Development of a low-smoke Mongolian coal stove using a heterogeneous testing protocol

We report on the application in domestic stove development of heterogeneous test methods that can simultaneously quantify gaseous emissions, condensed particulates and the mass of fuel burned in real time. Such measurements can rapidly identify ideal combustion conditions by post-facto dividing the test into arbitrary segments for detailed analysis. Domestic coal stoves typically operate daily across a wide range of operating conditions. The analysis technique was applied repeatedly throughout the development of a lignite burning stove suitable for use in Ulaanbaatar, Mongolia, the coldest and most heavily air-polluted capital city in the world. The outcome is a natural draft chimney stove with a >99% reduction in PM 2.5 emissions and >90% reduction in CO, relative to the baseline product. Including the ignition phase, the fire emits less than 0.5 mg of PM2.5 per MegaJoule. This challenges the popular notion that high-volatiles ‘low quality’ coals are inherently smoky

The uncontrolled cooking test : measuring three-stone fire performance in northern Mozambique

The assessment of cooking system performance in developing countries is a continued area of interest, with laboratory testing methods often being unrepresentative of real world use, and field based methods tending to be resource intensive with high levels of variability. This paper presents the Uncontrolled Cook Test (UCT), a relatively low cost field testing protocol that assesses the task-based performance of the system when cooking any meal and operated as per local conditions and practice. A total of 29 UCTs were conducted in households in a study village in rural northern Mozambique, all on wood-burning three stone fires. The UCT proved a capable method for the assessment of cooking system performance and, critically, returned a data set with less variation than is typically reported by existing field test methods, so offering the potential to use fewer resources to detect a statistically significant difference between baseline and ‘improved’ stove results

For cook and climate: Certify cookstoves in their contexts of use

Improved cookstoves are widely promoted as a health and climate improving technology, yet there remains a wide gap between their reputed benefits and the inconclusive outcomes of most interventions. An increasing number of scientists suggest that the popular lab protocols used to test, rate and model the benefits of improved cookstoves are at least partly to blame. Insights from a recent study of improved cookstove users in Darfur, Sudan, reveal the extent to which the logic and goals of lab-based testing protocols differ from actual cooking practices. We elaborate on the climate and energy policy implications of decontextualized lab tests and conclude with a call to design, test and select for dissemination only those improved cookstoves that are rated on the basis of their intended contexts of use

Optimising the imbaula stove

In South Africa, human and environmental health implications from domestic solid fuel combustion have spurred interest in cleaner alternative sources of energy and better combustion technologies. Field research among wood and coal burning informal settlements in Johannesburg has shown that the most prevalent mode of combustion is self-made imbaula (brazier) stoves, manufactured from discarded 20 L steel drums. Such stoves are made without any measure of performance optimisation, leading to fuel inefficiency and high emissions - previous field surveys have indicated that the number, size and placement of primary and secondary air inlets (taken as holes below and above the fire grate respectively) vary over a wide range, starting from an extreme with no holes below the grate [1]. Researchers at SeTAR Centre, University of Johannesburg, have set out to develop an enhanced imbaula, by investigating performance in terms of size and distribution of primary and secondary air inlets, and height of grate level. The test imbaulas are constructed out of standard 20 L drums with a height of 360 mm and diameter of 295 mm. A range of hole configurations has been designed, from which selected test configurations are fabricated for experimental evaluation of thermal and emissions properties, using the SeTAR heterogeneous testing protocol. The results indicate that higher hole densities (above and below the grate) lead to higher power outputs and lower specific CO emissions, but with lower thermal efficiency. Further, results indicate that adequate air holes below the grate (primary air) are more important for proper combustion in an imbaula; however this should be synchronised with secondary air in-lets (above the grid) in order to have congruence of all the performance criteria. This study should lead to the development of a set of criteria that can further enhance emissions reductions and fuel efficiency obtained by top-down stove ignition methods (Basa njengo Magogo) for imbaula type stoves

