape Yacht Club, the Automatic Weather Station (AWS), and the Cape Town Weather Office (WO)) showed potential for the installation of a small scale wind turbine, with the Horizontal Axis Wind Turbines (HAWTs) performing better than the Vertical Axis Wind Turbines (VAWTs). This is possibly due to the lower cut in wind speeds of the HAWTs compared to the cut in wind speeds for the VAWTs. The conclusions of this study show that the UWE resource potential in Cape Town is characterised by high resource variability between the various locations. Three of the six locations that were evaluated showed potential for UWE installations. This study has identified the major challenges associated with UWE to be the turbulence, lower hub heights of the wind turbines (this study used 20m as the standard hub height), and variability of the wind regime between locations.
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    Open Access
    An assessment of the impact of land acquisitions for biofuels on local livelihoods' in Zambia.
    (2014) Petrik, Dania; Madhlopa, Amos
    Biofuels are considered a mitigation tool, as an energy alternative to the global conventional oil reliance. Moreover, biofuels are seen as aiding rural development priorities for developing countries by increasing agricultural investment through foreign direct investment. Driven by international blending mandates, large agricultural investments for biofuels have been made in sub-Saharan Africa. This study examined the biofuels industry in Zambia using the Sustainable Livelihoods theoretical framework in order to investigate economic, social and environmental indicators of resilience and vulnerability for local people in the face of such agri-investments. A desktop study, case studies and interviews were used to assess the impacts. The study found that a lack of strong policy governance and appropriate support for the industry in Zambia is a challenge facing the development of a successful biofuels sector. For rural communities who are dependent on land held under community tenure, the conversion of communal land to commercial agro-fuel crops through land transfers to investors has led to loss of access to land necessary for subsistence and increased competition over natural resources. Biofuel investments based on employing local people through outgrower schemes have had no real economic benefits. When land was directly transferred, it decreased the land available to landholders and had implications for food security, livelihood diversification and welfare. In negotiations over land between investors and local elites, local landholders were excluded from voicing their needs, and impacts related to benefit sharing, conflict and gender disparity were felt. Land demarcation led to loss of access to marginal lands, important for the cultivation of crops by women, and forests - crucial for supplementing livelihoods with forest products such as ifishimu.
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    Assessment of the potential contribution of biogas to mitigation of climate change in south africa
    (2014) Vanyaza, Sidwell Luvo; Madhlopa, Amos
    South Africa has its fair share in the global greenhouse gas (GHG) emissions, with recorded 2010 emissions per capita of 10tons/year. This is caused by the energy supply of the country which relies heavily on fossil fuels to drive its energy intensive economy. If this continues under “business as usual”, consequences like water and food shortage may be exacerbated. The waste sector has a share of 3 in national GHG emissions. These are caused by methane from biogas produced through anaerobic digestion of organic waste. The objective of this study was to assess the potential contribution that can be achieved in reducing the national GHG emissions by converting waste emissions into useful energy or capturing and destroying them. Three waste resources were investigated because of their abundance in the country: municipal solid waste, municipal wastewater and livestock manure. The national picture of municipal waste was extrapolated from the waste data available in 7 metros in the country (City of Cape Town, Johannesburg, Tshwane, Ekurhuleni, EThekwini, Nelson Mandela Bay, and Buffalo City municipalities). Projected GDP and population growths were used as indicators for extrapolating the national data. The total national organic waste derived from these waste categories was used to estimate their emission share in national GHG emissions and biogas generation in terms of methane production from each waste type. This was forecasted from 2010 to 2025. The methane gas production was optimised by assuming different waste combinations like: municipal solid waste and wastewater, wastewater and livestock manure, and remaining wastewater. In addition, the possible amount of electricity or heat produced from this biogas was estimated. This useful energy was used to evaluate the emission reduction potential (ERP) in the national GHG emissions of the country under “growth without constraints”. All these computations were performed by using MS Excel software. It was found that the total organic waste predicted during this period varied from 12 to 17Mton, with the waste emissions share being about 2 of the national GHG emission. Methane generated from this waste was about 644-1075Mm3 while the total optimal methane generated from these waste combinations was estimated to be 1770- 2650Mm3. In addition, 673-1123GWh of electricity and 1255-2150GWh of heat could be produced (without optimization) from methane over the same period of the forecast. For optimal methane production, the possible useful energy was estimated to be 1362-2037GWh of electricity and 2894- 4362GWh of heat. The ERP of methane capture and conversion to useful energy was about 2.1- 2.5. It is concluded that a) capturing and utilisation of methane gas from waste contributes to the reduction of the GHG emissions, b) optimisation of biogas production from waste increase methane yield and therefore useful energy, and c) the best contribution of biogas in climate change mitigation in South Africa would come from the optimal production of methane from waste.
