The Energy Justifies the Means, I An Old Exam Question
Everyone knows that energy is essential to our economy and is directly
or indirectly responsible for foreign policy woes. What some may not know
is how an oil war can be waged by someone claiming to have the moral high
ground. Thinking about the Nixonian philosophy, "the ends justifies the
means", I started thinking about energy and an old exam question I wrote
for my freshman, UM Environmental Geology class. The exam question is cynical,
but is intended to promote energy awareness.
In class, I had students ride an exercise bicycle hooked to an electric
power generator hooked to a bank of household light bulbs (borrowed compliments
of the UM physics department. Thank you, Warren!). My students can verify
that illuminating a 25-watt lightbulb for 2 minutes is quite a bit of exercise.
Now granted, there are considerable energy losses converting those calories
into kinetic energy into electrical energy into light energy, but that's
the whole point!
Energy is sold in units of kilowatt-hours. I don't like the unit for teaching
purposes because it confuses the unit of power, that is energy delivered in
a unit time, the Watt, with the unit of energy, the Joule. One has to keep
in the back of one's mind that for units, E = P t. For this reason, on a
2 point multiple choice question, I provided a bit of "explanatory" which
may seem intimidating to a freshman exam taker. Don't be intimidated, work
the problem. The answer and the political point will follow in the next section:
#8. Explanatory: It has been cynically suggested that human slavery did not end because of higher human consciousness, but because slaves could be replaced by machines after the Industrial Revolution. If true, this would make William "Strata" Smith the great emancipator, rather than Abraham Lincoln. In class, two minutes on the exercise bike illuminating a 25-watt lightbulb produced 25 watt-2minutes of energy. If this exertion could be sustained 6 times per hour for 10 hours a day, a human can produce 3000 watt-minutes of energy (3 kilowatt-minutes) each day, which is the same as 0.05 kilowatt-hour each day.
Problem:
If an electric bill was $33.60 for a 30-day month, and the cost is $0.07 per kilowatt-hour, what is the average daily amount of energy consumed in kilowatt-hours? What is the equivalent number of humans needed to produce this energy, assuming each human can produce 0.05 kilowatt-hour each day?
(A) 2 kilowatt-hours ... 40 humans
(B) 16 kilowatt-hours ... 320 humans
(C) 20 kilowatt-hours ... 350 humans
(D) 480 kilowatt-hours ... 1000 humans
The Energy Justifies the Means, II The Point
(B) 16 kilowatt-hours ... 320 humans
This fact bashes every idealistic President to ever take office. Now take
Cheney and Bu$h. They know this. They think you don't know this. They view
it as their moral imperative (and political future) to provide this country
with their energy.
But do not despair. You should know: this is not your grandfather's energy crisis! There are amazing breakthroughs occurring in alternative energies. I will plug one: the Solar constant is 1368 W/sq. meter of which the Earth receives, on average over it's whole surface (the Earth's profile is 1/4 of it's surface area), 342 W/sq. meter, a tremendous amount of power. Granted, not all of this is available for our use, but the breakthroughs in solar technologies are making solar power competitive, even in foggy San Francisco!
http://www.powertothepeople.org/features/sfvotesolar.shtml
[ Original AP stories available in the archive sections of http://www.washingtonpost.com and http://www.nytimes.com for a fee. ]
For more information on sustainable energy, please read the letter from
Scientists for a Sustainable Energy Future:
http://www.bu.edu/cees/openletter.html
The Energy Justifies the Means, III Sources of Energy
I hope the attached table explains why energy issues are so contentious.
I hope the solar calculation shows that it doesn't have to be like this.
Please read the Open Letter from Scientists for a Sustainable Energy Future:
http://www.bu.edu/cees/openletter.html
Just what are we willing to sacrifice for energy?
