Adsorption of methane by modified-biochar aiming to improve the gaseous fuels storage/transport capacity: process evaluation and modeling.

The CH4 storage by adsorption on activated carbons for natural gas handling has gained interest due to the appearance of lightweight materials with large surface areas and pore volumes. Consequently, kinetic parameters estimation of the adsorptive process can play a crucial role in understanding and scaling up the system. Concerning its versatility, banana peel (BP) is a biomass with potential for obtaining different products, such as biochar, a solid residue from the biomass' thermal decomposition of difficult disposal, where through an activation process, the material porous features are taken advantage to application as adsorbent of gaseous substances. This research reported data for the CH4 adsorption kinetic modeling by biochar from BP pyrolysis. The activated biochar textural characterization showed particles with fine mesoporous structure (pore diameter ranging between 29.39 and 55.62 Å). Adsorption kinetic analysis indicated that a modified pseudo-first-order model was the most suitable to represent the experimental data, with equilibrium adsorption of 28 mg g-1 for the samples activated with 20.0% vol wt.-1 of H3PO4 and pyrolysis at 500 °C. The equilibrium constant was consistent with the Freundlich isotherm model, suggesting a physisorption mechanism, and led to a non-ideal, reversible, and not limited to monolayer CH4 adsorption.

Measurement Uncertainty and Risk of False Compliance Assessment Applied to Carbon Isotopic Analyses in Natural Gas Exploratory Evaluation.

The concept of uncertainty in an isotopic analysis is not uniform in the scientific community worldwide and can compromise the risk of false compliance assessment applied to carbon isotopic analyses in natural gas exploratory evaluation. In this work, we demonstrated a way to calculate one of the main sources of this uncertainty, which is underestimated in most studies focusing on gas analysis: the δ13C calculation itself is primarily based on the raw analytical data. The carbon isotopic composition of methane, ethane, propane, and CO2 was measured. After a detailed mathematical treatment, the corresponding expanded uncertainties for each analyte were calculated. Next, for the systematic isotopic characterization of the two gas standards, we calculated the standard uncertainty, intermediary precision, combined standard uncertainty, and finally, the expanded uncertainty for methane, ethane, propane, and CO2. We have found an expanded uncertainty value of 1.8‰ for all compounds, except for propane, where a value of 1.6‰ was obtained. The expanded uncertainty values calculated with the approach shown in this study reveal that the error arising from the application of delta calculation algorithms cannot be neglected, and the obtained values are higher than 0.5‰, usually considered as the accepted uncertainty associated with the GC-IRMS analyses. Finally, based on the use of uncertainty information to evaluate the risk of false compliance, the lower and upper acceptance limits for the carbon isotopic analysis of methane in natural gas are calculated, considering the exploratory limits between -55‰ and -50‰: (i) for the underestimated current uncertainty of 0.5‰, the lower and upper acceptance limits, respectively, are -54.6‰ and -50.4‰; and (ii) for the proposed realistic uncertainty of 1.8‰, the lower and upper acceptance limits would be more restrictive; i.e., -53.5‰ and -51.5‰, respectively.

Design of an innovative system for hydrogen production by electrolysis using waste heat recovery technology in natural gas engines.

This research proposes designing and implementing a system to produce hydrogen, utilizing the thermal energy from the exhaust gases in a natural gas engine. For the construction of the system, a thermoelectric generator was used to convert the thermal energy from the exhaust gases into electrical power and an electrolyzer bank to produce hydrogen. The system was evaluated using a natural gas engine, which operated at a constant speed (2400 rpm) and six load conditions (20 %, 40 %, 60 %, 80 %, and 100 %). The effect of hydrogen on the engine was evaluated with fuel mixtures (NG + 10 % HEF and NG + 15 % HEF). The results demonstrate that the NG + 10 % HEF and NG + 15 % HEF mixtures allow for a decrease of 1.84 % and 2.33 % in BSFC and an increase of 1.88 % and 2.38 % in BTE. Through the NG + 15 % HEF mixture, the engine achieved an energy efficiency of 34.15 % and an exergetic efficiency of 32.84 %. Additionally, the NG + 15 % HEF mixture reduces annual CO, CO2, and HC emissions by 9.52 %, 15.48 %, and 13.39 %, respectively. The addition of hydrogen positively impacts the engine's economic cost, allowing for a decrease of 1.56 % in the cost of useful work and a reduction of 3.32 % in the cost of exergy loss. In general, the proposed system for hydrogen production represents an alternative for utilizing the residual energy from exhaust gases, resulting in better performance parameters, reduced annual pollutant emissions, and lower economic costs.

