Introduction

Most industrial systems (aircrafts, engines, trains, power-plants etc…) involve a wide variety of materials (metals and alloys, polymers and composites, ceramics etc…). Therefore, robust, and generic approaches are required to model, to simulate and to characterize environmental impacts of materials and components made and used in complex and various conditions. New designs and technologies often stem from introduction of advanced materials or new processes. This is the case of FARBioTY project, which proposes to develop efficient technical and eco-friendly innovations to meet the needs of railways sector. 

The objectives of our study are to evaluate the environmental impacts of a widespread solutions composed by the consortium members. The formulation of material involves reasoning on the entire product lifecycle and more particularly requires an adaptation of Product Process Material triptych presenting for the scenario. Because the process influence is crucial to the final performance of the product (technical as well as economic), we prefer to work with a functional unit corresponding to an annual industrial series of 15000 railway beacon rather than comparing the impacts of a single part (or a given amount of material). A variant will be, for example, the number of molds necessary to ensure such a series according to the cadences of the chosen method.

The potential collection of materials employed in this industrial application is very large, the emphasis is put on generic methods, based on fundamental principles.

A life cycle assessment (LCA) from cradle to grave has been performed on a railway beacon shell. This part is made from vinyl ester Sheet Molding Compound (SMC) a hot-pressing process. It is the reference state for our comparison with Life FARBIOTY solutions.


Railway Beacon shell

The vinylester also contains some fillers to improve flame resistance and outdoor aggressions. 

The LCA investigates in detail composite material formulation by using of natural fibers (flax) and modified resins and in comparison, with more traditional solutions based on petrosourced matrix and glass fibers reinforcement. Another aim of the project is to compare environmental impacts consequences of flame-retardant technologies used in the materials that are compared. 

The use phase has been modelled with the assumption of a service life of 10 years. The end-of-life phase is modelled with incineration scenarios for the composite components and with the most suitable scenarios for other remaining waste (cardboard, plastic packaging, consumables). 

Objectives

The objective of the LCA study is to investigate the composite components and understand their environmental impacts in a life cycle perspective. The study will focus on the composite formulation that includes:

 

Rough LCA inventory of FARBioTY solutions for Railway Beacon shells

General description of life cycle assessment

Life cycle assessment (LCA) is a technique to assess environmental impacts associated with all the stages of a product’s life from cradle to grave, i.e., from raw material extraction through materials processing, manufacture, distribution, use, repair, and maintenance, to disposal or recycling. 

Schematic pictures of a product’s life cycle phases.

Environmental impacts include emissions to air, water, and soil as well as consumption of resources in the form of both energy and material, in the different stages of the life cycle.

The purpose with performing an LCA is to get a fair and comparable evaluation of the environmental performance of a product (both services and goods can be assessed). The life cycle perspective is essential in order to avoid sub-optimization, i.e., that a certain process step or component is optimized, however the whole life cycle of the product does not reach its optimal environmental performance. Sub-optimization can occur when only parts of the life cycle are studied, and the overall performance is not evaluated.

To facilitate the comparability of a study’s results, a clear definition of the functional unit used should be made. The functional unit describes the basis for the calculation, e.g.,” transporting one person one km “, or “one-year use of a vehicle”.

Another important LCA concept that facilitates comparability is system boundaries. The system boundary describes what has been included in the assessment or not. The study of a transport of one person one km can include or not include for example: the production of the vehicle, the tools used during the production of the vehicle, the transports of goods and employees during the production of the vehicle, the production of the fuel, the combustion of the fuel, the infrastructure (roads, gas stations etc.), the waste management of the vehicle depending on what is relevant for the specific study. It is important that the setting of the system boundaries follows the same principle when two products are compared.

This life cycle assessment is performed in accordance with International Organisation for Standardization (ISO) 14040 and 14044 and the International Reference Life Cycle Data System (ILCD) Handbook.

Method

In this study, a detailed LCA has been performed for composite material and their respective molding process. 

Functional Unit

The functional unit (F.U) for this LCA study was defined as the production of an annual quantity of 15000 railway beacon shells (final products).

This includes the total amount of materials, the process cadences, moulds using and so on (tools, single-used materials, etc.). We choose to work on this F.U because it characterizes an industrial approach. 

The results are also expressed as the whole life cycle impact of railways beacon packaging, where the life length is set to 10 years.

System boundaries

The system boundary for the study is shown below.

