This IPython notebook demonstrates a energy calculations for the analysis of an infrastructure for transportation fuels.
#Initializations
from IPython.core.display import HTML
HTML(open("../styles/custom.css", "r").read())
Are electric cars 'greener' than other vehicle technologies? That's a question that appears frequently in the popular press (see here and here, for example), and one that we should be able to address through basic material and energy balances. In fact, we can extend the analysis to examine alternative vehicle energy technologies.
Assume that natural gas produces heat through the combustion reaction
$$CH_4 + 2\,O_2 \longrightarrow CO_2 + 2\,H_2O$$for the generation of electricity in a combined cycle turbine at a net heat rate of 6,300 BTU/kwh. (that is, the net generation of 1 kwh requires 6,300 BTU of natural gas at its higher heat value). The higher heating value of natural gas is 52.225 MJ/kg.
HR = 6300 # BTU/kwh
HHV = 53.225 # MJ/kg
HR = 0.001055056*HR # MJ/kwh
mCH4 = HR/HHV # kg/kwh
nCH4 = mCH4/16.01 # kg-mol/kwh
nCO2 = nCH4
mCO2 = 44.0*nCO2
eCO2 = mCO2/(0.935*0.60) # kg CO2/brake-kwh
mCH4,eCO2
(0.12488215688116486, 0.6117850700232199)
Ash-free and moisture-free
Per kilogram
mC = (1 - 0.235)*0.813
mH = (1 - 0.235)*0.053
mO = (1 - 0.235)*0.098
mC,mH,mO
(0.621945, 0.040545, 0.07497000000000001)
HR = 0.001055056*10350 # MJ/kwh
GHV = 2.20462*0.001055056*12000 # MJ/kg
mCOAL = HR/GHV
mCO2 = (44.0/12.0)*mCOAL*((1-0.235)*0.813)
eCO2 = mCO2/(0.935*0.6)
mCOAL,eCO2
(0.39122388438823924, 1.5903250900381922)