Comparison between polymer shopping bags and paper shopping bags
A draft report by the Environment Agency, obtained by the Independent on Sunday, has found that ordinary high density polythene (HDPE) bags used by shops are actually greener than supposedly low impact choices.
HDPE bags are, for each use, almost 200 times less damaging to the climate than cotton hold-alls favoured by environmentalists, and have less than one third of the Co2 emissions than paper bags which are given out by retailers such as Primark.
It found that an HDPE plastic bag would have a baseline global warming potential of 1.57 kg Co2 equivalent, falling to 1.4 kg Co2e if re-used once, the same as a paper bag used four times (1.38 kg Co2e).
A cotton bag would have to be re-used 171 times to emit a similar level, 1.57 kg Co2e.
The researchers concluded: “The HDPE bag had the lowest environmental impacts of the single use options in nine of the 10 impact categories. The bag performed well because it was the lightest single use bag considered.”
Plastic Bags
Cause less global warming pollution and have less of an impact on biodiversity and water, according to scientists at the National Resources Defense Council (NRDC). For example, plastic bags use 40 percent less energy during production and less than 4 percent of the water used to make paper bags. And plastic bags generate 79 percent fewer greenhouse gas emissions than composted paper bags.
Cost less to transport, saving on fuel costs. In fact, it would take about seven trucks to transport the same number of paper bags as a single truck of plastic bags, according to The Environmental Literary Council.
Take up less landfill space. Plastic bags account for about 9 to 12 percent of waste volume, while paper occupies about half of overall landfill volume.
Take less energy to recycle. It takes 91% less energy to recycle a pound of plastic than it takes to recycle a pound of paper.
On the other hand:
Ninety percent of grocery bags are plastic, which is made from petroleum. It takes 12 million barrels of oil to make a year's worth of plastic bags (100 billion of them) for Americans.
Five of the top six chemicals that produce the most hazardous waste (according to EPA rankings) are used in plastics production.
Less than 5 percent of plastic bags are recycled. About 4 billion plastic bags are thrown away -- littered throughout the world -- each year. Tied end to end, they could circle the earth 63 times. Instead they hang from fences and trees, blow across streets and fields.
Because recycling plastic is expensive and time-consuming, many of the plastic bags collected for recycling are shipped for incineration to countries with lax environmental laws.
When improperly disposed of, plastic bags cause problems in coastal areas, where they threaten sea life for as long as 1,000 years while the plastic remains in the water. Sea turtles mistake them for jellyfish and as many as one million sea creatures are killed each year by plastic bags, which also clog sewer pipes and cause stagnant, unhealthful water for humans.
Plastic does not break down in the landfill. It will always be there. Even biodegradable plastic -- which is made of wood fibers mixed with plastic fibers -- leaves tiny plastic pieces in the earth.
Our biodegradble system degrades on an aerobe landfill.
Paper Bags
Can hold more than plastic bags, if packed well.
Are more often recycled than plastic bags. According to the EPA, Americans currently recycle 19.4% of paper bags but only 0.6 percent of plastic bags. (Granted, both numbers are too low!)
Are biodegradable. While modern landfills don't allow for this process to occur as it should (the bags are buried and receive no air and sunlight for decomposition), paper bags do naturally break down -- as mulch in the garden, for example.
Our biodegradble system degrades on an aerobe landfill.
On the other hand:
The paper industry has an enormous environmental footprint. It takes more than four times as much energy (2,511 BTUs) to produce a paper bag as it does a plastic bag (594 BTUs). And paper bag production generates 50 times more water pollutants and 70 percent more air pollutants than the plastic bag production.
About 14 million trees were used in 1999 to make 10 billion paper bags for Americans. And when forests are cut down to make paper, major absorbers of greenhouse gases are eliminated.
A paper bag generates greater methane emissions in the landfill than a plastic bag.
For strength, most paper grocery bags are made from virgin pulp, not recycled materials.
