"Given that each Volvo has two 50 watt headlamps and two 30 watt tail lights, how much gas would you save if a law banning having your headlights on in broad daylight was brought in? 746watts = 1 horsepower"
Resources:
--------------
Car math: Fuel consumption
Units of measure conversion: Lbs to gallons
We know:
--------
SFC: Specific Fuel Consumption measures the amount of fuel needed to provide one horsepower for a period of one hour, typically in lbs of fuel burned.
Typical gas engines have an SFC of 0.51lbs/hp.
A Volvo uses (2 * (50 + 30)) / 746 hp to sustain the lights.
This means:
---------------
A Volvo would burn (0.51 * 160) / 746 lbs of fuel per hour to sustain the lights. This works out to 0.10938337801608579088471849865952 lbs of gas per hour.
Converted to gallons:
-------------------------
One US gallon of gas weighs about 6 lbs (depending upon its temperature).
So, if we divide 0.10938337801608579088471849865952 by 6 we get 0.018230563002680965147453083109833 gallons consumed per hour per Volvo.
First assumption:
-----------------
I don't really know how many US cars are on the road during the daytime or how many of them have daytime running lights or what their average watts are. But, I can show that if all the cars in the US were Volvos and all on the road for one hour what they'd consume in fuel.
The numbers:
----------------
135,921,000 cars * 0.018230563002680965147453083109833 gallons of fuel per hour yields:
2,477,916.3538873994638069705093717 gallons of gasoline per hour
$4,336,353.62 gas dollars per hour (at $1.75)
5,229,773.2092095868080348121303301 gallons of crude oil 124,518.40974308540019130505072214 barrels of oil PER HOUR $5,229,773.21 oil dollars per hour (at $42 per barrel of oil)
In English
------------
It would cost the US 5 million dollars per hour in oil and 4 million dollars per hour in gas to pay for the daytime running lights in 135.921 million Volvos.
Assumption two:
---------------
The total miles driven per year in the US is: 1,658,640,000,000
If we divide that by 85mph and 35mph we get a low and high estimate for the number of hours spent driving:
19,513,411,764.705882352941176470588 hours at 85mph
47,389,714,285.714285714285714285714 hours at 35mph
Earlier we worked out a figure of 0.018230563002680965147453083109833 gallons per hour to maintain the lights.
Multiplying yields these figures for one year:
At 85mph
------------
355,740,482.57372654155495978550469 gallons of gas
$622,545,844.50 gas dollars (at $1.75)
750,809,058.69831732388483974830087 gallons of oil
17,876,406.159483745806781898769068 barrels of oil
$715,056,246.38 oil dollars (at $40 barrel)
At 35mph
------------
863,941,171.96476445806204519336883 gallons of gas
$1,511,897,050.94 gas dollars (at $1.75)
1,727,882,343.9295289161240903867377 gallons of oil
41,140,055.807845926574383104446135 barrels of oil
$1,645,602,232.32 oil dollars (at $40 barrel)
So, it is reasonably safe to estimate that the US would spend between 715 million and 1.645 billion oil dollars per year if every car had daytime running lights (or between 622 million and 1.5 billion gas dollars). Since lights are necessary at night, the savings would be equivalent to computing only the daytime usage. I don't know that statistic, but I would guess about 70% of our driving is daytime driving (which still yields a figure between $500.539372 million and $1.151921562 billion dollars).
It is also important to note that these figures are for cars only and do not include motorcycles, trucks, light trucks, airplanes, or other forms of conveyance.
Pretty surprising isn't it?
No comments:
Post a Comment