Describe the purpose and focus of the paper:''On a global scale, the share of renewable energy sources (RES) in electricity production is small but growing contin- uously. To prevent economic losses and idle green resources caused by energy curtailments, corrective actions need to be taken. Moreover, RES must become accessible for sectors that still heavily rely on fossil resources, i.e., chemical indus- try, heating, and transportation [1], if global climate targets are to be met. In this context, technologies termed Power-to-[K], such as Power-to-gas, Power-to-chemicals, or Power-to-fuels, have attracted increasing interest in recent years (cf. Sect. 2). The terminology has been used for an ever-increasing num- ber of applications, and the large diversity of applications associated with this terminology has resulted in the term Power-to-X. However, we are not aware of an established definition about what the X may or may not include. Look- ing at most instances of Power-to-X concepts, these aim at converting electricity into gases, liquids, heat, fuels, or even back from those into electricity [2–7]. We believe that in addition to the new aspect of bringing renewable electricity into production processes to replace fossil-based products, many recently proposed technologies under the term Power-to-X are closely related to the much older concepts of electricity storage and demand side management (DSM). Therefore, a broad definition of Power-to-X as processes with the goal to exploit the environmental and economic potential of renewable electricity is proposed. This explicitly encompasses electricity storage and DSM as well as the newer aspect that we call e-Production. In the following, first, a brief overview of the literature is given (Sect. 2). Then, details on the definition and classification of Power- to-X are provided, before key challenges and benefits for given external conditions are discussed (Sect. 3). Illustrative examples that demonstrate how process systems engineer- ing (PSE) methods support overcoming these challenges are also given (Sect. 4). Finally, the most important findings and still open questions are summarized''

introduction:'' On a global scale, the share of renewable energy sources (RES) in electricity production is small but growing contin uously. To prevent economic losses and idle green resources caused by energy curtailments, corrective actions need to be taken. Moreover, RES must become accessible for sectors that still heavily rely on fossil resources, i.e., chemical indus try, heating, and transportation [1], if global climate targets are to be met. In this context, technologies termed Power-to-[K], such as Power-to-gas, Power-to-chemicals, or Power-to-fuels, have attracted increasing interest in recent years (cf. Sect.2). The terminology has been used for an ever-increasing num ber of applications, and the large diversity of applications associated with this terminology has resulted in the term Power-to-X. However, we are not aware of an established definition about what the X may or may not include. Look ing at most instances of Power-to-X concepts, these aim at converting electricity into gases, liquids, heat, fuels, or even back from those into electricity [2–7]. We believe that in addition to the new aspect of bringing renewable electricity into production processes to replace fossil-based products, many recently proposed technologies under the term Power-to-X are closely related to the much older concepts of electricity storage and demand side management (DSM). Therefore, a broad definition of Power-to-X as processes with the goal to exploit the environmental and economic potential of renewable electricity is proposed. This explicitly encompasses electricity storage and DSM as well as the newer aspect that we call e-Production. In the following, first, a brief overview of the literature is given (Sect.2). Then, details on the definition and classification of Power to-X are provided, before key challenges and benefits for Chem. Ing. Tech. 2020, 92, No. 1–2, 1–12 given external conditions are discussed (Sect.3). Illustrative examples that demonstrate how process systems engineer ing (PSE) methods support overcoming these challenges are also given (Sect.4). Finally, the most important findings and still open questions are summarized (Sect.5).''

Methods and Tools: Explain the methodologies and tools used in the studies outlined in the paper.''3 Beneficial Utilization of Electricity by Power-to-X Here, Power-to-X processes are defined as processes with the goal to exploit the environmental and economic potential of renewable electricity. This comprises the production of gases and liquids from renewable electricity as well as the provision of heat with the intention to replace fossil-based products, which is called e-Production. Additionally, this definition encompasses the older fields of electricity storage and DSM. With this definition, Power-to-X is not restricted to technologies for the conversion of predominantly electric power into products that are currently based on fossil sources. With DSM, it also incorporates approaches that enable the utilization of renewable electricity for industrial processes that have not been able to utilize such in an effective way until now. We believe that such a broad definition is useful to highlight the relationship and overlap of these fields that become particularly apparent in many Power-to-X technologies falling into more than one of these three categories (gray areas in Fig. 3). We explicitly confine our definition to processes that aim at utilizing renewable electricity and exclude, e.g., general energy management technologies from our definition of Power-to-X. However, contrary to their intended purpose, associated technologies could in principle also utilize other types of energy sources, e.g., for producing synthetic fuels from nuclear power in one country and transport it to another one. In the following, these three main approaches for a beneficial utilization of renewable electricity are briefly introduced, their relations are identified, and their opportunities and common challenges are stated''

