Life Cycle Analysis Of Paper Production Environmental Sciences Essay

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1st Jan 1970 Environmental Sciences Reference this

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During the typical life of a product, it will progress through 5 stages . At each stage there is interaction with the environment. In many cases the material processing and manufacture will occur in the same factory. The interaction between the product and the environment can be direct or indirect. For example, the pulping of the wood into paper will release emissions that are directly related to the paper. On the other hand, the transport of the paper will have an environmental impact from the emissions of the vehicle however this emission does not come directly from the paper. A Life Cycle Analysis (LCA) takes these emissions into account as well as other environmental impacts such as the destruction of habitat and can be used to quantify the environmental impact of a product from its original raw materials to its eventual fate (cradle to grave). The whole life cycle has to be considered, as the environmental impacts of different products will be greater at different parts of the cycle. For example, paper will have a bigger environmental impact during the material extraction and material processing stages than it will for the use stage of its life cycle. However, an electrical item such as a washing machine will cause most of its environmental impact during its use stage because of its consumption of electricity, the majority of which are generated by the burning of fossil fuels. The life cycle must also consider the potential for the product to be recycled, remanufactured and reused. Reusing obviously has the lowest environmental impact as it requires less energy to convert the useless product into a usable product again.

life cycle.gif

Figure 1: The product life cycle showing the five phases and the potential to recycle, remanufacture and reuse products (Tarr, c. 2007)

Paper is an essential product that the modern world relies upon. It is a highly functional product and is used to fulfil a variety of functions. It can be manufactured into many practical goods, with varying properties. It may be combustible or be made fire-resistant. It may be a carrier or a barrier or a filter. It may be tough enough to withstand acid or soft enough for a baby’s skin (Confederation of Paper Industries, 2010). Paper is a multipurpose commodity that can be used utilized to do anything from being printed on to deliver daily news to the masses, to create bank notes or even to make air and oil filters for cars. The worldwide consumption of paper in 2007 was about 300 million metric Tons (PaperOnWeb, c.2007).

An LCA is a way of linking the inputs and outputs of any product to the environment and provides an insight into possible solutions to lower the environmental impacts of that product. A typical paper production process and each stage’s environmental impact are shown in figure 2 (below).

recycling paper.jpg

Figure 2: shows the stages in the life cycle of paper: the logging of wood in the forest and the environmental impact of this, its conversion to fibres, the processing of the fibres to make paper, the distribution of this paper to the consumers, the collection of waste paper, after which it is either recycled back into paper fibres or it is removed from the cycle and sent to incineration or landfill. Adapted from (Axel Springer, 1998)

The paper industry uses a great deal resources and as waste paper is continually removed from the process, the paper industry is only viable if fresh fibres are constantly added. This means that trees have to be persistently cut down and removed from forests. This could lead to unwanted climate change due to their being less trees to absorb the CO2 and from the emissions from the manufacturing process and from the vehicles that are transporting the raw material. This wood could also have been used to generate energy, so removing it to create paper could lead to energy depletion. The trees used to produce paper should only be purchased from companies that will ensure that the trees are harvested and grown in a sustainable manner, as deforestation of local forests is unacceptable. If the trees were not harvested in a sustainable manner, and the trees were removed and not replaced the soil that would normally be held in place between the trees could be washed away when there is rainfall. During periods of exposure to the sun the soil would be dried out and the nutrients would be removed from it. This soil erosion would cause the land to become useless. Non-sustainable management of the forests will cause a disruption of the water cycle reducing the biodiversity of the forest. The paper industry is a very energy intensive one so carrying out an LCA on paper would allow us to see how much damage is being done to the environment by the paper industry. If the LCA shows that the paper industry is causing a significant environmental impact, it could cause a campaign for conservation.

Goals

The goals of this LCA were to assess environmental impacts of paper produced in Portugal, which is mainly exported and consumed in Germany, in order to discover what processes contribute the most to the environmental impacts. The environmental impacts being considered are the global warming over 100 years, acidification, eutrophication, non-renewable resource depletion and photochemical oxidant formation. The secondary aim of this LCA is to compare the environmental impacts of paper production, if the market was changed from German market to the Portuguese market.

Limitations

The LCA is limited by a few factors; firstly there is no data on the effectiveness of CO2 sequestration, so it was assumed that the CO2 released from renewable energy sources balanced the CO2 absorbed by forest growth. Secondly, even though fibres are recycled it is not clear how many times the original fibres can be recycled before they are too short to form a decent product, so it has been assumed that the paper is recycled 4 times at most before being sent to landfill or being incinerated. Thirdly, the materials that were present in less than 1% (in mass) in 1 tonne of paper of 80 g/m2 were ignored. Finally, the construction and maintenance of equipment, machinery and buildings were not included in the LCA.