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    Draft policy framework for efficient water use in energy production.
    (Energy Research Centre, University of Cape Town., 2014) Madhlopa, Amos; Keen, Samantha; Sparks, Debbie; Moorlach, Mascha
    South Africa faces imperatives to secure a supply of clean water and to protect water resources, as well as to provide a secure supply of energy. Over and above the mandates of ensuring clean water provision and of improving the coverage and security of a reliable energy supply, the government faces challenges of reducing poverty and unemployment, and of ensuring sustainable development. In order to meet these challenges, the national government has developed a set of progressive policies. Harmonisation of these policies is itself a considerable challenge.
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    Exploring the potential of nanofluids to enhance the productivity of solar stills
    (2019) Charitar, Deepti; Madhlopa, Amos
    Desalination technologies are being used to augment access to safe drinking water around the world. Nonetheless, most of these technologies are energy-intensive and driven by fossil fuels which emit greenhouse gases into the atmosphere, thereby contributing to climate change. Additionally, fossil fuels are non-renewable sources of energy and the exhaustion of such reserves can cause a threat to energy security. Consequently, exploitation of sustainable sources of energy for the desalination process has attracted a lot of attention. One such strategy is the use of a solar still which utilises solar energy to produce fresh water from saline or brackish water. However, the major drawback of a solar still lies in its low productivity. Many studies have investigated means of increasing the productivity of a solar still. One such technique which has recently been studied is to disperse nanoparticles into the impure water inside the basin of a solar still in order to obtain a nanofluid with enhanced optical and heat transfer characteristics. Since this is a relatively new topic, very few numerical studies on solar stills with nanofluids are available. Moreover, based on a literature review, no study examining the effect of nanoparticle size on the productivity of solar stills, and on the economic and environmental performance of solar stills was found. Additionally, the few available numerical studies on solar stills with nanofluids have not taken into account the view factor in the computation of the internal radiative heat transfer coefficient. Therefore, the aim of this study was to investigate both numerically and experimentally the effect of nanoparticle size on the performance of solar stills. Mathematical models with the view factor (Model 1) and without the view factor (Model 2) were developed for single slope solar stills, and a code was written in MATLAB software to solve a system of equations iteratively. Calculations were performed using climatic data from Stellenbosch (latitude 33.93°S, longitude 18.86°E) and University of Cape Town (latitude 33.96°S, longitude 18.46°E), South Africa, in order to evaluate the performance of solar stills with varying nanoparticle sizes. For the experimental phase, four identical solar stills were designed and built, and they were first tested with water only (base fluid) in all of them to test their performance and for calibration purposes. An Analysis of Variance (ANOVA) test was conducted on the experimental data collected from this first test. Subsequently, nanofluids containing aluminium oxide (Al2O3) nanoparticles of size 10 nm, 50 nm and 100 nm were used in three of the solar stills, with the other solar still containing the base fluid only. All the experiments were conducted at the University of Cape Town. The mathematical models were then validated using experimental data. Simulations in MATLAB based on Stellenbosch climatic data showed that for the month of January, which is a summer month in South Africa, the productivity of the solar still with the 10 nm, 50 nm and 100 nm Al2O3 nanoparticles was 9.01%, 8.94% and 8.89%, respectively higher than the productivity of the solar still with the base fluid only. On the other hand, for the month of July, which is a winter month in South Africa, the average productivity of the solar still with the 10 nm, 50 nm and 100 nm Al2O3 nanoparticles was 1.31%, 1.23% and 1.19%, respectively higher than the productivity of the solar still with base fluid only. In terms of the economic analysis, the simulations in MATLAB based on annual climatic data from Stellenbosch revealed that the cost of distilled water obtained from the solar still with the 10 nm, 50 nm and 100 nm Al2O3 nanoparticles was 10.42%, 6.21% and 3.51%, respectively higher than the cost of water obtained from the solar still with the base fluid only. Additionally, the payback period for the solar still with the 10 nm, 50 nm and 100 nm Al2O3 nanoparticles was 13.32%, 7.86% and 4.37%, respectively higher than the payback period for the solar still with the base fluid only. In terms of the environmental performance, the amount of carbon dioxide equivalent (CO2 equivalent) mitigated by the solar still with the 10 nm, 50 nm and 100 nm Al2O3 nanoparticles was 6.18%, 6.11% and 6.06%, respectively higher