This spreadsheet allows you to enter in your monthly consumption of gasoline, electricity, natural gas therms, and miles travelled by various forms of transportation. For each type of consumption of energy, the spreadsheet will calculate the equivalent amount of energy in terms of gallons of gasoline. Click here for an explanation of the calculations. This spreadsheet will also calculate the total amount the user should contribute to the dime-a-gallon fund given a commitment of $.10 per equivalent gallon of gasoline.
It’s OK to estimate when you don’t know exact numbers.
All formulae give the equivalent of $0.10 per gallon of gasoline for all forms of fossil fuels, based on the energy content of each fuel.
The formulae for air, bus, and train travel are based on current average load factors (70% for air, 66% for intercity bus (like Greyhound), 20% for intra-urban bus (like AC Transit), 36% for Amtrak, and 50% for BART). For more accurate results, charge yourself less if your plane, bus, or train was fuller than these averages, and charge yourself more if it was emptier.
1. Gasoline - actual fuel use.
2. Ride-share travel - when you ride in a carpool or take taxi; you didn’t buy the gas, but you know how far you traveled. Average US passenger fuel efficiency in 2000 was 22 mpg (Bureau of Transportation Statistics, National Transportation Statistics, 2002 – www.bts.gov/publications/national_transportation_statistics/2002/). If there are four passengers, 4 x 22 = 88 pmpg, or 1.1 gallons per 100 passenger miles @ $0.10/gal = $0.11 per 100 miles.
3. Commercial air travel: assumes modern jets achieve 40 passenger
miles per gallon (pmpg) at average 60% load factor:
40 pmpg = .025 gallons/passenger-mile.
(Airline industry claims average 38 pmpg. BTS year 2000 reports 49
seat-miles/gallon domestic and 46 seat-miles/gallon international, 71%
load factor domestic and 75.9% load factor international (yielding
about 35 pmpg)).
4. Intercity bus travel: uses American Bus Association 160 pmpg at
66% average load factor:
160 pmpg = .006 gallons/passenger-mile.
2.6 billion miles/498 million gallons = 5.2 pmpg = 240 pmpg for 100%
load factor (average 46 seats), implying current average load factor is
160/240 = 66%.
5. Intra-urban bus travel: uses Bureau Transportation Statistics
4147 BTU/passenger-mile and 138,700 BTU/gallon, yielding 33.4 pmpg =
.030 gallons/passenger-mile.
BTS also reports average gas mileage for all buses was 6.8 mpg in 2000.
City/highway mpg were not reported separately but presumably vary. At 5
mpg and 40 passengers, 200 pmpg is possible, implying an average load
factor of less than 20% for city buses.
6. Train travel: uses Bureau Transportation Statistics AMTRAK 2134 BTU/passenger-mile and 138,700 BTU/gallon, yielding 65 pmpg = .015 gallons/passenger-mile. Amtrak reports 108 pmpg at 60% load factor for Pacific Northwest route, so 65 passenger miles/gallon implies 36% load factor (1970 Amtrak load factor was 35%).
7. BART travel: assumes same energy intensity as AMTRAK trains but
powered by electricity with 50% load factor, yielding about 90 pmpg.
90 pmpg * (0.6 generated from fossil fuels) x (3 fossil
fuel-to-electricity conversion) = .016 gallons/passenger-mile.
8. Walking and bicycling: no direct fossil fuel use (0 gallons/pasenger-mile). Later refinement could consider food calories.
9. Natural gas: therms x (10**3 cubic feet/10.2 therms) x (1.138 x 10**6 Joules/cubic foot of natural gas) x (1 gallon gas / 1.318 x 10**8 Joules) = .846 gallons/therm.
10. Electricity: kilowatt-hours x (0.6 generated from fossil fuels) x (3 fossil fuel-to-electricity) x (3.6 x 10**6 Joules/kilowatt-hour) x (1 gallon gas/1.318 x 10**8 Joules) = .049 gallons/kilowatt-hour
Question: I just see a gray square instead of the calculator. I have
a Mac with OS 9.1, and I use Internet Explorer.
Answer: Upgrade to Mac OS X. It's great. That includes the required
version of Java 1.4.
Question: I see only a gray square and I run Windows 2000 and I use
Internet Explorer.
Answer: Go to http://java.com/en/index.jsp and download and install the
latest Java runtime (click the "Get it now" button).
In Internet Explorer, go to tools/Internet Options, select the
"Advanced" Tab, scroll down and check "Use Java 2 v1.4.2_01 for applet
(requires restart), check "Java console enabled", check "Java logging
enabled". Restart Internet Explorer.
Question: Can you make a servlet so that the dimeagallon calculator
can be used by people who don't have Java installed on their computers?
Answer: Yes, I'll do it if there is enough interest.