Question 4 0/1pts Despite being a major contributor to global greenhouse gas emissions, coal power plants are still a ubiquitous source of energy worldwide, with China, India, and the United States being the largest consumers of coal, accounting for roughly 50%, 11%, and 9% of global coal consumption respectively. Coal-fired power plants consume coal as fuel. They burn this coal to generate thermal energy and use this thermal energy to generate steam, spin a turbine, and thus produce work. Thus, coal power plants operate as heat engines. The cost of coal is currently around $150 per metric ton. Consider a coal power plant that uses thermal energy from burning coal to heat steam at 996F and cools it down at 58F. Let e be the power plant's actual operating efficiency, and let ey.x be its theoretical maximum efficiency. Suppose that e/emax is equal to roughly 0.28, and it produces about 9 kWh of thermal energy to heat the steam for each kilogram of coal it burns. We define the "cost efficiency" of such a plant as the quantity of work it outputs divided by the corresponding cost in dollars of coal it needs to produce that work. What is the cost efficiency of this coal power plant in kWh per dollar? 10.83 (with margin: 0.5) Solution given, cost of coal C= $150 per metric ton Actual operating efficiency of power plant ce) to its thoutical maximum efficiency lmay = - - = 0.28 Energy produced per kilogram of coal R= 9KWh Explanation is the cost efficiency of a power plant can be calculated by the amount of electrical energy it can produce per dollar spent on bull. =1 This requires converting the cont of coal into cost per ky , and then determining how much electricity is produced perky based on the plant's efficiency. -content of cost of coal to cost per ky cost per KG - 100 0 = $0.15 / kg calculated the energy produced per ky in K.lou based on efficiency. Energy / kg = gkwh xe Energy / kg = 9kwoh X 0. 28 - Energy / kg = 2.52 kwh / kg calculate the cost efficiency, which is the energy produced per ky divided by cost per kg cost efficiency - 2.5 2 kah 0.15- = 16.8 KWh /$