Life cycle assessment for production of PVC pipes

1.0 INTRODUCTION

The aim of this report is to perform a Life Cycle Assessment for the production and use of 5 kg of PVC (Polyvinyl Chloride) pipes. PVC is a product that can withstand high pressures and thus is highly preferred for piping. It is a product which is consumed worldwide and the demand for high quality pipes has been increasing globally. A high demand for the product comes with high environmental impacts and as such it is vital to perform a Life Cycle Assessment to uncover and evaluate the major areas of concern. Attempts will be made to discover ways to condense the negative impacts.

An LCA is conducted in researching and developing products since environmental footprint is considered crucial for future marketing and price structures. The software used is Sima Pro and the LCA is conducted by following the four step approach outlined in the ISO 14040 standards.

2.0 BRIEF BACKGROUND ON IDENTIFICATION OF PROCESSES

The report deals with the environmental impact assessment of 5kg of PVC pipes. The most important applications of PVC pipes are seen in the construction industry for sewage pipes, irrigation and water mains. Its unique properties like superior pumping efficiency, longevity and corrosion resistance provide long term savings and makes it a low initial cost option. It has gained popularity due to its durability and easy installation process.                             

Firstly, the major processes involved in the manufacture of PVC pipes are studied.  The raw material for the pipes is thermoplastic Polyvinyl Chloride and the process used in the manufacture is called extrusion. The process used to obtain PVC for making pipes is called Suspension polymerisation. Suspension PVC accounts for about 80% of its market and is used for the most rigid applications (Boustead, 2005). PolyVinyl Chloride in the form of powder/pellets are extracted, melted and then heated in the extruder zones. They are then shaped into pipes, cooled and cut into desired sizes. The diameter of the pipes are maintained using the extruder. After this they are stored, packaged and transported to end users. At the end of its life it is either recycled, incinerated or disposed of to the landfill. Due to complexity and limited availability of data, we focus on three influential processes which are raw material processing, transportation of the pipes and the disposal of used pipes to the landfill. The main life cycle of a PVC pipe is illustrated in the figure below. The negative impacts due to the manufacture of PVC pipes can be reduced by identifying and analysing the key processes involved.

3.0 GOAL AND SCOPE

Life Cycle Assessments are strongly goal and scope dependent. The specification of goal and scope is an important phase in LCA methodology as this is where the determination of the exact approach is done (Curran, 2017). The software used is Sima pro which helps in the application of sustainability expertise to make changes to a products life cycle and help reduce its impacts. An inventory analysis representing the life cycle is carried out along with impact assessment which includes damage assessment, characterisation, normalisation, weighting and single score. A critical discussion is done on the social and ethical issues with respect to the product. The LCA complies with the international standard ISO 14040 and the method used is Recipe Endpoint (H).

The main objective of this report is the analysis of 5kg of PVC pipes from raw material extraction to transportation and end of life disposal. Sima pro database is used to identify and evaluate the various environmental and health impacts related to the activities included in the process. The main focus of our assessment will be on the processes which are major contributing factors to the ecosystem, human health, global warming, acidification, ozone depletion and so on. To reduce such impacts, there is a need to be more proactive and give complementary insights (Rebizter et al., 2004).

3.1 ASSUMPTIONS

A few assumptions are made due to the limited availability of data. The raw material for the pipe, Polyvinyl Chloride is obtained by Suspension polymerisation. The transportation of the pipes is done across a distance of 2000 km from factory to store, in a truck with a capacity of 10 20 t. The process uses alternating current up to 60kV and the amount of electricity used for the process is assumed to be 6.5 MJ medium voltage. At the end of its life, the pipes are disposed of in the landfill.