than the amount of CO2 equivalent mitigated by the solar still with the base fluid only. For the experimental phase, the ANOVA test based on the first set of experimental data (with base fluid only in all four solar stills) gave a probability-value (P-value) of 1.00. Moreover, experimental data collected from solar stills with base fluid and nanofluids revealed that the productivity of the solar still with nanoparticles of size 10 nm and 50 nm was 26.46% and 1.46%, respectively higher than the productivity of the solar still with base fluid only. On the other hand, the productivity of the solar still with nanoparticles of size 100 nm was 9.38% lower than that of the solar still with base fluid only. Furthermore, the root mean square error (RMSE) for the solar stills with nanofluids for Model 1 and Model 2 was 22.02% and 36.03%, respectively. It was confirmed that the performance of the calibrated solar stills was not significantly different. Moreover, the enhancement in the productivity of a solar still with nanofluids is much more distinct in summer than in winter. It was also demonstrated that the productivity of a solar still decreases with increasing nanoparticle size. Additionally, it was established that the cost of distilled water, the payback period and the amount of mitigated CO2 equivalent decrease with increasing nanoparticle size. Theoretically, the distillate yield and environmental performance of a solar still with nanofluids were marginally sensitive to the nanoparticle size while the cost of distilled water and payback period were significantly affected by the nanoparticle size. The effect of nanoparticle size on distillate yield was experimentally significant. Finally, it was demonstrated that the inclusion of the view factor improves the accuracy of modelling of solar stills with nanofluids.
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    Investigating household energy poverty in South Africa by using unidimensional and multidimensional measures
    (2018) Mbewe, Samson; Madhlopa, Amos; Tait, Louise; Moyo, Alfred
    The ability to access affordable, reliable and modern energy services presents a pathway to social and economic development. Yet, the lack of access to modern energy services is widespread in sub-Saharan Africa and developing Asia. Following the declaration to achieve universal access to energy by 2030 in the United Nation’s Millennium Development Goals and Sustainable Development Goals – several tools have emerged tracking and monitoring energy access and energy poverty. Earlier efforts have focused on measuring energy poverty from a unidimensional perspective while recent efforts have focused on a multidimensional measurement. However, the growing trend in tracking and monitoring energy poverty using multidimensional indicators has been applied limitedly in the context of South Africa. Part of this has been associated with the lack of detailed and reliable survey data. With access to detailed survey data, this study aimed to evaluate household energy poverty in South Africa by using both unidimensional and multidimensional measures. This study constructed the energy budget share, also known as Tenth-Percentile Rule (TPR) (unidimensional) and the multidimensional energy poverty index (MEPI) using data from wave 1 (2008) and wave 4 (2014-2015) of the National Income Dynamic Study (NIDS) of South Africa. A 10 percent threshold was used for the energy-budget share while a 0.3 cutoff point was used for the MEPI. This study first computed national-level estimates of household energy poverty, and subsequently decomposed these estimates by province, household income poverty status and household location (urban versus rural). A sensitivity analysis was performed to test for the stability in ranking of provinces when the energy poverty threshold of the TPR was varied from 7 to 13 percent, and the energy poverty cutoff k of the MEPI was changed from 0.2 to 0.4. The Spearman rank correlation coefficient was determined for each pair of ranking of provinces to establish the strength of correlation. Based on the TPR measure, results show that 21 and 13 percent of South African households lived in energy poverty in 2008 and 2014-2015, respectively. The MEPI measure indicates that 37 and 19 percent of the households lived in energy poverty in 2008 and 2014- 2015, respectively. Limpopo province had the highest rates of energy poverty in 2014-2015 with values of 25 percent (using TPR) and 52 percent (using MEPI). This study also found that by 2014-2015, only 23 percent (using the TPR) and 46 percent (using the MEPI) of energy poor households lived below the food poverty line of R430. Further, this study found that household energy poverty has reduced in rural areas and by 2014-2015, only 18 percent (using TPR) and 49 percent (using MEPI) of households located in rural areas lived in energy poverty. The lowest observed value of the Spearman rank correlation coefficient was 0.90. It is concluded that the overall household energy poverty has reduced in South Africa between 2008 and 2014-2015. The TPR gives lower estimates of energy poverty than the corresponding values obtained from the MEPI measure. There is negligible effect of varying the threshold values (within the studied range) of the TPR and k.
