This paper presents the implementation of natural gas vehicles (NGVs) in Tanzania’s road transportation sector. The peculiarity of this analysis is the evaluation of the technical and economic performance of the converted gasoline and diesel engines to use compressed natural gas (CNG) as the cleanest-burning hydrocarbon. The technical performance involved vehicle mileage (MiCNG), fuel consumption (Fcons), speed drop, engine fuel enhancement (Fenh), and fuel saving, while the economic performance involved conversion cost (Cc), fuel cost saving (FCsaving), and payback (PB). Considering the conversion of gasoline vehicles, the MiCNG could reach an average of 100 to 500 km per filling, depending on the CNG cylinder size. The Fenh and fuel saving were ranging between 1.9 and 3.9 and 71 and 78%. With a proportion of 30:70 diesel-CNG fuel, the heavy-duty truck with 180 kg of CNG could reach 1300 km, saving about 440 L, which is 78.6% per roundtrip, while the medium passenger car with 15 kg of CNG could reach 350 km, presenting a fuel saving of about 75%. From an economic point of view, gasoline retrofitted NGVs cost about 50 to 200 TZS/km, yielding a fuel cost saving of up to 79% and starting to pay off between 2 and 7 months or 10,000 and 40,000 km, depending on the engine capacity. Considering dual fuel, the heavy-duty truck consumes about 496 TZS/km, saving about 62.3% of diesel fuel and starting to pay off after 2.5 months or 29,304 km. To conclude, NGV technologies have been successfully implemented in Tanzania’s road transportation sector, presenting significant fuel savings and reducing reliance on imported oil. While taking measures, this study paves a way for Tanzania and other sub-Saharan countries to promote NGV growth.
本文介绍了天然气汽车（NGV）在坦桑尼亚道路运输部门的实施情况。该分析的特点是评估汽油和柴油发动机使用压缩天然气（CNG）作为最清洁燃烧碳氢化合物的技术和经济性能。技术性能涉及车辆里程（MiCNG）、油耗（Fcons）、速度下降、发动机燃油增强（Fenh）和燃油节约，而经济性能涉及转换成本（Cc）、燃油成本节约（FCsave）和回收率（PB）。考虑到汽油车的改装，根据CNG气缸的大小，MiCNG每次加注的平均里程可达100至500公里。Fenh和燃油节省在1.9到3.9之间，在71到78%之间。在30:70柴油CNG燃料的比例下，180 kg CNG的重型卡车可行驶1300 km，节省约440 L，每次往返可节省78.6%，而15 kg CNG的中型客车可行驶350 km，节省燃油约75%。从经济角度来看，汽油改装的NGV的成本约为50至200坦桑尼亚先令/公里，可节省高达79%的燃油成本，并在2至7个月或10000至40000公里之间开始获得回报，具体取决于发动机容量。考虑到双燃料，重型卡车的油耗约为496坦桑尼亚先令/公里，节省了约62.3%的柴油，并在2.5个月或29304公里后开始获得回报。总之，NGV技术已在坦桑尼亚的道路运输部门成功实施，显著节省了燃料，减少了对进口石油的依赖。在采取措施的同时，这项研究为坦桑尼亚和其他撒哈拉以南国家促进NGV增长铺平了道路。
{"title":"Compressed Natural Gas as an Alternative Vehicular Fuel in Tanzania: Implementation, Barriers, and Prospects","authors":"Gerutu Bosinge Gerutu, K. Greyson, P. V. Chombo","doi":"10.3390/methane2010006","DOIUrl":"https://doi.org/10.3390/methane2010006","url":null,"abstract":"This paper presents the implementation of natural gas vehicles (NGVs) in Tanzania’s road transportation sector. The peculiarity of this analysis is the evaluation of the technical and economic performance of the converted gasoline and diesel engines to use compressed natural gas (CNG) as the cleanest-burning hydrocarbon. The technical performance involved vehicle mileage (MiCNG), fuel consumption (Fcons), speed drop, engine fuel enhancement (Fenh), and fuel saving, while the economic performance involved conversion cost (Cc), fuel cost saving (FCsaving), and payback (PB). Considering the conversion of gasoline vehicles, the MiCNG could reach an average of 100 to 500 km per filling, depending on the CNG cylinder size. The Fenh and fuel saving were ranging between 1.9 and 3.9 and 71 and 78%. With a proportion of 30:70 diesel-CNG fuel, the heavy-duty truck with 180 kg of CNG could reach 1300 km, saving about 440 L, which is 78.6% per roundtrip, while the medium passenger car with 15 kg of CNG could reach 350 km, presenting a fuel saving of about 75%. From an economic point of view, gasoline retrofitted NGVs cost about 50 to 200 TZS/km, yielding a fuel cost saving of up to 79% and starting to pay off between 2 and 7 months or 10,000 and 40,000 km, depending on the engine capacity. Considering dual fuel, the heavy-duty truck consumes about 496 TZS/km, saving about 62.3% of diesel fuel and starting to pay off after 2.5 months or 29,304 km. To conclude, NGV technologies have been successfully implemented in Tanzania’s road transportation sector, presenting significant fuel savings and reducing reliance on imported oil. While taking measures, this study paves a way for Tanzania and other sub-Saharan countries to promote NGV growth.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45385487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. A. Pacífico, Nelson M. Lima Filho, Cesar A. Moraes de Abreu