4.0 LCA INVENTORY ANALYSIS

4.1 NETWORK ANALYSIS

A graphic representation of the life cycle of the PVC pipes is shown below. The contribution of processes to the overall network is shown by the thickness of the connecting lines. The materials used in the manufacture of PVC pipes forms the major component in the network. It can be seen that the major impact in the manufacture of the pipes is contributed by the material used which makes up 92.1 % of the overall impact. The material used is Polyvinyl chloride resin which is obtained by suspension polymerisation. The network tree for the impact of suspension polymerisation has not been analysed due to limited availability of data on the demo version of the software. A certain amount of electricity is required for the extrusion of pipes from PVC. Alternating current is used with a voltage of up to 60 kV, which accounts for the second major impact with 4.6%. The transportation of the finished pipes are done made a distance of 2 tkm in a truck which runs on diesel from crude oil. The capacity of the truck is between 10 20 t and this accounts for an impact of 1.99 %.

Another process that will be looked upon in this analysis report is the impact caused due to the disposal of the used pipes. Used PVC products are disposed of in the landfill. It can be seen from the network diagram that the disposal process accounts for an impact of 1.29 %.

4.2 CHARACTERISATION

The characterisation of the PVC pipe is calculated at the endpoint level, which includes the various factors like transport (orange), resin S PVC (light green), electricity grid(yellow), PVC pipes(dark green) and the disposal to landfill(blue). Resin S PVC has the highest impact when compared to all the other materials used. The largest impact of the landfill to disposal is on the emission impact category. The electricity grid consumption has a relatively lower impact when compared to it. Whereas transport is the one with the least impact when focused on the entire process. The resin has a high impact which serves as a factor to be considered for the PVC pipes and on the other hand the electricity grid has some amount of impact on the repository organics, this depends on the emission in terms of kg and time.

There are different impact categories, the freshwater and marine ecotoxicity, these damages are calculated by disability adjusted life years daily/kg emission. Climate change, it is calculated emission as a result of increase in death and disease because of climate change. Ionising radiation, this is caused as an emission resulting from radioactive radiation. The ozone depletion concerns the damage due to increased UV radiation as a result of emission of different substances in air. Land use, this shows the range of diverse lands and the damage depends on the occupancy. The metal and foil deposit acts as a factor which affects the natural resources and also the human toxicity emission is calculated as a result of the substance of effect from mad made toxic waste.

4.3 DAMAGE ASSESSMENT:

The PVC pipe material that has precisely reported their sustainability and different environmental aspects, throughout the lifecycle of PVC from production to disposal, is the most environmentally damaging material of all plastics, it releases toxic and chlorine based chemicals. Whenever chlorine based chemicals are burned, Dioxin and Dioxin like components are produced, PVC is mainly accountable for a higher portion of the overall annual dioxin burden than any industrial product. Largest amounts of Dioxin are due to PVC items in medical and garbage waste and accidental fire in any building which causes dioxin releases, affects health problems which includes immune system damage, impaired childhood development and hormone disruption.

The study on the damage assessment of PVC pipes while manufacturing and transporting an impact like human health, ecosystem and resources are discussed, while comparing with three impacts, production of PVC pipes which is shown in green which has an highest impact on resources which is 94% and human health is 90% and orange which is used to indicate transportation of PVC which has a lowest impact on environment and human health.

PVC is manufactured by Polymerization in suspension process which requires 13 ATM pressures to keep the monomer in liquid phase, so energy required is around 1KV 60KV, Yellow layer indicates an impact made while using energy, even though the ecosystem which has the highest impact. Landfills are shown in blue which have the lowest impact on given categories.

4.4 NORMALISATION:

To make ease of understanding and to simplify the results after interpretation, we use normalisation and weighting. International organisation of standardisation (ISO) 14040/44 says that normalisation which is similar to weighting is an optional process in LCA inventory analysis.

Results of normalisation provide the impact category to what extent the results are high or low when compared with reference.

The above bar chart represents the impact generated on human health, eco system through Life Cycle Assessment when analysis performed on Poly Vinyl Chloride resins (S PVC). Each result executed in the normalisation process is compared to a reference.

The executed results mentioned in the above tabular shows the impact/damage category on human health, eco systems and resources. It is observed that manufacturing of PVC pipes has a decent impact on each category when compared to a reference. Damage impact on human health is quite low compared to resources where resources have much higher damage impact within LCA. Comparatively, ecosystems have very lesser damage impact throughout analysis.

