Question

Consider two separate, hypothetical 1.05 GWe coal-fired electric power plants. Both have overall efficiencies of 35% (C>E) and operate continuously through one year. One uses air in combustion and the other uses pure oxygen (O2) - both in stoichiometric combustion with coal, simulated as elemental carbon (C).

Estimate the mass flow rate of CO2 out the flue stack (in metric tons/year) and the volumetric fractions of CO2 in the flue gas in both plants. Which is easier to equip with CO2 separation equipment?  

CO2 Flow Rate _________________tons/year

Air-Fired Plant Exhaust ________ % CO2

Oxy-Fired Plant Exhaust ________% CO2

Answer 1

Approximately 30,000 tons/year of CO2 :

Carbon dioxide (CO2) is the most important element your plants need. Plants absorb CO2 from the air via small pores in their leaves called stomata and use it as a building block to grow and bloom. CO2 is naturally present in the air at around 360-395 PPM. If you don’t keep CO2 levels topped up (either by ventilating with fresh air or supplementing with a CO2 cylinder or burner) your plants will run out of food. If this happens you can expect stretched, leggy growth, smaller fruits and airy, wispy flowers.            

Air-Fired Plant Exhaust 30% CO2

Carbon dioxide (CO2) is the most significant greenhouse gas that contributes to global warming. The dangers of global warming include disruption of global weather patterns and ecosystems, flooding, severe storms, and droughts. A warming climate will also extend the range of infectious diseases. Coal combustion is responsible for more than 30% of total U.S. carbon dioxide pollution.