Contradictory electric energy policies and its impacts on the renewability of the electric matrix: Brazil as a case study.

This unprecedented analysis of the factors that determine the performance of Brazil electric energy contradictory policies identifies the irregular path followed by one of the largest national oil companies in the world. As high convenience comparative case study, the increase and decrease of production and investment within the context of the Brazilian electric matrix in the last 20 years can shed light on Petrobras' disparities in relation to itself and in relation to external variables over time such as policies and investment choices, international oil prices and exploration cost.

Clay exfoliation method as a route to obtain mesoporous catalysts for CO2 methanation.

A unique method for obtaining a mesoporous catalytic support through the exfoliation of a montmorillonite is reported. This method consisted of the intercalation of Na-clay with Al-Keggin species and polyvinyl alcohol followed by microwave irradiation. The mesoporous support was employed to prepare Ni-catalysts which were used in the natural gas synthesis through CO2 methanation. The synthesis method was validated confirming the clay exfoliation and the main formation of mesopores. Also, the Ni-catalysts have mainly weak basic surface properties lower than 38 µmol.g-1, and containing Ni0 nanoparticles with sizes between 9 and 12 nm which were thermally stable after reduction and methanation reaction. The catalyst with 5% Ni wt. gave conversions between 50 and 80% with temperatures ranging from 200 to 300 °C and selectivities of 100% towards the formation of CH4 without coke formation. The (3 and 5% Ni) Ni-catalysts are stable up to 8 h at 400 °C in the methanation reaction maintaining 100% of selectivity.•Mesoporous catalytic supports are obtained through a unique clay exfoliation method (Al-keggin, PVA, and microwaves).•(3% and 5% wt.) Ni-mesoporous catalysts are thermally stable and Ni0 nanoparticles between 9 and 12 nm are achieved.•5%wt. Ni-catalyst have no deactivation up to 8 h at 400 °C and displays unprecedented performance at low temperatures in CO2-methanation with 100% of selectivity.

Geographic Information Systems based approach for assessing the locational feasibility for biomethane production from landfill gas and injection in pipelines in Brazil / Abordagem baseada em sistemas de informação geográfica para avaliação da viabilidade locacional da produção de biometano a partir de gás de aterro sanitário e injeção em dutos no Brasil

ABSTRACT Biomethane can readily replace fossil fuels including natural gas, which has similar physical and chemical properties. In Brazil, municipal solid waste is predominantly disposed of in landfills. Landfill gas is mostly employed for electricity generation, but still at low levels when compared to the existing potential. Production of biomethane from landfill gas may be an alternative to exploit the existing potential, but Brazil's pipeline network is rather limited and concentrated along the country's coast. In this context, the research sought to identify the locational viability of using landfill gas to produce biomethane and injecting it into pipelines, considering the available potential and its proximity to Brazil's existing pipeline network. The QGis software was used to integrate the information. Territorial arrangements with a biomethane production capacity of more than 15,000 Nm3 day−1 and located up to 50 km from the pipeline network were considered feasible. The research estimated a potential production equivalent to 3,407,027 Nm3 day−1 of biomethane from landfills in Brazil. This potential corresponds to 6% of country's natural gas consumption in 2019 and is almost 32 times greater than current production of biomethane from all substrates used with this purpose in that year. The results indicate the suitability of using geographic information systems to identify regions that can benefit from the production of biomethane from landfill gas using the existing natural gas pipelines as an alternative to the electricity generation and provides relevant subsidies to the formulation of more efficient public policies in both the sanitation and energy sectors.

