Size distribution of nano particles from residential fixed-bed coal combustion

Abstract: Particle size distribution (PSD) from domestic coal combustion is an important parameter as it affects air quality, climate modelling, and health. There is limited information in the literature on particle size distribution from residential fixed-bed coal combustion processes. This study aimed to investigate the influence of coal combustion phases (ignition, flaming, and coking) on PSD of fine and ultrafine particles. Fine particle emissions from combustion of D-grade type coal (Ø 40 – 60 mm), in a lab-fabricated coal brazier (imbaula), were monitored using a NanoScan Scanning Mobility Particle Sizer (SMPS). Experiments were carried out using the reduced smoke top-lit updraft method, colloquially known as the Basa njengo Magogo (BnM) method. Particles from the top-lit updraft (TLUD) showed an ultrafine geometric mean diameter centred at approximately 110 nm for the ignition phase, 55 nm for the pyrolysis/ flaming phase, and 33 nm for the transition phase. The particle mode diameter rapidly increased during the ignition phase (145 nm) and gradually decreased during the flaming phase (35 nm) and the transition phase (31 nm)

Public participation in technological innovation : the case of the Tshulu stove development programme

Abstract: The design of products for developing communities often excludes the end-users in the decision making process. The study aims to investigate public participation and engagement in the design and development of the Tshulu woodstove. Results of this research point to the need for improved communication between citizens and technical experts, as well as for narrowing the gap between the designer and the user by encouraging meaningful engagement and inclusion. Bottom-up approaches ensure sustained participation of the public, in turn increasing a sense of ownership in the product. These results have implications for energy policy and improved cookstove programmes for developing communities

Design and performance evaluation of wood-burning cookstoves for low-income households in South Africa

Abstract: Many cookstove programmes implemented around the world aimed to reduce fuel consumption and pollutant emissions through the dissemination and adoption of improved cookstoves. A study was carried out for the design of wood-burning cookstoves for low-income households in South Africa by employing user-centred design and co-design/cocreation approaches. Six designed variants of the biomass stove were constructed. Water-heating and emissions tests, using black wattle wood, were conducted to evaluate them for thermal and emissions performance. The large hopper stove with two secondary air inlets ranked highest, with best performance regarding thermal and emissions parameters. It outperformed the small hopper stove in time to boil, heat flux and firepower, although the latter had higher thermal efficiency values..

Influence of coal properties on the performance of fixed-bed coal-burning braziers

Abstract: Informal fixed-bed coal-burning braziers are used extensively in low-income communities of South Africa for space-heating and cooking needs. An investigation was carried out on the effects of coal moisture content and coal quality on the thermal and emissions performance of domestic coal-burning braziers in three field-procured braziers (with three different air ventilation rates), using the bottom- lit updraft (BLUD) and top-lit updraft (TLUD) ignition methods. Results showed that an increase in coal moisture content (from 2.4 wt.% to 8.6 wt.%) led to 18% and 30% decreases in fire-power when using the TLUD and BLUD methods, respectively. The combustion efficiency increased by 25% with an increase in moisture content. Measured carbon monoxide (CO) emission factors increased with an increase in moisture content, while carbon dioxide (CO2) emission factors remained unchanged. The use of A-grade coal resulted in a 49% increase in PM emissions compared with D-grade coal at high ventilation rates, despite no statistically significant differences (p > 0.05) in CO and CO2 emission factors produced between coal grades

Energy content and combustion behaviour of loose biomass available in Limpopo

Solid biomass continues to be the primary energy source for a significant proportion of Sub-Saharan African society. It is estimated that 80% of energy for heating and cooking in this subcontinent is derived from round wood biomass resulting in estimated annual rate of deforestation of 0.7%. This is unsustainable. This is despite the existence of a substantial resource of loose biomass (forest and agricultural residues) that is produced and disposed of annually. However, one major challenge in harnessing loose biomass as a source of energy is low energy density and poor combustion behaviour. Biomass briquetting technologies can be deployed to improve energy density and combustion behaviour of loose biomass. This requires understanding of the energy content in locally available loose biomass sources. This paper investigates the calorific values (energy content) and combustion behaviour of loose biomass collected from a region in the Limpopo Province of South Africa. The aim of the investigation is to understand the energy value and hence viability of using such loose biomass with the overall goal of developing recipes for biomass briquetting in the region. Calorific values were measured for 12 samples of loose biomass and their combustion behaviour analysed. Certain loose biomass sources are then identified as potential briquetting candidates

