----- Original Message -----

From: "De Clarke" <de@...>

> 400 watt/hours is .4 KWH ... and (hmmm)

>

> kWh x 3.6 = MJ x 0.2778 = kWh

>

> and

>

> Btu x 1.05506 = kJ x 0.9478 = Btu

>

> so if 3.6 KWH is a MJ and 1.055 BTU is a kJ, then

> 1055 BTU is a MJ is 3.6 KWH

>

> which means that 293 BTU (1055/3.6) is 1 KWH

Online sources seem to agree that the conversion factor is 3413 BTU / KWH:

http://www.google.com/search?sourceid=navclient&q=%22btu+per+kwh%22+conversi

on

So you would need to deflate your can counts by a factor of about 11.6. So a

Hummer owner needs to recycle 84 cans to drive 10 miles on the energy saved.

Thanks for the number fun. Someone will be along any minute now to correct

me.

Steve

>

> so now we're getting someplace at last. we now know that

>

> 400 watt/hours is .400 * 1KWH, or .400 * 293 BTU, or 117.2 BTU.

>

> and we remember that there are 114K BTU in a gallon of gas. so...

>

> to "save" enough energy to be the equivalent of 1 gallon of gas, we need

> to recycle on the order of 114,000/117.2 or 972.7 cans [assuming we accept

> the peculiar notion of "saving" which means that the *more* cans we make

> out of recycled metal, the more we "save" -- "the more you spend, the more

> you save!" but let us assume for the moment, for sake of the thought

> experiment, that the making of cans is a categorical imperative and our

> only choices are whether to make them out of virgin metal or recycled

metal...]

>

> we think a Hummer gets 10 MPG; so to drive a Hummer 10 miles on the

energy

> saved by recycling cans takes one gallon, or 972 recycled cans-worth of

> energy savings. the average American drives about 10,000 miles per year

> (or so I have read), so the Hummer-owning American would need to buy 1,000

> (10,000Mi/10MPG) gallons of gas per year, or 1000 * 972 recycled cans,

> or

>

> 972,000 cans

>

> now, tomfrostjr recently guesstimated that

>

> The rest area near me has enough aluminum cans going into its

> dumpster to probably run a Hummer 50,000 miles per year on the amount

> of energy that's being wasted by not recycling them.

>

> which is how I got to thinking about this little problem in the first

place.

>

> 50,000 miles would be 5x the estimate above, or 4.86 million cans. now we

> need another rough metric. how many cans can one individual account for

per

> year?

>

> 99 billion aluminum cans, or 374 cans per person were used in 1995.

>

> http://www.green-networld.com/tips/aluminium.htm

>

> so to run one Hummer 50,000 miles on "aluminum can recycling energy

savings"

> would require the total aluminum can discard of 12,994 people (as of 1995)

to

> be recycled. (4.86M/374)

>

> while it's quite possible for 13K people to visit a rest area on a major

> insterstate highway in one day, let alone one year, they obviously only

pass

> through briefly and discard only a few, at most, of the hundreds of cans

> they would use in one year -- the rest end up in home garbage cans, tossed

> out the window onto the verge, or at other rest areas etc.

>

> if we posit that each person would throw away an average of, say, 2 cans

> at the rest area during a brief stop, then we only need 2.43 million

> people to use the rest area in a year, callously discarding recyclable

> cans, for its dumpster(s) to yield enough wasted can-energy to run

> that Hummer 50K miles. [if the rest area has recycling bins as well

> as dumpsters then the problem becomes intractable, as we have a hard time

> estimating the percentage of people who will use the recycle bins vs those

> who will just toss a can into the garbage; so let's assume there are no

> recycle bins at the rest area.]

>

> given all this, 13,315 cans per day would have to be tossed, or 459 lbs of

> alloy per diem (I think there are about 29 cans to a pound of metal these

days),

> in order to waste enough energy in a year to drive that Hummer 50K miles.

> that does seem like rather a lot of cans, but I guess it could be a very

busy

> and popular rest area.

>

> of course only *one* Hummer could be driven 50,000 miles on the saved

> energy if those 2.43 million people all recycled their cans properly at

> the rest area. GM, on introducing the H2, hoped to sell 40,000 of them in

> the first year. to fuel all those Hummers at 10MPG and 50K miles per year

> each, busy little recycling bees would have to "save" the energy from the

alloy

> cans used by (hmmm) 2.43 million people per year using 40,000 major rest

areas.

> a sobering thought... especially since the H2 has been on the market for

more

> than one year.

>

> if a Hummer gets 10 MPG and 40,000 Hummers drive 50K miles per year, then

> collectively they consume 5000 gallons * 40K or 200 Mgals per year.

> and since 972 cans roughly equals a gallon, that means 200M * 972 or

> 194K-million (billion) cans... which is almost twice the total number

> of cans produced in the US in 1995 (99 billion vs 194 billion). another

> sobering thought -- Hummers are a niche vehicle and represent only one

> small elite slice of FUV-dom; we can breathe a sigh of relief because

> they don't all drive 50K miles per year, only to gasp in dismay as we

> realise how outnumbered they are by the legions of other FUVs on the road.

>

> a perhaps more interesting sidelight is this: if you have to drive

> 10 miles in your Hummer to the recycling centre and 10 miles back, how

> many cans must you carry with you for recycling in order to make the

> trip a net energy savings?

>

> looks like the answer is: 20 miles round trip, 10 miles is 972 cans,

> so 20 miles is 1944 cans, or the average yearly can-consumption of 5.2

> people. so if the trip is made any more than once yearly for a family of

> 5, or if each person in the family doesn't consume their quota of 374

> cans per annum, the trip would be a net loss. (and of course we're not

> counting the trips made to the grocery store at 10 MPG to buy the cans

> in their filled incarnation...)

>

> more vividly yet, if you were to drive a 30 mpg car rather than a 10

> mpg car, you might then buy only 300 gallons rather than 1,000 gallons

> of gas for your average-American 10K miles per year of driving. the 700

> gallons you didn't buy would be the equivalent of recycling 700*972 or

> 680,000 cans that year, at 972 recycled cans per gallon -- or 1819

> years' worth of your average American alloy can consumption at 374 cans

> per annum.

>

> oh well... enough fun with numbers. like I say, someone should

double-check

> 'em because it's late at night and zeroes can get misplaced when one is

sleepy.

>

> on the whole I'd say a pretty good case can be made that no matter how

> much you recycle, your gasoline consumption is likely to be a far bigger

> contributor to your net energy footprint -- even scrupulous recycling

> for a family of 5 would only "pay" for one 20 mile round trip per year

> in the Hummer...

>

> de

>

> --

>

............................................................................

.

> :De Clarke, Software Engineer UCO/Lick Observatory,

UCSC:

> :Mail: de@... | Your planet's immune system is trying to get rid

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> :Web: www.ucolick.org | of you. --Kurt Vonnegut :

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E76E:

>

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>

>- On 3 Oct 2003 at 10:41, De Clarke wrote:

> it's rather sad to me that we all come out of school with a pretty good

Not me, though I did have a pretty good grasp of the far more

> grasp on feet and yards, pounds and gallons (well most of us anyway),

sensible metres, kilogrammes and litres.

> but

I agree that it is relatively few. However, those of us with a good

> relatively few people I know -- including myself -- have a good grasp on

> quantitative energy.

grasp do not always want to do the same thing in our leisure as we do

during work time.