Life Cycle Assessment Of Laptops And Printed Notes Engineering Essay
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For the last few years, the society had started to use electronic devices for reading instead of using printed paper especially for university students. However, the paper is still used for printing and other usage. Paper is one of the main causes of global warming as trees will be cut down and processed into wood as wood is the main ingredient of producing paper. Without trees, there will be less photosynthesis phenomena occurring to reduce carbon dioxide concentration in the atmosphere. Carbon dioxide is produced by human activities such as breathing, power generation, combustion etc. To reduce the cutting of trees, several electronic devices have been introduced to replace the paper used for several purposes.
1.2 Life Cycle Assessment
Life Cycle Assessment (LCA) is a method used to analyze the impacts caused by products and services to the environment surrounding. It is used to study the life cycle from the extraction of raw materials, processing, transport, use, reuse, recycling or disposal of the products and services. There are four stages in LCA which includes goal identification, life cycle inventory, impact analysis and improvement analysis. LCA is used to identify and analyze the input and output of materials, energy and waste emissions in solid, liquid and gaseous state in order to make the improvement from the environmental impacts determined. (Life cycle assessment n.d)
2. Goal and scope definition
2.1 Goal of this study
The goal of this study is to compare the Global Warming Potential (GWP) of the service between reading printed lecture notes and reading lecture notes on the laptop. Life Cycle Assessment (LCA) of printed and computer document as learning materials for an undergraduate engineering student of Swinburne University of Technology Sarawak Campus is conducted.
The LCA of this study is done by the undergraduate Civil Engineering students of Swinburne University of Technology Sarawak Campus. The results of this study is based on the two reports titled 'Scanning Life Cycle Assessment of Printed and E-paper Documents based on the iRex Digital Reader' by Sebastiaan Deetman and Ingrid Odegard in March 2009 and 'Life Cycle Assessment of a Laptop Computer and its Contribution to Greenhouse Gas Emissions' by Anh Hoang, Wei li Tseng, Shekar Viswanathan and Howard Evans. The study will compare the environment impacts of the printed paper and laptop.
2.2 Scope of this study
Scope of this study consists of function and functional units. Function of the product will be analyzed and functional units will be included in this study is used to make comparison of the services and the LCA of the laptop.
Laptop can be useful in reading lecture notes and making notes in a document files. These are the functions that will be analyzed. However, laptop can also be used to read online newspaper, journals, magazine and for doing assignments. These functions will not be included in this study but they can definitely help in reducing the environment impacts. The use of Microsoft Office software in laptop enables students to make own notes and read lecture notes for e-paper and printed documents. This function has made the comparison between computer documents and printed paper viable.
In this report, it is assumed that the time taken for a student to download lecture notes from the BlackBoard System used by Swinburne University of Technology into the computer is the same. Therefore, it can be excluded from this study because initially, both alternatives need to use this function. Besides, the wireless connection in Swinburne University should be neglected as both printed notes and e-notes require the wireless connection to download the lecture notes from the BlackBoard System.
2.2.2 Product System
The manufacturing and assembly of components for the laptop including packaging result in releasing greenhouse gases.
To distribute the laptop to retails, transportation of the laptop is included in this study. The greenhouse gases also will be released through the transports used.
The usage of the laptop will be four years equivalent to the four years course. The total usage of laptop including lecture, tutorial and self-study per unit for one week is included in this study. So, the laptop usage for one year can be calculated.
d. End of life
End of life in this study is about recycling a laptop that can no longer be used or function anymore. The laptop will be recycled under the US recycling requirements.
2.2.3 Functional Unit
The functional unit of LCA is to study the service of the paper used for printing notes for a student which is four years as the engineering courses for Swinburne University of Technology takes four years to complete. However, the laptop is assumed to replace all the printed notes in this study throughout the four years course. The assumptions of the laptop and printed paper that need to be taken into the consideration in this study are as shown as below.