The reforming of methane with CO2 was carried out efficiently in a fluidized bed reactor at 973 K under atmospheric pressure, taking advantage of the nickel catalyst efficiency achieved with a bed of particulate fines. The fluidization operation was characterized by determining a minimum velocity of 3.11 × 10−3 ms−1 and higher velocities. The reactor worked with surface speeds of up to 1.84 × 10−2 ms−1, providing conversions from 45% to 51% and a syngas yield of 97%. The control base of the operation focused on the use of CO2 was established through the reaction steps assumed for the process, including methane cracking, reverse Boudouard reaction, and RWGS (reverse reaction of water gas-shift). The reactor designed to operate in two zones was able to simultaneously process surface reactions and catalyst regeneration using feed with 50% excess CO2 in relation to methane. Predictions indicating the production of syngas of different compositions quantified with the H2/CO ratio from 2.30 to 0.91 decreasing with space-time were validated with the results available for process design.
{"title":"Efficient Performance of the Methane-Carbon Dioxide Reform Process in a Fluidized Bed Reactor","authors":"J. A. Pacífico, Nelson M. Lima Filho, Cesar A. Moraes de Abreu","doi":"10.3390/methane2010004","DOIUrl":"https://doi.org/10.3390/methane2010004","url":null,"abstract":"The reforming of methane with CO2 was carried out efficiently in a fluidized bed reactor at 973 K under atmospheric pressure, taking advantage of the nickel catalyst efficiency achieved with a bed of particulate fines. The fluidization operation was characterized by determining a minimum velocity of 3.11 × 10−3 ms−1 and higher velocities. The reactor worked with surface speeds of up to 1.84 × 10−2 ms−1, providing conversions from 45% to 51% and a syngas yield of 97%. The control base of the operation focused on the use of CO2 was established through the reaction steps assumed for the process, including methane cracking, reverse Boudouard reaction, and RWGS (reverse reaction of water gas-shift). The reactor designed to operate in two zones was able to simultaneously process surface reactions and catalyst regeneration using feed with 50% excess CO2 in relation to methane. Predictions indicating the production of syngas of different compositions quantified with the H2/CO ratio from 2.30 to 0.91 decreasing with space-time were validated with the results available for process design.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48477880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arthur Pignataro Machado, Saulo Amaral Carminati, Eliane Ribeiro Januário, Patricia Silvaino Ferreira, J. Moreira Vaz, E. Spinacé
Here, Pd nanoparticles supported on ZnO were prepared by the alcohol-reduction and the borohydride-reduction methods, and their efficiency towards the photocatalytic conversion of methane under mild conditions were evaluated. The resulting Pd/ZnO photocatalysts were characterized by X-ray fluorescence, X-ray diffraction, X-ray photoelectron spectroscopy, UV–Vis, and transmission electron microscopy. The reactions were performed with the photocatalysts dispersed in water in a bubbling stream of methane under UV-light illumination. The products formed were identified and quantified by gas chromatography (GC-FID/TCD/MSD). The principal products formed were C2H6 and CO2 with minor quantities of C2H4 and CO. No H2 production was observed. The preparation methods influenced the size and dispersion of Pd nanoparticles on the ZnO, affecting the performance of the photocatalysts. The best performance was observed for the photocatalyst prepared by borohydride reduction with 0.5 wt% of Pd, reaching a C2H6 production rate of 686 µmol·h−1·g−1 and a C2H6 selectivity of 46%.
