Today my reusable nylon bag which I was given for Christmas two years ago has reached it's 500th birthday...that means I have not used new 500 bags which means a lot of saved CO2e.
To explain about why using reusable bags is so important I have reproduced a section of the book Facing up to Global Warming. The thing that really annoys me is when I am offered a paper bag they always double or triple up the bags in case it rips. Do we really need fancy thick paper bags with ribbons and metal rivets when we buy clothing or luxury goods? Of course not. So hopefully this will answer some important questions about bag use and why we should all used reusable bags.
Plastic v paper bags
Globally between 500 -1000 billion
standard supermarket high density polyethylene (HDPE) bags are used each year with 6 billion handed out free
to shoppers just in UK during 2012. The
problem of these bags is really the major litter problem that they pose as well
as being a major threat to wildlife. In terms of their carbon footprint this is significant
due to the large numbers used. The
transparent ultra thin lightweight HDPE bags (just 0.025 mm thickness) that you
use to put loose vegetables in have a footprint of 3g CO2e each. The standard printed lightweight supermarket
HDPE bag is equivalent to 10g CO2e
each. The thicker reusable supermarket HDPE bag can vary between 100-280 g CO2e in their manufactured
footprint. So for those worried about their footprint, what are the alternatives
to the standard supermarket HDPE bag?
Well interestingly the standard
printed lightweight supermarket HDPE bag contains 35% less CO2e than
the equivalent sized paper bag. When
paper bags are used for groceries then you are often given two bags one inside the
other to give the bag sufficient strength, so an equivalent paper bag may have
six times more embedded CO2e than the plastic version to give it the
same strength. A standard reusable HDPE bag contains 10-28 times more CO2e
than the standard printed lightweight supermarket HDPE bag, while cotton or canvas
bags contain on average 171 times more CO2e. This means that you would need to reuse your
plastic or canvas bag in excess of 20 or 170 times respectively in order to
gain an emissions advantage over using the thinner bags just once. A study by
the Environment Agency in the UK found that canvas bags are used on average
only 51 times with composting the best disposal, making them potentially far
less climate friendly than the plastic bags in terms of overall carbon
emissions. To put the standard supermarket HDPE bag into perspective, then it
contains only one thousandth of the CO2e than food inside the bag.
What to do with plastic bags? Interesting there are three options. Burning
or incineration releases toxins and 100% of the embedded CO2e is released,
although some heat is generated. If we recycle the bags then up to 50% of the embedded CO2e
is lost in the process. In contrast, burying
the bag in a landfill ensures the embedded CO2e is stored
permanently with virtually no CO2e released to the atmosphere. Difficult decisions eh?
In Ireland the standard supermarket
HDPE bags have a levy of 15 cent each on them so that they are virtually never
used by customers. Before the levy was
introduced the countryside was littered with the bags, and now such bags are
virtually never seen as litter items, except unfortunately containing dog poo,
but that is another story. Transparent
ultra thin bags are still given out free in supermarkets. In contrast, China banned both the standard
and ultra thin HDPE bags and called people to use baskets or cloth sacks
instead to reduce environmental pollution, including marine litter. This ban, introduced in 2008 saves 35 million
barrels of oil a year in their manufacture.
Ironically China has been the largest manufacture and exporters of such
bags to the rest of the world.
So perhaps in terms of
emissions the best option if you need a plastic shopping bag is to use a
reusable HDPE bag and make sure you use it at least 20 times for a thick
plastic bag or 35 times for a woven plastic bag otherwise you will have emitted
more CO2e than if you had used disposable bags. I called the standard lightweight supermarket
HDPE bag disposable because we tend to consider them as a single use item. In fact they can be used again and again if
you are careful, which is putting the investment in reusable bags under
pressure. Lightweight supermarket HDPE
bags have loads of different uses so it is important that they are reused as
many times as possible, finally using the bag to wrap contaminated unrecyclable
waste for disposal to landfill.
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We all have cupboards full of reusable
bags…the trick is to actually use them carefully to ensure that they have
long lives.
The challenge is how many times can you
use them beyond their breakeven point?
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More information: http://www.independent.co.uk/environment/green-living/plastic-fantastic-carrier-bags-not-ecovillains-after-all-2220129.html
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Paper is hard to reuse so
ALWAYS RECYCLE
to save CO2e emissions
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What about paper bags? Using them certainly feels that you are
caring for the environment being a natural product. The paper industry is very
energy intensive so that the carbon footprint for all paper is quite high
ranging from 12g CO2e for a lightweight recycled bag to in excess of
80g CO2e for a virgin paper
(e.g. clothing) bag excluding the non-paper handles. Virgin paper releases between 2.5-3.0 kg CO2e
per kg of paper manufactured compared to 1.25-1.50 kg CO2e per kg of
recycled paper. Of course the embedded
CO2e in the paper is released when paper is either burnt, landfilled
or composted which is equivalent to 500g CO2e per kg paper on top of
the emissions from its manufacture. So
only use paper bags when necessary and ensure that they are full.
Plastic bags, paper bags, and recyclable bags…what do we do? The
golden rule is to avoid plastic and paper bags
whenever possible. If you buy reusable bags
put a date on them and ensure that you use them well over the breakeven point
in terms of emissions. I know it looks awful but rips and holes can be repaired
with sticky tap. I would recommend that you invest in long life alternatives (e.g. rucksack, stacking trays for the
car). I brought a high quality canvas bag
from Oxfam ten years ago which I have used everyday not only for shopping but
for work. Of course neither my wife nor my
daughters will be seen out with me when I am carrying it, but it has proven
exceptionally climate friendly. So you
need to find a compromise.
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Having a strategy in place for carrying
goods without disposable bags is a surprisingly effective way of minimizing
CO2e emissions over a lifetime
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