Hydrocarbons
– The Weapons of Mass Combustion™
There is much debate regarding the need
for energy self sufficiency in the US. The
discussions are also shaded by opinion on the possible problems of global
warming. All this public debate is
for good reason even if the debate is not always well reasoned.
Of course the US should wean itself from imported oil if we want to
improve the environment and reduce our balance of payments deficit.
The problem is difficult to solve not because of lack of discussion but
rather because of fundamental thermodynamics.
Hence, I chose the title Hydrocarbons – The Weapons of Mass Combustion
™ for this article.
First we need vivid analogies to
describe energy content. The sad
truth is no lay person, politician, or most techies can describe the energy
contained in a kilowatt hour in simple terms.
Here are some clearly understood analogies of a kilowatt hour of stored
energy (not necessarily fully recoverable but stored).
A water tank with 1,000 gallons of water on top of a structure or hill
315 feet above the reference point has the potential energy of 1 kilowatt hour.
A 12 volt automobile battery with 83 amp hours of capacity has one
kilowatt hour of stored energy. Now
the kicker 3.1 fluid ounces (80 ccs) of diesel has one kilowatt hour of stored
energy.
From the above analogies one can see
that diesel has massive energy density per unit volume. Volume is the
method by which things are stored in the three dimensional space that we live
within. While many tout the high
energy density of hydrogen per unit mass, the energy density per unit volume of
liquid hydrogen is only one fifth that of diesel.
Forgetting how expensive and inefficient it is to produce and store
liquid hydrogen, it simply makes no sense to store a fuel that contains only 20%
of energy content of another fuel when considering personal or other
transportation vehicles. The space
shuttle jettisons its external hydrogen tanks for this very reason.
This space vehicle would be too large and too heavy if it did not have
throw away hydrogen tanks. I doubt
we can litter the roads with throw away hydrogen tanks for Hummers even if Arnie
likes to say “hasta la vista baby”..
Why does diesel have such a high energy
density per unit volume? The simple
answer is that the carbon hydrogen bond (hence hydrocarbon) when oxidized
(burned) releases substantial energy. The
second part of the answer is also that the specific gravity or density of diesel
is much greater than that of liquid hydrogen.
Diesel is more than 15 times denser than liquid hydrogen and more than
10,000 times denser than gaseous hydrogen.
While the density of our politicians may not be tolerable, high density
of fuels are a desirable quality.
Self service gasoline stations are now
the norm in the US. There is hardly
ever any mention in the news of accidents occurring while the least technical
amongst us fill their vehicle tanks with gasoline or diesel.
The amount of energy transferred into a 15 gallon tank from the diesel
pump equals more than 600 kilowatt hours of stored energy.
The transfer of the 15 gallons of fuel is accomplished in approximately 3
minutes. This implies a rate of energy transfer greater than 12,000
kilowatts or about the capacity of an electrical substation for a housing
development with 8,000 homes. Another
analogy is as follows: If the Hoover Dam’s entire electrical output is used to
fill the kilowatt hours in the fuel tanks of personal vehicles, the Hoover Dam
could simultaneously fill 165 vehicles. These
vehicles would be filled with their energy in 3 minutes.
Therefore 3,300 vehicles could be filled in an hour, or about 2,900,000
vehicles could be filled with their energy in a year.
This is about half the number of vehicles in the San Francisco Bay Area.
I guess we are not going to build two Hoover Dams soon in the Bay Area
just to fill our cars with fuel only once a year.
Methane is another weapon of mass
combustion™. This fuel has 4
carbon hydrogen bonds in each molecule just waiting to release a mushroom cloud
of energy when burned. Methane is 8
times as dense as gaseous hydrogen and as fuels are stored on a volume basis,
methane gas compressed to the same pressure as hydrogen has approximately 3.5
times energy content compared with hydrogen.
We all know, how relatively few vehicles in the US fleet have been
converted to run on compressed natural gas (methane). Compressed
methane in fact is a good candidate for substituting for gasoline or diesel as a
transportation fuel for urban travel, however the logistics are more complicated
and consumer prefer convenience to reduced emissions.
Methane is gaining market share as the fuel of choice for electric power
generation. As the US has no active
policy to include new nuclear power stations in the generation mix, methane has
taken up the challenge of adding generation capacity to the grid.
There will be increased importation of pipelined methane from Canada and
liquefied methane (LNG) transported by the US in specialized ocean freighters.
Methane will continue to play a major role as a weapon of mass combustion
™ well into the future.
Now we come to the heavyweight weapon of
mass combustion™ – Coal. This
carbon compound is a solid and holds a prominent position in our energy mix.
More than 55% of the electric power generated in the US is from coal
fired stations. There is significant interest in coal gasification and ultra
supercritical coal fired power generation stations. These technologies that soon will be widely deployed, produce
electricity more efficiently than older coal fired stations.
Coal is relatively abundant in the US and China and is a likely candidate
for remaining in medal position (gold or silver) in the Olympic stage of weapons
of mass combustion™.
Other heavily carbonaceous fuels such as
tar sands and shale will be extracted in increasing quantities and will perform
that wonderful trick of breaking the carbon hydrogen to release energy to the
energy hungry world. The Chinese
are trading bicycles for Buick Rendezvous SUVs so that they can enjoy the full
energy content of an American lifestyle. Why
not, they too have been allowed in the club that enjoys the security of weapons
of mass combustion ™.
The brave new world does have a few
arrows in our quiver to combat the weapons of mass combustion™.
These are the hybrid drive train, mass transportation, mini personal
vehicles, telecommuting, bicycling, and walking.
There is no doubt that these measures can and will hold back and delay
the date when the stockpiles of the weapons of mass combustion™ are exhausted.
The folly of the modern lifestyle is best expressed in the universal term
of TV Hours ™. The TV Hour ™
not only refers to supposed enjoyment that mankind obtains from watching the 1.5
billion tube TVs that are connected to replays of the Brady Bunch, but also
refers to the universal constant for energy content.
A TV Hour ™ is the amount of energy in electrical form needed to power
a 20” tube TV for an hour. Just
so we can relate energy usage in transportation, my governator Arnie driving his
Hummer 15,000 miles each year uses over 550,000 TV Hours ™ or energy in the
process. Arnie could therefore have
62 TV’s running 24/7 with the replay of that wonderful film “The
Terminator”. I doubt that even
this “Mr. Universe” has enough peripheral vision to take in this amount of
visual stimulation. Even my
favourite vehicle the Toyota Prius driven 15,000 miles per year could power 12
TVs constantly.
By comparison the 2,000 calorie daily
diet, equals one TV running constantly. Having
reduced life to the number of TVs running, I suggest we stop and have a 20 fluid
ounce Venti® sized cup of Starbucks® coffee.
Incidentally, the quantity of energy needed to heat 20 fluid ounces of
water to make the Starbucks® coffee equalled approximately half a TV Hour™.
I guess we will never escape Starbucks®, TVs, or hydrocarbons.
© Lindsay Leveen 2004.