Author: Lawrence Jongi
Introduction
The Swedish coast guard needs to renew their fleet of vessels, in this quest their desire is to have a new fleet with little environmental footprint throughout the entire life cycle of the product from material, manufacturing, usage, end-of life, GHG emissions and energy usage. In this problem the author will design for functionality, however with the following in mind:
Minimum impact in use phase;
Minimize amount of material for the design;
Choose the best material;
Distance between Gothernburg to Stockholm by coastal freight is 800km;
The fleet will be using diesel;
A day is 24hrs to convert the hours per year to days per year;
The coastal fleet will travel 250km per day;
For fiberglass molding the author chose compression molding because of superior strength needed for this design;
Choose the cost-effective material however retaining functionality and sustainability.
The analysis will be focused on exposition and comparison of Aluminum and Fiberglass material in shipbuilding, however, all other materials in the interior are not included in the analysis, also the paint coat on the ship is not included in this analysis, this makes the analysis somehow skewed, because these materials use paint differently. During fiberglass production materials such as releasing agents (used to release the fiberglass from the mold), accelerators (used to quicken the trying process), sanding paper (used to make it smooth) is assumed negligible even though they are key materials in fiberglass production. The traditional and the most often used Al-alloys in shipbuilding are 5083 type Al- Mg alloy for plates, and 6082 type Al-Mg-Si alloy for extrusions. These alloys were found to be reliable in marine service as well as during manufacturing. Aluminum alloys meet or exceed the minimum yield strength requirements for normal strength steels (mild steels), and could even compete with high strength steels. They also have superior corrosion resistance (steel corroded at a rate of 120 micrometer per year, while in a similar study, aluminum corroded at a rate of only 1 micrometer per year), (Djukanovic, 2023). Based on this reference the author chooses to use 5083 type Al-Mg because ship building use plates for the eco-audit analysis. In this analysis the author will compare the two material specifically against two functional units, i.e CO2 footprint and energy footprint through the two designs’ product life cycle.
Method
The author will cross reference the materials properties in the software and apply filters in terms of costs and load although, according to the literature referenced above, a particular Aluminum alloy has been chosen, the author will put it test against other contenders in the data base and eco-efficiency, using Level 1 of the database of the software. The author will use the worst-case scenario, meaning will take the minimum values of the materials properties, however, for cost will take the maximum value, refer to table 1. The author will then put the selected material into the eco-audit and compare the two designs. Since the type of fire and noise is not specified the author will cross reference different materials which display good insulation but at the same time sustainable.
Table 1: Material Properties
Material | Thermal Conductivity(W/m.oC) | Cost(SEK/kg) | Yield Strength (MPa) | Hardness (HV) | Recyclability | Density (kg/m3) | |
Aluminium | 121 | 20 | 109 | 57 | Yes | 2.81X103 | |
CFRP | 1.26 | 369 | 550 | 10.8 | No | 1.6X103 | |
Insulator | Â | Â | Â | Â | Â | Â | |
Rigid Polymer (MD) | 0.027 | 136 | 0.4 | 0.095 | Not | 78 | |
Rigid Polymer (HD) | 0.034 | 136 | 0.8 | 0.28 | Not | 136 | |
Rigid Polymer (LD) | 0.023 | 136 | 0.3 | 0.037 | Not | 36 | |
Insulator (cork) | 0.04 | 117 | 1.1 | Â | Not (however reusable) | 240 |
Figure 1: Foam Properties Chart
From figure1 it is clear that the polymer foam with superior thermal conductivity is also the one with less density, which makes it a best fit in terms of design. Less density means less energy use, during manufacturing, transportation and usage, and it also mean less material for end-of-life. Hence the author choses Flexible Polymer Foam (VLD).
Now to choose the appropriate insulator the author at stage 1 made a thermal conductor or insulator versus density, and put filters for superior insulation, should be a poor electrical conductor, low density and also it should be recyclable into the Granta software and to make it economically sustainable put the cost filter. For an insulator it adds little value for it to have a superior yield strength.
Figure 2: Insulator selection
It seems from figure 2 Flexible Polymer Foam is also displaying superior properties for the design, low density and good insulator. However, a trade-off is needed between insulation and density, because cork is renewable resource than, hence the author will go for cork, for the design as a fire and noise resistance, not mentioning that it is biodegradable hence perfect fit for landfill. Cork oak forests contribute to the preservation of biodiversity and the survival of many indigenous animal species, some of which in danger of extinction. Equally important is its role in capturing CO2, the regulation of the hydrological cycle and restraining environmental and social desertification, (Composites). The slow combustion of cork makes it a natural fire retardant, forming a barrier against fires. Its combustion does not release smoke or toxic gases, (Composites).
Results
Figure 3 and figure 4 shows energy and carbon dioxide footprint respectively for the two design.
Figure 3: Energy footprint of the two design
Figure 4: Carbon footprint of the two design
From the two figures the dominating contributor is the usage of the fleet followed by material for both designs, however, the eco-efficient design is the aluminum design, it also displays potential of EoL.