4.5 WEIGHTING:

The effect weighting phase of an item life cycle includes doling out every one of the examination classes an incentive to deliver a single result. The elements allocated to every classification are emotional and can base on various factors (Johnson, 2008). ISO does not permit weighting to utilize in applicable statements because of the uncalled for the impact the arrangement can have. Consequently, the utilization of weighting is considered the most dubious stage in an actual existence cycle evaluation, especially for midpoint (impact 2002+). Regardless of this, the weighting is irregularly utilized for dynamic purposes. Instances of weighting arrangements incorporate board weighting, which requires a board of experts to evaluate the significance of every class s natural effect and separation to an objective, which sets the weighting based on how close every part is to arrive at its ecological decrease target (Goedkoop, 2016). The weighted outcomes all have similar units, so can, in this manner, be added to make a general score for the natural effect. One of the numerous favourable circumstances of utilizing weighting is that it presents a single score. This variable takes into consideration the simplicity of the correlation between items, clarifying, which thing has the most significant effect on the earth (Brilhuis Meijer, 2019).

In this case, Resources has considered the most crucial impact category, and it was assigned a weighting factor of 0.619. Human Health followed this with a weighting factor of 0.558 and ecosystem quality with 0.262.

From the above figure, the weighted LCA results for each impact category associated with the PVC pipes production process. The weighting factor should decrease in the order of Human Health, Ecosystem, and Resources, but the results of PVC pipes had decreased in the order of Resources, Human Health, and Ecosystem.

Here, the most significant impact of PVC pipes is the Polyvinyl Chloride resin (S PVC), its impact was highest in order of Resources with (0.584mPt), followed by Human Health (0.503mPt) and Ecosystem (0.238mPt). Now the use of Electricity has the second largest impacts on human health (0.283mPt) followed by Resources (0.0228mPt) and Ecosystem (0.0151mPt). Moreover, Transport has the third largest impact of PVC pipes with Human Health (0.0133mPt) followed by Resources (0.0101mPt), Ecosystem (0.00519mPt). The least impact of PVC pipes is Disposal to the landfill with Human Health (0.0134mPt) followed by Ecosystem (0.00318) and Resources (0.00195mPt).

4.6 SINGLE SCORE:

The single score results shown in graph 5 above illustrates a simplified version of the weighting of the results rather than the total score of each category. The single score results show that Polyvinylchloride resin (S PVC), suspension polymerisation what impacted the most with a value of 1.33 Pt, mainly affecting Human health (0.503 Pt) and resources (0.584 Pt) whilst only impacting ecosystems 0.262 Pt. The other three show very little impact was made. However, altogether resources and human health were much highly impacted throughout with resources having a total combination of 0.619 Pt and human health 0.558 Pt from the 1.44 Pt total score. The remaining 0.262 Pt came from the ecosystem impacts.

Although single score results can be used to provide us with an easier evaluation of how one impact can affect another it can often be problematic and/or inaccurate due to the simplification of the data as important data can be lost (Sauro and Kindlund, 2005).

5.0 INTERPRETATION OF RESULT AND CRITICAL ANALYSIS:

It is observed that whole LCA process was carried out in step by step process. Talking about the tree diagram of whole process, initially raw material which is used is of 5kg to manufacture PVC pipes. The contribution of processes to the global network is illustrated by the thickness of the connection lines. The materials used in the manufacture of PVC pipes are the main component of the network. It is seen that lot of unspecified parameters were considered which are known as dummy parameters namely hydrogen gaseous which comprises of 0.0189 pt followed by unknown chemicals which comprises of 0.0211 pt. since the output of this poly vinyl chloride resin will produces plastic pipes, an unspecified plastic of 0.00317 pt was considered to produce proper output. Considering various more other parameters like unspecified paper and dummy wood which resulted combining weights 0.00000000189 pt and 0.000217 pt. We note that the main impact in the production of pipes derives from the material used, which represents 92.1% of the overall impact. The material used is a polyvinyl chloride resin obtained by suspension polymerization. The network tree for the impact of suspension polymerization was not analysed due to the limited availability of data in the demo version of the software. A certain amount of electricity is required for the extrusion of PVC pipes. The alternating current is used with a voltage up to 60 kV, which represents the second biggest impact with 4.6%. The transport of the finished pipes is carried out at a distance of 2 tkm in a truck that runs on diesel oil from crude oil. The truck s capacity is between 10 20 tons and this represents an impact of 1.99%.