1. The life span of the laptop and printer are four years as engineering courses take four years.
2. Plug is used for laptop for all the time instead of using battery.
3. Laser printer is used for printing.
4. Wooden uncoated paper is used for printing.
5. The printed paper is in greyscale.
2.2.4 Impact Categories
In this study, the laptop usage and the printed paper are compared to analyze the data of greenhouse gas emission for both alternatives which contributes to Global Warming Potential (GWP).
3. Life Cycle Inventory (LCI)
In this report, the data collected are the manufacturing, distribution, use and end-of-life of a standard laptop. The CO2-e emission of each stage are also calculated and included in the report.
3.1 Inventory of Laptop Computer
It includes the manufacturing and assembly of components as well as manufacturing and assembly of laptop which comes with packaging. On the whole, the greenhouse gas emission is approximately 160 kg CO2-e which is obtained from the graph on a report entitled 'Carbon Footprint of a Typical Business Laptop from Dell' which is written by Markus Stutz (2010).
Transportation of laptop by all means to assembly locations and distributed to local retails, including transportation to customers themselves. For this report, the greenhouse gas emission of distribution of laptop is approximately 50 kg CO2-e (Stutz 2010) following the US region. However, the transportation may vary with region. So the emissions will vary as well but not much difference.
The life span of the laptop is estimated to be four years which is assumed to be used for the whole four years course of engineering students of Swinburne University Sarawak. One laptop is used by one student only. It is assumed that for one week, the total usage (hours) of laptop is 28 hours inclusive of 3 hours lecture, 2 hours tutorial and 2 hours of self-study per unit. There are four units altogether so 7 hours multiply by 4 equals to 28 hours. Assuming two semesters which consists of 32 weeks (inclusive of exam weeks) are equivalent to one year, the total hours is 896 hours. Hence, for four years, the total hour is 3584 hours. To calculate the power consumption and greenhouse gas emission, the mode taken into consideration is "Active" mode. Based on the report written by the students of National University entitled 'Life Cycle Assessment of a Laptop Computer and its Contribution to Greenhouse Gas Emissions', the electricity used for average "Active" mode is 0.032 kWh. The power consumption is tabulated in the table below.
Electricity Used (kWh)
Hours for 4 Years
Power consumed (kWh)
Based on the report too, the formula is converted to kWh. Hence, the greenhouse gas emission for usage is equal to 45.88 kg CO2-e.
Once the laptop can no longer be used or it is unable to function anymore, the laptop will be sent for recycling. Sometimes laptops can be reformatted but it will not perform as well as before. Hence, according to Stutz 2010, it is assumed that 75 percent of the laptop will be recycled under the US recycling requirements. So, the greenhouse gas emission of -30 kg CO2-e is obtained.
Kg CO2-e released
End of life
Table 1: The CO2e emission for laptop
3.2 Print Alternative
Other alternative is that, the lecture notes, tutorial sheet and solutions can be printed out for study. The significant part which manipulates the GWP value is the type of paper used for printing. In this inventory, woodfree uncoated paper will be used to print out the lecture notes as well as tutorial questions. The GWP of manufacturing, distribution, use, end-of-life stage was taken from the LCA done by the ecoinvent for the inventory of the print alternative.
3.2.1 The use of printer
A laser printer is used to print all the lecture notes and tutorial exercises. According to the report of LCA done by the student of University of Technology in Delft, they are using the process description of Ecoinvent database, which includes the life-time of printer, energy use during 3 different operational modes(active, stand-by and off), the print speed and average paper consumption.
These numbers were all converted to an average inventory for an hour of printer use, as summarized in Table 4 below [Lehmann, 2007].
Amount (per hour of printer use)
Electricity, low voltage, production UCTE
Paper, woodfree, uncoated, at regional storage
Printer laserjet, b/w, at plant [GLO]
Toner, black, used for printing [RER]
Transport, freight, rail[RER]
Table 1: The usage of printer and papers per hour
In table 4, the usage of printer, paper and toner was converted to per hour usage. This is because Ecoinvent database recorded the lifetime of a printer is about four years. However, the usage of the laserjet printer will not be operating twenty four hours per day for four years. Therefore, the inventory is converted to per hour determination.