RESUMO O biometano pode substituir facilmente os combustíveis fósseis, incluindo o gás natural, que possui propriedades físicas e químicas similares. No Brasil, os resíduos sólidos urbanos são descartados predominantemente em aterros sanitários. O gás dos aterros sanitários é empregado principalmente na geração de eletricidade, mas ainda em níveis baixos quando comparado ao potencial existente. A produção de biometano a partir do gás de aterro pode ser uma alternativa para explorar o potencial existente, mas a rede de gasodutos do Brasil é bastante limitada e concentrada ao longo da costa do país. Nesse contexto, esta pesquisa buscou identificar a viabilidade locacional do uso de gás de aterro sanitário para produzir biometano e injetá-lo em dutos, considerando o potencial disponível e sua proximidade com a rede de dutos existente no Brasil. O software QGis foi utilizado para integrar as informações. Foram considerados viáveis arranjos territoriais com uma capacidade de produção de biometano maior que 15.000 Nm3 dia−1 e localizados a até 50 km da rede de gasodutos. A pesquisa estimou uma produção potencial equivalente a 3.407.027 Nm3 dia−1 de biometano a partir de aterros sanitários no Brasil. Esse potencial corresponde a 6% do consumo de gás natural do país em 2019 e é quase 32 vezes maior que a produção de biometano de todos os substratos utilizados com essa finalidade naquele ano. Os resultados indicam a adequação do uso de sistemas de informação geográfica para identificar regiões que podem se beneficiar da produção de biometano a partir de gás de aterro sanitário, utilizando os gasodutos de gás natural existentes como alternativa à geração de eletricidade e fornece subsídios relevantes para a formulação de políticas públicas mais eficientes, tanto no setor de saneamento quanto no de energia.

Energy demand and emissions of a passenger vehicle fueled with CNG, gasohol, hydrous ethanol and wet ethanol based on the key points of the WLTC.

A compact sedan vehicle powered by a 1.4 dm3 spark ignition engine fueled with compressed natural gas (CNG), Brazilian gasoline, hydrous ethanol 95% v/v and wet ethanol 88% v/v was evaluated throughout the Worldwide harmonized Light vehicles Test Cycle (WLTC) key points. The vehicle operating points with longest residence time on the WLTC were selected to fuel consumption and emissions evaluation at steady state conditions. The top five key operating points reported in this work accounted for 22% of the total time spent in the entire cycle. The results indicated a significant reduction on greenhouse gases (GHG) emissions and energy demand for operation with CNG. The ethanol-water blends provided reduced emissions of nitrogen oxides (NOx), but increased specific fuel consumption, carbon monoxide (CO) and GHG emissions in comparison to CNG and gasoline. The operation with gasoline resulted in the minimum CO emissions for all fuels tested, as well as the best fuel consumption between liquid fuels, despite the highest values of carbon dioxide (CO2), and increased NOx. Even though ethanol produced little total unburned hydrocarbons (THC), the emissions of alcohols and aldehydes raised an alert for this renewable fuel, whereas CNG emitted the least amount of such pollutants.

Robust Multi-Objective Optimization for Response Surface Models Applied to Direct Low-Value Natural Gas Conversion Processes.

The high proportion of CO2/CH4 in low aggregated value natural gas compositions can be used strategically and intelligently to produce more hydrocarbons through oxidative methane coupling (OCM). The main goal of this study was to optimize direct low-value natural gas conversion via CO2-OCM on metal oxide catalysts using robust multi-objective optimization based on an entropic measure to choose the most preferred Pareto optimal point as the problem's final solution. The responses of CH4 conversion, C2 selectivity, and C2 yield are modeled using the response surface methodology. In this methodology, decision variables, e.g., the CO2/CH4 ratio, reactor temperature, wt.% CaO and wt.% MnO in ceria catalyst, are all employed. The Pareto optimal solution was obtained via the following combination of process parameters: CO2/CH4 ratio = 2.50, reactor temperature = 1179.5 K, wt.% CaO in ceria catalyst = 17.2%, wt.% MnO in ceria catalyst = 6.0%. By using the optimal weighting strategy w1 = 0.2602, w2 = 0.3203, w3 = 0.4295, the simultaneous optimal values for the objective functions were: CH4 conversion = 8.806%, C2 selectivity = 51.468%, C2 yield = 3.275%. Finally, an entropic measure used as a decision-making criterion was found to be useful in mapping the regions of minimal variation among the Pareto optimal responses and the results obtained, and this demonstrates that the optimization weights exert influence on the forecast variation of the obtained response.