{"title":"Photocatalytic Methane Conversion over Pd/ZnO Photocatalysts under Mild Conditions","authors":"Arthur Pignataro Machado, Saulo Amaral Carminati, Eliane Ribeiro Januário, Patricia Silvaino Ferreira, J. Moreira Vaz, E. Spinacé","doi":"10.3390/methane2010003","DOIUrl":"https://doi.org/10.3390/methane2010003","url":null,"abstract":"Here, Pd nanoparticles supported on ZnO were prepared by the alcohol-reduction and the borohydride-reduction methods, and their efficiency towards the photocatalytic conversion of methane under mild conditions were evaluated. The resulting Pd/ZnO photocatalysts were characterized by X-ray fluorescence, X-ray diffraction, X-ray photoelectron spectroscopy, UV–Vis, and transmission electron microscopy. The reactions were performed with the photocatalysts dispersed in water in a bubbling stream of methane under UV-light illumination. The products formed were identified and quantified by gas chromatography (GC-FID/TCD/MSD). The principal products formed were C2H6 and CO2 with minor quantities of C2H4 and CO. No H2 production was observed. The preparation methods influenced the size and dispersion of Pd nanoparticles on the ZnO, affecting the performance of the photocatalysts. The best performance was observed for the photocatalyst prepared by borohydride reduction with 0.5 wt% of Pd, reaching a C2H6 production rate of 686 µmol·h−1·g−1 and a C2H6 selectivity of 46%.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46709744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Farah T. Alsudani, Abdullah N. Saeed, N. S. Ali, H. Majdi, Hussein G. Salih, T. Albayati, N. Saady, Zaidoon M. Shakor
The interest in Gas-to-Liquid technology (GTL) is growing worldwide because it involves a two-step indirect conversion of natural gas to higher hydrocarbons ranging from Liquefied Petroleum Gas (LPG) to paraffin wax. GTL makes it possible to obtain clean diesel, naphtha, lubes, olefins, and other industrially important organics from natural gas. This article is a brief review discussing the state-of-the-art of GTL, including the basics of syngas manufacturing as a source for Fischer-Tropsch synthesis (FTS), hydrocarbons synthesis (Fischer-Tropsch process), and product upgrading. Each one is analyzed, and the main characteristics of traditional and catalysts technologies are presented. For syngas generation, steam methane reforming, partial oxidation, two-step reforming, and autothermal reforming of methane are discussed. For Fischer–Tropsch, we highlight the role of catalysis and selectivity to high molecular weight hydrocarbons. Also, new reactors technologies, such as microreactors, are presented. The GTL technology still faces several challenges; the biggest is obtaining the right H2:CO ratio when using a low steam-to-carbon ratio. Despite the great understanding of the carbon formation mechanism, little has been made in developing newer catalysts. Since 60–70% of a GTL plant cost is for syngas production, it needs more attention, particularly for developing the catalytic partial oxidation process (CPO), given that modern CPO processes using a ceramic membrane reactor reduce the plant’s capital cost. Improving the membrane’s mechanical, thermal, and chemical stability can commercialize the process. Catalytic challenges accompanying the FTS need attention to enhance the selectivity to produce high-octane gasoline, lower the production cost, develop new reactor systems, and enhance the selectivity to produce high molecular weight hydrocarbons. Catalytically, more attention should be given to the generation of a convenient catalyst layer and the coating process for a given configuration.