 

 System boundaries for the project

All material and resource consumption were tracked back to the point of resource extraction, mainly by using cradle-to-gate data from the Ecoinvent database (version 3.2).

Allocation criteria

In the processes of the systems presented in the Life Cycle Inventory, different co-products are generated and valued either directly in the system itself (no allocation) or in another system, it is therefore necessary to make an allocation in order to take only the share of impacts of the process concerned. Especially:

  • Agricultural phase (co-products of the flax, vegetal oils)
  • Bio-refining phase (co-products of the bio-gas oil, glycerin, etc.)
  • Refining phase (co-products of cracking and vapocracking processes, etc.)

According to the Product Classification Group (PCR) standard: UN CPC 341 – Basic Organic Chemicals three types of allocation are proposed:

  • The physical allocation (preferably) of partitioning system inputs and outputs into different products in a way that reflects a physical parameter such as the mass or heat energy of this product.
  • The economic allocation (worst case scenario) of considering the average market price over 3 years as a weighting.
  • A specific allocation for electric / heat cogeneration from the fossil resource is also used.

System models: Cut-Off model

The system model “Allocation, cut-off by classification”, or cut-off system model in short, is based on the Recycled Content, or Cut-off, approach. The underlying philosophy of this approach is that primary (first) production of materials is always allocated to the primary user of a material. If a material is recycled, the primary producer does not receive any credit for the provision of any recyclable materials. Therefore, recyclable materials are available burden-free to recycling processes, and secondary (recycled) materials bear only the impacts of the recycling processes.

Selected environmental indicators and methods

Impact categories Unit Method
Abiotic Depletion Potential kg Sb eq. CML-IA baseline V3.05 / EU25
Abiotic Depletion Potential (fossils fuel) MJ CML-IA baseline V3.05 / EU25
Global Warming Potential (GWP100) kg CO2 eq. CML-IA baseline V3.05 / EU25
Ozone layer depletion (ODP) kg CFC11 eq. CML-IA baseline V3.05 / EU25
Human toxicity kg 1,4 DB eq. CML-IA baseline V3.05 / EU25
Terrestrial ecotoxicity kg 1,4 DB eq. CML-IA baseline V3.05 / EU25
Photochemical oxidation kg C2H4 eq CML-IA baseline V3.05 / EU25
Acidification kg SO2 eq CML-IA baseline V3.05 / EU25
Eutrophication kg PO43- eq CML-IA baseline V3.05 / EU25
Non-renewable, fossil MJ CED
Non-renewable, nuclear MJ CED
Non-renewable, biomass MJ CED
Water resource depletion m3 water eq ReCiPe

SIMAPRO™ 8.5.2.0 software from Pré® consultants was used for calculations. 

CML-IA : Centrum voor Milieuwetenschappen in Leiden, Institute of Environmental Sciences, Leiden University, NL 

CED :  Cumulative Energy Demand

ReCiPe : RIVM and Radboud University, CML, and PRé Consultants Method

LCA of railway Beacon Shells production – Reference state

There are no-maintenance operations during the use phase of beacons. Lifetime is 10 years. 

A French waste treatment mix option is available in the software database and is used for plastics parts in France which is a combo of landfilling and incineration. 

Beacons travel an average of 100 km to run waste treatment site.

The main raw material used in fibreglass production processes is sand. Since the quarries went depleted, cheap access sand has been taken from rivers increasing flood phenomena and preventing the sand provisioning of beaches at river ends. In the world, 15 billion tons of sand is used each year, including 75 million tons of ocean sand extracted from beaches. The Global Environmental Alert Service (GEAS) of the United Nations Environment Programme (UNEP) has thus expressed strong concerns about sand scarcity and associated environmental issues

A brief summary of the LCA results with the 3 main indicators: Global Warming, Water and Energy Consumption is given in the following table.

Complete life cycle 

Unsurprisingly, SMC systems, which contain many chemical and mineral components, are the main contribution of the actual railway beacon life cycle.

Waste treatments sometimes have useful outputs, such as heat or materials that are reclaimed for incineration or recycling processes. SimaPro allows to specify these useful outputs as a close looped recycling procedure. This means that we subtract the amount of energy given by the recycling process of the global energy demand of the whole production process. This also explains why there are frequently negative environmental loads in the end-of-life product stages and in consequential assessment. 