Virtual Reality Applied in a Thermoelectric Power Plant Planning

Abstract The planning of a new thermal power plant is linked to the various decision elements and evaluation criteria. Factors such as the plant's geographic positioning, primary energy supply points, paths, and means of delivery of this primary energy should be analyzed. Similar studies are imposed when studying the change of a thermoelectric plant's primary energy source occurs. In Brazil, several plants are currently investigating the exchange of their primary fuel from oil to gas due to the decrees issued by ANEEL. This paper presents software, which uses virtual reality to assist in the various stages of the planning process and in the analyses that must be performed. This software was developed for the Hidrotermica Group and had as the primary target the Borborema Thermoelectric Power Plant.

CFD study and experimental validation of low liquid-loading flow assurance in oil and gas transport: studying the effect of fluid properties and operating conditions on flow variables.

Low liquid-loading flow frequently occurs during the transport of gas products in various industries, such as in the Oil & Gas, the Food, and the Pharmaceutical Industries. Even small amounts of liquid can have a significant effect on the flow conditions inside the pipeline, such as increased pressure loss, pipe wall stresses and corrosion, and liquid holdup along the pipeline. However, most studies that analyze this type of flow only use atmospheric pressures and horizontal 1-in or 2-in pipes, which do not accurately represent the range of operating conditions present in industrial applications. Therefore, this study focused on modeling low liquid-loading flow in medium-sized (6-10 in) pipes, using CFD simulations and experimental data from the University of Tulsa, and then applying it to real operating conditions from a Colombian gas pipeline. An acceptable difference was observed between experimental and CFD data, both for the liquid holdup (18%) and for the pressure drop (12%). Variables like pressure drop and wall shear stress increase with phase velocity, operating pressure, and pipe inclination. Liquid holdup increases with liquid velocity but decreases with all other factors. The relation of flow variables with phase velocities is of particular interest: Doubling the gas velocity decreased holdup 70% and increased pressure drop tenfold. On the other hand, the presence of the liquid phase seems to be more influential on process variables than its exact flowrate; the introduction of the liquid phase to a single-phase gas causes an increase in pressure loss by a factor of three, but doubling the liquid velocity only increases the pressure loss by a further 30%.

Designing silica xerogels containing RTIL for CO2 capture and CO2/CH4 separation: Influence of ILs anion, cation and cation side alkyl chain length and ramification.

CO2 separation from natural gas is considered to be a crucial strategy to mitigate global warming problems, meet product specification, pipeline specs and other application specific requirements. Silica xerogels (SX) are considered to be potential materials for CO2 capture due to their high specific surface area. Thus, a series of silica xerogels functionalized with imidazolium, phosphonium, ammonium and pyridinium-based room-temperature ionic liquids (RTILs) were synthesized. The synthesized silica xerogels were characterized by NMR, helium pycnometry, DTA-TG, BET, SEM and TEM. CO2 sorption, reusability and CO2/CH4 selectivity were assessed by the pressure-decay technique. Silica xerogels containing IL demonstrated advantages compared to RTILs used as separation solvents in CO2 capture processes including higher CO2 sorption capacity and faster sorption/desorption. Using fluorinated anion for functionalization of silica xerogels leads to a higher affinity for CO2 over CH4. The best performance was obtained by SX- [bmim] [TF2N] (223.4 mg CO2/g mg/g at 298.15 K and 20 bar). Moreover, SX- [bmim] [TF2N] showed higher CO2 sorption capacity as compared to other reported sorbents. CO2 sorption and CO2/CH4 selectivity results were submitted to an analysis of variance and the means compared using Tukey's test (5%).

A phenomenological base semi-physical thermodynamic model for the cylinder and exhaust manifold of a natural gas 2-megawatt four-stroke internal combustion engine.

