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Cost & Savings

Environmental Impact  

Conclusions

Notes and Sources

Shopping with durable canvas grocery bags is a simple, but effective solution to that mountain of bags you’re hiding in your kitchen pantry, not to mention a great opportunity to save money and resources.

Cost and Savings:

    Let’s say you buy two bags for $4 total ($2/bag).  Every time you use those bags, the supermarket will take $0.10 off your grocery bill ($0.05/bag) as a bag credit.  That may seem minor, but even if you only visit the supermarket once per week, the bags will pay for themselves in about nine months (if you go twice per week, they’ll pay for themselves in 4 ½ months…you get the idea).  After that, you’re making money!  $0.05/bag isn’t going to make you rich, but if you can save money, why wouldn’t you? 

    The Wall Street Journal and other organizations have estimated that the US consumes 80-100 billion plastic shopping bags annually [1] (that comes to about 1000 bags per household per year).  That seems like a lot, but considering that the average family uses 12 plastic bags per trip to the grocery store, it would only take about 7 trips per month to the grocery store alone to acquire that many bags.

    Those plastic bags cost retailers an estimated $4 billion per year [1], a cost that is, of course, passed on to us, the consumers.

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Environmental Impact:

    Reusable bags clearly make sense financially, but what about their environmental impacts?  Among other things, plastic bags contribute over ½ million tons of plastic waste to our landfills each year2.  And once in the landfills, plastic bags will not biodegrade for centuries.  Paper bags are no better for the environment and might even be a little worse (unless you reuse them several times).  Also, plastic debris (including plastic bags) comprises a large proportion of the garbage polluting marine environments, which puts thousands of marine animals, including birds, fish, and mammals, at risk of suffocation, entanglement, illness, and death [3].

    Finally, it is estimated that 12 million barrels of oil are required annually to manufacture those 100 billion bags [1].  If we all make a smart investment in reusable cloth bags, we could easily cut our national plastic bag consumption in half, which would save 6 million barrels of oil annually.  That’s equivalent to taking nearly 200,000 cars off the road4, just for halving our plastic bag consumption! 

    Switching to reusable bags won’t make quite the financial or environmental impact of switching to CFLs or choosing Energy Star appliances, but it’s yet another responsible step in the right direction.

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Conclusions:

    Most of our calculations are fairly rough, back-of-the-envelope-type estimates.  Your actual cost and energy savings will probably be a little higher or lower depending on your particular circumstances.  But the overall message is consistent and clear:  smart investments in efficiency are win-win decisions; they are not only environmentally responsible, but fiscally responsible as well.  In other words, even without the environmental benefits, these improvements would still  So what are we waiting for? be smart choices.

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Notes and Sources:

1)   http://www.reusablebags.com/

2)   Assuming low recycling rates and approximately 15 lbs of plastic per thousand bags

3)   Derraik, J.G.B.  2002.  The pollution of the marine environment by plastic debris: a review.  Marine Pollution Bulletin 44: 842-852.

4)   Figures used for calculating equivalent removal of cars from the road:

Average US car fuel economy:  ~20 mpg (http://www.epa.gov/otaq/cert/mpg/fetrends/420s07001.pdf)

Average miles driven/car/year:  12,000 miles (http://www.epa.gov/otaq/climate/420f05004.pdf)

Average gallons/car/year:  12,000 miles/20mpg = 600 gallons/car/year

Average gallons of gas from one barrel (42 gallons) of crude: ~20 (USDoE)

Barrels consumed/car/year:  600 gallons/20 gallons per barrel = 30 barrels/car/year

Barrels crude saved by reducing plastic bag consumption by half:  6,000,000 barrels