The table is space delimited and is 90 cols wide:
Daily household electric consumption (see footnote 1)
= 16 kW-hr = 320 humans
Daily (day + night), world-averaged, albedo-adjusted
solar energy incident on a 80 sq meter rooftop
solar panel on a double-wide (see footnote 2)
= 460 kW-hr = 9,200 humans
860 Diet calories
= 1 kW-hr = 20 humans
1 gram sugar (see footnote 3)
= 0.00459 kW-hr = 0.0918 humans
1 page paper assumed equal 3 g sugar
= 0.0138 kW-hr = 0.275 humans
1 barrel (42 gallons) crude oil = 5.80E+06 Btu*
= 1,698 kW-hr = 33,968 humans
1 Geneva Convention (657 p)
= 9 kW-hr = 180 humans
1 Enron stock certificate (1 p)
= 0.0138 kW-hr = 0.275 humans
1 barrel (42 gallons) home heating oil = 5.83E+06 Btu*
= 1,707 kW-hr = 34,143 humans
1 copy of Beethoven's 9th Symphony (43 p)
= 0.592 kW-hr = 12 humans
1 barrel (42 gallons) gasoline = 5.25E+06 Btu*
= 1,537 kW-hr = 30,747 humans
1 U.S. Constitution (4 pages)
= 0.055 kW-hr = 1 humans
1 gallon of gasoline = 1.25E+05 Btu*
= 37 kW-hr = 732 humans
1 U.S. Bill of Rights (1 page)
= 0.0138 kW-hr = 0.275 humans
1 barrel (42 gallons) jet fuel (kerosene) = 5.67E+06 Btu* =
1,660 kW-hr = 33,206 humans
1 wall-sized Guernica by Pablo Picasso (estimated)
50 kW-hr = 1,000 humans
1 barrel (42 gallons) motor oil = 6.29E+06 Btu*
= 1,842 kW-hr = 36,837 humans
1 Emancipation Proclamation (1 page)
= 0.0138 kW-hr = 0.275 humans
1 gram fissioned U-235 = 7.40E+07 Btu*
= 21,669 kW-hr = 433,382 humans
1 The Scream by Edvard Munch (estimated, includes frame)
3 kW-hr = 60 humans
1 short ton coal (anthracite) = 2.54E+07 Btu*
= 7,438 kW-hr = 148,755 humans
1 C-minor Mass by Wolfgang Mozart (63 p)
= 0.868 kW-hr = 17 humans
1 short ton coal (bituminous) = 2.50E+07 Btu*
= 7,321 kW-hr = 146,413 humans
1 copy 1984 by George Orwell (232 p)
= 3.19 kW-hr = 64 humans
1 short ton coal (sub-bituminous) = 2.00E+07 Btu*
= 5,857 kW-hr = 117,130 humans
1 Gettysburg Address (1 envelope assumed equal 1 g sugar) = 0.00459 kW-hr
= 0.0918 humans
1 short ton coal (lignite) = 1.40E+07 Btu*
= 4,100 kW-hr = 81,991 humans
1 box of cardstock Florida Ballots (estimated)
5 kW-hr = 100 humans
1 cord of wood (128 cf) = 1.95E+07 Btu*
= 5,710 kW-hr = 114,202 humans
1 copy The Crucible by Arthur Miller (413 p.)
6 kW-hr = 114 humans
1 horsepower-hour
= 0.746 kW-hr = 15 humans
1 Lynne Cheney academic blacklist (562 p.)
= 7.75 kW-hr = 155 humans
1 day Hoover Dam (max cap, post 1993; see footnote 4) = 49,776,000 kW-hr
= 9.9552E+08 hums
1 Cal State Sacramento commencement address (7 p)
= 0.096 kW-hr = 2 humans
1000 cf natural gas (dry) = 1.03E+06 Btu*
= 302 kW-hr = 6,038 humans
1 copy Fahrenheit 451 by Ray Bradbury (173 p.)