A conceptual framework for evaluating cooking systems

PUBLISHED 7 March 2022Tami C Bond, Christian L, Orange, Paul R Medwell, George Sizoomu, Samer Abdelnour, Verena Brinkmann, Philip Lloyd and Crispin Pemberton-Pigot

DEVELOPMENT OF A LOW SMOKE MONGOLIAN COAL STOVE USING A HETEROGENEOUS TESTING PROTOCOL

ABSTRACT We report on the application in domestic stove development of heterogeneous test methods that can simultaneously quantify gaseous emissions, condensed particulates and the mass of fuel burned in real time. Such measurements can rapidly identify ideal combustion conditions by post-facto dividing the test into arbitrary segments for detailed analysis. Domestic coal stoves typically operate daily across a wide range of operating conditions. The analysis technique was applied repeatedly throughout the development of a lignite burning stove suitable for use in Ulaanbaatar, Mongolia, the coldest and most heavily air-polluted capital city in the world. The outcome is a natural draft chimney stove with a >99% reduction in PM 2.5 emissions and >90% reduction in CO, relative to the baseline product. Including the ignition phase, the fire emits less than 0.5 mg of PM2.5 per MegaJoule. This challenges the popular notion that high-volatiles 'low quality' coals are inherently smoky

Mitigation of Ulaanbaatar city's air pollution - from source aportionment to ultra-low emission lignite burning stoves

The extraordinary air pollution in Ulaanbaatar (up to 4 200 μg m-3) was monitored using Nucleopore® filters and particle counters. Particle analysis confirmed low temperature coal combustion as the major air quality problem in poor districts. High time-resolution PM 2.5 data showed particles are emitted during the ignition of lignite fires. Over 50% of all PM comes from the ignition phase of stoves lighted in the morning and in the late afternoon after people arrive home from work. A laboratory (modelled on the SeTAR Centre Laboratory, University of Johannesburg) was established to quantify domestic stove emissions. Measured particulate matter was as much as 12 g m-3 of flue gases. Data analysis uses the SeTAR Centre Heterogeneous Testing Protocols and analytical methods. A combustor testing programme led rapidly to the development of an extremely clean-burning cooking and space heating stove that has been developed and brought to market within a single year. An acceptable 9 kW low-emission (up to 99% reduction of PM 2.5) and high efficiency (50% fuel savings) crossdraft cooking and space heating stove was developed and is being piloted for large scale production in Ulaanbaatar at this time

Towards a standard for clean solid-fuelled cookstoves

Conference ProceedingsWorldwide, millions of people with limited access to modem energy sources cook food using a wide variety of solid fuels, primarily biomass. Often the cooking arrangement is no more than three stones supporting a pot; sometimes there is an appliance which may be fashioned from local materials; sometimes there is a fabricated appliance. In most cases the combustion of the fuel exposes the cook and often the whole family to smoke and particulates. The World Health Organisation indicates that this exposure is one of the leading causes of Disability Adjusted Lost Years of life. Many organisations have taken credible steps to alleviate the problem, specifically by supplying improved stove technologies, improved or alternate fuels, or a combination thereof. One of the challenges, however, is that there is no agreement on what the performance criteria should be for a so-called "clean stove" or improved cooking technology. Some have focused on the efficiency of the cooking process, arguing that the use of less fuel for a given duty would inherently lower the risks, implicitly assuming that emissions are an inherent property of the fuel. Some have focused on minimizing the total energy used per task, not the total fuel, treating the leftover charcoal as 'unburned fuel,'similarly assuming that less energy means less emissions. Others have focused on ensuring the cleanest possible bum, often by careful preparation of the fuel, which often leads to the inefficient use of the available fuel resource and rejection by the users. Some have focused on the nature of the fuel, overlooking the fact that emissions arise from the choice of the fuel-stove combination. Moreover, users tend to use what is most readily and most cheaply to hand, and are not readily persuaded to use "better" alternative fuels. In this contribution we seek to explore the range of demands from users, in the hope of finding some common threads which would permit the rational development of standards for clean solid-fuelled cookstoves adaptable to the huge range of fuels and cooking cycles employed worldwide