Experimental Investigations of the Effects of Secondary Air Injection on Gaseous Emission Profiles (NOx, NO, NO2, CO) and Hydrocarbons (CxHx) in Cookstoves Using Charcoal from Eucalyptus glandis

Use of biomass in domestic cookstoves leads to the release of oxides of nitrogen (NOx), nitric oxide (NO), nitrogen dioxide (NO2), carbon monoxide (CO) and hydrocarbons CxHx that can be detrimental to health of the public and the environment. Attainment of complete combustion is the best strategy for mitigating the release of these emissions. This study sought to experimentally determine the effects of secondary air injection on the emission profiles of NOx (NO & NO2), CO and CxHx in a charcoal operated cookstove. Charcoal from Eucalyptus glandis was bought from Kakuzi PLC. Composites from three batches were analyzed for chemical composition and the stoichiometric air equivalent. Proximate analysis data show that the charcoal composed 58.72% ± 3.3% C, 15.95% ± 1.2% Volatile Matter, 4.69% ± 0.55% Moisture, 20.7% ± 0.8% Ash, High heat value (HHV) of 30.5 ± 1.1 and 29.3 ± 1.3 Low heat value (LHV) (MJ/kg) with a chemical formula of C18H2O and a stoichiometric air requirement of 5.28 ± 0.6 with a fuel flow rate of 1 kg fuel/hr. Emission profiles for CO and CxHx reduced significantly by 70% and 80% respectively with secondary air injection whereas those of NOx increased by between 15% and 20% for NO2 and NO. The study reveals that secondary air injection has potential to mitigate on emission release, however other measures are required to mitigate NOx emissions.

Impact of Improved Cookstoves on the Level of Household Exposure to CO and PM2.5 in Sub-Saharan Cities: The Case of the City of Ouagadougou

Air pollution is one of the major global threats to human health. In Burkina Faso, more than 80% of the population uses solid fuels as the main source of cooking energy. This paper reports a comparative study on the exposure of household to the carbon monoxide (CO) and particulate matter (PM2.5) emitted by improved cookstoves (ICS) or traditional cookstoves (TCS). A cross-sectional study was conducted in the city of Ouagadougou for 4 months during the rainy season (July to October) in households with an outdoor kitchen. The investigation involved 92 households where air pollutants, such as PM2.5 and CO were measured with Indoor Air Pollution Meters (IAP meter). These measurements were focused on the concentration levels of the pollutants during cooking. The results of this study show high levels of PM2.5 and CO for all type of stoves. Wood stoves led to higher PM2.5 and lower CO emissions than charcoal stoves. ICS reduce emissions of indoor air pollutants compared to TCS. This reduction raised up to 82% for PM2.5 and 37% for CO. The analysis of the data measured with the student test (t-test) shows that there is a statistically significant difference between the average values of the concentrations of the pollutants emitted with the TCS compared to ICS, except for CO emissions measured on multi-pot sizes cookstoves (MM). This study shows that the concentrations of indoor air pollutants are very high regardless of the type of cookstoves used. The CO exposure obtained varies from 119.10 to 362.72 μg/m3 for 15-minute and 10.83 - 55.11 μg/m3 for 1-hour exposure. The exposure in PM2.5 varies from 4762 to 16,257 μg/m3 for 15-minute and 106.63 to 1597 μg/m3 for 1-hour of exposure. It was noted that the CO exposure levels obtained over 15-minute of exposure are 1.36 to 4.15 times higher than the WHO recommendation and 1.8 times higher for an exposure time of one hour. This means that women in charge of cooking have a high risk of exposure to air pollutants.

Effectiveness of Improved Cookstoves to Reduce Indoor Air Pollution in Developing Countries. The Case of the Cassamance Natural Subregion, Western Africa

The Spanish NGO “Alianza por la Solidaridad” has installed improved cookstoves in 3000 households during 2012 and 2013 to improve energy efficiency reducing fuelwood consumption and to improve indoor air quality. The type of cookstoves were Noflaye Jeeg and Noflaye Jaboot and were installed in the Cassamance Natural Subregion covering part of Senegal, The Gambia and Guinea-Bissau. The Technical University of Madrid (UPM) has conducted a field study on a sample of these households to assess the effect of improved cookstoves on kitchen air quality. Measurements of carbon monoxide (CO) and fine particle matter (PM2.5) were taken for 24-hr period before and after the installation of improved cookstoves. The 24-hr mean CO concentrations were lower than the World Health Organization (WHO) guidelines for Guinea-Bissau but higher for Senegal and Gambia, even after the installation of improved cookstoves. As for PM2.5 concentrations, 24-hr mean were always higher than these guidelines. However, improved cookstoves produced significant reductions on 24-hr mean CO and PM2.5 concentrations in Senegal and for mean and maximum PM2.5 concentration on Gambia. Although this variability needs to be explained by further research to determine which other factors could affect indoor air pollution, the study provided a better understanding of the problem and envisaged alternatives to be implemented in future phases of the NGO project.

