3.The average electrical generating capacity of the United States was about 475,

Question

3.The average electrical generating capacity of the United States was about 475,000 MW in 2007. If trends continue, this will double in about 15 years.
1.How many new plants of the size of the system seen below will be required?
2.If half of these are coal-fired, how many tons of coal will be required per year for the new plants, and how many tons/yr of ash and SO2 will have to be handled in 2024?

(HERE IS SYSTEM)

Large central power stations with power outputs capacity of 1000 MW and convert about 35 percent of the input energy to electricity burns coal with an energy content of 24 MJ/kg.

Amount of coal (tons) required by this plant per year, assuming it operates continuously = mc(tons) =  3.754e6 tons

10 % the coal mass remains as residual ash.  The amount in tons  over 30 years ma(tons) = 9.461e6 tons 

Amount CO2 produced for every kg of coal burned

mco2 = 7.996e6 tons 

Amount of SO2 is produced for every 250 tons of coal consumed

mso2 =  15.016e6 tons

Explanation / Answer

a) We need 475,000 MW more, and the capacity of each plant is 1000MW, hence
475000/1000 = 475 new plants are needed

b) half are coal-fired: 475/2 = 237.5 (Apparently we cannot have 0.5 plant, so let consider 237 plants)
coal required by each plant per year: 3.754e6 tons

237 x 3.754e6 = 890e6 tons/year coal is needed

The amount of ash in tons over 30 years: 9.461e6tons

237 x 9.461e6 / 30 = 74.7e6 tons/year ash is produced

Amount of SO2 is produced for every 250 tons of coal consumed: 15.016e6tons (it seems 15.016tons is right because this number cannot be greater than 250 tons)

890e6 x 15.016 / 250 = 53.5e6 tons/year SO2

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