Life Cycle

What is the life cycle of a shopping bag? From start to finish, what energy, materials, labour, uses, problems, benefits are there to different types of bags?

How Plastic Bags Are Made
Suncor Oilsands Upgrading Facility.
Fort McMurray, Greg Halinda Photography
Life Cycle of a Plastic Bag   3 min.
How It's Made, Plastic Bag 5 min.
How plastic bottles are made 
The Story Of Stuff, Plastic Bottles

Plastic Is Made From Oil
Energy and Kids
EIA Energy Kids - Oil
Heavy Haulers digging oilsands 3 min.
Petroleum Refining 10 min

Grade 3, Life Cycle of a Bag

Many Materials
Shopping bags are made of these common materials.
Polyethylene Wickipedia 

They're cheap and light, and uses less energy to make than paper bags. But they don't degrade into soil, ever. Their light weight means they end up flying out of landfill. They are not easily washed, not truly reusable (once or twice at most), and only 2% are recycled.

BiodegradableThey're polyethylene with and additive that help them break into smaller parts, usually within a couple of years. They need to be exposed to air and light to break down, which does not happen in conventional landfill situations where everything is just piled up very deeply, then buried.

Compostable  eg. Biobag
They're a type of plastic made out of a food or mineral product, often corn starch. They break down within a few months if they have the air, moisture, and warmth that are needed. Micro-organisms are what eat food items to break them down into soil - including these bags - and those same micro-organisms cannot survive and function in a convential land-fill situation. So most compostable bags don't decompose. Another concern is that food is being used to create a single-use item, an intentionally disposable item. With starvation in many parts of the world, is this ethical?

Polyester, Nylon Made of oil, they are durable, washable, and often reyclable at the end of otheir long cycle. A reusable bag made of polyester or nylon can last up to 2,000 uses, and up to 10 years.

They are biodegradable, not reusable, not washable, not durable. It takes 40% more energy to produce paper bags than plastic. Deforestation is a global concern, with decreased forests increasing the mass of desert or dry areas, and adding to global warming. Trees process carbon dioxide, which can't happen when they are decreasing in number. Plus it takes 60 years to grow a tree to maturity in Alberta, 30 in B.C. We are consuming trees faster than they are growing.
Paper Bag Life Cycle

Cotton They're biodegradable, reusable, washable, durable. There is a high use of pesticides in growing cotton so organic is better. At the end of their long life cycle, they are compostable.

  Biodegradable, reusable, washable, durable. At the end of their life cycle, they are compostable. Bamboo grows quickly.

Biodegradable, reusable, washable, durable, and compostable at the end of their life cycle.

97% of plastic bags are thrown out after 1 or 2 uses.
Greg Halinda Photography

Which materials are best? Not everyone agrees.
Use your cotton bag 131 times  Is polyethylene the best?
Cotton bags are best

The End of Their Life
The Majestic Plastic Bag - a Mokumentary  4 min   LA Save the Bay spoof on the life of the bag

Bill Nye The Science Guy: Garbage  24 min. 

Magic School Bus   22 min.
Recycle Plastic Bags  1 min.
Recycling Revolution, Reuse trash ideas