Read the passage carefully and pick the option whose answer best aligns with the passage:In a low-carbon world, renewable energy technologies are hot business. For investors looking to redirect funds, wind turbines and solar panels, among other technologies, seem a straightforward choice. But renewables need to be further scrutinized before being championed as forging a path toward a low-carbon future. Both the direct and indirect impacts of renewable energy must be examined to ensure that a climate-smart future does not intensify social and environmental harm. As renewable energy production requires land, water, and labor, among other inputs, it imposes costs on people and the environment.Hydropower projects, for instance, have led to community dispossession and exclusion . . .Renewable energy supply chains are also intertwined with mining, and their technologies contribute to growing levels of electronic waste . . . Furthermore, although renewable energy can be produced and distributed through small-scale, local systems, such an approach might not generate the high returns on investment needed to attract capital.Although an emerging sector, renewables are enmeshed in long-standing resource extraction through their dependence on minerals and metals . . . Scholars document the negative consequences of mining . . . even for mining operations that commit to socially responsible practices: “many of the world’s largest reservoirs of minerals like cobalt, copper, lithium, and rare earth minerals”—the ones needed for renewable technologies—“are found in fragile states and under communities of marginalized peoples in Africa, Asia, and Latin America.” Since the demand for metals and minerals will increase substantially in a renewable-powered future . . . this intensification could exacerbate the existing consequences of extractive activities.Among the connections between climate change and waste, O’Neill . . . highlights that “devices developed to reduce our carbon footprint, such as lithium batteries for hybrid and electric cars or solar panels, become potentially dangerous electronic waste at the end of their productive life.” The disposal of toxic waste has long perpetuated social injustice through the flows of waste to the Global South and to marginalized communities in the Global North . ..While renewable energy is a more recent addition to financial portfolios, investments in the sector must be considered in light of our understanding of capital accumulation. As agricultural finance reveals, the concentration of control of corporate activity facilitates profit generation. For some climate activists, the promise of renewables rests on their ability not only to reduce emissions but also to provide distributed, democratized access to energy . . .But Burke and Stephens . . . caution that “renewable energy systems offer a possibility but not a certainty for more democratic energy futures.” Small-scale, distributed forms of energy are only highly profitable to institutional investors if control is consolidated somewhere in the financial chain. Renewable energy can be produced at the household or neighborhood level. However, such small-scale, localized production is unlikely to generate high returns for investors. For financial growth to be sustained and expanded by the renewable sector, production and trade in renewable energy technologies will need to be highly concentrated, and large asset management firms will likely drive those developments.Based on the passage, we can infer that the author would be most supportive of which one of the following practices?Please select your Answer.The localized, small-scale development of renewable energy systems.More stringent global policies and regulations to ensure a more just system of toxic waste disposal.Encouragement for the development of more environment-friendly carbon-based fuels.The study of the coexistence of marginalized people with their environments.

Methods and Tools: Explain the methodologies and tools used in the studies outlined in the paper'' 3.5 When is Their Application Beneficial? Given that Power-to-X technologies aim at achieving economic and/or environmental benefits by utilizing renewable electricity, the question arises which approach is favorable under which conditions. In Fig. 4, general trends are given where the decisive factors that affect the economic viability are twofold: the average electricity price and its fluctuations.Herein, the fluctuations indicate the absolute changes in price with time. From the environmental point of view, particularly for mitigating greenhouse gas (GHG) emissions, the Power-to-X applications are evaluated according to the average electricity carbon footprint and its absolute fluctuations over time. E-production in steady-state operation becomes more viable with decreasing average electricity price as this is its major operating cost factor. This way, e-products can become cost-competitive with fossil-based products only if the average electricity price is low. Similarly, e-Production must consume electricity with a low carbon footprint to result in low GHG emissions. By utilizing electricity with a high carbon footprint, GHG emissions might even exceed those of fossil-based products [48]. For steady-state operation, the fluctuations in both factors have no influence on process economics and environmental impact, because the plant does not adapt to those fluctuations. Power-to-X applications for DSM and electricity storage are economically beneficial if the fluctuations in electricity prices are high. In such a case, the capacity of processes operated under DSM and processes for electricity storage can be increased when electricity is available at low costs and the load can be reduced or the energy can be reconverted at high electricity prices, respectively. The benefit needs to recoup the capital investment for gaining operational flexibility. The achievable cost savings do not depend on the average price, because the (absolute) revenue of both buying and reselling electricity and of shifting periods of electricity consumption only depends on the magnitude of fluctuation. Electricity storage facilities and DSM favor a high fluctuation in carbon footprint of the electricity mix in order to exploit the environmental potential. Electricity is used/ stored when the share of RES in the electricity grid is high and reconverted when the share is low [35]. As already stated in Sect. 3.4, combinations of these applications can outperform individual applications. One combination could be DSM for e-Production with an increased production rate when electricity prices are low. Then, equipment oversizing that enables flexible operation should be addressed in process design. The considered fluctuations occur on very different time scales: hourly, daily, or even seasonal.''

Which of the following is a renewable energy source commonly used in developing countries?*1 pointNatural GasCoalSolar PowerNuclear Power