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Discussion
It is critical to notice that Aluminum alloy is a critical rear material that’s why the author chose age hardening alloy, to prolong the life of the design. It is critical to note that although the software is explicit on many parameters, it is silent on the environmental footprint of materials upstream, e.g biodiversity losses during open cast mining, water pollution, toxic waste footprints, if this is critically evaluated for aluminum, the author is optimist to get different results. Fiberglass has less audit, such materials which are used to make a composite exist are missing e.g epoxy (releasing agent), accelerator (used to quicken the drying process), sanding materials, not mentioning that during fiberglass production huge amount of water is used which comes with water pollution, which makes the audit skewed. Both materials have huge gaps in terms of missing information or data to make the analysis reliable. Fiberglass has traditionally been treated with formaldehyde. This toxic chemical is proven to cause damage to human health. When fiberglass is thrown out, the formaldehyde can leach into the ground. This can cause contamination of the soil and water and will eventually end up in our food chain and drinking water, (Megan, 2023). With this is in mind, since most fiberglass operations are manual to semi-automated this pose a healthy hazardous threat to operators in the plant. Fiberglass present the following benefits; Fiberglass does not require a lot of energy to produce; it is lightweight and easy to transport, this keeps costs and consumption to a minimum; glass is made from sand, which means that fiberglass is also primarily made from sand and sand is a natural resource that can be found across the planet in great supply; fiberglass is very efficient, which is why it has earned an Energy Star rating, (Megan, 2023). Although it is arguably energy efficient, it has less End of Life potential because of not recyclable, with the combustion only option, which in turn contribute to GHG emissions.
Although aluminum is superior on the material on either energy and CO2 emission, it is critical to mention that the weight of aluminum fleet is 13.9 tons against fiberglass fleet of 7.3 tons, this will eventually attract huge amount of energy and CO2 emissions during use surprisingly the results are showing a huge CO2 and energy footprint on the fiberglass, which makes the result questionable, demanding further investigations.
There is evidence that fiberglass if inhaled the fibers can settle in your airway and lungs and short-term exposure will typically lead to irritation this can include itching or coughing, (Megan, 2023). The diagram below, show that most fiberglass production is semi-automatic.
 Figure 5: Open Moulding laminating Process, (Fibreglass, 2021)
Figure 5 shows that humans are always in exposure to chemical fumes from chemical reaction of the production process, (Fibreglass, 2021).
The Aluminum cradle-to-grave results, are based on an assumed EOL recycling rate of 95 percent for each product system. It is a snapshot of potential life cycle impacts of the products when the use phase is excluded and when the indicated EOL recycling rate is achieved. Different assumptions for EOL recycling rates will generate very different cradle-to-grave results, (Wang, 2022). Against this background it is critical to understand that the assumption of rate of recovery will come with accurate data from the manufacturer which is missing in most missing because it comes with Intellectual Property rights. Original production data (primary data) of each individual unit process was directly collected either by the Aluminum Association (AA) or the International Aluminium Institute (IAI), from more than 100 production companies, (Wang, 2022), however this will attract a lot of resources to gather such information i.e the rate of recyclability with respect to different aluminum alloys.
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Conclusions
There where so many assumptions in this audit, it is important to have direct measurements when carrying out audits, this makes the audit less biased and without variances. Fiberglass is a promising material (with a change of more than 200%) but needs to be exposed with all elements that makes it, from upstream to downstream. Conversely it is of huge importance to have an audit of aluminum at the extraction end to balance the scales. Other metrics needs to be included such as water pollution, toxicity levels, loss of biodiversity and carbon storage due to deforestation caused by open cast mining. Aluminum presence a superior quality in that, it has the potential of end of life, which means strategies such as closing the loop and slowing loops, (Nancy M. P. Bockena, 2016)Â can be employed, through refurbishment, reuse, recycling, designing for remanufacturing and design for maintenance, as opposed to fiberglass when it is damaged or on joins due to vibrations might prove difficult to refurbish or maintain. Although aluminum is reusable it is critical to investigate the nature of products to venture into for value capture and value proposition for the recycled aluminum, this includes what is the nature of infrastructural and structural investment. To have an accurate audit especially aluminum, it is critical to understand that, the location and process of the aluminum supplier is critical, because this has an impact on the production capacity against energy usage (energy mix) and CO2 emissions of the country, of which this software is not cognizant with during the audit, this will make aluminum looks more of a sustainable option with misleading hope. This point of view makes Life Cycle Analysis more complex as we look into all minerals and materials, their original point of extraction and manufacturing process, this requires to be supplied with sensitive accurate data from actors in the supply chain, which comes with protections of intellectual property and this requires trust within the value network. With this analogy, to come up with a reliable and comprehensive life cycle assessment of coast guard vessels requires a summation of different life cycle assessment of the entire value chain. From the analysis it is clear that there is need for trade-off on all fronts, i.e losses and gains on different parameters and functional units which are critical to the product, production operations, regulations and regional to national by-laws and directives and the organization.
References
Composites, A. C. (u.d.). About Oak Forest. Cork Oak Forestry, https://amorimcorkcomposites.com/en/why-cork/facts-and-curiosities/about-oak-forest/#section-WhyAreCorkOakForestsNaturalFireRetardants-3660.
Djukanovic, G. (2023). Aluminium alloys in shipbuilding – a fast growing trend. Aluminium Insider, https://aluminiuminsider.com/aluminium-alloys-in-shipbuilding-a-fast-growing-trend/.
Fibreglass, G. (2021). OPEN MOLD LAMINATING PROCESSES. Fibreglass Manufacturing Process, https://www.goldshield.com/fiberglass-manufacturing-processes.html.
Megan. (2023). Is Fibreglass Biodegradable. Citizen Sustainable, https://citizensustainable.com/fiberglass/#Is_Fiberglass_Harmful_to_the_Environment.
Nancy M. P. Bockena, I. d. (2016). Product design and business model strategies for a circular economy. Journal of Industrial and Production Engineering.
Wang, J. (2022). The Environmental Footprint of Semi-Fabricated Aluminium Products in North America: A Life Cycle Assessment Report.