Some Timely and Time Saving Observations Concerning
Gasoline, Solar Power, and Horses (horsepower),Zebras (zebrapower) 

 Using conversion factors found in an old hydraulics book, some data on a covert 
 government website and assuming zebras are just horses with a striped attitude, 
 let us establish the conversion between gasoline and horsepower-hours:


Step 1-Establishing Zebra - Gasoline equivalency
 If you have 100% efficiency and as many books would suggest 
 one gallon is about 140000 Btu/gal, converting you would get about
 55 Horsepower-hrs/gallon (this is an optimistic estimate based on U.S. gallon).
 This means one gallon of gas is the equivalent of:
		2 zebra days with one zebra working 24hrs/day for two days at 
		100% efficiency or
		a wishful 6 zebra days if zebras would work 8 hrs days and then shut off.... They don't.
In truth, we have over estimated because zebras don't stop metabolizing when 
they are asleep (as per most non-theoretical animals, e.g. crocodiles), they 
can't work a 24 hour day.  And worse, their metabolism is less than 50% efficient so you only get
about 1/6 as much work as you would hope.  To keep things simple, however we will grant that
error and say:
1 gallon of gas is about 55 HP-hours(mechanical) or about 2 zebra days, 55 ZP-hrs
hours (actual zebras) based on a 100% efficiency, 24 hour wonder zebra.
We can call this the gasoline zebra equivalence. Although the truth is you only get about
only about 10 ZP-hours :(
Factoid: Zebras have been used to farm in Africa because of their immunity to disease.
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Step 2. Dispelling the myth of the 300 mile per gallon car (LOL).
This is a matter of calculating force times distance to find the energy consumed or the force times 
velocity to calculate power!  Assume a car has a 5ft x 5ft profile pushing the wall of air in front
of it to 55 mph, we can calculate the approximate zebra power needed to do this 
based on pressure and velocity using

Bernoulli's formula with appropriate conversion factors as a first approximation (see wikipedia etc.):

P/(0.433*ϒ)=v^2/2g    P=pressure in psi, v=velocity in ft/sec, g=acceleration
                      of gravity in ft/sec^2, about 32.2ft/sec^2.

My wife would laugh, I couldn't remember the approx. molecular mass of air so I used
nitrogen (close at 28). This means the approx. density(ϒ) of air at STP 
(Standard Temperature and Pressure) is, in gm/cc,
			28gms/22400cc=0.00125gm/cc  

Next convert speed to ft/sec using the factor label system:
v=55mi/hr*(hr/3600sec)*(5280ft/mi)=80.66ft/sec

Therefore, completing the Bernoulli calculation, the pressure roughly would be:       
p=.433*.00125*80.66*80.66/(64.4)=0.0546 lb/in2

Since we know the pressure and the area we can estimate the force.
Or, if you want to do this right, hire Arnold Shwarzenegger to hold a bathroom scale and
a 5'x5' piece of plywood out the window of your car! Using Pascal's formula:
F=P*A=    (.0546*60*60) ≈ 196 lbs of force on that 5'x5' piece of plywood (Thanks Arnold!)     

Knowing the force and the speed we can now estimate the horsepower zebrapower:
ZP=(lbs*Vft/sec)/550=196*80.66/550=28.74 ZP
At one hundred percent efficiency, traveling 55 mph would take 28.74 ZP 
(roughly 30 zebras if you could actually get them in your car).
Total hours for one gallon of gas at about 55 hp-hrs/gal is estimated as
 55/28.74=1.91hrs or 105 miles if traveling at 55 mph.
With 100% maximum mechanical efficiency you only get 105 mpg at 55 mph,
and this does not include road friction which increases with weight and tire compliance.
Note a delightful conclusion: %efficiency is roughly miles/gallon 
===============================================================
Hence, unless you reduce your wind profile, the best you will ever get for mileage at 55mph

 is about 105 miles/gal..