Inventory Analysis

The first stage of an LCA is to carry out an inventory analysis. Here the overall life cycle of paper and the inputs required to make it are split up into smaller sections which are then broken down into individual processes and outputs which can be analysed. The life cycle was split into; forestry, paper production, distribution, final disposal in Germany and final disposal in Portugal. This is shown in figure 3 (below).

Input: Raw Materials: Wood, Water and Chemicals

Energy: Coal, Diesel and Electricity

Forestry

Paper production

Distribution

Final Disposal Germany:

Landfilling 17%

Incineration 8%

Recycling 75%

Final Disposal Portugal:

Landfilling 53%

Incineration 18%

Recycling 25%

Composting 4%

Output: Usable Products

Paper

By-products e.g. wood for domestic purposes

Output: Environmental Impacts

Airborne Emissions

Water Effluents

Solid Wastes

Figure 3: A diagram showing how the life cycle of paper was split into forestry, paper production, distribution, final disposal in Germany and final disposal in Portugal and how the inputs and output interact with each stage.

Each stage was now separated into individual processes so that an inventory analysis could be carried out. This is summarised in figure 4 (below), which shows all the materials used and links them to the processes that occur.

Stages

Processes

Forestry

E. globulus forest

Pine forest

Paper Production

Pulp production

Chemical production

Energy production in the grid

Transport of wood to the pulp mills then to the paper mill

Transport of chemicals

Paper Distribution

Transport of paper to Germany

Paper distribution in Germany

Paper distribution in Portugal

Final Disposal in Germany

Landfilling

Incineration

Recycling

Energy production in the grid

Transport of wastepaper from the user to the several disposal alternatives

Final Disposal in Portugal

Landfilling

Incineration

Composting

Recycling

Energy production in the grid

Transport of wastepaper from the user to the several disposal alternatives

Figure 4: A table of the processes involved at each stage of the paper life cycle, adapted from (Dias et al., 2007)

To complete the inventory assessment data on the growth and harvesting of forests in Portugal would have to be found. It would also have to be known whether the paper mills in Portugal import trees from Scandinavia, as this would then change the size of the emissions generated from transporting the raw material to the paper mills. However, as the raw material is coming from Scandinavia there is a possibility that the emissions could be lower because the average emissions of CO2 from an articulated lorry carrying a load of 40 tonnes is 2.68 kg of CO2 per litre/km, where as a the emissions from a ship carrying the same amount of material would only be 0.4 kg of CO2 per litre/km (Davies, 2003). This means the material brought in by shipping can come from nearly 7 times the distance that it can if it is brought by road and still only have the same amount of overall emissions. A disadvantage of shipping raw material to Portugal is that the trees will still need to be transported from the port to the paper mill. This would not generate a significant amount more of emissions if the paper mill was located near a port. However, if the paper mill is located far from the port, the environmental impacts of transport will increase.

The amount of pulp produced and the emissions that producing the paper pulp release would also have to be found. If the pulp is bleached to make it whiter, then there will be additional emissions with respect to wastewater. The paper making process is a very energy intensive one, so data would have to be found on the energy requirements of the paper making machinery and equipment. If the paper mill used some of its useful by-products to generate its own electricity, this would also have to be taken into account, as it may reduce the emissions generated by the plant as it will require less energy from non-renewable sources. However, it could cause an increase in the amount of particulate matter dispersed in the air from the paper mill.

The environmental impact from the transport and distribution of the paper would have to be considered. As the paper is distributed in both Portugal and Germany, the environmental impacts of the distances involved in the distribution would have to be accounted for. The average distance for paper distribution in Portugal could be considered to be 200 km, for Germany this could be considered to be 2700 km.

The environmental impacts of the final disposal of the paper in both Portugal and Germany have to be considered, as the policy for dealing with paper waste varies with country. In Germany, it is deemed that 5.8% of the paper produced is retained as archives. Seventy five percent of the paper that is discarded in Germany is recycled, 17% is landfilled and 8% is incinerated (Dias et al., 2007). In Portugal again it is assumed that 5.8% of the paper produced is retained as archives. Of the paper that is discarded 53% is landfilled, 25% is recycled, 18% is incinerated and 4% is composted (Dias et al., 2007). Using this information the environmental impacts of landfilling, incineration, composting and recycling could be calculated. The environmental impacts of the transport required to transfer the used paper to the recycling facilities would need to be determined in order to gain a more accurate representation of the environmental impact of the paper making process.

