1. The problem statement, all variables and given/known data If all the solid waste of 230 million tonnes were burned in waste-to-energy power plants that are 20% efficient, a) how many kilowatt-hours of electrical energy could be produced in a year? Compare this quantity with the total U.S. electrical energy production of approximately 3.8 trillion kWh annually. b) what would be the equivalent average electric power output from all these waste burning power plants? how many 1-GW coal-fired plants could they displace 2. Relevant equations 20 MJ/KG from waste 3. The attempt at a solution Part A) 230 million tonnes=230 billion kg 230kg x 20 MJ/KG= 4.6x10^12 MJ 4.6x10^12 MJ/3600 seconds per hour = 1.28x10^9 MWh 2.56 x 10^11 kWh/3.8 trillion kWh = 6.7 % Part B I'm not sure where to start. The back of the book says the answer is 29 Gw and 29 coal fired plants but I don't know how they got to this answer. I tried to convert the 2.56x10^11 Kwh to GW and got 256000 GWH but according to the book, that's not correct.