Which laptop is best for losing weight?
by John Lansdale
I started to write an article titled "Power Is Out". I
was going to hypothesize a billion computer geeks like myself
using a computer as much as I do for the next fifty years and
compare. In these times of energy crisis, would there be enough
power for all of us or would we have to fight? I'd get my facts
from the Wikipedia Orders of Magnitude (Energy) page. Smugly,
I presumed in this test of sustainability my own cool little
Asus Eee or XO1, would use so little energy compared to the older
laptops that it would reign supreme. I was surprised by the result.
Actually, the world has enough energy to power either. As computing
goes, power won't be out. A discovery made while researching
proved more interesting.
To do the analysis, I had to first gather all the energy variables
and convert to a common unit of measurement. The International
Standard of Units or SI for energy is the joule. Energy is power
over time. The power SI we understand (and can look up reference
to on the backs of transformers, electric bills, etc.) is the
Watt which equals Amps x Volts. One watt hour is 3600 joules.
Ten watts was a good assumption for the low energy laptop. It"s
the average for either the Asus Eee or OLPC XO. For high energy,
one hundred is about what an older laptop or a smaller energy
efficient small workstation would use. A good serious use for
each user would be fifty weeks per year forty hours a day (at
the computer) for 2,000 hours per year.
A few terms need to be clarified. Order of magnitude" is
just an easy way of understanding big numbers. Numbers are changed
to scientific notation and listed smallest to largest. They're
split into two parts which, multiplied together, give something
close to the original. One is a decimal number usually with just
one or two places so it's easy to read. The other is the power
10 must be raised to in order make the number come out right.
For example the national debt estimated at $9,451,094,214,451
in order of magnitude terms is 9.45 * 10 ^ 12 or since that much
precision isn't needed for comparison of numbers this large 9.5
* 10 ^ 12 is good enough. Another way of writing it is 9.5E+12.
In computer lingo "*" means multiply or "x" and "^" means
raised to the power of or raised-to. I use the term interpolate
somewhat loosely but you'll see it best expresses the idea. In
mathematics interpolation is a method of constructing new data
points within the range of a discrete set of known data points.
Figure 1. Google calc automatically calculates numbers and translates
units.
There are other factors to consider. Energy can’t just
be converted between forms, transmitted and stored without sometimes
large losses mandated by the laws of physics. Also, computer
speed is directly related to power. There is little way around
this. One of these is to replace slow startup hard disk drives
with solid sate drives. Software efficiency is another. Over
time though, restraining speed limits functionality so this example
assumes little hardware innovation. Even so, looking at numbers
this way helps set limits and best and worst cases.
Scenario 1. Brave New World: A billion computer geeks using
high power laptops.
Average power (watts) = 100
Hours per year = 2000
Users = 1 billion (10 ^ 9)
One watt hour = 3600 Joules
Energy requirement = 100 * 2000 * 10 ^ 9 * 3600 = 7.2* 10^17
Joules
Scenario 2. Brave New
World Improved: Same as above, using low energy laptop
Average power (watts) = 10
Energy requirement = 10 * 2000 * 10 ^ 9 * 3600 = 7.2*
10^16 Joules
Interpolate with
other energy magnitudes and compare. A few extra
numbers are included for perspective. Note. My
calculated data is bolded, Wikipedia data isn’t.
7.2 * 10^10 J, the energy consumed by the average U.S. automobile
in the year 2000
7.2 * 10^16 J, 1
billion geeks using low energy
laptops
7.2 * 10^17 J, 1
billion geeks using high energy laptops
7.2 * 10^17
J, energy consumed by 10
million automobiles
3.6 * 10^19 J, 1
billion geeks using high power laptops for the next 50 years
6.25 * 10^19
J, the yearly electricity generation of the world as of 2005
8.01
* 10^20 J, Estimated global uranium resources for generating electricity
2005.
3.9 * 10^22 J, the estimated energy contained in the world's
fossil fuel reserves as of 2003
You can see my presumption was wrong. Laptops,
environmental or not, won't put much strain on the world's
resources. If anything
automobiles are the problem, and while it looks like there's
plenty of nuclear power for laptops, there isn't much compared
to the amount automobiles use!
Another number in the “order of magnitude” table
really caught my eye. By generating power ourselves for our laptops
with a hand crank or bicycle generator device or something we
could lose weight. It is 4186 Joules = 1 Calorie (or kcal, commonly
used for food, not to be confused with “calorie”).
Scenario 3. Brain New World: Exercise per day charging a low
power laptop with a mechanical device.
Power to charge (watts) = 20
Hours = 4
Users (me) = 1
One watt hour = 3600 Joules
Energy requirement burned in a day =
20 * 4 * 1 * 3600 = 2.88 * 10 ^ 5 Joules or 69 Calories
Some more magnitude numbers from the low end of the Wikipedia
list are needed.
1.7*10^4 J, the energy released by the metabolism of one gram
of sugar or protein
3.8*10^4 J, the energy released by the metabolism
of one gram of fat
5.0*10^4 J, the energy released by the combustion
of one gram of gasoline
7.2x10^5 J, the energy used to
charge a low energy laptop
6.3*10^6 J, the recommended nutritional intake
per day for a woman not doing heavy labor
8.4*10^6 J, the recommended
nutritional intake for a man
My final and most significant discovery came from Wikipedia
Orders of Magnitude (power) All this calculation can be avoided.
Time is the real enemy of weight loss. Small improvement over
long periods is most effective. Thinking (not so much the Calories
but the lessons) fits this category. Both fears of world energy
Armageddon and high cholesterol can be assuaged by increased
thought alone. The brain is the best laptop.
Scenario 4. Brain New World Improved: Thinking all day and night.
Approximate power consumption of the human brain (watts) = 20
Hours
per day = 24
Users = 1
Energy burned in a day = 1.7 * 10^6 Joules or 413 Calories
Some nit-picker's have probably noticed a few flaws in this
reasoning. For example, mechanically charging a laptop four hours
a day only yields two of computing, in the electricity scenario
there are eight. And, someone mechanically charging a laptop
must also be thinking 24 hours .. or not which is my point. I’ve
shown you a few tools, you’ve got a computer, and now it’s
your turn.
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