the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 02 Apr 2025
Emissions from fuel combustion by stoves in residential kitchens in São Paulo – Brazil
Abstract. This study investigates greenhouse gas (GHG) emissions and indoor air quality associated with residential cooking practices in São Paulo, Brazil. Measurements were conducted in 30 households, focusing on kitchens using natural gas (NG) or liquefied petroleum gas (LPG) stoves. A measurement protocol was developed to assess emissions of carbon dioxide (CO2), methane (CH4), and nitrogen oxides (NOx) under different operational conditions. Emission rates and factors were calculated using 5 mass balance approaches, considering kitchen volume, air exchange rates, and gas concentrations. The results show different behavior for the type of fuel, especially for methane, which has a significant response to the use of NG, unlike LPG. It was also possible to observe a difference between the temporal variability cycles, as the burners responded quickly to the increase in concentration, while the oven showed a delayed increase observed in the environment. There was a high variability in the concentrations in the different residences, which may be associated with factors such as the age of the stove, model, leak 10 and internal influence. The emission factors obtained were three times higher than the IPCC considering only the close values, but when considering the outliers it is up to 10 times higher for CH4 in the case of NG. For CO2 the factor obtained was lower than the IPCC. The findings highlight the importance of considering fuel type in evaluating GHG emissions from residential cooking and the need for robust data on residential emissions in Brazil.
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RC1: 'Comment on egusphere-2025-968', Anonymous Referee #1, 15 Apr 2025
This paper investigates greenhouse gas emissions associated with residential kitchens. The topic is relevant because it analyzes natural gas and liquefied petroleum gas that are widely used in many countries for cooking and can affect human health and ultimately might have climate impacts. Electric stoves may be ideal to minimize emissions, but there are challenges in their implementation in many countries and Brazil can be a typical example. The manuscript is clear and concise, which is really appreciated, and results are clearly illustrated and supported by the data. I have only one concern before recommending the publication in AMT: The authors claim in the text and in the supplementary material that they have measurements from 30 different kitchens. However, the discussion is focused in SP_CASA02 and SP_CASA03. I miss the link between these two examples and a global conclusion that includes measurements in all kitchens. Saying that, are the results of emission rates and emission factors representative of all cases or only of SP_CASA02 and SP_CASA03 ?
MINOR REVISONS
- Introduction: I miss the objectives at the end of the introduction section. This can enrich the manuscript.
- Line 119: Give a reference for US EPA
- Line 120: Give a reference for European Norm (EN)
- Line 125: Give a reference for Integrated Cavity Output Spectroscopy technique.
- Lines 133-135: Give a reference for equation 1.
- Lines 146-147: Can you explain better how air exchange rate was determined?
- Give a reference for equation 2
- Line 158: How did you compute normalized concentration profiles?
- Figure 5a: I recommend reducing y-axis to values of 0.2, even though you miss the outlier in cycle 2. Another recommendation could be reducing to values of 0.3 and including the outlier in cycle 2. Also, Figure 5 caption can be improved.
- Figure 7c: Again, I think that y-axis should be re-scaled to enhance the Box-Whisker plot.
- I recommend joining Discussion and Conclusion in just one section.
- Line 225: Give link/reference to Abregas
- Line 274: Give link/reference to Sistema de Estimativas de Emissoes e Remocoes de Efeito Estufa
Citation: https://doi.org/10.5194/egusphere-2025-968-RC1 -
AC1: 'Reply on RC1', Tailine Corrêa dos Santos, 17 Apr 2025
Thank you very much for your careful reading and valuable feedback. We appreciate your positive comments regarding the clarity and relevance of the manuscript.
Regarding your concern: SP_CASA02 and SP_CASA03 were selected as illustrative examples to describe the temporal variation in emissions from the two main types of fuel studied (liquefied petroleum gas and natural gas, respectively). These cases were used only in the initial analysis to exemplify the emission dynamics under each fuel type. Similar temporal patterns were observed across the remaining households, which is why we focused on just these two for this part of the discussion.
However, all subsequent analyses — including variability in concentrations, emission rates, and emission factors — were based on data from the full sample of 30 households. We will clarify this point in the revised manuscript to ensure it is clear that the broader results are representative of the complete dataset.
We will also incorporate your minor suggestions directly into the text. Thank you again for your thoughtful review.