2 kW-hr = 48 humans
*British Thermal Unit (Btu) equivalences provided by Lebel, P.G., 1982; Energy, Economics, and Technology: Johns Hopkins University Press, 551 p.
footnote 1: "humans" equals 1 human riding exercise bicycle hooked to power generator 6 times per hour (2 minutes each ride) for 10 hour day,delivering 25 Watt-2minutes each ride.
footnote 2: using value of 238 W/sq. m (assuming 30% average albedo), "...availabe for the atmospheric and oceanic energetics," obtained from equation 6.42, page 118 of Peixote, J.P. and A.H. Oort, 1992; Physics of Climate: Springer-Verlag, New York, 520 p.
footnote 3: Enthalpy of combustion of 5648 kJ/mol and GMW of 342
g/mole for sugar (C12H22O11) taken from bomb calorimetry experiment summarized
as a problem set at:
http://www.science.uwaterloo.ca/~cchieh/cact/c120/calorimetry.html
footnote 4: 2074 Megawatts output of Hoover Dam taken from:
http://www.hooverdam.com/workings/generate.htm
Reference regarding improved output (post 1993) taken from readings at:
http://www.physics.umd.edu/rgroups/ripe/perg/abp/aha/hoover.htm
> Story by AP, printed in Cleveland Plain Dealer, Sun. Dec 23, 2001,
p. A2,
> noting that the year was the second warmest globally since 1860 and
that
> 9 of the 10 warmest had occurred since 1990, included the quote
>
> "It's global warming, dude" said Pito Robles, 28, an auto
mechanic
> who on Thursday was dangling his fishing line into the
Hudson River
> near W. 66th St. in Manhattan. "I don't care if the
whole planet
> burns up in a hundred years. If I can get me a fish
today, it's
> cool by me."
The Energy Justifies the Means, IV A solar / fuel cell conversation with Eric
Dear John:
I'm just a day laborer, so my scientific input is limited to Popular Science. I once read that a physicist calculated that 214 square miles in New Mexico set aside with photovoltaics could electrolyze enough seawater into hydrogen and oxygen to run every car in America on hydrogen.
My questions are:
1) Is this truth or a pile of Bush?
2) How dangerous is a tank of hydrogen compared to a tank of gas?
Imagine the joy of watching every oil cartel in America and the Middle
east realize that their oil is only needed for lubrication.
Eric Hedick
Seems reasonable, though I would have to run the numbers. The 238 W/sq
meter is the world average: the average for New Mexico would be higher.
The 214 sq miles is approx. 554,000,000 sq. meters. Take that times the 238
W/sq. meter times 24 hours (238 is day-night averaged) divide by 1000 to
convert # of Watt-hours to kW-hrs and compare to the U.S. consumption of
gasoline. I don't have that number in kW-hrs. Now that of course is assuming
you could convert all the incident energy into useful energy. You need to
adjust the number by the efficiency of the solar panels, but you also have
to adjust the energy output from a barrel of oil by its efficiency to produce
useful energy. Perhaps that physicist was working with the latest solar technologies,
I don't know.
Yes, hydrogen in a Hindenburg blimp is dangerous, but in a pressurized tank (like propane) less so. There have been technological improvements in the handling of hydrogen as well! Even Bushit is pushing for fuel cells, so I think hydrogen fuel is inevitable. Obviously we need the investment in infrastructure and a willingness to go there (those are business/wall street/political issues outside my area), but I think you are looking at our future. It's going to take day laborers to build it, so keep the dream alive. If you build it, they will come!
John
duh-bya will never build it. Carter pushed through PURPA and tons of other alternative energy initiatives, only to have them removed by Reagan(read Poppy Bush). You think they'll give up all that good oil money? Hell, the Bush family did business with Nazi's AND the Taliban. You think people who would do that for money-and defy the Constitution-would change that?
But....
What would it take to buy, oh, 5 acres of desert land in New Mexico-or Nevada? Arizona? someplace rich folks don't want a piece of-and set up an experimental area that splits sea water into hydrogen and oxygen? I know that the conversion of cars to propane gas is minimal, is this true of hydrogen? And if the town of Podunk, NM used hydrogen, leaving emissions of nothing but water, would other towns follow suit? Would New York City, in an effort to clean their air, pass city law that only hydrogen cars could be driven? Would $8,000 bring down Middle East money and every oil conglomerate in 20 years?
.....God forbid anyone get rich beyond belief as well as clean the planet at the same time. Oh yeah, what would environmental impact be on having so much more oxygen?