{"title":"Fisher–Tropsch Synthesis for Conversion of Methane into Liquid Hydrocarbons through Gas-to-Liquids (GTL) Process: A Review","authors":"Farah T. Alsudani, Abdullah N. Saeed, N. S. Ali, H. Majdi, Hussein G. Salih, T. Albayati, N. Saady, Zaidoon M. Shakor","doi":"10.3390/methane2010002","DOIUrl":"https://doi.org/10.3390/methane2010002","url":null,"abstract":"The interest in Gas-to-Liquid technology (GTL) is growing worldwide because it involves a two-step indirect conversion of natural gas to higher hydrocarbons ranging from Liquefied Petroleum Gas (LPG) to paraffin wax. GTL makes it possible to obtain clean diesel, naphtha, lubes, olefins, and other industrially important organics from natural gas. This article is a brief review discussing the state-of-the-art of GTL, including the basics of syngas manufacturing as a source for Fischer-Tropsch synthesis (FTS), hydrocarbons synthesis (Fischer-Tropsch process), and product upgrading. Each one is analyzed, and the main characteristics of traditional and catalysts technologies are presented. For syngas generation, steam methane reforming, partial oxidation, two-step reforming, and autothermal reforming of methane are discussed. For Fischer–Tropsch, we highlight the role of catalysis and selectivity to high molecular weight hydrocarbons. Also, new reactors technologies, such as microreactors, are presented. The GTL technology still faces several challenges; the biggest is obtaining the right H2:CO ratio when using a low steam-to-carbon ratio. Despite the great understanding of the carbon formation mechanism, little has been made in developing newer catalysts. Since 60–70% of a GTL plant cost is for syngas production, it needs more attention, particularly for developing the catalytic partial oxidation process (CPO), given that modern CPO processes using a ceramic membrane reactor reduce the plant’s capital cost. Improving the membrane’s mechanical, thermal, and chemical stability can commercialize the process. Catalytic challenges accompanying the FTS need attention to enhance the selectivity to produce high-octane gasoline, lower the production cost, develop new reactor systems, and enhance the selectivity to produce high molecular weight hydrocarbons. Catalytically, more attention should be given to the generation of a convenient catalyst layer and the coating process for a given configuration.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45083366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Alvarez-Borges, O. N. King, B. N. Madhusudhan, T. Connolley, M. Basham, Sharif I. Ahmed
Methane (CH4) hydrate dissociation and CH4 release are potential geohazards currently investigated using X-ray computed tomography (XCT). Image segmentation is an important data processing step for this type of research. However, it is often time consuming, computing resource-intensive, operator-dependent, and tailored for each XCT dataset due to differences in greyscale contrast. In this paper, an investigation is carried out using U-Nets, a class of Convolutional Neural Network, to segment synchrotron XCT images of CH4-bearing sand during hydrate formation, and extract porosity and CH4 gas saturation. Three U-Net deployments previously untried for this task are assessed: (1) a bespoke 3D hierarchical method, (2) a 2D multi-label, multi-axis method and (3) RootPainter, a 2D U-Net application with interactive corrections. U-Nets are trained using small, targeted hand-annotated datasets to reduce operator time. It was found that the segmentation accuracy of all three methods surpass mainstream watershed and thresholding techniques. Accuracy slightly reduces in low-contrast data, which affects volume fraction measurements, but errors are small compared with gravimetric methods. Moreover, U-Net models trained on low-contrast images can be used to segment higher-contrast datasets, without further training. This demonstrates model portability, which can expedite the segmentation of large datasets over short timespans.
{"title":"Comparison of Methods to Segment Variable-Contrast XCT Images of Methane-Bearing Sand Using U-Nets Trained on Single Dataset Sub-Volumes","authors":"F. Alvarez-Borges, O. N. King, B. N. Madhusudhan, T. Connolley, M. Basham, Sharif I. Ahmed","doi":"10.3390/methane2010001","DOIUrl":"https://doi.org/10.3390/methane2010001","url":null,"abstract":"Methane (CH4) hydrate dissociation and CH4 release are potential geohazards currently investigated using X-ray computed tomography (XCT). Image segmentation is an important data processing step for this type of research. However, it is often time consuming, computing resource-intensive, operator-dependent, and tailored for each XCT dataset due to differences in greyscale contrast. In this paper, an investigation is carried out using U-Nets, a class of Convolutional Neural Network, to segment synchrotron XCT images of CH4-bearing sand during hydrate formation, and extract porosity and CH4 gas saturation. Three U-Net deployments previously untried for this task are assessed: (1) a bespoke 3D hierarchical method, (2) a 2D multi-label, multi-axis method and (3) RootPainter, a 2D U-Net application with interactive corrections. U-Nets are trained using small, targeted hand-annotated datasets to reduce operator time. It was found that the segmentation accuracy of all three methods surpass mainstream watershed and thresholding techniques. Accuracy slightly reduces in low-contrast data, which affects volume fraction measurements, but errors are small compared with gravimetric methods. Moreover, U-Net models trained on low-contrast images can be used to segment higher-contrast datasets, without further training. This demonstrates model portability, which can expedite the segmentation of large datasets over short timespans.