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Global gas markets are changing as natural gas (NG) is replaced by biomethane. Biomethane is produced by upgrading biogas, which can have a molar concentration of methane to over 98%. This renewable energy has been injected into the pipeline networks of NG, which offers the possibility to increase its usage in industrial and residential applications. However, the expectation of the increase in biomethane proportion on the NG grids could increase the fluctuations on the composition of the NG–biomethane mixture in amplitude and frequency. In this context, the injection of biomethane into the existing network of NG raises a discussion about the extent to which variations in gas quality will occur and what permissible limits should exist, as variations in combustion characteristics can affect the operation of the combustion processes, with consequences for consumers, distributors and gas producers. This study describes a gas quality analysis with regard to the use of biomethane in industrial equipment, mixed or not mixed with NG, taking into account the indicators for gas interchangeability and provides a discussion on the necessary gas quality level to be achieved or maintained for efficient combustion in equipment originally designed to operate with NG. NG and biomethane real data collected for 92 consecutive days in 2022 and provided by two different companies in Brazil were used for this study. It is shown that the maximum deviation of the Wobbe Index (WI) of 5%, which is allowed for industrial plants, does not work for the operation of furnaces at temperatures of 1200 °C or more. In addition, it is shown that the WI, as defined in relation to the calorific value of the fuel, may allow inappropriate substitution of fuel gases, which is likely to reduce the range of blending of biomethane in NG pipelines. The results can be assessed to analyze how the addition of biomethane to NG grids will impact the WI and the equipment operation parameters such as the air-to-gas ratio, products-to-gas ratio, adiabatic flame temperature and furnace temperature. [ABSTRACT FROM AUTHOR]

Interest in biofuels is growing, and ethanol has been the most used biofuel as an additive and as a gasoline substitute and, it is considered a potential alternative to traditional fuels. Ethanol represents 17% of energy consumption in transportation in Brazil, the transport sector's share in the energy matrix is 32.4%, which is the second most energy-consuming sector. The production of first and second-generation ethanol in the same industrial plant presents better financial results compared to the isolated processes. Also, ethanol obtained from the sugarcane has renewability, biodegradability and provides CO2 emissions mitigation. The objective of the work is to perform an analysis of the ethanol with several levels of hydration in terms of energetic, economic, environmental and safety. The results showed that each 10% of water in ethanol dilution the temperature in the flame surround decreases by 4%. Besides, the ethanol with 20% of water dilution emits 20% less radiation compared to 10% of water dilution. Indeed, the energy consumed in the distillation to produce ethanol with 10% of water is double. On the other hand, this energy difference in the production of ethanol diluted with 30% of water is not enough to compensate for the losses in the energy use process. Also, large amounts of water in ethanol dilution might be unfeasible the use due to the total cost of transportation. Therefore, ethanol with 20% of water represents the more efficient, cleaner and safe fuel in free flame applications. [ABSTRACT FROM AUTHOR]