El modelo de Purnell para la Competencia Cultural

There is a rapidly growing number of publications on the design and optimization of shale gas energy system in recent years. These publications cover various topics, including the scheduling of drilling activity, planning of shale gas production, construction of infrastructure, shale water management, design of shale gas supply chain, exploration of processing schemes, selection of technologies and contracts, mitigation of environmental impacts, and modeling of new operations, etc. Besides, the scales of problems addressed in the literature range from a single process to the global shale gas industry.

By reviewing the existing literature, we can obtain the following remarks. First, although the global economic and environmental impacts of shale energy have been well acknowledged by both industry and academia, almost all the existing studies at national or global-scales are still limited to simple systems analysis. This is due to the limitation of computational power for exascale computing problems to account for many complex decisions in shale gas energy systems. Besides, a shale region normally includes thousands of shale wells, so it could easily result in a exascale mathematical problem that is computationally intractable. On the other hand, different shale plays feature distinctive production properties, environmental conditions, and regulation policies. Each shale well has its own ultimate recovery and shale gas composition that are usually different from others. Thus, integrated modeling of shale gas energy systems could involve huge amount of data and uncertainty. These challenges motivate the need of developing novel modeling frameworks and more efficient solution strategies for the shale gas energy systems. Second, most of the PSE publications mainly put their efforts on the supply chain scale problems. However, these articles either focus on the design and operations of shale gas supply chain [4, 5, 56] or center on the water management problem [57-59]. The water management issue is brought about by the shale gas development. Meanwhile, the shale gas production can be limited by multiple water-related constraints, such as fresh water availability and wastewater treatment. Therefore, it is necessary to develop an integrated modeling framework taking into consideration both shale gas development as well as water management. There are a few publications presenting such integrated modeling frameworks [6, 60]. Nevertheless, these models

either suffer from oversimplifications and restricted optimization criteria, or are computationally challenging to solve for large-scale applications.

Despite the importance of optimizing the shale gas processing system, there are only limited number of publications exploring the potential opportunities in process design and potential integration. To make use of the methane feedstock from shale gas industry, Martín and Grossmann [54] presented a superstructure optimization approach for the simultaneous production of liquid fuels and hydrogen from switchgrass and shale gas.

Ehlinger, et al. [55] presented a shale gas processing design that aims to produce methanol with shale gas feedstock. In another work by Noureldin, et al. [61], an optimization model was proposed targeting on modeling and selection of reforming strategies for syngas generation from natural/shale gas. This work was further extended to account for economic and environmental performances for the production of methanol from shale gas [62]. In addition to methane, ethane is another important product from shale gas energy systems. He and You [49] proposed three novel process designs for integrating shale gas processing with ethylene production. Following this work, the authors extend the scope and further develop a novel process design for making chemicals from shale gas and bioethanol [63]. Recently, the same authors develop a mega-scale shale gas supply chain olefin production network model with explicit consideration of process designs, energy integration, and alternative processing technologies [64]. Additionally, an efficient cold energy integration scheme is proposed to integrate NGLs recovery from shale gas and liquefied natural gas (LNG) regasification at receiving terminals [65]. However, most works on shale processing design and synthesis are based on an isolated system, neglecting the impacts of shale

gas supply chains. Meanwhile, existing shale gas supply chain models typically approximate the shale gas processing plant as a simple input-output process without considering sufficient details. Now that shale gas processing is a crucial component in the shale gas supply chain, it is important to develop integrated multi-scale optimization frameworks for shale gas supply chain with explicit consideration of process design and operational decisions.

Moreover, although sustainable design of shale gas energy system is of great interest to both academy and public, current research on this topic heavily relies on the life cycle analysis (LCA) approach. The drawback of LCA approach is its incapability of discerning the optimal solution among multiple design alternatives. The environmental performance is normally calculated based on the average estimation of shale gas development. Thus, with different data and assumptions, the LCA approach may easily lead to disparate conclusions. To overcome this shortcoming, several studies aimed to incorporate sustainability perspectives into the design and optimization of shale gas energy systems. Attempts are made including choosing environment-oriented objective functions [57, 58], integrating LCA approach with multiobjective optimization [6, 7], introducing extra environmental constraints in the optimization model [59], and addressing safety concerns with quantitative risk analysis [66]. However, there are still a number of knowledge gaps: First, only certain types of environmental impact are considered, such as water consumption and GHG emissions, while a comprehensive evaluation of systems sustainability is absent in the literature. Besides, process-based LCA is the dominating method applied in the environmental impact analysis, which succeeds in modeling detail but suffers from systems boundary truncation. More

advance approaches such as hybrid LCA is expected to overcome this shortcoming [67, 68]. Besides, although multiple methodologies have been recognized as useful tools in sustainable design of energy systems [69], including material flow analysis (MFA), LCA, and mathematical optimization, they were typically applied in isolation. Since each tool has its advantages and drawback, it is of great value to explore the synergies among these tools and develop an integrated approach for the sustainable design of shale gas energy systems. Last but not least, important issues that are not fully addressed in the current literature includes hedging against multiple types of uncertainty, capturing interactions among multiple stakeholders, and modeling multi-scale decisions as well as emerging technologies and operations.