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44120990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The consumption of methane and the production of biodegradable polymers using alphaproteobacterial methanotrophs offers a promising strategy to mitigate greenhouse gas emissions and reduce non-biodegradable plastic pollution. This study identified an ideal amount of added methane and N:C ratio in 100 mL batch cultures of the alphaproteobacterial methanotroph Methylocystis sp. Rockwell growing in 1-L sealed bottles using Response Surface Methodology (RSM) to achieve both high biomass and high polyhydroxybutyrate (PHB) production. RSM analysis showed achievement of optimal biomass at 474.7 ± 10.1 mg/L in nitrate mineral salts (NMS) medium and 480.0 ± 65.5 mg/L biomass in ammonium mineral salts (AMS) medium with 8 mmol of methane and an N:C ratio of 0.022. However, optimal PHB concentration was achieved with 6 mmol methane at N:C ratios of 0.012 in NMS medium (149.7 ± 16.1 mg/L) and 0.022 in AMS medium (200.3 ± 5.1 mg/L). A multi-objective RSM analysis projected maxima in PHB production and %PHB cell content (based on dry weight) when using 4.88 mmol methane and N:C ratio of 0.016 in NMS cultures, and 6.28 mmol methane and the 0.016 N:C ratio in AMS cultures. Cultures grown under these projected conditions produced 173.7 mg PHB/L with 46.8% PHB cell content in NMS and 196.9 mg/L with 53.1% PHB cell content in AMS. Taken together, these analyses predicted the optimal conditions for growth and PHB production in batch cultures of Methylocystis sp. Rockwell and confirmed a preference for ammonium as the N-source for PHB production. This information is valuable for media formulation in industrial scale-up of Methylocystis sp. Rockwell in PHB production.
{"title":"Optimization of Methane Feed and N:C Ratio for Biomass and Polyhydroxybutyrate Production by the Alphaproteobacterial Methanotroph Methylocystis sp. Rockwell","authors":"H. Sharma, Dominic Sauvageau, L. Stein","doi":"10.3390/methane1040026","DOIUrl":"https://doi.org/10.3390/methane1040026","url":null,"abstract":"The consumption of methane and the production of biodegradable polymers using alphaproteobacterial methanotrophs offers a promising strategy to mitigate greenhouse gas emissions and reduce non-biodegradable plastic pollution. This study identified an ideal amount of added methane and N:C ratio in 100 mL batch cultures of the alphaproteobacterial methanotroph Methylocystis sp. Rockwell growing in 1-L sealed bottles using Response Surface Methodology (RSM) to achieve both high biomass and high polyhydroxybutyrate (PHB) production. RSM analysis showed achievement of optimal biomass at 474.7 ± 10.1 mg/L in nitrate mineral salts (NMS) medium and 480.0 ± 65.5 mg/L biomass in ammonium mineral salts (AMS) medium with 8 mmol of methane and an N:C ratio of 0.022. However, optimal PHB concentration was achieved with 6 mmol methane at N:C ratios of 0.012 in NMS medium (149.7 ± 16.1 mg/L) and 0.022 in AMS medium (200.3 ± 5.1 mg/L). A multi-objective RSM analysis projected maxima in PHB production and %PHB cell content (based on dry weight) when using 4.88 mmol methane and N:C ratio of 0.016 in NMS cultures, and 6.28 mmol methane and the 0.016 N:C ratio in AMS cultures. Cultures grown under these projected conditions produced 173.7 mg PHB/L with 46.8% PHB cell content in NMS and 196.9 mg/L with 53.1% PHB cell content in AMS. Taken together, these analyses predicted the optimal conditions for growth and PHB production in batch cultures of Methylocystis sp. Rockwell and confirmed a preference for ammonium as the N-source for PHB production. This information is valuable for media formulation in industrial scale-up of Methylocystis sp. Rockwell in PHB production.","PeriodicalId":74177,"journal":{"name":"Methane","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42046179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A significant portion of global greenhouse gas emissions is attributed to methane (CH4), the primary greenhouse gas released by dairy animals. Thus, livestock farming has a new challenge in reducing enteric CH4 for sustainability. In anaerobic microbial ecosystems such as the rumen, carbohydrates are converted into short-chain, volatile fatty acids that animals use for energy and protein synthesis. It is, therefore, essential to understand rumen physiology, population dynamics, and diversity to target methanogens. Thus far, numerous CH4 mitigation strategies have been studied, including feeding management, nutrition, rumen modification, genetics, and other approaches for increasing animal production. As new molecular techniques are developed, scientists have more opportunities to select animals with higher genetic merit through next-generation sequencing. The amount of CH4 produced per unit of milk or meat can be permanently and cumulatively reduced through genetic selection. Developing eco-friendly and practical nutrigenomic approaches to mitigating CH4 and increasing ruminant productivity is possible using next-generation sequencing techniques. Therefore, this review summarizes current genetic and nutrigenomic approaches to reducing enteric CH4 production without posing any danger to animals or the environment.