Development of Advanced Biomass Cookstove and Performance Comparisons Using the Modified Star Rating Methodology

A disruptive approach to a fundamental process has been applied in a biomass combustion device with two variable speed fans to supply air for gasification and another for combustion processes,separately.Besides,the preheating of secondary air,required for combustion process was also ensured through annulus chamber before being fed into the combustion chamber.The turbulent flow and homogenous mixing were also ensured by controlling the flow rate resulting in the reduced emissions of carbon monoxide(CO)and fine particulate matter(PM 2.5,particulate matter having aerodynamic diameter<2.5 micron).The design approach applied here has also ensured the homogeneous mixing of preheated air with the volatiles,resulted in cleaner combustion.This arrangement has led to the emissions of PM2.5 and CO much better than those of the earlier cookstove models,and very close to that of a liquefied petroleum gas(LPG)stove.Further,the comparative analysis based on the modified star rating of total 15(14 are biomass and another LPG)cookstove models tested using the same standard methodology has been done and presented in this study.Based on the star rating,the performance of the LPG stove was found to be best and assigned as a 5-star product followed by the IITD model(4-star),while the other 13 models got different ratings starting from 1-star to 3-star,respectively.Also,the thermal performance of the IITD cookstove model is found to be the highest,while the emission characteristics are found to be the least among all biomass cookstove models,presented here.

Environmental Impacts (ER CO₂) of an Improved Multi-Fuel Gasifier Forced Air Cookstove in the City of Kinshasa

Sub-Saharan African countries depend 80% on the biomass-wood to meet their daily needs in terms of cooking foods. Traditional cookstoves are much more used to this effect. Many change programmes for replacing cookstove model have been planned. Yet many of these programmes have not been preceded by environmental impact studies. This work offers high-performance cookstove models and determines their impact on the reduction of CO2 emissions, a very harmful greenhouse gas causing the planet warming and climate change. Replacing the traditional cookstove by an improved stove may lead to an economy in terms of fuel ranging from 33.2% to 75.4% according to the model of cookstoves. Yet the Gasifier using pellets as fuel remains the most beneficial stove in terms of fuel saving (75.4%) and in terms of ER CO2, i.e. 2748 t CO2/Year. An improved gasifier cookstove is multi-fuel. He can use charcoal, pellets and wood. This is an indispensable cooking tool with alternative fuels. In this work, the ER CO2 was evaluated using two methods. The KPT, which is a field method and the CCT which is a laboratory method. By the KPT method a gasifier ICS/GAS/P records up to an ERCO2 of 2748 t CO2/Year, while with the same gasifier, an ERCO2 of 2619 t CO2/year is found by the CCT method. The comparison between the two methods shows the same trend but with very high values of ERCO2 for the KPT method results. The variation between the two methods ranges between 1% approximately to 6.9 percent.

A simplified model for understanding the performance of two-pot enclosed mud cookstoves

The objective of this study is to develop a mathematical model for a two-pot enclosed mud cookstove.A new model has been developed combining transient heat transfer,combustion chemistry and fluid flow.The model can be used for variation of the operation and design parameters.The model predicts performance parameters such as efficiency,boiling time,excess air ratio(EAR),transient wall,flame and char temperature.For an input power of 5.1 kW,the estimated overall efficiency,EAR and boiling time were 17.1%,1.97 and 43 minutes,respectively.The model outcome is compared with experimental results.Further,10 parameters are varied and their impact on cookstove performance is analysed.The optimum dimension for the door opening,combustion-chamber height and wall thickness are suggested.Therefore,this study can serve as an effective tool for cookstove design.