Considering the tabular values obtained from graph 2 damage assessment,

it is seen that human health has much impact with a value of 0.0000282pt, followed by ecosystems which comprises value of 0.000000118pt and found that resources has less impact from PVC resins throughout normalisation process and resources comprises  of 0.956pt which brings total count to 0.95602pt  .

Now impact assessment method for normalisation is observed that resources have high impact around 0.0031 followed by human health of 0.0014 daily which is seen in below mentioned table.

The damage assessment for normalisation is very low for ecosystems which comprises of 0.000655 species per year. Summing up this whole we get 0.005155pt.

Now, taking the impact assessment for single score from above graph 5:

The results of he single score show that the polyvinyl chloride resin (S PVC), the suspension polymerization, had the greatest impact with a value of 1.33 Pt, mainly affecting human health (0.503 Pt) and resources (0.584 Pt) while it affects only ecosystems 0.262 Pt. Overall, however, resources and human health have been significantly affected throughout the process, with resources having a total combination of 0.619 pt and human health of 0.558 pt compared to a total score of 1.44 pt. The remaining 0.262 pt came from impacts on the ecosystem.

Since all the values given in input while performing LCA are assumptions, results that are executed may or may not have impact on every factor. Further executions are needed with precise inputs.

6.0 Social and ethical dimensions:

To begin with, oil and chlorine are not what you would call green substances in terms of extraction, refining and by products. Much of our modern life is based on oil, which if production suddenly stops, not only will transportation be affected, but it will affect all aspects of our lives. We really need to relaunch our addiction to fossil fuels before being forced to withdraw.

The durability of PVC is also its environmental loss: it is not biodegradable or degradable. PVC articles will keep their shape for decades and the break that occurs is only granulation: the pieces become smaller. Animals can ingest these pieces and plastic can block their digestive tract.

Greenpeace pushed for the cessation of PVC production because dioxin is created by the production and incineration of the substance. Dioxin is one of the most lethal human poisons and is a cumulative toxin, which means it remains in the body for a long time, focusing on food chains at the highest level. carnivores, which includes us.

PVC is extremely difficult to recycle. Very little PVC is recycled, and this situation should not change in the near future. Since each PVC product contains a unique mix of additives, post consumer recycling of mixed PVC products is difficult and cannot produce vinyl products of equivalent quality to the original. Even in Europe, where PVC recycling is more advanced than in the United States, less than 3% of post consumer PVC is recycled and most of these products are simply recycled in other products, which means that it does not exist. a net reduction in virgin PVC production. By 2020, only 9% of all post consumer PVC waste in Europe should be recycled, with a maximum potential of 18% maximum.

To make PVC flexible, substances like phthalates are added. Animal studies show that some of these chemicals can cause cancer, kidneys and damage to the reproductive system. The phthalates issue is now a concern, the United States Environmental Protection Agency (EPA) recently announced a series of actions.

It has often been reported that no other plastic represents a direct threat to the environment and human health like PVC throughout its life cycle; from production to use and disposal; however, our demand is increasing.

Recommendations:

Since PVC pipes has many environmental and health hazard issues, new materials are now being produced with most of the desirable properties of PVC, without concern for health and the environment. These degradable plastic materials are designed to decompose in landfills (darkness, heat and humidity) in a few years without emitting toxic gases or other pollutants. Currently, these types of materials are not widely available and are quite expensive.

However, there are still more environmentally friendly materials that PVC initially replaced. These are inexpensive and widely available anywhere.