1. Introduction
In recent years one can observe special attention being paid to the greenhouse effect, which like some scientists stress, may directly threaten large areas of the planet. As a result of global warming and in effect ice melting, sea levels could rise by about 1µm, flooding most of the river deltas, islands on the Atlantic USA coast, part of China, islands in the Indian Ocean and Pacific.
Scientists predict those climate changes will result in warmer winters and dangerously hot summers. Droughts will worsen, rainfall will lead to sustained flooding. This phenomena of increase of the Earth's temperature is caused by the presence of greenhouse gases (carbon dioxide, ozone, chlorofluorocarbons, methane, nitrous oxide, halons, water vapour) in the atmosphere.
2. Greenhouse effect and related questions
On Earth term greenhouse effect refers both to temperature increase associated with natural factors, as well as to this effect’s change, caused by greenhouse gas emissions resulted from human activities. The greenhouse effect (natural) is a phenomenon favourable for the formation of life on Earth. It is estimated it raises the surface temperature of about 20–34°C. The average temperature of our planet is 14–15°C. If there were no greenhouse effect, the Earth's average temperature would be about -19°C. Global temperature increase in the years 1850–2007 shows diagram #1.
Scientific community is mostly in agreement that this increased greenhouse effect, and therefore the raisin mean temperature is caused by human activity. Average air temperature increase in years 1906–2005, near the Earth’s surface was 0.74 ± 0.18°C. According to the IV Report of Intergovernmental Panel on Climate Change (IPCC) [2], global warming on a probability if more than 90% is caused by human activities. Natural factors impact is estimated at the level of 5%. Basic IPCC conclusions was supported by at least thirty scientific societies and academies, including all the national science academies of the G8 countries.
Some scientists question human impact on the climate change. Suggested alternative explanation of global temperature increase since industrial revolution are for example the effect of solar activity, warmer and colder periods in the history of the Earth theory, etc. According to these reviews, there are no convincing scientific evidence that emissions of carbon dioxide, methane or other greenhouse gases caused by human activities results or will result in foreseeable future in catastrophic warming of the Earth's atmosphere and the earth's climate problems. Additionally they claim there are substantial scientific evidence that increased carbon dioxide content in the atmosphere causes many beneficial effects for the natural vegetation and animal communities on Earth.
IPCC scientists strongly confirm global warming results from human activity. The cause are fossil fuels (coal, oil, gas) burning, deforestation, industrial processes (e.g. cement production) and
in a smaller way agriculture (cows emit methane, nitrous oxide is emitted by rice fields and crops of rape). International community accepted Framework Convention on climate change, which is considered one of the most important global environmental agreements. The Convention entered into force on March, 21 1994, and until 7 September 2000 has been ratified by 186 countries. Additional obligations relating to restrictions on greenhouse gas emissions resulting from the protocol signed in Kyoto [3].
3. Carbon footprint
Restrictions on greenhouse gas emissions have caused emissions calculating techniques development in terms of products. One of them is called carbon footprint or carbon profile. Regarding to industrial products carbon footprint describes total number of CO2 and other greenhouse gases emitted directly and indirectly during the entire life cycle of the product. Usually this carbon footprint is expressed in tonnes or kilograms of carbon dioxide (CO2), or in terms of CO2. For example:
n 1 kg of methane CH4 corresponds to 25 kg of CO2 emissions;
n 1 kg of nitrous oxide N2O emission corresponds to 298 kg CO2;
n 1 kg of HFCs corresponds to emissions of 124–14800 kg CO2;
n 1 kg of halogenated hydrocarbons SF6 emission corresponds to 124–14800 kg CO2.
Some express carbon footprint in kg of carbon rather than kg of CO2. To convert kg of CO2 to kg of coal there is factor 0.27 used (1000 kg of CO2 means 270 kg of coal).
Carbon footprint can be calculated using LCA but without other environmental influences. Carbon footprint is an important factor helping to understand the impact of every person, process or article on global warming, and actually every human activity causes direct or indirect CO2 emissions [4].
4. Carbon profile of packaging
Carbon dioxide emission into the environment reducing and the greenhouse effect are the most important challenges facing humanity. Therefore, it is worth paying attention to the impact of packaging on CO2 emissions. According to some analysts, packaging share in total CO2 emissions is negligible, about 1%. Information about connection between packaging and CO2 emission is discussed by Packaging Model consultancy company. It refers the thesis of Andreas Detzel from the Institute for Energy and the Environment Research (IFEU) in Heidelberg, who presented a paper on the carbon footprint and the role of packaging in carbon dioxide emissions.