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    Investigating Pre-Financial Close Risks Associated with Communal Land Ownership Rights in Onshore Wind Energy Development in South Africa
    (2020) Mokone, Bothokgami; Madhlopa, Amos
    There are challenges to be addressed if South Africa is to reach its full potential in exploiting wind energy resources. One of such challenges is communal land ownership, which is used for the development of wind energy in rural areas. Often, communal lands have no formal land structures, ownership or title deeds to support the individuals and communities that claim possession thereof. This challenge of communal land ownership and the associated risks impact upon investments by independent power producers in wind energy infrastructure. Land in South Africa remains a highly sensitive issue given the historical injustice of land dispossession which became the source of poverty and inequality. Moreover, transitioning to renewable energy sources would add more pressure on land scarcity. Commercial wind energy projects are capital intensive, with high annual turnovers. Achieving financial close is a risk mitigation strategy that confirms that early-stage contractual agreements have been reached in the development stage of a wind project lifecycle. Therefore, risk identification and allocation are fundamental to ensuring that the structuring and contractual obligations of non-recourse project financing are met. Wind energy plants require significant stretches of land, and this is progressing at an industrial scale and often, onshore wind energy projects are located in rural areas, thereby impacting local communities. Land ownership rights are a key element for communities, in which renewable energy development takes place. Households living on communal land, of which the right to use land is vested in individual households, are situated on such lands. This study uses the theory of risk management to investigate pre-financial close risks in developing wind energy associated with communal land ownership rights and the extent to which those risks inhibit wind energy projects from reaching financial close in South Africa. An exploratory research design was applied, while a questionnaire survey was used to collect data from wind developers. The study identified the pre-financial close risks associated with communal land to be technical, legal, economic, social and political risks. Indeed, there is a lack of clear, long-term policy framework to support investments in clean energy infrastructure. This causes significant delays to wind energy project development and it negatively affects financial close. In addition, there are competing interests among multiple stakeholders, leading to the burdensome processes involved in securing leasehold agreements on communal land. As a result, projects which were initially proposed on communal land, have not always reach financial close as planned while others were stopped. The results show that risk mitigation tools could include effective and continuous stakeholder management which is critical to reaching financial close. Furthermore, the Department of Rural Development and Land Reform has not established a streamlined process that developers can follow to secure communal land leasehold rights, given that the process is time-consuming.
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    Numerical study of a hybrid photovoltaic thermal desalination system
    (2016) Noble, Cole Douglas; Madhlopa, Amos
    The world as we know it depends highly on fossil fuels. However, these resources are finite, and evidence suggests that their combustion contributes to climate change. In addition, fresh water supplies are becoming scarcer amidst instabilities in weather patterns and unsustainable water consumption levels. As such, photovoltaic (PV) systems have emerged as a potential off-grid alternative to traditional fossil fuel energy generation. However, their widespread proliferation is, in part, inhibited by their inefficiency as less than 20% of incident solar energy is converted to electrical energy. Hybrid photovoltaic thermal (PV/T) desalination systems have emerged as one way of improving the overall efficiency of PV panels as they make use of the waste heat from panels to aid the desalination process in solar stills. Solar stills have been modelled with software for the purpose of performance optimisation, but most of them do not account for the still's view factor in the calculation of internal radiative heat transfer coefficient. The aim of this study was to construct a numerical model for a hybrid PV/T desalination system and determine its accuracy. The modelling was undertaken in Matlab and was validated against experimental data from a previous study using Root Mean Square Error (RMSE) and correlation values. It was observed that the model performed adequately as a water yield RMSE value of 22.0% was found. Furthermore, it was found that the view factor reduces the RMSE of hourly water yield from 28.9% to 22.0% and improves the correlation factor from 0.9890 to 0.9896. Sensitivity analyses were performed with annual data from Stellenbosch, South Africa (33.935°S 18.7817°W) and indicated an optimal water depth of 0.02m for high water yield, and 0.04m for high electrical energy yield. Also, an optimal panel tilt angle of 30° was found for both water and electrical energy yields and optimal cover tilt angles of 40° and 60° were observed for maximum water and electrical yields respectively. The conclusion of this study was that the incorporation of a view factors does indeed improve the accuracy of hybrid PV/T desalination system models. Additionally, low basin water depth is favourable for high water yields and high basin water depth, for high electrical energy yields. Furthermore, a panel tilt angle of 30° is optimum for both types of yield. Finally, the still cover tilt angle should be set to 40° for optimal water yields, but should be as steep as possible for optimal electrical energy yields.