This paper presents the application of a systematic methodology to obtain a semi-physical model of phenomenological base for a 2 MW internal combustion engine to generate electric power operating with natural gas, as a function of the average thermodynamic value normally measured in industrial applications. Specifically, the application of the methodology is focused on the cylinders, exhaust manifold, and turbocharger turbine sections. The proposed model was validated with actual operating data, obtaining an error rate not exceeding 5%, which allow a thermal characterization of the Jenbacher JMS 612 GS-N based on the model. A parametric analysis is conducted; considering the volumetric efficiency, the output electric power, the effective efficiency, the exhaust gas temperature, the turbine mass flow, the specific fuel consumption under the nominal operation conditions, which is 1.16 bar in the gas pressure, 65 °C in the cooling water temperature, 35 °C in the average ambient temperature, and 1500 rpm. The results of this model can be used to evaluate the thermodynamic performance parameters of waste heat recovery systems. On the other hand, new control strategies and the implementation of state observers for the detection and diagnosis of failures can be developed based on the proposed model.

Supported ionic liquids as highly efficient and low-cost material for CO2/CH4 separation process.

Physical immobilization of ionic liquids (ILs) in solid materials appears as an interesting strategy for the development of new sorbents for CO2 separation from natural gas. In this work the effect of physical immobilization of two ionic liquids with different anions (bmim[Cl] and bmim[OAc]) on two mesoporous supports (commercial silica SBA-15 and silica extracted from rice husk) was evaluated for CO2 separation from natural gas by experimental determination of CO2 sorption, CO2/CH4 selectivity and sorption kinetics. Results showed that the pure supports present the greatest CO2 sorption capacity when compared to immobilized ILs. However, CO2 removal efficiency improves considerably in the CO2/CH4 mixture when ILs are immobilized in these supports. The best selectivity results were obtained for supports immobilized with the IL bmim[Cl] and values increased for SIL-Cl by 37% and SBA-Cl 51% when compared with their respective supports. The contribution of SIL-Cl (3.03 ± 0.12) to separation performance (CO2/CH4) is similar to SBA-Cl (3.29 ± 0.39). ILs supported also presented fast sorption kinetics when compared to pure ILs thus being an interesting alternative in the search for highly efficient and low-cost separation processes.

Revisión del proceso de separación de fases del gas natural a alta presión en la industria Oil&Gas / Review of the natural gas phases separation process at high pressure in the Oil&Gas industry / Revisão do processo de separação de fases do gás natural para alta pressão na indústria de Oil&Gas

Resumen La separación física de líquidos y gases es una de las operaciones de producción, procesamiento y tratamiento en la industria petrolera, necesaria para prevenir daños en equipos rotativos, evitar corrosión en tuberías y cumplir con las especificaciones de calidad del gas natural para uso doméstico. Cuando la presión de operación aumenta, la diferencia de densidades entre las fases disminuye, lo cual dificulta el proceso de separación. Se realiza la revisión del estado del arte, desde los años 90 hasta el presente, de las diferentes metodologías para separar las fases líquida y gaseosa del gas natural, así como las variables de diseño con aplicación a sistemas que operan a alta presión; prestando especial énfasis en los avances encontrados utilizando Dinámica de Fluidos Computacional. Los resultados muestran que, aunque los separadores centrífugos y los separadores supersónicos son más compactos y de fácil mantenimiento comparados con los separadores gravitacionales, éstos últimos continúan siendo la estrategia más favorable cuando se combinan alta presión y baja cantidad de líquido (menos del 4% vol), como es el caso del gas natural. Conclusión adjudicada, en parte, a la falta de estudios experimentales/numéricos que involucren al gas natural en equipos alternativos al separador gravitacional

Abstract The Physical separation of liquids and gases is one of the main operations of production, processing and treatment in the oil industry; it is necessary to prevent damage to rotating equipment, to avoid corrosion in pipes and to achieve with the natural gas quality specifications for domestic use. When the operating pressure increases, the density difference between the phases decreases, which makes the separation process difficult or in some cases impossible. In this work, the state of the art of the different methodologies to separate the liquid and gaseous phases of natural gas is reviewed , as well as the design variables applied to systems that operate at high pressure from the 90's to the present; with special emphasis on the advances found using Computational Fluid Dynamics. The results show that, although both centrifugal and supersonic separators are more compact and easy to maintain compared to gravitational separators, gravitational separators remain the most favorable strategy when combining high pressure and low liquid load (less than 4%vol), as is the case of natural gas. Conclusion awarded, in part, to the lack of experimental/numerical studies involving natural gas in alternative equipment to the gravitational separator