Adoption of Improved Biomass Cook Stoves: Case Study of Baringo and West Pokot Counties in Kenya

Biomass cookstove improvement has been a global active research area for many decades and has resulted into much progress towards cleaner and more efficient energy conversion cooking devices. Irrespective of the perfection and development of improved cookstoves, many households in Kenya are still using three stone cookstoves. In Baringo County, 71.8% used three stone cookstoves. The focus of research needs to change towards adoption of improved cook stoves. A cross-sectional survey was conducted in rural, peri-urban and urban households regarding current cookstoves types in relation to fuel use categorized as improved and un-improved in Baringo and West Pokot counties. Biomass was the primary fuel in the two counties used in the form of firewood and charcoal at average of 70% and 26% respectively. The main un-improved cookstoves in the two counties were three stone and metallic jiko. The two were commonly used in Baringo County with 28.5% of the households using metallic stove. Whereas in West Pokot, Chepkube was the main cookstove used for cooking at 47.8% seconded by improved three stone at 36.6%. The use of un-improved cookstove was popular in Baringo County at 77.6% while infamous in West Pokot County at 21.7%. The results showed that West Pokot County is more conscious to energy related issues unlike Baringo County. The difference in dynamic of the two Counties in terms of land ownership, access to biofuel, social groupings, availability of cookstove installers and improved jikos could be the reason.

Thermal Performance and Emission Analysis of a New Model Cylindrical Cook Stove with Controlled Air Flow

We present in this paper the results of experimental and numerical study of the thermal performances of a cook stove prototype intended for the parboiling of paddy rice. Thus, the experimental results show that the optimal mass of husk rice is M = 7.15 kg for a good combustion within the combustion chamber and got a maximum temperature at the level of the burners surface. This temperature is Tcu1=304.78°C. The circulating air flow rate by forced convection is Qm = 0.09112 m-3·s-1. The vertical side walls temperature is Tple = 140.6°C and the water temperature and vapor is about 144.6°C in the stockpot. The gas combustion is composed of carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and the ratio of hydrogen to nitrogen (H2/N2). The results from the numerical modeling indicate Tcu1=307.8°C, Tple = 144.55°C and a Qm = 0.09258 m-3.s-1. The average thermal efficiency of the cookstove is η = 46.6% and the power developed by the cookstove is about ≈6 kW. Despite the heat losses, the cookstove remains interesting for paddy rice parboiling activities.

Effectiveness of a home-environmental intervention package and an early child development intervention on child health and development in high-altitude rural communities in the Peruvian Andes: a cluster-randomised controlled trial

Background: Unsafe drinking water,poor sanitation and hygiene,exposure to household air pollution and low cognitive and socio-emotional stimulation are risk factors affecting children in low-and middle-income countries.We implemented an integrated home-environmental intervention package(IHIP),comprising a kitchen sink,hygiene education and a certified improved biomass cookstove,and an early child development(ECD)programme to improve children´s health and developmental outcomes in the rural high-altitude Andes of Peru.Methods: We conducted a one-year cluster-randomised controlled trial among 317 children<36 months divided into 4 arms(IHIP+ECD,IHIP,ECD,and Control)and 40 clusters(10 clusters per arm).ECD status(socio-emotional,fine and gross motor,communication,cognitive skills,and an overall performance)measured with the Peruvian Infant Development Scale and the occurrence of self-reported child diarrhoea from caretakers were primary outcomes.Secondary outcomes included the occurrence of acute respiratory infections and the presence of thermo-tolerant faecal bacteria in drinking water.The trial was powered to compare each intervention against its control arm but it did not allow pairwise comparisons among the four arms.Primary analysis followed the intention-to-treat principle.For the statistical analysis,we employed generalised estimating equation models with robust standard errors and an independent correlation structure.Results: We obtained ECD information from 101 children who received the ECD intervention(individually and combined with IHIP)and 102 controls.Children who received the ECD intervention performed better in all the domains compared to controls.We found differences in the overall performance(64 vs.39%,odd ratio(OR):2.8;95%confidence interval(CI):1.6–4.9)and the cognitive domain(62 vs 46%,OR:1.9;95%CI:1.1–3.5).Data analysis of child morbidity included 154 children who received the IHIP intervention(individually and combined with ECD)and 156 controls.We recorded 110,666 child-days of information on diarrhoea morbidity and observed 1.3 mean episodes per child-year in the children who received the IHIP intervention and 1.1 episodes in the controls.This corresponded to an incidence risk ratio of 1.2(95%CI:0.8–1.7).Conclusions: Child stimulation improved developmental status in children,but there was no health benefit associated with the home-environmental intervention.Limited year-round access to running water at home and the possible contamination of drinking water after boiling were two potential factors linked to the lack of effect of the home-environmental intervention.Potential interactions between ECD and home-environmental interventions need to be further investigated.