
Efficiency Problems
I'm having a hard time wrapping my mind around what is required of me in this question.
"A power plant is designed to capture all CO2 from the flue gas. It runs on pure methane and oxygen, so the flue gas consists of only CO2 and H2O:
CH4 + 2O2→ CO2 + 2H2O ΔH =  .244 kWh/mole CH4
The plant must produce its own O2. The energy requirement for air separation is 250 kWh (electric) / tonne O2. An equal amount of electric energy is required for liquefaction of 1 tonne of CO2. The plant has a gross thermal efficiency of 45% (not counting air separation and CO2 liquefaction). (a) What percentage of the plant’s electricity output is available for dispatch into the grid? (b) What is the net thermal efficiency (electricity output per heat input after air separation and CO2 liquefaction)?"
Any help is appreciated. Thank you!

Here's what i've worked out so far.
1 mol CH4 = 16 g
1000000g/16g = 62500 mol x .244 KWh/mol = 12250 kWh x .45 = 6862 KWh.
a) (6862750)/6862=89%
b) 6862/750= 9.15
I'm not so sure I've done the correct thing for either answer. Feedback?