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How We Calculate
Carbonfund.org’s Carbon Calculator uses information from the US Department of Energy’s Energy Information Agency and other sources to develop an accurate assessment of carbon dioxide emissions emitted per energy type or use. (By the way, the EIA maintains an excellent website with easy-to-understand and easy-to-access figures about all things energy related. We recommend you check it out at: www.eia.doe.gov.)
Residential
Electricity – From 1998–2000, the average US emissions of CO2 from electricity generation was 1.34 lbs per kWh, or .000606 metric tons per kWh. While state figures vary, we have chosen the national average in order to best represent all of our supporters (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program).
US Avg.: In 2004, retail electricity sales totaled 3,548 billion kWh. Of this, the residential sector was responsible for 1,294 billion kWh. There were about 294 million people living in the US then, making the US residential average annual consumption 4,401 kWh per person. (Sources: Energy Information Agency, US Census Bureau)
Natural Gas – There are 12.0593 pounds CO2 per CCF of natural gas. We multiply 12.0593 by the number of CCF consumed annually and divide by 2,205 to get metric tons of CO2 (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program).
US avg.: In 2005 62.5 million households used natural gas. Collectively, they used 4,838 billion cubic feet of natural gas annually, or 774.08 CCF (approximately 812 therms) per household or 296.58 CCF (approximately 311 therms) per person per household using natural gas. (Source: Energy Information Agency, US Census Bureau)
Heating Oil – There are 22.384 pounds of CO2 per gallon of heating oil (diesel fuel). We multiply 22.384 by the number of gallons of heating oil consumed annually and divide by 2,205 to get metric tons of CO2 per gallon. (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program).
US avg.: In 2004, 5,997 million gallons of heating oil were consumed by 8.1 million households, resulting in an average of 740.37 gallons per household or 283.67 gallons per person per household using heating oil. (Source: Energy Information Agency (volume, households)
Transportation
Vehicles – Unleaded gasoline has 8.87 kg (19.56 lbs) of CO2 per gallon. By dividing number of miles driven by miles per gallon, we get the number of gallons of gasoline consumed annually. We multiply this by 8.87 and divide by 1,000 to get metric tons of CO2 (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program).
US avg.: Automobiles fuel efficiency (MPG) varies widely so averages are not all that useful. It is useful for you to have an idea of your own car’s fuel economy. The average fuel economy for cars sold in 2005 is about 25.2 MPG (Source: National Highway Traffic Safety Administration). The Department of Transportation’s MOBILE 6.2 model, used by regional governments to model air quality, uses a fleet average (all cars, old and new) of 20.3 mpg. (Source: EPA)
Metric users: To convert liters per 100 km, the metric standard, to CO2, do the following: kilometers per year * 0.62 and enter it in the miles driven per year box. There are 3.79 liters per gallon. Hint: 7.58 l/100km = 30mpg.
British users: Take your MPG and multiply by .83 to get US MPG (Source: Digital Dutch web converter).
In 2001, the average distance driven by US drivers was 13,785 miles (Source: Federal Highway Administration, page 41).
Air Travel – CO2 emissions in air travel vary by length of flight--ranging from .24 kg CO2 per passenger mile for short flights down to .18 kg CO2 per passenger mile for long flights. Our new calculator (as of April 2007) allows the user to take the issue of radiative forcing into account. (Sources: Emissions factor based on 2006 data collected in the United Kingdom available from the The World Resources Institute. For more information on air travel-related radiative forcing, please see this IPCC document).
US avg: We do not have accurate figures for numbers of miles flown per flyer in the United States. Using per capita figures would be misleading because not every person flies. We would welcome any information that would help us determine an accurate average.
Total US CO2-equivalent Emissions
Total US emissions were 7,122 million metric tons CO2-equivalent in 2004. Dividing by the US population of 299 million, this equals 23.8 metric tons of CO2-equivalent per person. (Source: Energy Information Agency, US Census Bureau)