Resumo A separação física de líquidos e gases é uma das principais operações de produção, processamento e tratamento na indústria do petróleo, necessária para evitar danos ao equipamento rotativo, para evitar a corrosão nos tubos e para cumprir as especificações de qualidade do gás natural para uso doméstico. Quando a pressão de operação aumenta, a diferença de densidade entre as fases diminui, o que torna o processo de separação difícil ou, em alguns casos, impossível. Neste trabalho, é realizada a avaliação do estado da arte de diferentes metodologias para separar as fases líquida e gasosa do gás natural e as variáveis de design com aplicação para sistemas que operam a alta pressão a partir dos anos 90 até a data atual; com ênfase especial nos avanços encontrados usando a Dinâmica dos Fluidos Computacional. Os resultados mostram que, embora ambos os separadores centrífugos e supersónicos são mais compactos e de fácil manutenção comparado com separadores gravitacionais, o último continua a ser a estratégia favorecida quando a alta pressão e de baixa quantidade de líquido são combinados (menos de 4% vol), como é o caso do gás natural; Conclusão concedida, em parte, à falta de estudos experimentais/numéricos envolvendo gás natural em equipamentos alternativos ao separador gravitacional

Costs and emissions assessment of a Blue Corridor in a Brazilian reality: The use of liquefied natural gas in the transport sector.

Technical, economic, social and environmental conditions are turning natural gas into a feasible solution for sustainable transportation systems in the State of São Paulo (Brazil). Blue Corridors are routes that aim to enable the use of liquefied natural gas (LNG) for heavy vehicles as a substitute to Diesel oil. Therefore, this work proposes four scenarios for a Blue Corridor in the State of São Paulo and analyzes its environmental and economic impacts. The results are presented in cartographical figures and show that LNG costs up to 40% less than diesel, while reducing CO2 equivalent emissions by up to 5.2%. Particulate matter (PM) emissions are reduced by 88%, nitrogen oxides (NOx) by 75% and hydrocarbon emissions are eliminated. However, despite the economic and environmental advantages presented in the results of this study, LNG still faces regulatory barriers that must be addressed in order to allow its widespread use in the transportation sector.

Thermodynamic DFT analysis of natural gas.

Density functional theory was performed for thermodynamic predictions on natural gas, whose B3LYP/6-311++G(d,p), B3LYP/6-31+G(d), CBS-QB3, G3, and G4 methods were applied. Additionally, we carried out thermodynamic predictions using G3/G4 averaged. The calculations were performed for each major component of seven kinds of natural gas and to their respective air + natural gas mixtures at a thermal equilibrium between room temperature and the initial temperature of a combustion chamber during the injection stage. The following thermodynamic properties were obtained: internal energy, enthalpy, Gibbs free energy and entropy, which enabled us to investigate the thermal resistance of fuels. Also, we estimated an important parameter, namely, the specific heat ratio of each natural gas; this allowed us to compare the results with the empirical functions of these parameters, where the B3LYP/6-311++G(d,p) and G3/G4 methods showed better agreements. In addition, relevant information on the thermal and mechanic resistance of natural gases were investigated, as well as the standard thermodynamic properties for the combustion of natural gas. Thus, we show that density functional theory can be useful for predicting the thermodynamic properties of natural gas, enabling the production of more efficient compositions for the investigated fuels. Graphical abstract Investigation of the thermodynamic properties of natural gas through the canonical ensemble model and the density functional theory.

Composition of the C6+ Fraction of Natural Gas by Multiple Porous Layer Open Tubular Capillaries Maintained at Low Temperatures.

