Sun Jun 12th, 2005 at 04:09:45 PM EST
The following question was raised in a discussion group online, under the general topic of SUVs and energy wastefulness: how much blame and dislike is it reasonable to attach to drivers of SUVs for their energy wastefulness, relative to other wasteful behaviours? One member said
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.
or in other words, "people who don't recycle their aluminium cans are at least as wasteful as people who drive Hummers." The related question immediately arose: if you drive your Hummer to the recycling center to recycle some cans, how many cans must you carry to "save" or reclaim as much energy as you have spent by driving the Hummer to the recycling center? At what point is this a negative-sum exercise in absurdity?
Interesting questions, but how the devil can one figure out the answers? Show Me The Numbers!
These are typical of a whole set of questions that in an energy-literate society would be immediately obvious, but in an energy-illiterate (or energy-obfuscated) society are quite opaque. They set me off on a research project whose results are summarised below (many thanks to various members of carfree discussion list who helped with proofreading, math checking, etc). Food for thought.
Here's a table of approximate equivalencies -- unit conversions, if you like -- from which we may be able to draw some conclusions:
|ONE GALLON OF GAS ||114,000 BTU
|ALLEGED E-SAVINGS OF RECYCLING |
ONE AL CAN
|BTU PER KWH ||3413 BTU
|BTU SAVED PER RECYCLED CAN ||.4 * 3413 or 1365 BTU
|CAN-SAVINGS-EQUIV per GALLON ||83.5 CANS
|MPG of HUMMER ||10 MPG
|BTU to drive HUMMER 10 MILES |
(= 1 GAL)
|CAN-SAVINGS-EQUIV to |
drive HUMMER 10 MILES
|CSE to drive HUMMER 10,000 MILES |
(Average American driver's
|CSE to drive HUMMER 50,000 MILES |
(thought experiment about
rest-area can discards)
|NUMBER OF AL CANS PER YEAR |
PER PERSON (1995 datum)
|NUMBER OF AL CANS MFRD PER ANNUM |
|99,000,000,000 (99B) CANS
|NUMBER OF PEOPLE'S annual CSE NEEDED to |
DRIVE HUMMER 50K MILES
|NUMBER OF CAN DISCARDERS at rest area |
(at 2 cans per person) needed
to drive HUMMER 50K MILES, in 1 year
|NUMBER OF CSE PER DAY to drive HUMMER |
50K miles in one year
|NUMBER OF CAN DISCARDERS per day |
to achieve this rate at rest area
|NUMBER OF CSE needed to drive |
(one years' projected unit sales)
10K MILES per year
|NUMBER OF CSE needed to offset |
20 MILE round trip
in 10 MPG HUMMER
|167 (83.5 * 2) CANS
|NUMBER OF CSE achieved by |
driving 30 MPG car
intstead of 10 MPG car
|YEARS OF INDIVIDUAL CAN CONSUMPTION |
equiv to above CSE
|NUMBER OF CSE achieved by |
not driving a 30 MPG car,
as opposed to driving one,
for one year at an assumed 10,000 miles
|333 GALLONS = 27,805 CANS
|NUMBER OF PERSON/CAN/YEARS |
equivalent to above
And now in English: 1122 people would have to recycle every single Al can
they use in one year, to "save" enough energy to offset the energy consumption
of driving one Hummer 50K miles. (And those people would have to recycle
their cans without incurring any further energy costs, such as driving
to the recycling centre or using an electric can-crusher).
If that one Hummer
only drove the national average of 10K miles in one year, then "only"
1/5 as many people -- 224 people -- would have to dedicate their recycling
lives to compensating for the gas consumption of this Hummer. As my
yuppie neighbour memorably said, some years ago "Oh, it's so nice that
you're conserving water -- that means we can use more!"
You would have to recycle every Al can you use for 156 years, to produce
the same "energy savings" benefit you would achieve by driving a 30 MPG
car rather than a 10 MPG car for just one year. Since you won't live
156 years, it appears you'll need a friend or two to participate in this
justification of a 10 MPG car :-)
The Hummer driver who drives 20 miles r.t. to recycle cans must carry
at least 167 cans per trip to make the "savings" from the cans offset
the energy cost of the trip -- for a zero-sum game. The cyclist who
eats organic and locally-grown food would have a much higher "profit
margin" on this trip (not to mention the benefits of exercise and
improved humour) for far fewer cans.
And we are still begging the question of why the H we "need" to manufacture
99 Billion cans per annum to contain watered-down sugar syrups with fizz,
produced and marketed via an insanely wasteful web of long-haul transit.
We wouldn't need high-tech light containers for drinks if the drinks weren't
being hauled by air and truck several thousand miles before reaching their
consumers... glass (also recyclable, at lower temps) would work fine if
we weren't obsessed with reducing freight weight and packing more cans in
each cu ft of container space, or making the containers proof against the
violent stresses of longhaul transit and repeated middleman handling. But I digress :-)
Back to the implications of the above numbers:
The Hummer driver who thought better of it and decommissioned his Hummer
in favour of a 30 MPG compact, would save more energy than he could ever
achieve in 2 lifetimes of recycling cans, in just one year of average
driving mileage (10,000 miles).
Or looked at another way: if a person could, by reason or wheedling
or flattery or shaming or tax disincentives, be persuaded to trade in
their 10 MPG Hummer for a 30 MPG compact -- then the carping critic, nagging
spouse or preachy enviro who persuaded them to take this step would have
achieved 2 lifetimes' worth of can recycling activity in energy savings,
in just the first year of that Hummer's inactivity, and the same savings
for every year thereafter. That seems worth nagging about.
The person who refrains from driving their 30 MPG car for one year or
10,000 miles, choosing to walk or bike instead, achieves an energy savings
in just that one year, equivalent to the average can-consumer recycling
every single can they use, faithfully, for 74 years (or an average lifetime).
Likewise the person who persuades, cajoles, bribes, shames, begs or ridicules even one other
person to stop driving their 30 MPG car and ride a bike or walk instead,
has contributed to an energy savings in the first year that is equivalent
to a 74-year lifetime of faithful recycling.
The lesson I draw from this is that it is very much worth our while to
make every kind of outreach and effort to "uncool" gas guzzling SUVs and
encourage at least a return to moderate gas frugality, and at best, an
increased popularity of carfreedom. Each year of the difference between
Hummer and subcompact or moped is worth 2 lifetimes of can recycling,
and each year of the difference between subcompact and feet/bike is worth
1 recycling lifetime.
The choice of transport we make -- its energy cost -- seems to outweigh the importance of
our recycling activity by about the ratio of 1 or 2 lifetimes to one year.
BTW, "recycled" Al cans are not made from 100 pct recycled alloy. some
virgin metal is also introduced into the process. the "savings" is a reflection
of the percentage of recycled material and the E-cost of resmelting it as opposed
to the cost of refining virgin ore. but virgin ore is still dug and refined
and smelted in the making of "recycled" cans.
Axiomatically, the savings accrued not not making 1 can will always be far
larger than the savings accrued by making 1 can partly out of recycled metal.