Citation: https://doi.org/10.5194/egusphere-2025-968-AC1
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RC2: 'Comment on egusphere-2025-968', Anonymous Referee #3, 07 Jun 2025
The manuscript presents methods and results from an investigation of indoor greenhouse gas (GHG) emissions from household kitchens in the metropolis of São Paulo, Brazil. Measurements of indoor GHG concentrations and emissions are very scarce, especially in developing countries, hindering the assessment of their impacts on national GHG inventories and human health. Despite the limited number of households investigated (30), the study provides valuable information, reporting high variability in CH₄ emission factors and values up to three times higher than IPCC estimates. The manuscript requires minor corrections, particularly in the description of the methods.
Specific comments
- Introduction: I suggest to include a brief discussion about similar studies around the world. What are the main references supporting, for example, the IPCC estimates on GHG emissions by residential kitchens?
- Section 2.3: the description of the measurement protocol should be improved, in the main text of the manuscript. The scope of this journal leans toward the development and validation of measurement techniques. As such, to enable reproducibility of the protocol you have adapted, it should be better described. For example, you have used the terms “cycles”, “modules”, “Inject Gas” without a clear description of what they mean, at least in the main text. What is the difference between the “St_ON” and “ON” modules? The reader should be able to understand the measurement protocol from the main text. Consider including a diagram to illustrate the steps of the measurement protocol.
- Did you encounter problems following this measurement protocol? Were you able to use data from the 30 households in the calculation of emission rates? Would you recommend changing something in the protocol? This is important information that may provide guidance for future studies.
- Line 130 you have mentioned a CO2 cylinder, what was it used for? In line 147 you have mentioned a controlled release of CH4.
- Section 2.5: equations 1 and 2 should be better described. Please inform the units of the quantities involved in the calculation of emission rates and emission factors. In which cycle/module was the background concentration determined? How was the concentration rate of change (delta_C/delta_t) calculated, in which cycle/module? Did you fit a line to obtain the rate of change, or have you considered the conditions at start and end times only? What values of LHV have you considered in equation 2?
- Lines 146-147: Consider including a plot to illustrate the concentration decay and calculation of the ACH. The calculation of delta_C/delta_t could also be illustrated with an example. That would be informative to the readers.
- Line 188: what do you mean by “steady state ON”? Is it the same as “St_ON”? Please standardize the terminology.
- Table 2 and Table 3: There are too many significant figures in the reported emission rates. Considering the measurement uncertainties, are you really able to provide 2 decimal figures in the emission rates? Also, I recommend reporting median and interquartile values, instead of mean values, since the data distribution is very skewed. In Table 3, I recommend including the IPCC and the National emission factor estimates, for a direct comparison.
- Line 195: what could result in “negative emissions”?
- Line 201: NO2 emission rates were calculated based on the concentration rate of change (delta_C/delta_t). They should not be affected by the background concentrations, unless the kitchens were not properly sealed.
- Line 205 (for example): standardize the emission factor units for each pollutant, to facilitate the comparison. For example, here you have used kg CH4/TJ, while in Table 3 you have used mg/MJ.
Technical corrections
Line 10: Reformulate the sentence. “Close values” is not a scientifically sound term.
Fig1: Include the data source in the figure caption (SVMA, 2022).
Line 76: Rephrase the sentence.
Line 150: “M” is not included in Equation 2.
Standardize the usage of “LPC” and “NG” along the whole text and figures. For example, in Figures 5, 6, 7 you have used “GLP” and “GN”.
Figure 5: Consider using a y axis log scale for CH4 concentrations.
Citation: https://doi.org/10.5194/egusphere-2025-968-RC2 -
AC2: 'Reply on RC2', Tailine Corrêa dos Santos, 09 Jun 2025
Thank you very much for the detailed and constructive comments, which will undoubtedly contribute to the improvement of our manuscript. We agree with the points raised and will incorporate the suggested revisions and corrections one by one. In particular, we will focus on improving the description of the measurement protocol, standardizing units and terminology, enhancing the presentation of data and figures, and addressing the technical corrections indicated.
Once again, we sincerely appreciate the reviewer’s careful evaluation and valuable contributions.
Citation: https://doi.org/10.5194/egusphere-2025-968-AC2
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