Environmentally, ‘Paper or Plastic?’ Is No Longer the Question
Compared with plastic bags, paper shopping bags make a much larger carbon footprint from production through recycling.
A paper bag requires four times more energy to produce than a plastic bag — 2,511 BTUs vs. 594 BTUs. (British thermal unit (symbol Btu or sometimes BTU) is a traditional unit of energy equal to about 1055 joules)
In the manufacturing process, paper bags generate 70 percent more air and 50 times more water pollutants than plastic bags.
Nearly twice as much energy (91 percent) is required to recycle a pound of paper than a pound of plastic.
Global oil consumption for plastic production is about 5%.
Only five percent of oil consumption goes to plastic production! From overall plastic production! That means five percent of global oil consumption (=5% of 245 million tonnes used oil) goes for plastic packaging for food/drink, plastic packaging for transporation, plastic for electronic component, plastic for furniture, plastic for housing, plastic for tire production, etc.
Comparison of Biodegradable and Compostable Plastic
|
systems |
HYDRO systems |
| Usually made from a by-product of oil-refining | Made from fossil fuel, derived polymers and starch |
| Can be recycled as part of a normal plastic waste-stream | Damages recyclate as of 1% addition unless extracted from feedstock (Roediger report 5 December 2013) |
| Can be made from recyclate | Cannot be made from recyclate |
| Emits CO2 slowly and less while degrading and forms biomass | Emits CO2 rapidly while degrading |
| Inert deep in landfill. So that it will not generate methane | Can emit methane in landfill if the landdill turns anaerobe |
| Can use same machinery and workforce as for conventional plastic | Needs special machinery |
| Suitable for use in high-speed machinery | ? |
| Can be compostable. Comparable to the time line of pine needles, straw, leaves. | Compostable (if hydrolysed) at lab scale insufficient on industrial / municipal composting plants. Prohibitions already pronounced in US and G |
| Little or no on-cost (max 4-5%) | Three to five times more expensive than conventional plastic |
| Same strength as conventional plastic | Weaker than conventional plastic |
| Same weight as conventional plastic | Heavier |
| Can be made very thin (15 – 20 µm) in order to save raw material | Thicker |
| Degrades anywhere on land or sea
Degradation upon accidental littering starts immediately due to the integrated UV light activation. mandatory in some areas of the Middle-East, Asia and Africa. |
Degrades only in high-microbial environment (if hydrolysed)
Degradation under littering ?? |
| CO2 burden / carbon footprint is 6 kg per produced kg of PE/PP | CO2 burden / carbon footprint is 38,4 kg per produced kg of plastic |
| Safe for food contact | Safe for food contact |
| No PCB’s Organo-chlorines, or “heavy metals” | No PCB’s Organo-chlorines, or “heavy metals” |
| Can be incinerated with high energy-recovery as it has a similar calorific value to the raw product (fossil fuel) | Can be incinerated, but lower calorific value |
| Production uses no fertilisers, pesticides or water | Production uses fertilisers, pesticides and water |
| No limit on availability of feedstock | Limited availability of feedstock |
| Can easily blended up to 50% with minerals like CaCO3 with a tremendous low energy input at the point of production with ca 18 MJ/kg (just PE has 29 MJ/kg ) | High energy input at point of production.
Eg: PLA 69 MJ/kg (Polylactic acid) PHA 89 MJ/kg (Polyhydroxy & alkanoates) Paper up to 600 MJ/kg |
| With only 10% mineral content a > 60% faster photodegradation in case of incidental littering (report Prof. Jacques Lemaire) | Not |
| bio products pass the eco-toxicity tests in ASTM D6954, EN13432, ASTM D6400 | pass the eco-toxicity tests in ASTM D6954, EN13432, ASTM D6400 |
| The biodegradation process resulting in CO2, H2O and Biomass is progressive | The biodegradation process resulting in CO2 and CH4, methane. The biodegradation process is degressive |