As Mr Detzel informed, annually Germany emits about 900 million tons of CO2, clearly overtaking France (about 400 million tons) and of course Poland. The highest levels of emissions have United States. (5800 million tonnes) and China (4800 million tonnes). CO2 emissions per capita in Germany is 11 tons per year, in the United States 19 tons and 4 tons in China. In Poland, the level is just over 5 tons. Most of the CO2 emitted from power plants (43%), to the remaining emissions contribute: transport (20%), households (15%) and so called industrial heating (15%) Detzel also drew attention to the amount of CO2 emitted during production of one tonne of packaging material. Most, 12 kg of CO2 is emitted during production of 1 kg of aluminum. During the production of kraft paper there is 0.5 kg of CO2 produced, during the production of recycled paper 0.75 kg of CO2. Testliner –cardboard for flat layers of corrugated cardboard emits more carbon dioxide than kraftliner. Emission of starch it is 1.3 kg of CO2.
In comparison of different model 200 ml beverage packaging, including non-returnable glass, PET bottles, aluminum cans, boxes for drinks with a layer of aluminum and PE, the best result achieved glass bottles (13 kg of CO2) and beverages cartons, which emission of CO2 during the production of 1 000 units is 20 kg. Non-returnable glass bottles cause emission of 87 kg, aluminum (mostly cans) around 124 kg of carbon dioxide. It is clear, that the production and incineration contributes to the emission of CO2 in little way. It was calculated, that production and use of packaging causes about 1 percent of total CO2 emissions in nature. Reduction of packaging amount by 20% theoretically would make reduction of CO2 emissions level per one citizen maximum by 1/500.
A detailed list of carbon footprint for various packaging materials and life cycle stages are shows table #1.
Taking into account the stage of packaging materials manufacturing, according to prof. R. Narayan [5] of Michigan State University, concerning CO2 emissions, raw materials of plant origin, including biodegradable polymers such as polylactide (PLA) have better results than conventional plastics PET, HDPE or PA. Comparison of the carbon footprint of these polymers is presented in diagram # 2. Diagram #3 depicts carbon footprint results for Ingeo polylactide (Ingeo – trade mark of PLA produced by NatureWorks LLC), from production in year 2005 and 2009 and predicted future production, PP, PET and PS are presented for comparison.
Packaging materials of natural origin (sources) are produced by plant organisms, which absorb from the air CO2, needed in the process of photosynthesis with evolution of oxygen [6, 7]. Be
cause plants absorb CO2 from the air during photosynthesis, many scientists assume zero carbon footprint (diagrams #4 and #5) for production of vegetable materials stage, and even negative carbon footprint, due to the amount of assimilated CO2. An example of such calculations with negative CO2 emissions are summarized in diagram #6. The calculation relates to Ingeo polylactide production process. As the data in diagram show, the amount of CO2 assimilated during the growth of corn largely offsets the amount of CO2 emitted during PLA polymer production process.
As diagrams show, carbon footprint factors presented in different publications are different, but CO2 emission level for polymers produced now from renewable raw materials are significantly lower than in case of conventional plastics.
References
[1] Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.
[2] web page [http://www. ipcc. ch/publications_and_data/publications_and_data_reports. shtml].
[3] Kyoto Protocol to the United Nations Framework Convention On Climate Change, United Nations 1998.
[4] web page [http://www. samar. pl].
[5] Narayan R., LCA: How to report on the carbon and environmental footprint of PLA, 1st PLA World Congress, Munich 9-10.09.2008.
[6] Adler P. R. et al., Life-Cycle assessment of net greenhouse gas flux for bioenergy cropping systems, „Ecological Applications” 17 (3). 2007 pp. 675-691.
[7] Mckechnie J. et al., Forest bioenergy of forest carbon? assessing trade-offs in greenhouse gas mitigation with wood-based fuels, „Environ. Sci. Technol.” 2011 pp. 789-795.
[8] M Patel, R. Narayan, in „Natural Fibers Biopolymers and Biocomposites”, A. Mohanty, M Misra, L. Drzal, Taylor & Francis Group, 2005, Boca Raton.
[9] Hagen R., Basics of PLA, „Bioplastics Magazine” No 1/2009, pp. 38-40.
[10] web page [http://www. natureworksllc. com/news-and-events/press-releases/2009/02-10-09-ingeo-ecoprofile. aspx].
[11] Improved Eco Credentials for PLA, „Bioplastics Magazine” No 6/2010, p. 8.
Acknowledgments
The European Cooperation in the Field of Scientific and Technical research, COST Action FP1003: Impact of renewable materials in packaging for sustainability – development of renewable fibre and bio-based materials for new packaging applications, is thanked for providing the opportunity to perform this article.
