Calculation methodology

The functional unit of the assessment is waterjet, which main function is to generate thrust to vessel. Its secondary functions are steering and breaking/reversing. Unit in-cludes several different materials, but two main material can be identified: casted stain-less steel and aluminum. First one is used for pump unit components and latter one for inlet duct and bearing house.

System boundary is limited to mechanical components of waterjets, which means that hydraulic- and control system components will be left out from the assessment. Se-lected size of waterjet’s mass range is 1000-3000 kg, depending about the configura-tion. Hydraulics and control components represent around 9-12 % of the total mass.

Main mechanical components were presented in figure 9 in chapter 3.1. Geographical boundary is not limited as the components are supplied from Europe and Asia. Assess-ment will apply the cut-off rule from PAS 2050, including at least 95 % of the system mass and its emissions. Table 4 combines the component mass proportions and mate-rials, which will be included in our study. These contains 97,6% of the total mass of waterjet.

Table 4. Waterjet component mass proportions and materials

Waterjet supply chain and manufacturing process flow is visualized in figure 11. As pre-viously defined cradle-to-gate approach will be applied, leaving out use and disposal stages. This approach can be justified with 3 reasons: Firstly, waterjet unit is part of the final product, vessel. Secondly, waterjets are used in multiple vessel types, meaning that user profile and annual operation hours varies and in most cases are unknown.

Thirdly, the goal of the thesis is to analyze only one life cycle impact, climate change, but emissions that generate from waterjet use stage are mostly related to water pollu-tion.

No: Component Material Mass (%)

1 Guide vane chamber Casted stainless steel 23,67 2 Impeller chamber Casted stainless steel 6,80 3 Steering nozzle Casted stainless steel 3,82 4 Reversing bucket Casted aluminum 9,47

5 Impeller Stainless steel 5,95

6 Inlet duct Welded aluminum 28,82

7 Impeller shaft Stainless steel 14,44

8 Coupling boss Stainless steel 2,00

9 Bearing house Aluminum 2,18

10 Sacrificial anodes Casted Aluminum 2,85

Total 100,00

The first phase of LCA is raw material extraction. This includes mining operation at mines and refining of the material. Component manufacturing is divided to out-sourced- and internal manufacturing. Outsourced manufacturing processes include ma-terial processing such as casting, turning, milling and rolling. The number of internal processes is depending of each component. On Assembly, components are mounted together, which’s output is one waterjet unit. The last stage of the LCA is packing, where unit is packed to plywood box before storage or loading to truck. Different type of transportation is used between stages. Components are carried with container ship and/or truck depending of the component origin. Internal material handling is done by electric forklift. Due to a wide range of processes and globality, process flows of com-ponents are presented in more detailed level in Chapter 4.1.

Figure 11. Waterjet manufacturing process flow

3.3.2 Modelling with Open LCA

The emission inventory analysis will be conducted by using Open LCA 1.10.3 –soft-ware, which is currently the only full access software available for free. Commercial software offering free trial period 14-30 days have limited their functions on free ver-sions by limiting the amount of processes and do not allow to use any database reliable enough for LCI.

Starting the LCI assessment with Open LCA, user may download the software to the computer or use it as an online version. First task of LCI is to create new database for the functional unit, in this case “Waterjet” as showed in figure 12. The whole LCI as-sessment in Open LCA is based on product systems, processes and flows. Flows are individual inputs and/or outputs that are used to create a process. Open LCA includes substantial amount of elementary flows for emissions and resources.

Figure 12. Navigation panel of Open LCA 1.10.3

Instead, Open LCA does not offer any pre-created processes, which must create by user or imported from other available database. Open LCA has its own database cata-logs called Nexus. Totally 24 databases contain more than 180,000 datasets from dif-ferent industries and activities. Databases are divided to free- and purchased bases (Greendelta GmbH, 2020). For waterjet LCI calculations, 7 different free bases were utilized. First, Agribalyse V3.0.1 is French agriculture and food sector data-base, which also includes processes for electricity production. Bioenergiedat is German background database focused on bioenergy supply chain data and nuclear safety.

Ecoinvent only include different types of impact assessments that are utilized with LCA calculation mainly in case of full LCA process. Environmental Footprints (EF) originated from European Commission’s Single Market for Green Products initiative and carry wide range of processes from material production, transport services and energy carri-ers. European reference Life Cycle Database (ELCD) offered by European Joint Re-search Center is similar to previous one and additionally include different product pack-aging processes. Exiobase is global process database with large number of country specific data from different industry sectors such as raw material-, energy- and product production. Last database is similar to Ecoinvent database, offering different LCIA methods created by Open LCA itself (GreenDelta GmbH, 2020).

In case relevant process data is not available in mentioned databases or software’s el-ementary flows, new process must be created, and relevant flow data collected from Ecoinvent online database. Unlike Ecoinvent importable database, online database is

free to use but requires account creation and manual importing to software. Manually means that every input- and output flows under every process taken from Ecoinvent must be added one by one to Open LCA making the inventory analysis much slower.

Figure 13. Electricity production processes in Open LCA software

Every process has its inputs and outputs and in case of pre-created processes, these are already added and are customizable. Process creation starts with naming the pro-cess and choosing if new reference flow will be created simultaneously. The new refer-ence flow is the output of the created process and it can be used as an input for other processes. Example of this is represented in figure 13, where left process input/output system is created for electricity production with coal in South East Asia and on right, in-put/output system for electricity production mix in South East Asia. It can be seen that red circled output on left side is added as an input on right side together with other sim-ilarly created reference flows. The last function of new process creation is to define ref-erence flow unit. In above picture, chosen unit for electricity production is kilowatt-hours (kWh), which can be change to other energy related unit. Following units are used for inventory analysis of waterjet: kilograms (kg), kilowatt-hours (kWh), mega-joule (MJ), square meter (m²), cubic meter (m³) and ton-kilometer (t*km).

Once all components under functional unit has its own process including all the rele-vant process flows, the last process created will be waterjet manufacturing -processes, where inputs are the components and masses listed in table 5 including internal mate-rial handling and packing. Creating LCI calculation for waterjet, process is converted to a product system which enables to make quick result calculation and more comprehen-sive analysis showing different LCIAs based on chosen impact assessment method.

The highest level of function in Open LCA database is “Projects”, which allows to com-pare different product systems’ environmental impact. This function is very useful when comparing the component freight- or production methods across supply chain.