 

Overview of the complete life cycle presented as a network – 15000 railway beacon shells (vinylester, 35% glass fibers)

LCA of Railway Beacon Shells

Impact category Unit VINYLESTER
GLASS FIBRE
Global warming (GWP100a) kg CO2 eq 777 893
Water consumption m3 6 272
Non-renewable, fossil MJ 9 398 672

Environmental impact for 15 000 Railway Beacon Shells / year

LCA inventory of Polyester based FARBioTY bio-composites

Bio-based Reinforcement 

Composite materials are modelled in detail with specific data from the suppliers to each consortium member and, depending on the matrix, various composites systems are modelled to be manufactured using hand lay-up, vacuum infusion or light resin transfer moulding process. Each input and each process are therefore subject to inventory.

  • Production process

The whole flax process is managed by Teillage Vandecandelaere – Depestele (TVDC)

Stream process for flax fibres fabrics.

  • Inventory

 

Process tree for flax fabric

 

 

Environmental impact of flax fabric production steps

  • Fire resistant Treatment on Flax Reinforcement

Veramtex applies Flam Fixe treatment to flax fabric samples received from TVDC in their industrial production tools in Belgium. The full operation to be applied is as follows:

 

Process steps for fabrics fireproofing treatment

 

Process tree for fibrefoofing treatment

  • LCA Comparisons between bio-based and glass reinforcements

 

LCA comparisons of FARBioTY composite reinforcements with standard glass fabric

Impact of the THPC treatment is high. Both water for chemical reactions and energy use to dry the fabrics during the process increase the water and energy results but slightly below the glass fabric environmental impacts for global warming and energy consumption. Of course, no optimisation have been done to mitigate the environmental impact by reducing the THPC intake during the flax treatment. We can assume that the results should be far better by adjusting the treatment intensity without any degradation of the fire and smoke properties. 

Implementation Processes

  • Hand lay-up & spray-up methods

Hand lay-up is the oldest and the simplest process for manufacturing fibers reinforced products (FRP). Even if it is slow and very intensive labour, hand lay-up is a simple, low cost and easy to apply process for FRP product.

Hand layup process consists of hand tailoring and placing one or more layers of fibers reinforcement on a mold and then saturating the reinforcement layers with a liquid resin. 

According to resin preparation, material in/or around a mold can be cured with or without heat. Inexpensive materials such as wood and plaster are used to make the moulds. The hand lay-up process is specially recommended for a large and complex range of products which require high strength and reliability.

Depending on the part shape, the scrap ratio is near 20% of material lost during processing. In fact, it is necessary to trim the lost edges at the contour of the mold and at the pre-cut fiber fabrics.

Spray-up, or chopping, is an open mold method similar to hand lay-up in its suitability for making boats, tanks, transportation components in a large variety of shapes and sizes. A chopped laminate has good conformability and is sometimes faster to produce than a part made with hand lay-up when molding complex shapes. As with hand lay-up, gel coat is first applied to the mold and allowed to cure. Continuous strand glass roving and initiated resin are then fed through a chopper gun, which deposits the resin-saturated “chop” on the mold. 

The laminate is then rolled to thoroughly saturate the glass strands and compact the chop. Additional layers of chop laminate are added as required for thickness. Roll stock reinforcements, such as woven roving or knitted fabrics, can be used in conjunction with the chopped laminates. Core materials of the same variety as used in hand lay-up are easily incorporated.

  • Vacuum infusion method

Vacuum infusion is a composite processing method that enables manufacturing of large structures with high mechanical properties. It is a method in which fibre reinforcement is impregnated by a resin flow using vacuum help at the outlet side. This technique is often used for the following reasons:

  • low investment, material and mould cost, compared to other closed moulding processes such as RTM, RFI, pre-preg with or without autoclave;
  • good mechanical properties, high fibre volumes up to 60% are possible, and the composite material can be made void free;
  • the technique prevents hazardous styrene emissions except for the application of gelcoat.

In this method, a dry reinforcement is placed in a mould, the mould is covered by a vacuum infusion bag and sealed with tacky tape and then, the resin flows into the mould and impregnates the fibres layers. Vacuum draws resin from a container into the vacuum bag along the line, for example along a symmetry line in the component. The impregnation time depends on the fibre content.