Eric,
Of course duh-bya will never build it, and you're right about Carter. He was responding to the 1973 oil crisis that everyone forgot about. This frustrates the Bu$h out of me. The two issues that struck me during my formative years were the 1973 oil crisis (I was 10 and still remember odd-even days and pushing cars to the gas station) and Love Canal (1979; I was 16). Add 3-Mile-Island (also, 1979). I became a geologist, graduated with my masters in1987 when the oil industry was laying off 2/3 of their employees, so I went into ground water. It's like everyone has amnesia!! Yes, it's going to take private initiatives, and that's happening! Look at San Francisco!!! Yes, hydrogen can be used as a fuel pretty easily, but the key here is breakthroughs in fuel cells which more efficiently convert the chemical potential energy into mechanical energy. We've got fuel cells that fit in cars now. This is not your grandfather's energy crisis, but unfortunately the government is run by your grandfather's mentality (Cheney). We need a leader with vision, which is why I voted for Al Gore (yes, despite the Nader/Bu$h fueled criticisms, he does have vision.) The problem is: Gore's not "made for T.V."? I'm not running for President, nor will I ever, but I'm not "made for T.V. either", so how will I get anyone to listen to me? Maybe by the irony that I'm a geologist (historically a profession on the fossil fuel teat) pushing for solar!
As for extra oxygen, not a problem. You convert water to hydrogen and oxygen, but then you recombine it when you use the hydrogen fuel (either by combustion or in a fuel cell), hence the water emission. It would be in balance. The hydrogen is only used to solve the energy storage problem.
John
P.S. We ought to post our discussion on CLG. I will await your permission and/or look for your post on CLG.
Oh yeah, you have my permission. What exactly are fuel cells? Is it like
those things that give electricity to a 3BR house for 20 years, and then get
replaced for about $15M?
Eric,
I didn't know about a $15M device for serving electricity to a 3BR house,
but it sounds like a fuel cell. A fuel cell converts the chemical potential
energy of a fuel straight into electrical energy. The standard fuel cell
runs on hydrogen:
2H2 + O2 => 2H2O (water) + energy
In a combustion engine, this energy is released as heat and work, expanding
a piston converting the heat and work energy into mechanical energy. In
a fuel cell, this energy is released as electrical energy for an electric
engine. Hybrid electric vehicles (Toyota Prius and Honda Insight) already
exist on the market (hybrids have both an EV and combustion engine and recharge
their EV batteries from standard gasoline), and straight electric vehicles
(EV's) are already a viable alternative, except for the lack of nationwide
infrastructure of recharging stations.
The fuel cell technology existed for years at the huge, laboratory scale,
but about 5 years ago there were some material breakthroughs that enabled
fuel cells to be downsized into a car. Not to plug any one automaker, but
here is a March 1999 press release from Daimler-Chrysler unveiling their
fuel cell car.
http://www.enn.com/news/enn-stories/1999/03/031899/necar4_2203.asp
Notice the last paragraph:
"In a related development, a group of 15 scientists and engineers were honored by the [Clinton] White House Wednesday for their development of a fuel processor that produce hydrogen from commonly available fuels such as methanol, ethanol, natural gas and gasoline. This means a fuel cell vehicle equipped with their fuel processor onboard could fill up at any conventional service station."
This is why Bu$h is pushing for fuel cells (even he must acknowledge that
he can't stop the march of these new technologies!): with the converter (fuel
processor), you can use straight gasoline. BUT YOU DON'T NEED TO. All you
need is the hydrogen from that New Mexico solar farm you mentioned. Standard
gasoline is comprised of a large number of hydrocarbons including the
100-octane-rated 2,2,4 trimethylpentane (C8H18); the 0-octane-rated n-heptane
(C7H16); benzene (C6H6) and benzene related hydrocarbons; and impurities
like sulphur (plus additives that arguably can be removed, i.e. not added).
I don't know how these converters work, but if they just strip gasoline
to hydrogen fuel, you gotta do something with the residual carbon and/or
impurities. To be fair to Bu$h, this technology would work in the interim
(i.e. until that solar farm can be built).
John