Introduction - Mathematics and Statistics for the Environment - page 31

1.7.5.1 Calculation
Due to rounding, performing the calculations given in the equations below may not return the
exact results shown.
(5.80 mmbtu/barrel) × (20.31 kg C per mmbtu) × (44 g CO 2 per 12 g C) × (1 metric ton/ 1000 kg)
= 0.43 metric tons CO 2 per barrel.
1.7.6 t anKer t ruCKs F illed With g asoline
Carbon dioxide emissions per barrel of gasoline are determined by multiplying the heat content
times the carbon dioxide coefficient times the fraction oxidized times the ratio of the molecular
weight of carbon dioxide to that of carbon (44/12). A barrel equals 42 gallons. A typical gasoline
tanker truck contains 8500 gallons. The average heat content of conventional motor gasoline is
0.125 mmbtu/gal, and the average carbon coefficient of motor gasoline is 71.35 kg CO 2 ( USE PA ,
2012). The fraction oxidized to CO 2 is 100% (IPCC, 2006).
1.7.6.1 Calculation
Due to rounding, performing the calculations given in the equations below may not return the
exact results show.
(0.125 mmbtu/gal) × (71.35 kg CO 2 per mmbtu) × (1 metric ton/1000 kg)
= 8.92 × 10 -3 metric tons CO 2 per gallon.
(8.92 × 10 -3 metric tons CO 2 per gallon) × (8500 gal per tanker truck)
= 75.82 metric tons CO 2 per tanker truck.
1.7.7 h ome e leCtriCity u se
The U.S. Department of Energy's Residential Energy Consumption Surveys defines a single-family
home as follows: A housing unit, detached or attached, that provides living space for one home or fam-
ily. Attached houses are considered single-family houses as long as they are not divided into more than
one housing unit and they have an independent outside entrance. A single-family house is contained
within walls extending from the basement (or the ground floor, if there is no basement) to the roof. A
mobile home with one or more rooms added is classified as a single-family home. Townhouses, row-
houses, and duplexes are considered single-family attached housing units, as long as there is no home
living above another one within the walls extending from the basement to the roof to separate the units.
In 2009, there were 113.6 million homes in the United States; of those, 71.8 million were single-family
detached homes and 6.7 million were single-family attached homes for a total of 78.9 million single-
family homes nationally (USEIA, 2009). On average, each single-family home consumed 11,319 kWh
of delivered electricity. The national average carbon dioxide output rate for electricity generated in
2009 was 1216 lb CO 2 per megawatt-hour (USEPA, 2012), which translates to about 1301 lb CO 2 per
megawatt-hour for delivered electricity (assuming 7% in transmission and distribution losses). Annual
single-family home electricity consumption is multiplied by the carbon dioxide emission rate (per unit
of electricity delivered) to determine annual carbon dioxide emissions per home.
1. 7. 7.1 C a l c u l a t i o n
Due to rounding, performing the calculations give in the equations below may not return the exact
results shown.
(11,319 kWh per home × 1301.31 lb CO 2 per megawatt-hour delivered)
× (1 mWh/1000 kWh) × (1 metric ton/2204.6 lb)
= 6.68 metric tons CO 2 per home.