Design and optimization of shale gas energy systems: Overview, research challenges, and future directions

A review of the development in shale oil and gas wastewater desalination

The development of the shale oil and gas extraction industry has heightened concerns about shale oil and gas wastewater (SOGW). This review comprehensively summarizes, analyzes, and evaluates multiple issues in SOGW desalination. The detailed analysis of SOGW water quality and various disposal strategies with different water quality standards reveals the water quality characteristics and disposal status of SOGW, clarifying the necessity of desalination for the rational management of SOGW. Subsequently, potential and implemented technologies for SOGW desalination are reviewed, mainly including membrane-based, thermal-based, and adsorption-based desalination technologies, as well as bioelectrochemical desalination systems, and the research progress of these technologies in desalinating SOGW are highlighted. In addition, various pretreatment methods for SOGW desalination are comprehensively reviewed, and the synergistic effects on SOGW desalination that can be achieved by combining different desalination technologies are summarized. Renewable energy sources and waste heat are also discussed, which can be used to replace traditional fossil energy to drive SOGW desalination and reduce the negative impact of shale oil and gas exploitation on the environment. Moreover, real project cases for SOGW desalination are presented, and the full-scale or pilot-scale on-site treatment devices for SOGW desalination are summarized. In order to compare different desalination processes clearly, operational parameters and performance data of varying desalination processes, including feed salinity, water flux, salt removal rate, water recovery, energy consumption, and cost, are collected and analyzed, and the applicability of different desalination technologies in desalinating SOGW is qualitatively evaluated. Finally, the recovery of valuable inorganic resources in SOGW is discussed, which is a meaningful research direction for SOGW desalination. At present, the development of SOGW desalination has not reached a satisfactory level, and investing enough energy in SOGW desalination in the future is still necessary to achieve the optimal management of SOGW.

Sustainable development index of shale gas exploitation in China, the UK, and the US

While shale gas could complement the world's natural gas supply, its environmental tradeoffs and sustainability potential should be cautiously assessed before using it to satisfy future energy needs. Shale gas development in China is still in its infancy but has been progressing by the Central Government at a fast pace nowadays. Advanced experience from North America would greatly benefit sustainable design and decision-making for energy development in China. However, the lack of consistency concerning internal and external parameters among previous investigations does not allow an integrated impact comparison among shale gas-rich countries. Herein, we applied a meta-analysis to harmonize environmental tradeoff data through a comprehensive literature review. Greenhouse gas emission, water consumption, and energy demand were selected as environmental tradeoff indicators during shale gas production. Data harmonization suggested that environmental tradeoffs ranged from 5.6 to 37.4 g CO₂-eq, 11.0-119.7 mL water, and 0.027-0.127 MJ energy to produce 1 MJ shale gas worldwide. Furthermore, sustainable development indexes (SDIs) for shale gas exploitation in China were analyzed and compared to the United States and the United Kingdom by considering environment, economy, and social demand through an analytic hierarchy process. The United States and China elicit higher SDIs than the United Kingdom, indicating higher feasibility for shale gas exploitation. Although China has relatively low scores in the environmental aspect, large reservoirs and high future market demand make Chinese shale gas favorable in the social demand aspect. Region-specific SDI characteristics identified among representative countries could improve the sustainability potential of regional development and global energy supply.

Process modelling and life cycle assessment coupled with experimental work to shape the future sustainable production of chemicals and fuels

Meeting the sustainable development goals and carbon neutrality targets requires transitioning to cleaner products, which poses significant challenges to the future chemical industry. Identifying alternative pathways to cover the growing demand for chemicals and fuels in a more sustainable manner calls for close collaborative programs between experimental and computational groups as well as new tools to support these joint endeavours. In this broad context, we here review the role of process systems engineering tools in assessing and optimising alternative chemical production patterns based on renewable resources, including renewable carbon and energy. The focus is on the use of process modelling and optimisation combined with life cycle assessment methodologies and network analysis to underpin experiments and generate insight into how the chemical industry could optimally deliver chemicals and fuels with a lower environmental footprint. We identify the main gaps in the literature and provide directions for future work, highlighting the role of PSE concepts and tools in guiding the future transition and complementing experimental studies more effectively.

