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The increase in the concentration of geological gas emissions in the atmosphere and particularly the increase of methane is considered by the majority of the scientific community as the main cause of global climate change. The main reasons that place methane at the center of interest, lie in its high global warming potential (GWP) and its lifetime in the atmosphere. Anthropogenic processes, like engineering geology ones, highly affect the daily profile of gasses in the atmosphere. Should direct measures be taken to reduce emissions of methane, immediate global warming mitigation could be achieved. Due to its significance, methane has been monitored by many space missions over the years and as of 2017 by the Sentinel-5P mission. Considering the above, we conclude that monitoring and predicting future methane concentration based on past data is of vital importance for the course of climate change over the next decades. To that end, we introduce a method exploiting state-of-the-art recurrent neural networks (RNNs), which have been proven particularly effective in regression problems, such as time-series forecasting. Aligned with the green artificial intelligence (AI) initiative, the paper at hand investigates the ability of different RNN architectures to predict future methane concentration in the most active regions of Texas, Pennsylvania and West Virginia, by using Sentinel-5P methane data and focusing on computational and complexity efficiency. We conduct several empirical studies and utilize the obtained results to conclude the most effective architecture for the specific use case, establishing a competitive prediction performance that reaches up to a 0.7578 mean squared error on the evaluation set. Yet, taking into consideration the overall efficiency of the investigated models, we conclude that the exploitation of RNN architectures with less number of layers and a restricted number of units, i.e., one recurrent layer with 8 neurons, is able to better compensate for competitive prediction performance, meanwhile sustaining lower computational complexity and execution time. Finally, we compare RNN models against deep neural networks along with the well-established support vector regression, clearly highlighting the supremacy of the recurrent ones, as well as discuss future extensions of the introduced work. [ABSTRACT FROM AUTHOR]

Highlights • The flux of multivalent cations across non-selective CMX membranes was 1.4 times > sodium. • A CMX-S membrane at the cathode boundary reduced the flux of Ca, Mg, and Ba into the electrode rinse. • Ca, Mg and Ba interfered by blocking transfer sites on the CMX-S membrane at the cathode barrier. • Overall flux was improved by unblocking the CMX-S membrane with periodic polarity reversal. • Soluble Fe precipitated throughout the stack and within the diluate and concentrate tanks. Abstract Electrodialysis is an electrochemically driven membrane technology usually used for treating feed water containing several thousand mg/l total dissolved solids (TDS). This research investigated the use of conventional ED for the treatment of flowback water from shale gas hydraulic fracturing that contains up to tens of thousands of mg/l TDS and contain a mixture of multivalent cations. This paper discusses efforts to treat concentrated brines with electrodialysis and focuses on the mitigation of the detrimental effects of multivalent cations such as calcium, magnesium, barium, iron, and in the feedstock. A previous paper detailed the effects of calcium under defined lab conditions. The apparent calcium fouling (in and around) the electrode cells was mitigated by changing the single cathode chamber boundary membrane to a (CMX-S) that was more selective for monovalent cations. This paper covers efforts undertaken to mitigate problems associated with high concentrations of calcium, barium, iron, and magnesium. Four field samples of produced water from oil and gas operations in from the Marcellus shale formation (generally Pennsylvania, USA) and the Barnett shale formation (generally north central Texas, USA) were also tested. These results from field samples were similar to the results from lab defined tests. Mechanisms of process interference by the different multivalent cations appear different for each species. Calcium, magnesium, barium, and iron were preferentially transported from the diluate to the concentrate compared to sodium by a factor of about 1.4:1 on a charge basis resulting in a suppression of the flux of sodium to the concentrate. A single CMX-S membrane selective for monovalent cations was placed at the cathode barrier resulting in a reduced flux of calcium, magnesium and barium into the electrode rinse. However total ion flux was inhibited caused by apparent blockage of the cation transfer sites on the CMX-S membrane by the stagnant multivalent cations. A series of tests with periodic pulse polarity-reversal (anode and cathode reversed for a brief time) indicted the blockage by calcium and barium was immediately reversable, however, iron was more problematic and may have precipitated on membrane surfaces other than the cathode barrier. [ABSTRACT FROM AUTHOR]

State officials responsible for the regulation of hydraulic fracturing (fracking) operations used in the production of oil and gas resources will inevitably confront a key policy issue; that is, to what extent can statewide regulations be developed without reducing land use autonomy typically exercised by local officials? Most state regulators have historically recognized the economic importance of industry jobs and favor the adoption of uniform regulatory requirements even if these rules preempt local policymaking authority. Conversely, many local officials seek to preserve land use autonomy to provide a greater measure of protection for public health and environmental quality goals. This paper examines how public officials in three states--Colorado, Pennsylvania, and Texas--address the question of state control versus local autonomy through their efforts to shape fracking policy decisions. While local officials within Texas have succeeded in developing fracking ordinances with relatively little interference from state regulators, Colorado and Pennsylvania have adopted a tougher policy stance favoring the retention of preemptive oil and gas statutes. Key factors that account for between state differences in fracking policy decisions include the strength of home rule provisions, gubernatorial involvement, and the degree of local experience with industrial economic activities. [ABSTRACT FROM AUTHOR]