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    Numerical study of the thermal performance of solar chimneys for ventilation in buildings
    (2015) Charitar, Deepti; Madhlopa, Amos
    Building ventilation is crucial for improving the indoor air quality and thermal comfort. Nowadays, mechanical ventilation systems such as air conditioning and fans are most commonly used in buildings. However, these devices consume a lot of electricity which is mainly generated from the combustion of fossil fuels, resulting in the release of greenhouse gases and thereby contributing to climate change. Consequently, it is essential to switch to natural ventilation systems which are environmentally friendly as they are based on renewable sources of energy. One such type of natural ventilation system is the solar chimney which can either be roof-mounted or wall-mounted in buildings. The aim of this study was to develop a mathematical model for assessing the thermal performance of roof-mounted (inclined) and wall-mounted (vertical) solar chimneys. The model was validated using numerical simulations in MATLAB. Different configurations of solar chimneys were designed and modelled in MATLAB in order to compare their performances, in terms of the ventilation rate expressed as the number of air changes per hour, ACH. Raw climatic data, including the intensities of global and diffuse solar radiation on a horizontal plane, wind speed and ambient temperature were obtained for Stellenbosch, located in the Western Cape Province of South Africa. This was used for the MATLAB modelling of the solar chimneys. The effects of inclination angle, air gap, chimney height and view factor on the thermal performance of solar chimneys were explored in this study.
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    Political risk analysis of the Renewable Energy Sector in South Africa and the effect on Foreign Direct Investment
    (2019) Mokhele, Khothatso; Madhlopa, Amos
    Over the past decade, a strong business case has been established for the exploitation ofrenewable energy sources (hereinafter referred to as RES) due to ongoing falling costs and the recognition by many countries that renewable energy presents the pathway to global energy transformation, energy security, and abatement of climate change. Furthermore, renewables can bridge the gap for energy-poor societies, thus creating opportunities for sustainable livelihoods for the millions of people who lack energy access throughout the global economy. However, despite these desirable outcomes, there are risks involved in the application of renewable energy that have understated the scale and strength at which they can be implemented. This dissertation is a political risk analysis of the renewable energy sector in South Africa, based on the 2011 government programme designed to attract investment in grid-based renewable energy generation. A political risk analysis studies a broad spectrum of identified factors and their impact on foreign direct investment for a chosen sector. The Albert Venter (2005) model will be used as a framework of analysis. This is an indigenous model that focuses on South Africa as it positions itself favourably for foreign direct investment (FDI) flows and participates actively in the global economy. Using this model, this dissertation reveals the political risks and complexities relating to the implementation of South Africa’s policy driven renewable energy projects through the Renewable Energy Independent Power Producer Programme (REIPPP). Risks relate to regulatory risks, socioeconomic risks, and the impact of global market changes on the local environment as well as the potential of political interference from government institutions. Corrupt practices such as those surrounding an oscillating nuclear deal, the desire to maintain monopoly in state owned Eskom and the tensions that emerge as a result of a historically unequal society where there is unequal land distribution and access to the grid, manifest in South Africa’s energy sector leading to a curtailment of FDI in the energy sector. Based on the above-mentioned pointers, South Africa displays friction as government navigates international and local concerns that are at odds with the advancement of a robust renewable energy sector and its implied effect on foreign direct investment amidst an environment of limited capital in the country.