Uncoated woodfree paper is the type of paper that we used most for printing. The dataset of the production and distribution of the type of paper is based on the Ecoinvent database. And according to the database, the uncoated woodfree paper contains at least 90% of fibres in the form of chemical pulp.
The estimation of paper used in 4 years.
The approximate number of paper used for 1 chapter=15 sheets
There total chapters for 1 subject= 8 chapters
Subjects in 1 semester= 4
Semesters in 1 year=2
There are approximately 960 sheets of paper used in one year. And one student will consumed approximately 3840 sheets of paper in four years time.
There are three types of paper disposal flows are defined in Ecoinvent, they are:
· [G139] disposal, paper, 11.2% water, to municipal incineration [CH]
· [G449] disposal, paper, 11.2% water, to sanitary landfill [CH]
· [G1984] paper, recycling, with deinking, at plant [RER]
The first two processes, however, differ from the third. The disposal processes have economic outflow the 'service' of the disposal of 1 kg of the paper, as what is expected. A physical mass of recycled paper is the output for the recycling flow. According to Ecoinvent, there isn't recycling paper 'service' and recycling gives out recycled paper as output. This means that the printer not only provide service of printing, but also 'produce' recycled paper. Part of the total process to the recycled paper and part of the total process to the use of printer were allocated. This means that the environmental impacts of recycling the paper as waste are taken into account.
4.0 Impact Assessment
This stage is to assess the impacts will affect on human health and the environment associated with energy and raw material inputs and environmental releases quantified by the inventory. We have done the impact assessment for the category of global warming potential (GWP). From the result, we do a comparison of CO2-equivalent between the laptop and printed paper.
4.1 Break-even Point: GWP
Break-even point is when the GWP of both alternatives is the same occur. This can determine which alternative is more sustainable to the environment. When the GWP of both alternatives meets at this point, their emission is equal. After that, based on different situation, which ever goes higher is considered as not sustainable.
GWP (kg CO2 equivalents)
Printing 3840 pages for four years
Printing with woodfree uncoated paper
Table: GWP values (in CO2-eq) of printed notes and laptop usage.
From the table above, the relationship between the print alternative and laptop computer between two scenarios was assumed. After that, it can generate the graph as seen in figure below.
From the figure, the impact assigned to the laptop computer remains constant as it is used daily for reading and studying. The graph shows the GWP of print alternative is much lower than the laptop computer. The break-even point is too far that it is probably about 70000 prints for four years.
5.0 Improvement Analysis
Based on the research done, the usage of e-paper (laptops) still releases quite a high amount of CO2e which leads to Global Warming Potential. Hence, a few improvements to reduce emissions should be done. Improvements that could be done are as follows:
Optimization of electricity usage when manufacturing laptops
Minimize the number of transportation of laptops by distributing as many laptops as possible delivery process
Turn off laptop when it is not used (i.e when taking a break from studying lecture notes)
Purchasing laptops which has Energy Star label. Energy Star is a program by US government which helps to protect environment using superior energy efficiency. (Energy Star n.d.)
Public awareness - give talks on managing electricity and power usage
In order to reduce the effect of global warming potential for paper, improvement can be done in the ways of:
Conserving paper by printing on the both sides of the paper.
Select to print what is really needed. Print only a few pages that are needed instead of the whole book.
Recycle the used paper and use sustainable paper too.
Return the empty printing cartridges to the supplier for recycling.
From the life cycle assessment, we have compared the carbon dioxide equivalent of a laptop and paper for four years. It is shown that the CO2-e of a laptop is higher than paper. In other words, print alternative is a better choice to reduce the environmental impacts. It is more environmental friendly to study the lecture slides by printing paper instead of using laptop as paper emits less CO2e. The results above can only be applied to study lecture notes, not for office use and others.
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