Methane production is increasing with the advent of new drilling technologies. T
ID: 235547 • Letter: M
Question
Methane production is increasing with the advent of new drilling technologies. There is much debate in scientific literature about the environmental impact of burning natural gas (methane) vs. coal. In the US we use approximately 4,000 TWh (1 TWh = 1012 Wh) of electricity per year.
a )Calculate the lbs of CO2 released when creating this electricity with coal-fired power plants with an average efficiency of 40%. (9.7 x 1012 lb CO2)
b) Calculate the lbs of CO2 saved when increasing the average efficiency of the power plants to 48%.
c)What are the equivalent miles driven per car per year in the US? Assume there are 250 million cars in the US and the average mpg is 24.8. Assume the density of gasoline is 6.15 lb/gal with a molecular formula of C8H18. (8320 miles/year-car)
d)Calculate the lbs of CO2 produced if all the electricity came from natural gas power plants. Assume an efficiency of 38%.
e) The argument in the scientific literature is that methane leaks during the production of electricity. Assume that the heating content of 1 kg of natural gas is 15.4 kWh. This methane has a Global Warming Potential of 23. Calculate the new lbs of CO2 produced (including CO2 equivalents) if 8% of the methane leaks in the production of electricity. (6.5 x 1012 lb CO2)
Explanation / Answer
a.Since average lbs CO2 /kw of electicity=1.054
Now to produce 4000 Twh i.e. 4*10exp12 kwh electricity CO2 released
= 1.054*4*10exp12
=4.216* 10exp 12
since efficiency is 40% of CO2 produced=
4.216*10exp12-1.684*10exp12
=2.532* 10exp12 lbs CO2/released
b. Co2 produced = COz released+ CO2 saved
Since average of lbs Co2 produced/ kw of electricity=1.054
To produce 4000 Twh of electricity
=4.216*10exp12
Since efficiency is increased to 48%
=4.216*10exp12-2.02exp *10exp12
=2.196*10exp 12 Co2 released
then CO2 saved= total CO2 produced - CO2 relaeased
4.216*10exp12-2.196*10exp12
=2.02*10exp12lbs/kw CO2 saved
d. average CO2 in g/kw produced in generating electricity from natural power plants=465
So to produce 4000 twh i.e.4*10exp12 of electricity required CO2
=465*4*10exp12
=1860*10exp12g/kwh=4.1lbs*10exp12 CO2
If efficiency is 38%
=1.558 *10exp12lbs CO2 produced