 not 150, not 300.  Leave it to those foolish crocodiles!! Maybe scared zebras do better!
===============================================================
I used to drive about 25 miles to work at about 55 mph.  This same trip using a striped 
horse and avoiding crocodiles at 3-4mph would take about 8hrs.  Then assuming I drove 
home the next day that would be another 8hrs.  Since I actually take about 10 such trips 
per week for 10 gallons of fuel I'm not doing too bad even though I'm only getting 25 mpg (25% efficiency).
 (and my non-striped Chevy isn't tired, or drinking gasoline at night, or eaten by crocodiles, and I get
some work done, I'm not on the road 16 hours/day, plus I don't get those pesky saddle-
sores from riding all day, whew)!!  To be honest, you would have to swap ponies like the old west.
Restating our original analysis then, one gallon of gas gives me the use of about two
good domesticated zebras for about one very long troublesome crocolicious day, about 50 ZP-hours!!
============================= Eez Reel News Bureau file photo ===========================
Factoid: Many Amish farmers, like former President Bush shown on his ranch in Crawford, Texas shown below,
have plowing teams of 6 to 8 animals. 
Step 3- Dispelling the myth of solar powered tractors and going back to horses for farming
Now comes the fun part, suppose I want to do farming with old stripey dobbin but 
my neighbor convinces me to use solar power because of his sensitivity to Z vapors. 
Sunlight provides about 1kw/m^2 but with a solar array of ten percent efficiency 
I only get 100W.  To get the utility of one zebrapower I need 746 watts or translating
this into solar panels I need about 8 square meters (about 6ftx12ft).  So I build 
a solar powered tractor, I go to the store and get a 
hydraulic pump, a gear reducer, a battery, a big electric motor, a titanium trailer, 
a bunch of hoses, valves, etc.  I weld up a 3 point hitch and a single point plow and I go for it.  
Too slow, one horse pulling a shallow plow.  So now I double my solar array and I am 
starting to look like a caterpillar going across the field, but I'm still going pretty 
slow, a 6 by 24 foot trailer of solar panels.  So I go back to my HP formula 
and I crunch the numbers: 

1000 lbs of force*10ft/sec/550=18 HP ZP.  That's a lot of striped beasties or a whole 
caravan of pretty expensive solar panels. So, yes I can save my neighbor from the
vapors but I'm going to need weeks to plant my fields.  Maybe if we add that super GPS
tracker computer for a zillion$ to guide the whole thing we won't have to sunburn
ourselves so bad.  Or maybe we can charge the batteries from a panel array, this works but
you don't want to figure the size of the battery, huge. Consider the following estimates 
of farm HP-hrs to till a field
( From: http://www.ext.colostate.edu/PUBS/FARMMGT/05006.html).
With 24 hp-hrs to plow one acre (at 100% eff.), 100 acres would take between 50 and 200 gal of gas 
and up to 100 hours.  Our solar contraption might need 600 hours, roughly 100 days!!
For heaven sakes that must be wrong! To plow 8" deep with 25% efficiency, my 3HP rototiller
for example will do 1/16 acre in 2 hours (32hrs/acre) or 100 HP-HRS/acre at about
8 gallons of gas/acre (hmm, lovely!!!4 times as much as a regular tractor at 2 gallons/acre).
Who knew Colorado State might actually know their stuff?!! And it looks like I may need 
to tune up the old rototiller engine (But I already knew that!).
==================================================================================
As was just so miraculously discovered, Like driving where you don't get 105 mi/gal,
you also don't get 100% efficiency in plowing either.  If you want to know why hamburgers
became so popular in this country try spending the next 100 days behind a zebra, or
25 days behind 4 zebras!! Cows and grazing animals can save our farmers and farmgodesses
a lot of work and a lot of wear and tear on old Dobbin and friend!! Any body jewelry, 
however, that you apply to your zebra, ear rings, eyelid piecings, etc. no matter
how beautifully hand crafted, after 100 days they just fall off on the 
ground, causing the "anything zebra" avaricious crocodiles to eat the jewelry, and
this could drive up your bill and require prompt crocodile veterinary 
attention..   Unfortunately, this is the third ear ring they've eaten this week...... 
Our next installment: "The Chronic Need for New Reptile Veterinary Students" or 
"Talking your Zebra out of the need for body jewelry".  

Step 4- Interconverting

There is an obvious trade off between time and horsepower. You can now do the math. Take any of 
the tasks above and multiply the gas usage by 55. This give you the actual horsepower hours.  You can 
either up the hours or up the horsepower to achieve that task.


Note if you take that middle column, hp-hours, this would seem to equals the number of horses 
(or zebras) times the number of hours so you could plow but unfortunately this is at the PTO
(power take off) after a slew of inefficiencies, so you would have to multiply by 5.>>>> 
1 acre in five hour with 24 horses, or 
1 acre in 20 hours with 6 horses, or 
1 acre in fifteen days with one horse!!! etc. 

The point is it takes a lot of hungry furry beasts.
The alternative is to not plow so deep or to not use furry beasts at all.  Imagine now your
typical grain farmer doing 5000 acres.  Either he has a very large extended family or he uses 
gasoline!!