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Calculations
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The numbers and formulas that we used in making the calculations we display at the top of our webpages were determined as follows:
PRIZE MONEY |
Total Prize = Number of bulbs sold x $.10
Grand Prize = 1/2 of Total Prize
State Prize = 1/100 of Total Prize (one for each state) |
| TOTAL KWH SAVED OVER LIFETIME OF BULBS |
Avg Bulb Savings = 62 watts/bulb (average of 13/23 watt CFL vs. 60/100 watt incandescent)
Avg Bulb Lifetime = 8000 hours
1 kwh = 1000 watt hours
Total Bulb Lifetime KWH Saved =(Number of Bulbs x 62w x 8000hr) / 1000 |
TOTAL MONEY SAVED OVER LIFETIME OF BULBS
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Average national cost of kwh = $.092
Total Bulb Lifetime Savings = Total KWH Saved x .092
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| AMOUNT OF COAL SAVED |
Percentage of electricity generated by coal = 52%
KWH produced per ton of coal = 2460
Amount of coal(tons) = Total KWH x .52 / 2460 |
| AMOUNT OF NATURAL GAS SAVED |
Percentage of electricity generated by natural gas = 15%
BTU's of gas burned per kwh produced = 8571
Amount of BTU per cu ft gas = 1000
Amount of natural gas for 1 bbl oil equivalent = 5800 cu ft
Total Natural Gas saved in bbl equivalent = ((Total KWH x .15) x 8571 / 1000) / 5800
(Note: we combine oil and natural gas in barrel equivalents)
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| Amount of Oil Saved |
Percentage of electricity generated by oil = 3%
Number of bbl of oil to produce 1 kwh = .0018
Total Oil saved in bbl = (Total KWH x .03) x .0018 |
| Pollution |
CO2 by coal = 2.249 lb/kwh
CO2 by gas = 1.135 lb/kwh
CO2 by oil = 1.672 lb/kwh
SO2 by coal = .013 lb/kwh
SO2 by gas = .0001 lb/kwh
SO2 by oil = .012 lb/kwh
Average Miles driven/car by passenger car: 12,500 miles
CO2 emission per mile = .916 pound
Average CO2 emission per passenger car per year = 11,450 pounds
Pounds of CO2 sequestered by 1 acre of trees = 7,333 pounds
(Source: U.S. EPA, 2000)
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