Figure 4
The diagram has two parts labeled (a) and (b). Part (a) on the top is labeled “Co-occurrence and network of Keywords” and shows a network diagram. The network diagram has a densely connected cluster of nodes of different sizes and colors. The various labels are as follows: The green cluster is present at the top left and has the nodes with the labels: “electric power generation,” “electricity,” “gas emissions,” “hydrogen storage,” “oman,” “investments,” “costs,” “levelized costs,” “cost benefit analysis,” “hybrid systems,” “wind,” “wind energy,” “wind power,” “solar energy,” “biogas,” and “wind turbines.” The blue cluster is present at the top right and has the nodes with the labels: “mathematics,” “population,” “macroeconomics,” “electrical engineering,” “sociology,” “market economy,” “business,” “epistemology,” “law,” “philosophy,” “marketing,” “politics,” “finance,” “environmental economics,” “renewable energy,” “energy transition,” “bioenergy,” and “marketing.” The pink cluster is present at the bottom and has the nodes with the labels: “economic growth,” “carbon dioxide “united arab emirates,” “gulf cooperation council,” and “Qatar.” Four yellow nodes are shown in the center without any labels. Part (b) on the top is labeled “Word Cloud for Titles of the Selected Articles,” and shows a word cloud with words in different colors and sizes. The text includes: “economic development,” “renewable energy resources,” “environmental economics,” “photovoltaic system,” “solar power generation,” “energy efficiency,” “wind power,” “greenhouse gas,” “solar energy,” “sustainability,” “business,” “philosophy,” “investments,” “fossil fuel,” “law,” “economic growth,” “carbon dioxide,” “finance,” “natural gas,” “ecology,” “economic analysis,” “energy policy,” “fossil fuels,” “costs,” “waste management,” “renewable energy,” “economics,” “political science,” “saudi arabia,” “biology,” “engineering,” “hydrogen production,” “energy consumption,” “computer science,” “renewable energies,” “cost benefit analysis,” “chemistry,” “environmental science,” “macroeconomics,” “alternative energy,” “oman,” “natural resource economics,” “electrical engineering,” “sustainable development,” “hybrid systems,” and “united arab emirates.”Text analysis on titles and keywords. Source: The authors