{"title":"Genetic Improvement and Nutrigenomic Management of Ruminants to Achieve Enteric Methane Mitigation: A Review","authors":"Vasfiye Kader Esen, V. Palangi, S. Esen","doi":"10.3390/methane1040025","DOIUrl":"https://doi.org/10.3390/methane1040025","url":null,"abstract":"A significant portion of global greenhouse gas emissions is attributed to methane (CH4), the primary greenhouse gas released by dairy animals. Thus, livestock farming has a new challenge in reducing enteric CH4 for sustainability. In anaerobic microbial ecosystems such as the rumen, carbohydrates are converted into short-chain, volatile fatty acids that animals use for energy and protein synthesis. It is, therefore, essential to understand rumen physiology, population dynamics, and diversity to target methanogens. Thus far, numerous CH4 mitigation strategies have been studied, including feeding management, nutrition, rumen modification, genetics, and other approaches for increasing animal production. As new molecular techniques are developed, scientists have more opportunities to select animals with higher genetic merit through next-generation sequencing. The amount of CH4 produced per unit of milk or meat can be permanently and cumulatively reduced through genetic selection. Developing eco-friendly and practical nutrigenomic approaches to mitigating CH4 and increasing ruminant productivity is possible using next-generation sequencing techniques. Therefore, this review summarizes current genetic and nutrigenomic approaches to reducing enteric CH4 production without posing any danger to animals or the environment.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44647493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. K. Choudhury, Rajashree Jena, S. Tomar, A. K. Puniya
Climate change and the urgent need to reduce greenhouse gas (GHG) emission from agriculture has resulted in significant pressure on the livestock industry for advanced practices that are environmentally more sustainable. Livestock is responsible for more than 15% of anthropogenic methane (CH4) emission via enteric fermentation and improved strategies for mitigating enteric CH4 production therefore represents a promising target to reduce the overall GHG contribution from agriculture. Ruminal CH4 is produced by methanogenic archaea, combining CO2 and hydrogen (H2). Removal of H2 is essential, as its accumulation inhibits many biological functions that are essential for maintaining a healthy rumen ecosystem. Although several other pathways occur in the rumen, including reductive acetogenesis, propionogenesis, nitrate, and sulfate reduction, methanogenesis seems to be the dominant pathway for H2 removal. Global warming is not the only problem associated with the release of CH4 from ruminants, but the released GHG also represent valuable metabolic energy that is lost to the animal and that needs to be replenished via its food. Therefore, reduction of enteric CH4 emissions will benefit not only the environment but also be an important step toward the efficient production of high-quality animal-based protein. In recent decades, several approaches, relying on a diverse set of biological and chemical compounds, have been tested for their ability to inhibit rumen methanogenesis reliably and without negative effects for the ruminant animal. Although many of these strategies initially appeared to be promising, they turned out to be less sustainable on the industrial scale and when implemented over an extended period. The development of a long-term solution most likely has been hindered by our still incomplete understanding of microbial processes that are responsible for maintaining and dictating rumen function. Since manipulation of the overall structure of the rumen microbiome is still a significant challenge targeting key intermediates of rumen methanogenesis, such as H2, and population that are responsible for maintaining the H2 equilibrium in the rumen could be a more immediate approach. Addition of microorganisms capable of non-methanogenic H2 sequestration or of reducing equivalents are potential avenues to divert molecular H2 from methanogenesis and therefore for abate enteric CH4. However, in order to achieve the best outcome, a detailed understanding of rumen microbiology is needed. Here we discuss some of the problems and benefits associated with alternate pathways, such as reductive acetogenesis, propionogenesis, and sulfate and nitrate reduction, which would allow us to bypass H2 production and accumulation in the rumen.
