Overall 2 % of the total available thermal energy in this region heats water for steam . How many years can this source provide power for electricity generation at the rate of 2000 MW every year? Total Capacity required is 2000 Mw per year/0.02 = 100,000 MW per year . ... 100,000 MW * yr = 10 5 MW *yr * 10 6 W/MW 3.15 x 10 7 secs/yr = . 3.15 x 10 18 W secs = 3.15 x 10 18 Joules each yr . ... 8x10 19 Joules / 3.15 x 10 18 Joules/yr = 26 years . ...