As the sources of natural gas become more diverse, the trace constituents of the C6+ fraction are of increasing interest. Analysis of fuel gas (including natural gas) for compounds with more than 6 carbon atoms (the C6+ fraction) has historically been complex and expensive. Hence, this is a procedure that is used most often in troubleshooting rather than for day-to-day operations. The C6+ fraction affects gas quality issues and safety considerations such as anomalies associated with odorization. Recent advances in dynamic headspace vapor collection can be applied to this analysis and provide a faster, less complex alternative for compositional determination of the C6+ fraction of natural gas. Porous layer open tubular capillaries maintained at low temperatures (PLOT-cryo) form the basis of a dynamic headspace sampling method that was developed at NIST initially for explosives in 2009. This method has been recently advanced by the combining of multiple PLOT capillary traps into one "bundle," or wafer, resulting in a device that allows the rapid trapping of relatively large amounts of analyte. In this study, natural gas analytes were collected by flowing natural gas from the laboratory (gas out of the wall) or a prepared surrogate gas flowing through a chilled wafer. The analytes were then removed from the PLOT-cryo wafer by thermal desorption and subsequent flushing of the wafer with helium. Gas chromatography (GC) with mass spectrometry (MS) was then used to identify the analytes.

Costo efectividad del gas natural domiciliario como tecnología sanitaria en localidades rurales del Caribe Colombiano / The cost-effectiveness of installing natural gas as a sanitary alternative for rural communities on the Colombian Caribbean coast burning biomass fuels

Objetivo Valorar el impacto económico del Gas Natural Domiciliario -GND- como tecnología sanitaria sobre la enfermedad respiratoria asociada al humo de biomasa en localidades del caribe colombiano. Métodos Tres estudios combinados: a) carga de enfermedad respiratoria asociada al uso de combustibles de biomasa; b) costos de la enfermedad (Infección Respiratoria Aguda -IRA- y Enfermedad Pulmonar Obstructiva Crónica-EPOC); y c) análisis de costo efectividad del GND para reducir morbilidad por enfermedades respiratorias. Resultados En las localidades se esperarían anualmente 498 (477-560) casos de IRA que generaría 149 (119-196) hospitalizaciones, 6 (4-10) muertes y 7 291 (5 746 -9 696) AVAD. También se esperarían 459 (372-684) casos de EPOC, 138 (93- 239) hospitalizaciones, 11 (5-26) muertes y 1 500 (973-2 711) AVAD. Los costos de esta carga de enfermedad en ausencia del GND son anualmente de 5,2 (3,8-8,3) millones de dólares. De éstos, la mayoría son costos de EPOC (cerca del 85 por ciento). Los costos por IRA y EPOC, luego de instalado el GND, ascienden a 3,5 (2,5-5,7) millones de dólares. Los costos evitados serían 1,6 (1,2-2,6) millones de dólares, (30 por ciento de los costos de la carga). El costo efectividad incremental de introducir el GND sería un poco más de 56 (22-74) mil dólares por muerte evitada y entre 43 y 66 dólares evitar un AVAD. Conclusiones Frente a la no intervención, la instalación del GND resulta ser una tecnología costo efectiva para la reducción de las enfermedades respiratorias asociadas al consumo de combustibles de biomasa.

Objective Evaluating the economic impact of natural gas as a sanitary technology regarding respiratory disease associated with indoor air pollution in rural localities on the Colombian Caribbean coast. Methods Three studies were carried out: the burden of respiratory disease was evaluated (acute lower respiratory infection-ALRI and chronic obstructive pulmonary disease - COPD), disease costs were studied and the cost effectiveness of natural gas was analysed in terms of reducing indoor air pollution. Results Without natural gas in these localities, it would be expected that 498 (477-560) cases of ALRI per year would lead to 149 (119-196) hospitalisations, 6 (4-10) deaths and 7 291 (5,746-9,696) disability adjusted life years (DALY) annually. Furthermore, it is expected that 459 (372-684) cases of COPD per year would lead to 138 (93-239), hospitalisations, 11 deaths (5-26) and 1 500 (973-2 711) DALY annually. Annual disease burden cost was 5,2 (3,8-8,3) million dollars before installing domiciliary natural gas (DNG); most of such cost arose from COPD (around 85 percent). ARI and COPD costs after installing DNG would rise to 3,5 (2,5-5,7) million dollars; avoided costs would be 1,6 (1,2-2,6) million dollars, (30 percent of disease burden cost without DNG). The incremental cost-effectiveness (ICER) of installing DNG would be 56 (22-74) thousand dollars per life saved and ICER per DALY saved would be 43-66 dollars. Conclusion DNG is a sanitary technology which reduces the burden of indoor air pollution-associated respiratory diseases arising from burning biomass fuel in rural localities in a cost-effective way.