{"title":"Reducing Enteric Methanogenesis through Alternate Hydrogen Sinks in the Rumen","authors":"P. K. Choudhury, Rajashree Jena, S. Tomar, A. K. Puniya","doi":"10.3390/methane1040024","DOIUrl":"https://doi.org/10.3390/methane1040024","url":null,"abstract":"Climate change and the urgent need to reduce greenhouse gas (GHG) emission from agriculture has resulted in significant pressure on the livestock industry for advanced practices that are environmentally more sustainable. Livestock is responsible for more than 15% of anthropogenic methane (CH4) emission via enteric fermentation and improved strategies for mitigating enteric CH4 production therefore represents a promising target to reduce the overall GHG contribution from agriculture. Ruminal CH4 is produced by methanogenic archaea, combining CO2 and hydrogen (H2). Removal of H2 is essential, as its accumulation inhibits many biological functions that are essential for maintaining a healthy rumen ecosystem. Although several other pathways occur in the rumen, including reductive acetogenesis, propionogenesis, nitrate, and sulfate reduction, methanogenesis seems to be the dominant pathway for H2 removal. Global warming is not the only problem associated with the release of CH4 from ruminants, but the released GHG also represent valuable metabolic energy that is lost to the animal and that needs to be replenished via its food. Therefore, reduction of enteric CH4 emissions will benefit not only the environment but also be an important step toward the efficient production of high-quality animal-based protein. In recent decades, several approaches, relying on a diverse set of biological and chemical compounds, have been tested for their ability to inhibit rumen methanogenesis reliably and without negative effects for the ruminant animal. Although many of these strategies initially appeared to be promising, they turned out to be less sustainable on the industrial scale and when implemented over an extended period. The development of a long-term solution most likely has been hindered by our still incomplete understanding of microbial processes that are responsible for maintaining and dictating rumen function. Since manipulation of the overall structure of the rumen microbiome is still a significant challenge targeting key intermediates of rumen methanogenesis, such as H2, and population that are responsible for maintaining the H2 equilibrium in the rumen could be a more immediate approach. Addition of microorganisms capable of non-methanogenic H2 sequestration or of reducing equivalents are potential avenues to divert molecular H2 from methanogenesis and therefore for abate enteric CH4. However, in order to achieve the best outcome, a detailed understanding of rumen microbiology is needed. Here we discuss some of the problems and benefits associated with alternate pathways, such as reductive acetogenesis, propionogenesis, and sulfate and nitrate reduction, which would allow us to bypass H2 production and accumulation in the rumen.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43704930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. A. Marinho, R. Rabelo-Neto, F. Epron, F. Toniolo, F. Noronha, N. Bion
Biogas upgrading by a catalytic process has been studied in order to obtain syngas using renewable source of methane. This work evaluates the influence of metal dopant (Gd, Sm, and Zr) on the CeO2 structure for the dry reforming of methane over Ni nanoparticle embedded catalysts. The doping with Zr improved the thermal stability of the catalyst, leading to the formation of small Ni nanoparticles, while Ni metal sintering was observed for Ni@CeO2, Ni@CeGdO2, and Ni@SmO2, according to in situ XRD under reduction conditions. The ceria reducibility was affected by the dopant nature, for which the addition of Zr caused distortions in the ceria lattice, promoting the diffusion of oxygen bulk to surface. The doping with Gd and Sm created oxygen vacancies by charge compensation, and the saturation of oxygen vacancies in the fresh samples decreased the degree of Ce reduction, according to TPR results. The larger Ni particles and poor redox behavior for Ni@CeGdO2 and Ni@CeSmO2 were responsible for the high carbon formation on these catalysts during the DRM reaction. The Ni@CeZrO2 catalyst did not present coke formation because of smaller Ni crystallite size and higher ceria reducibility. Therefore, the control of Ni particle size and the high oxygen mobility in the Ni@CeZrO2 catalyst inhibits carbon deposition and enhances the mechanism of carbon removal, promoting the catalyst stability.
