Consider two coal-fired power plants that generate 5.0x10^12J of electricity dai
ID: 768578 • Letter: C
Question
Consider two coal-fired power plants that generate 5.0x10^12J of electricity daily. Plant A has an overall net efficiency of 38%. Plant B, would operate at with an overall net effieicy of 46%. The grade of coal releases 30kJ of heat per gram. Coal is pure carbon. a. if 1000 kg of coal costs $30, what is the difference in daily fuel costs for the two plants? b. How many fewer grams of CO2 are emitted daily by Plant B, assuming complete combustion? I started by using the equation: energy generated at plant x efficiency = energy required. Please help, I don't know where to go from there.Explanation / Answer
efficiency = desired effect / input energy
for plant A
38/100 = 5.0x10^12J/ input energy of plant A
input energy of plant A = 1.31579 x 10^13 J
amnount of coal = total energy / energy per gram of coal
= 1.31579 x 10^13 J / 30000 J/g
= 4.859 x 10^5 kg
cost = amount of coal in kg x $30
= $13157.9
C + O2 ---- CO2
12 kg of carbon gives 44 kg of CO2
4.859 x 10^5 kg of carbon will give = 1781633.33 kg CO2
amount of CO2 = 1781633.33 kg
for plant B
46/100 = 5.0x10^12J/ input energy of plant B
input energy of plant B = 1.0869 x 10^13 J
amount of coal = total energy / energy per gram of coal
= 1.0869 x 10^13 J / 30000 J/g
= 3.623 x 10^5 kg
cost = amount of coal in kg x $30
= $10869
C + O2 ---- CO2
12 kg of carbon gives 44 kg of CO2
so 3.623 x 10^5 kg of carbon will give = 1328433.33 kg CO2
amount of CO2 = 1328433.33 kg
thus difference in CO2 b/w plant A and plant B = 453200 kg
so plant B produces 453200 kg less CO2 than plant A