Impact of natural gas consumption on sub-Saharan Africa's CO2 emissions: Evidence and policy perspective

With huge natural gas(NG) reserves and current low (1%) share of non-hydro renewables in Sub-Saharan Africa (SSA), can natural gas offer SSA a low-carbon energy transition? Employing data from 1980 to 2017, this paper investigates the impact of NG consumption on SSA's CO₂ emissions using data-driven nonparametric additive regression(NPAR) which can reveal both linear and nonlinear effects. Augmenting NPAR with translog production function(TPF) estimates of interfuel substitution elasticities and bias technological progress over sample period(advantage of TPF), we further provide evidence of the indirect effect of NG consumption on SSA's CO₂ emissions through mechanism analysis. From the empirical results, the linear effect shows NG positively impact CO₂ emissions while the nonlinear effect indicates a downward decreasing trend (meaning expansion in NG consumption will gradually lower CO₂ emissions). Nonlinearly, urbanization and energy efficiency also show positive "inverted U-Shaped" and "downward slopping" respectively meaning sustainable urban energy and energy efficiency practices improvement can lead to CO₂ reduction respectively in SSA. The reducing effect of NG consumption on CO₂ (the nonlinear effect) is realized through the enhancement of positive bias technological progress of NG over coal and oil but not merely substitution of coal and oil for NG. Technological progress improvement in NG use will also reduce the positive linear effect of urbanization and energy efficiency on CO₂ emissions of SSA. Oil is more likely to be substituted for NG than that of coal in SSA. The scenario analysis shows a total of 6.9%, 7.6% and 8.3% of energy conservation is realized in 2022, 2026 and 2030 with a corresponding CO₂ reduction of 18.7%, 20.7% and 22.9% respectively for a continuous 10% investment in NG. Institutional, market-oriented and technology challenges hinder NG development among major producers in SSA. Based on the results, several policy measures are put forward to promote SSA's low-carbon energy transition.

Oxidative Coupling of Methane over Mn2O3-Na2WO4/SiC Catalysts

The oxidative coupling of methane (OCM) is operated at high temperatures and is a highly exothermic reaction; thus, hotspots form on the catalyst surface during reaction unless the produced heat is removed. It is crucial to control the heat formed because surface hotspots can degrade catalytic performance. Herein, we report the preparation of Mn2O3-Na2WO4/SiC catalysts using SiC, which has high thermal conductivity and good stability at high temperatures, and the catalyst was applied to the OCM. Two Mn2O3-Na2WO4/SiC catalysts were prepared by wet-impregnation on SiC supports having different particle sizes. For comparison, the Mn2O3-Na2WO4/SiO2 catalyst was also prepared by the same method. The catalysts were analyzed by nitrogen adsorption–desorption, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The transformation of SiC into α-cristobalite was observed for the Mn2O3-Na2WO4/SiC catalysts. Because SiC was completely converted into α-cristobalite for the nano-sized SiC-supported Mn2O3-Na2WO4 catalyst, the catalytic performance for the OCM reaction of Mn2O3-Na2WO4/n-SiC was similar to that of Mn2O3-Na2WO4/SiO2. However, only the surface layer of SiC was transformed into α-cristobalite for the micro-sized SiC (m-SiC) in Mn2O3-Na2WO4/m-SiC, resulting in a SiC@α-cristobalite core–shell structure. The Mn2O3-Na2WO4/m-SiC showed higher methane conversion and C2+ yield at 800 and 850 °C than Mn2O3-Na2WO4/SiO2.

Learning Curve, Change in Industrial Environment, and Dynamics of Production Activities in Unconventional Energy Resources

Since 2007, shale oil and gas production in the United States has become a significant portion of the global fossil fuel market. The main cause for the increase in production of shale oil and gas in the US is the adoption of new production technologies, namely, horizontal drilling and hydraulic fracturing. However, the production cost of shale oil and gas in the US is comparably higher than the production cost of conventional oil and gas. In 2014, the crude oil and natural gas price decreased significantly to approximately 40 dollars per barrel, and natural gas prices decreased to 3 dollars per million British thermal unit, and thus the productivity and financial conditions for the exploration and production of shale oil and natural gas for producers in the United States have worsened critically. Therefore, technological innovation has become one of the most interesting issues of the energy industry. The present study analyzes the trends in technological innovation having a relationship with production activities. This study calculates the learning rate of 30 companies from the petroleum exploration and production industry in the United States using an improved learning rate calculation formula that reflects the changes in the oil production ratio. Thus, more statistically confident calculation results and interpretations of strategic production activities with regard to changes in the industrial environment were achieved in this study.

An Investigation of the Underlying Evolution of Shale Gas Research’s Domain Based on the Co-Word Network

With the increasing shortage energy, the exploration and utilization of shale gas (SG) have greatly changed the world’s natural gas supply pattern. In this study, based on a bibliometric review of the publications related to SG, by analyzing the co-word networks during the past years, we provide comprehensive analyses on the underlying domain evolution of shale gas research (SGR). Firstly, we visualize the topical development of SGR. We not only identify the key topics at each stage but also reveal their underlying dependence and evolutionary trends. The directions of SGR in the future are implied. Secondly, we find the co-word network has small-world and scale-free characteristics, which are the important mechanisms of driving the evolution of SGR’s domain. Thirdly, we analyze China’s SGR. We find the co-word network in China’s SGR has not yet emerged obvious differentiation. Nevertheless, it has a similar self-organized evolution process with the co-word network of international SGR. Our above results can provide references for the future SGR of scholars, optimization or control of the domain and the strategy/policy of countries or globalization.