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    Renewable energy choices and water requirements in South Africa
    (University of Cape Town., 2013) Madhlopa, Amos; Keen, Samantha; Sparks, Debbie; Moorlach, Mascha; Dane, Anthony
    South Africa (SA) is an arid country, where water supply is often obtained from distant sources. There is also increasing pressure on the limited water resources due to economic and population growth, with a concomitant increase in the energy requirement for water production. This problem will be exacerbated by the onset of climate change. Recently, there have been concerns about negative impacts arising from the exploitation of energy resources. In particular, the burning of fossil fuels is significantly contributing to climate change through the emission of carbon dioxide (major greenhouse gas). In addition, fossil fuels are getting depleted, thereby decreasing energy security. Consequently, the international community has initiated various interventions, including the transformation of policy and regulatory instruments, to promote sustainable energy. In view of this, SA is making policy and regulatory shifts in line with the international developments. Renewable energy is being promoted as one way of achieving sustainable energy provision in the country. However, some issues require scrutiny in order to understand the water footprint of renewable energy production. Due to the large gap that exists between water supply and demand, trade-offs in water allocation amongst different users are critical. In this vein, the main objective of this study was to investigate renewable energy choices and water requirements in SA. Data was acquired through a combination of a desktop study and expert interviews. Water withdrawal and consumption levels at a given stage of energy production were investigated at international and national levels. Most of the data was collected from secondary sources (literature) and therefore the assessment boundaries are not fully comparable. Results show that there are limited data on all aspects of water usage in the production of energy, accounting in part for the significant variations in the values of water intensity reported in the global literature. It is vital to take into account all aspects of the energy life cycle to enable isolation of stages where substantial amounts of water are used. Conventional fuels (nuclear and fossil fuels) withdraw significant quantities of water over the life-cycle of energy production, especially for thermoelectric power plants operated with a wetcooling system. The quality of water is also adversely affected in some stages of energy production from these fuels. On the other hand, solar photovoltaic and wind energy exhibit the lowest demand for water, and could perhaps be considered the most viable renewable energy options in terms of water withdrawal and consumption.
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    Thermodynamic evaluation of the gasification of municipal solid waste
    (2021) Sebothoma, Dimakatso; Madhlopa, Amos; Ochende-Bello, Tunde
    The dependency on energy use is unavoidable in modern civilization. The burning of fossil fuels for energy use is regarded as one of the human activities that has a harmful environmental impact. Waste to energy is slowly becoming an evident argument that energy can be obtained from waste at a level that is enough to meet energy demands. Waste is viewed as a renewable source of energy and can lower emissions from the greenhouse gas (GHG) and mitigate climate change. The exploitation of municipal solid waste (MSW) can be implemented using various routes, either through thermal or biological conversion. The thermal conversion can be achieved through combustion, gasification, or pyrolysis. This study aimed to evaluate the gasification of municipal solid waste. The investigation focused on the effects the selected operating parameters have on the syngas composition, H2/CO ratio, and calorific value. The selection of the modelling approach focused on the problem statement. It was necessary to use a model that did not have a lot of limitations or relied on the geometry of the gasifier. A mathematical model that could analyse the selected operating parameters of the gasification process was utilized. A step-by-step procedure of the thermodynamic equilibrium model was implemented using MATLAB. The model was validated by comparing the predicted results of this study and empirical data in published literature. The results showed that operating parameters affected the amount of syngas quality, calorific value, and H2/CO ratio. The amount of carbon monoxide and nitrogen reduced with an increase in moisture content, and the amount of carbon dioxide increased with increased moisture content. A small amount of methane was recorded, with increased moisture content. Enhanced temperature brought about increased hydrogen while the amount of nitrogen remained constant. With high temperature, carbon dioxide composition reduced, and just over 1% of methane was recorded. The increased (ER) from 0.2 to 0.6 showed that ER has a notable impact on nitrogen. A sharp increase in nitrogen was noted when the ER increased while the amount of hydrogen and carbon monoxide decreased. Results showed acceptable agreement between the modelled data from this investigation and the experimental values reported in the literature. The overall conclusion is that the thermodynamic model gives accurate prediction results of the gasification process. Additionally, when the investigated operating parameters were adjusted, syngas composition, H2/CO ratio and calorific value were all affected (they either increased or reduced). Furthermore, it is concluded that the ER ratio is the most influential parameter in the gasification process.
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    Water considerations in selecting energy technologies
    (Energy Research Centre, University of Cape Town., 2014) Madhlopa, Amos; Keen, Samantha; Sparks, Debbie; Moorlach, Mascha
    Water plays a vital role in the socio-economic development of any nation. It is exploited in different economic sectors, including the energy sector. Water and energy are inextricably related, and this relationship is usually referred to as the water-energy nexus. Water is used for energy production in the abstraction, growth and preparation of some fuels as well as in some power plants. It is also used in the raw materials for plant infrastructure, manufacturing of plant components, and the construction of power generating infrastructure. The volume of water used in the raw materials will vary widely, not only with the technology, but also the material type and plant design. Furthermore, these materials can be imported from any location and the associated water use is not limited to any water catchment, water management area or local authority.