{"title":"Effect of Metal Dopant on the Performance of Ni@CeMeO2 Embedded Catalysts (Me = Gd, Sm and Zr) for Dry Reforming of Methane","authors":"A. A. Marinho, R. Rabelo-Neto, F. Epron, F. Toniolo, F. Noronha, N. Bion","doi":"10.3390/methane1040023","DOIUrl":"https://doi.org/10.3390/methane1040023","url":null,"abstract":"Biogas upgrading by a catalytic process has been studied in order to obtain syngas using renewable source of methane. This work evaluates the influence of metal dopant (Gd, Sm, and Zr) on the CeO2 structure for the dry reforming of methane over Ni nanoparticle embedded catalysts. The doping with Zr improved the thermal stability of the catalyst, leading to the formation of small Ni nanoparticles, while Ni metal sintering was observed for Ni@CeO2, Ni@CeGdO2, and Ni@SmO2, according to in situ XRD under reduction conditions. The ceria reducibility was affected by the dopant nature, for which the addition of Zr caused distortions in the ceria lattice, promoting the diffusion of oxygen bulk to surface. The doping with Gd and Sm created oxygen vacancies by charge compensation, and the saturation of oxygen vacancies in the fresh samples decreased the degree of Ce reduction, according to TPR results. The larger Ni particles and poor redox behavior for Ni@CeGdO2 and Ni@CeSmO2 were responsible for the high carbon formation on these catalysts during the DRM reaction. The Ni@CeZrO2 catalyst did not present coke formation because of smaller Ni crystallite size and higher ceria reducibility. Therefore, the control of Ni particle size and the high oxygen mobility in the Ni@CeZrO2 catalyst inhibits carbon deposition and enhances the mechanism of carbon removal, promoting the catalyst stability.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49415763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Methane pyrolysis can produce many valuable products besides hydrogen, e.g., C2 compounds or carbon black. In the conditions provided by microwave plasma, the distribution of these products might be shifted by the addition of hydrogen and nitrogen. In this work, different ratios of H2:CH4, ranging from 0:1 to 4:1, were tested. The most unambiguous and promising result was obtained for the highest H2:CH4 ratio. For this ratio, a significant improvement in methane conversion rate was observed (from 72% to 95%) along with the increase in C2H2 and C2H4 yield and selectivity. The results support the hypothesis that the H radicals present in the plasma are responsible for improving methane conversion, while the presence of molecular hydrogen shifts the product distribution towards C2 compounds. Based on the carbon balance, the increase in the output of C2 compounds was obtained at the cost of solid carbon. At the same time, the addition of hydrogen resulted in the formation of bigger carbon particles. Finally, with the addition of both nitrogen and hydrogen, the formation of carbon was completely inhibited. Hydrogen cyanide was the main product formed instead of soot and some of the acetylene.
{"title":"Shifts in Product Distribution in Microwave Plasma Methane Pyrolysis Due to Hydrogen and Nitrogen Addition","authors":"M. Wnukowski, J. Gerber, Karolina Mróz","doi":"10.3390/methane1040022","DOIUrl":"https://doi.org/10.3390/methane1040022","url":null,"abstract":"Methane pyrolysis can produce many valuable products besides hydrogen, e.g., C2 compounds or carbon black. In the conditions provided by microwave plasma, the distribution of these products might be shifted by the addition of hydrogen and nitrogen. In this work, different ratios of H2:CH4, ranging from 0:1 to 4:1, were tested. The most unambiguous and promising result was obtained for the highest H2:CH4 ratio. For this ratio, a significant improvement in methane conversion rate was observed (from 72% to 95%) along with the increase in C2H2 and C2H4 yield and selectivity. The results support the hypothesis that the H radicals present in the plasma are responsible for improving methane conversion, while the presence of molecular hydrogen shifts the product distribution towards C2 compounds. Based on the carbon balance, the increase in the output of C2 compounds was obtained at the cost of solid carbon. At the same time, the addition of hydrogen resulted in the formation of bigger carbon particles. Finally, with the addition of both nitrogen and hydrogen, the formation of carbon was completely inhibited. Hydrogen cyanide was the main product formed instead of soot and some of the acetylene.","PeriodicalId":74177,"journal":{"name":"Methane","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46413518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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