Impact Assessment

The impact assessment gauges the damage that will be done to the environment by the paper making process. The categories that could be considered are global warming over 100 years (GW), acidification (A), eutrophication (E), non-renewable resource depletion (NRRD), and photochemical oxidant formation (POF) (Dias et al., 2007). Figure 5 (below) shows the impact categories and factors that affect them. The factors that affect the impact categories are non-renewable CO2, CH4, NO2, emissions that are generated from renewable and non-renewable energy consumption, as well as chemical oxygen demand (COD) and adsorbable organic halogens (AOX).

impacts of paper.png

Figure 5: A table showing the impact categories and the parameters that affect each category

(Dias et al., 2007)

Using these weighting factors and the data collected in Dias et al. (2007), both an inventory analysis and an impact assessment were carried out. Each graph shows the analysis for both the German market and the analysis if the paper was to only be sold to the Portuguese market. Figure 6 (below) shows the results of the inventory analysis. Figure 7 (below) shows the results of the impact assessment. The negative values for various categories and stages of the life cycle reflect the parts of the process which have beneficial environmental impacts.

Figure 6: A graph showing the results of the inventory analysis (G = German market, P = Portuguese market). The FU is the functional unit, which in this study is 1 tonne of paper (Dias et al., 2007).

Inventory analysis results

The area of the paper life cycle that uses the largest amount of renewable energy is the pulp production. However, the negative contribution is larger for Germany as more of the waste paper is recycled in Germany than in Portugal. This shows that the production of paper from recycled fibres consumes much less energy than the production of paper from fresh fibres. The majority of the non-renewable energy is consumed by the paper making process. The amount of non-renewable energy consumed by paper distribution is also greater for Germany than it is for Portugal due to the fact that the paper mills are located in Portugal so the paper has a large distance to travel before it is distributed throughout Germany. The non-renewable CO2 emissions are in similar proportions to the non-renewable energy consumption meaning that the paper production is the major contributor to non-renewable CO2 emissions. The paper production and distribution are the main sources of NOx emissions due to the energy used from the national grid and the transportation of the paper. The SO2 emissions are mainly caused by the paper production stage of the life cycle, due to the energy production. On-site energy production provides a small negative contribution for NOx and SO2 emissions in Germany. The pulp production of the paper making process causes the largest contribution to COD emissions; however by recycling paper the final disposal stage can provide a slight negative contribution. Due to the chemicals used in the bleaching process of the pulping stage the AOX emissions are mainly created from the pulp production. Again from recycling the paper the final disposal stage can provide a negative input.

Figure 7: A graph showing the results of the impact assessment (G = German market, P = Portuguese market) (Dias et al., 2007)

Impact Assessment

The most significant contributor to global warming in Germany is the paper production due to the high non-renewable energy usage and CO2 emissions. However in Portugal it is the final disposal that has the largest impact on global warming, as most of the paper waste goes to landfill which produces a lot of methane.

As the paper production requires energy which produces high SO2 emissions, it is this part of the process that contributes most to acidification. The high COD and NOx emissions mean that the pulp production stage is the greatest contributor to eutrophication. A large portion of the eutrophication potential is down to the NOx emissions released due to the paper production stage. The electricity used during the paper production stage is the main contributor to the non-renewable resource depletion. Recycling the paper provides a positive impact to acidification and eutrophication, due to less material being sent to landfill and so fewer trees have to be removed from the forests.

The amount of acidification, eutrophication and non-renewable resource depletion is greater for paper distribution in Germany due to the fact that the paper mills are located in Portugal so the paper has further to travel before it is distributed throughout Germany.

The disposal of paper into landfill causes the release of CH4 which is a major contributor to photochemical oxidant formation. As Portugal sends more if its waste to landfill the impact of POF is greater.

Conclusions

The inventory analysis shows that Portugal consumes a larger amount of renewable energy and has higher emissions of SO2, COD, and AOX than Germany, this is due to the larger amount of paper sent to landfill. Therefore to change from the German market to the Portuguese market is less environmentally beneficial. However, the impact assessment shows that the acidification, eutrophication and NRRD are smaller for the Portuguese market due to the reduced transport required to distribute the paper. The pulp and paper production stages are major contributors to all the categories and environmental impacts due to the large energy requirements that are satisfied by both on-site energy production and consumption of electricity from the grid. From carrying out this LCA it has become apparent that the forestry stage does not provide any significant environmental impacts. Paper consumption in Germany is more damaging environmentally in categories in which the paper distribution stage has a considerable input due to the large distance that has to be covered in order to distribute the paper. However, due to the smaller amount of recycling that occurs in Portugal, the global warming potential and photochemical oxidant formation are greater. This LCA has shown that the best area of the life cycle of paper to approach in order to reduce the environmental impact of paper manufacture is the pulp and paper production stages. The environmental impact could be reduced by more efficient treatment of flue gases and liquid effluents.

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