  • Resin Transfer Molding (RTM)

Light Resin Transfer Molding, or Light RTM, is a process by which composite products are manufactured using a closed mold system. The closed mold consists of an “A” side mold (base mold) and a semi-rigid “B” side mold (counter mold) that is sealed to the “A” side mold using vacuum pressure. Resin is drawn into the resulting cavity under vacuum. The resin infusion may be assisted by a resin injection pump, which will accelerate the infusion process. Once an “A” side mold is cured, the “B” side mold is removed and the part is demolded from the “A” side mold. 

  • LCA Comparisons of implementation processes

The LCA of the process themselves shows that infusion is the worst case for environmental footprint. We do recommend the use of countermold technics like in RTM and, in a minor way, compaction in order to minimize wastes during the implementation process. 

LCA comparisons of implementation processes

Composite systems for mainstream parts

  • Inventory of polyester resin systems

Process tree for FARBioTY DCPD resin systems

The DCPD based resin was developed by Nord Composites. It was used for the needs of the study; however, we adjusted the transport by integrating the right distance (Nord composites to Saint Nazaire).

  • LCA of polyester resins

Environmental impact of FARBioTY DCPD systems

 

  • LCA of Polyester based bio-composites – 15 000 railway beacon shells / year

Process SMC Compaction
Impact category Unit VINYLESTER
GLASS FIBRE
POLYESTER
Global warming (GWP100a) kg CO2 eq 777 893 338 523
Water consumption m3 6 272 3 409
Non-renewable, fossil MJ 9 398 672 3 446 094

 

Environmental impacts of FARBioTY mainstream systems solutions

End of life

Incineration is the method, which is used to recover energy from the polymeric matrix. This method is, however, not recommended, especially for the carbon fibre based composites, as those fibres, are valuable products worth to be recovered for subsequent reuse in other composites. The landfill is the least desired solution for composite disposal due to the EU regulations. However, landfill of composites could be an option, while closing the landfill. The grinded composite waste can be used as an outer layer during landfill rehabilitation process. Pyrolysis and fluidised bed processes are the recycling methods, which take the advantage of composite constituents, fibres and matrix. The fibres are recovered and can be used in other components, while the matrix material is used for the energy recovery. In the chemical recycling, the fibres are recovered and the matrix is broken down to hydrocarbons, which can be reused as polymers, monomers, fuels or chemicals.

Incineration

Incineration may be used to reduce the amount of waste that must otherwise go into landfills or for its calorific value as well as for recovering energy. When composites are combusted with energy recovery, the calorific value will depend on the inorganic content. For example, a typical glass fibre based composite contains 40 % glass, 30 % inorganic fillers and 30 % of resin.

The glass and fillers do not burn, leaving 70 % of the composite as a residue after incineration. The incombustible glass fibres and fillers hinder the incineration, consuming ~1.7 MJ per kilogram of glass fibre content. Therefore, it is not recommended to incinerate glass fiber composite materials. 

Assumptions: The typical amount of net energy that can be produced per tonne municipal waste is about 2-3 MWh of electricity and 2 MWh of district heating. In the caculations, only the30 wt % from the matrix has been used. 

Conclusion

This analysis shows that bio-composites are more efficient than the fiberglass-based solution, more or less clearly depending on the application method and the resin used.  It should also be noted that these results should be taken as representative of the most impactful of the solutions and that optimization, especially in terms of the amount of flame retardants on flax, accurate choice of biobased resins and improved implementation process would further improve them.

 

International Organization for Standardization – ISO. Environmental management – life cycle assessment – principals and framework. International Standard ISO 14040, Geneva; 2006

Organization for Standardization – ISO. Environmental management – life cycle assessment – requirements and guidelines. International Standard ISO 14044, Geneva; 2006.

EC – European Commission – Joint Research Centre – Institute for Environment and Sustainability: International Reference Life Cycle Data System (ILCD) Handbook – General guide for Life Cycle Assessment – Detailed guidance. First edition March 2010. EUR 24708 EN. Luxembourg. Publications Office of the European Union; 2010

Ecoinvent data v3.2, Final reports ecoinvent 2018, Swiss Centre for Life Cycle Inventories,Dübendorf, 2018

Villioth, Building an economy on quicksand, EJOLT, 2014, www.ejolt.org/2014/08/building-an-economy-on-quicksand/

UNEP Global Environmental Alert Service – Sand, rarer than one thinks (2014)

Shen L, Patel MK. Life Cycle Assessment of Polysaccharide Materials: A Review. J Polym Environ, 2008;16:154–167