Daniel Masekameni

Optimisation of ventilation and ignition method for reducing emissions from coal-burning imbaulas

Despite more than 87% households in South Africa being electrified, domestic coal combustion still remain a major source of cooking and heating in low-income households on the Highveld. A majority of low-income households burn coal in informal braziers-imbaulas-constructed from 25 L metal drums with holes punched around the sides. These imbaula stoves are hand manufactured without any standard reference with respect to number, size and location of ventilation holes and position of the fuel grate. These devices tend to have poor combustion efficiencies, leading to high emissions of particulate matter and pollutant gases, affecting both indoor and ambient air. This paper focuses on a range of community designed imbaulas and ignition methods (top and bottom lit), with the aim of evaluating thermal and emissions performance using the SeTAR Centre Heterogeneous Testing Protocol (HTP). Three stoves were evaluated, differing primarily in the total area of the ventilation holes. Results show that the stove with largest area of ventilation holes emits less particulate matter, has improved combustion efficiency - CO:CO2 ratio (4%) and consumes less fuel compared to two other test stoves with smaller areas of ventilation holes. For all stoves tested, the top-lit ignition method showed an 80% reduction in particle emissions compared to the bottom-lit ignition method. From this work, it can be argued that a balance between primary and secondary air inlets and grate height will improve imbaula performance.

Energy use scenarios in an informal urban settlement in Johannesburg, South Africa

This paper presents a survey from a sample of 52 households from three informal urban settlements in Tembisa, Johannesburg, namely Vusimuzi, Madela Kufa Section 1 and Madela Kufa Section 2. The survey covered energy needs for cooking, space heating, water heating and lighting. No information was requested on the age, gender, status in the household, income level of the respondents, or the number of persons in the household. Coal was the primary source of energy for cooking, water heating and space heating, while kerosene was frequently used for cooking and lighting, and less for water heating. The majority of informal dwellings were not connected to the electricity grid at the time of the survey, save for a few which were connected through petrol-powered electric generators or through electricity obtained from a network of illegal connections. None of the households purchased LP gas for domestic use; the fuel is generally perceived to be unsafe for use in these settlements. Factors such as seasonality, the availability and price of fuels, and socio-cultural aspects affect fuel choices and the quantity consumed.

Performance evaluation of three charcoal stoves

Globally, introduction of alternative basic energy has proven to reduce the burden of household air pollution. In South Africa, charcoal present a viable energy resource in the peri urban areas. However, burning of charcoal in inefficient stoves leads to excessive release of harmful pollutants. Few studies have been conducted to investigate the burning of charcoal more cleanly and efficiently, hence the development of this study. This study set out to evaluate emissions and thermal performance of three improved charcoal stoves (Zambian, Kenyan Jiko and Madagascar charcoal stoves) that might be applicable for the South African market. In order to replicate real world use, a culturally appropriate burn sequence was developed prior to stove evaluation. The hood method was used to collect gaseous and particulate emissions. Stoves were rated in terms of the IWA rating matrix, and CSI metrics, and for CO emissions in terms of the South African standard for indoor combustion (SANS 1906: 2009). Results presented indicated the COEF in the range of 4.3–5.4 g/MJ, PMEF 5.2–7.5 mg/MJ while firepower was found to be between 3.1–7.3 kW. All three stoves rated as IWA Tier 4. The CO/CO2 ratios were found to be in the range of 7.5–9.6%, indicating that these stoves will not be suitable for indoor use in terms of the South African National Standard. Using the CSI rating method, the Zambian charcoal stove failed in terms of the firepower, while the Kenyan Jiko and Madagascar charcoal stoves passed, with average firepower between 3 and 5 kW.

A comprehensive review on small-scale combustion technologies in Southern Africa, what is known, done and emergent knowledge gaps?

This is a review paper written with the intention to shed light on continued reliance on high polluting energy sources in the Southern Africa. In developing countries the use of low cost fuels including coal, wood, pellets, charcoal and cow dung remains an obstacle in ensuring the right to clean air. In this study, several stove to fuel combustion technologies researches, were reviewed for similarities/ commonalities and differences. The review highlights on critical health and environmental effects associated with burning of solid fuels using inefficient cookstoves. The review deepens the understanding on various clean energy interventions and policy formulation in several countries within the Southern Africa Development Communities (SADC) region. Studies indicated the development of stove alone will not be enough in enhancing or reducing air pollution, but emphasis shall be put on stove to fuel combination. Findings also suggest a lack of clear or practical policy intervention to restore household indoor air quality, while single policy intervention proven inadequate in many studies. In sub-Saharan region, policy intervention focuses on energy switch thus from traditional solid fuels to modern energy resources namely electricity and liquid petroleum gas (LPG). This approach is not feasible given the difficulties in electricity generation and supply system, housing infrastructure and cost implication. In conclusion, policies which support energy stacking present a viable solution to improved indoor air quality.

Exploring access to clean energy for various domestic uses in Mpumalanga province, South Africa

Globally, many developing countries face several challenges in their energy sectors which could still exaggerate the global burden of non-communicable diseases. In South Africa, clean energy is available for most people in urban areas. However, continued reliance on unclean energy sources continues to increase exposure to harmful pollutants in enclosed cooking and heating spaces. Burning of coal and wood using informal cookstoves remains a major cause of increased emissions due to poor combustion conditions and fuel inherent characteristics. Few studies have been conducted to investigate accessibility to clean energy in rural South Africa, hence the development of this study. This paper presents a survey from a sample of 53 households taken in three rural settlements in Lowville, Mpumalanga, namely Duckies, Masekeni and Kamathomo. The survey covered some of the most basic households energy needs including cooking, space heating, illumination and entertainment. Energy cost scenarios were added to evaluate households energy costs measured in relation to the average income for each of the sampled households. In total, 87% of surveyed households were found to be electrified. However, the main uses of electricity grouped as: 89% for entertainment; 77% for lightning; 44% for cooking and 37% for space heating. The study also found that 91%, 57% and 28% of households use wood, paraffin and coal for cooking and heating respectively, and 13% use candles for illumination. In conclusion, this study shows continued reliance on multiple energy sources in rural communities of South Africa. This means access to electricity does not mean automatic switch from use of solid fuel to grid energy.

Influence of fuel-bed temperatures on CO and condensed matter emissions from packed-bed residential coal combustion

In this paper, the influence of fire-ignition methods (which determine the progression of the pyrolytic zone) and combustion temperatures on CO and condensed matter (smoke) emissions during fixed-bed coal combustion were investigated in a typical informal brazier/imbaula. Particle and gaseous samples were drawn from the exhaust through a rapid dilution sampling system (the SeTAR dilution system) before being channelled to respective gas and particle analysers. Particle morphologies and chemical composition of the particles were investigated by a VEGA3 SEM unit with EDS. Results showed that the propagation of bed temperatures in fixed-bed residential combustion has an influence on the characteristics of CO and PM10 emissions. Temperature stratification was found to depend on the fire-ignition methods. The top-lit up-draft (TLUD) fire-ignition method produced less emissions compared to bottom-lit up-draft (BLUD) fire-ignition method. Bed temperatures and the propagation front have an impact on aerosol formation and can highlight differences in the morphology of the emitted particles and the modes of formation. Increasing combustion temperature yields a decrease in emissions liquid “tarry” substances and super-aggregates (>10 μm) but also leads to an increase in emissions of sub-micron soot particles. This work is significant in that there is still scarce information available in literature on fuel-bed temperature profiles/stratification for packed-bed residential coal-burning devices.