Influence of fire-ignition methods and stove ventilation rates on gaseous and particle emissions from residential coal braziers

Despite extensive electrification of low-income residential areas on the South African Highveld, extensive use is still made of wood and coal as domestic fuels, particularly for winter space heating. In informal settlements characterised by poverty and lacking electrification, coal is combusted in non-standardised, inefficient and polluting metal braziers, colloquially known as imbaulas. Copious emissions from domestic coal fires result in elevated household and ambient air pollution levels well above national air quality limits. Despite the severity of this pollution as a public health issue, emissions data from residential coal-burning braziers are still scarce. Consequently, there is a need to evaluate the emission characteristics of these devices. In this paper, we report on controlled combustion experiments carried out to investigate systematically influences of fire-ignition methods and stove ventilation rates on gaseous and condensed matter (smoke) emissions from informal residential coal combustion braziers. Two methods of stove ignition—conventional bottom-lit updraft (BLUD) and the top-lit updraft (TLUD) (colloquially known as the Basa njengo Magogo) were investigated. Emission factors (EFs) were found to be dependent on fire ignition method and stove ventilation rates. The top-lit ignition method reduces PM10/PM2.5 by 76% to 80% compared to the BLUD method. Carbon monoxide emissions do not change significantly with the ignition method. Pollutant emissions from normal combustion in high ventilation conditions were low compared to pollutants emitted when an oxygen deficient atmosphere was created under low ventilation conditions. High stove ventilation rates resulted in a 50% reduction in PM10/PM2.5 emissions compared to the low ventilation rates. Emissions of gaseous and particulate matter from incomplete combustion can be minimised by design optimisation of the braziers. Ideally, the emissions of condensed matter particles (which form the bulk of emitted particles in residential coal fires) can be reduced through good mixing of emitted gases and air, and by ensuring a long residence time in the high temperature oxygen rich post combustion zone, to allow for complete oxidation. This study is significant in that it presents the first systematic and comprehensive study of factors affecting emissions from coal braziers

Dissemination of free basic electricity in rural settlements

Abstract: This paper evaluates the implementation of the Free Basic Electricity (FBE) programme in the needy South African households. A total of 5 governmental sites were used to assess the implementation of the FBE program; while 165 households were surveyed from 2016-2017 to determine the dissemination and use of FBE. The desktop survey revealed that approximately 1.8 million poor South Africans have access to FBE. Furthermore, tariff relief sets at 50 kWh based on 2001 household energy survey was found to differ per implementing agency, ranging from 20 kWh - 100 kWh. However, no data was available regarding the total number of South African who are energy poor. The survey found that 18% of households are employed, while 82% is unemployed and mainly depend on social grants. Majority of the households cannot afford electricity for cooking and heating, consequently spend over 14% of their income on energy budget which include a mixture of clean and dirty fuels such as wood, coal and paraffin. A total of 15 (9%) households are beneficiaries of FBE; while 91% indicated that they do not know about the tariff relief. Findings from this study suggest the need for an improved public communication strategy, especially in rural areas. It can be recommended that the 50-kWh tariff relief be reviewed to qualify the current household energy needs. Furthermore, enhanced community engagement is recommended in rural settlements to improve clean energy adoption strategies, either energy efficiency or FBE utilization

Biological Nitrogen Fixation: Sustaining African Agriculture into the Twenty-First Century?

A conference paper on sustaining African agriculture in the twenty-first century.The main objective of the African Association for Biological Nitrogen Fixation (AABNF) is to promote research, training and the use of biological nitrogen fixation systems to increase food production, reduce the need for purchased nitrogen fertiliser inputs, alleviate malnutrition and improve the environment in Africa. This objective contributes to the conservation and sustainable use of natural resources, and the sharing of benefits arising out of the utilisation of the results of relevant research, all key considerations in national development strategies, plans and programmes, as stipulated in Agenda 21 and in a number of Conventions in particular the Convention on Biological Diversity. The research carried out by scientists working on BNF in Africa has confirmed in controlled environments and in both experimental and farmers’ fields, the potential of biological nitrogen fixing systems to contribute to sustainable agriculture. In particular, the potential benefits to the well-being of the populations living in rural areas are significant