Keywords

1 Introduction

The increasing consumption of resources and generation of waste [1] have led society and companies to realize the need for a transition to the use of more renewable resources and more sustainable production systems. In that regard, products that are based on biomass and bioresources have shown to be a promising alternative [2], thus fomenting a circular bioeconomy [3]. The use of byproducts and wastes as substitutes of virgin material for the manufacturing of different products has been an alternative for boards and panels in the civil construction and decoration industries [4]. These products have been used with intents such as thermal [5] and acoustic insulation [4] and for decoration. Although they might have lower environmental impacts for being made from wastes, thus materials that might have been thrown away otherwise, these products still cause environmental impacts. It is imperative that manufacturers get to know the environmental impacts of their products and try to make their product systems as least impacting as possible, as they also play a role in knowing and advising the kinds of impacts their products might cause. In that regard, one widely known technique used to guide environmental improvement is the Life Cycle Assessment (LCA). LCA is a technique that allows determining the potential environmental impacts of products (either goods or services/experiences) and the results of an LCA support an informed decision-making [6, 7].

In the existing literature it can be found studies assessing the environmental profiles of thermo-acoustic panels which main input is recycled material, such as from wastepaper and textile fibers [8] (1kg CO2-eq/kg of panel), recycled paper and other scrap materials (e.g., as wool and nonwoven polyester fabric) [4] (21.8 kg CO2-eq/m2), also bio-based materials, such as sheep-wool and hemp [9], and hemp alone [10] (−4.28 kg CO2-eq/m2). However, even less is found on the environmental performance of thermoacoustic panels based on bio-based waste, such as the study by Ricciardi et al. [5], assessing the thermal performance and climate change impacts of thermal performance of panels from recycled waste (cork scraps, rice husk, coffee chaff, and end-life granulated tires) (analysis of various compositions, e.g., 58% of Cork, 21% of Rice Husk and 21% of Coffee Chaff: 2.2 kg CO2-eq/m2).

Therefore, building on the need of a more comprehensive knowledge of the environmental impacts of thermos-acoustic panels from bio-based waste, this study aims to identify the main environmental impacts of thermoacoustic panels manufactured from agricultural byproducts and thereafter propose measures to improve the environmental performance of the product system. To that end, we use the LCA technique and assess the environmental impacts of the product system considering 10 impact categories: climate change, abiotic depletion, eutrophication, ozone layer depletion, acidification, freshwater ecotoxicity, human toxicity, marine ecotoxicity, terrestrial ecotoxicity, and photochemical oxidant formation.

2 Methods

An LCA study should follow well-established standards, determined by ISO 14040 [6] and ISO 14044 [7], and comprises 4 phases: objective and scope definition, life cycle inventory (LCI), life cycle impact assessment (LCIA), and interpretation. How we framed the study within these phases and their implications to the product system analyzed in this study are presented hereafter.

2.1 Objective and Scope Definition, and Choice of LCIA Methods and Categories

A screening LCA study was conducted assessing the opportunities for improving the environmental performance of a thermo-acoustic panel that can be used in the decoration and civil construction sectors. A screening, thus simplified, LCA study was conducted because of restrictions regarding data collection and disclosure of results, since the product system assessed in this study is based on a patent-pending technology. The product is made by the growth of fungi using agricultural byproducts as main feedstock. The objective of this LCA study was to determine the environmental impacts of the product system thermo-acoustic panel, from a cradle-to-gate perspective, i.e., considering from the extraction of raw materials from nature up to the moment the product is ready to leave the manufacturing facilities. A simplified representation of the system boundaries of this study can be seen in Fig. 1.

Fig. 1.
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Simplified system boundaries - Organization Z’s thermo-acoustic panels.

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The system under which Organization Z works enables a certain degree of circularity, thus they also contribute to a circular economy or circular bioeconomy in this case. It starts with the use of plant waste, especially agricultural byproducts as feedstock to the thermo-acoustic panel.

Within the manufacturing facilities, the “core processes” comprise the production of a liquid medium, a solid medium, and a third process (here called final mix) where the mycelium (which is the fungus) and a few other inputs along with the liquid and solid mediums are added to the main feedstock (which is the agricultural byproduct). Thereafter, the mix is enclosed in molds for the mycelium to grow.

The mycelium grows up to a certain point and then it is inactivated by a thermal treatment. At this point, the final product (thermal-acoustic panel in the desired size and shape, according to the molds used) is obtained. The panel can have a range of practical uses, which is left at the end user’s discretion. At the end-of-life, the panels are compostable, which can be done either at home (e.g., in a garden or as feed for flowers even in small vases) or in any other earth-environment. As they do not make use of any toxic chemicals, it is safe to be used as an input for agro-systems, which wastes can then be once again used as feedstock to produce new panels.

Regarding the functional unit (FU) for this study, as the product can be used with different intents, it was chosen to establish a declared unit (DU) rather than an FU in this study. The DU used in this study was 1kg of thermo-acoustic panel ready for distribution. For that reason, the reference flow chosen was 1kg of thermo-acoustic panel.

Moreover, using as benchmark another study of a similar product, a cork agglomerate panel [11], which has a function like that of the panel analyzed in this study, a few impact categories were chosen to be assessed. The categories used were the same as the benchmark study, since no standardization of LCA studies for this of product are found. Recommendations on the methods to be used to assess each impact category were obtained from the international EPD® system [12]. The categories and the respective methods used to calculate the impacts are shown in Table 1. Ten impact categories were assessed at midpoint level (i.e., immediate impacts).

Table 1. Impact categories and the respective impact assessment methods.
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These midpoint categories provide the immediate impacts of the system. For the interpretation, the hotspots served as starting points for the proposal of improvement measures. Therefore, in line with the company representatives two main improvement measures were proposed (Sect. 4).

2.2 Life Cycle Inventory

The LCI was built from specific (primary, measured), selected generic (direct match data from well-established/renowned databases), and proxy (adjusted/close proximity data from well-established/renowned databases, and data based on assumptions) data. Specific data was used in LCIs of the core processes (solid and liquid medium, and final mix), selected generic data and proxy data was used to model the upstream processes. To model upstream processes, a commercial license of Ecoinvent v.3.7.1 was used, together with the database Agribalyse 3.0.1.

Core processes included the activities necessary to produce the thermo-acoustic panel within the manufacturing gates. Upstream processes included the production of all input materials from “cradle” (i.e., since the moment the resources are extracted from nature) up to the moment the materials/products arrive at the manufacturing facilities. At the manufacturing facilities, inputs are used to produce a liquid medium, a solid medium, and a final process that includes both mediums mentioned and a few other inputs. Further information showing the specific processes and materials included within the system boundaries are not provided for trade secret reasons. Organization Z has a patent-pending technology, hence, the specifics of their processes cannot be disclosed.

3 Life Cycle Impacts of Thermoacoustic Panels from Agricultural Byproducts

The environmental performance of the system under study, according to the 10 impact categories assessed, is summarized in Table 2 and Fig. 2.

Table 2. Results of LCA of the thermo-acoustic panel.
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Fig. 2.
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Life cycle impact assessment for thermo-acoustic panel.

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The greatest hotspot, contributing the most to the total impacts is electricity. This behavior is noted across almost all impact categories, where it contributed to more than 80% of total impacts. Besides the electricity that is consumed in the final mix, the second hotspot is the solid medium, where once again electricity is the main contributor to total impacts, followed by the use of wheat bran and waste wood. This behavior can be observed in all impact categories, except for eutrophication and terrestrial ecotoxicity.

For the category eutrophication, the hotspot is the solid medium, where the main contributor is the use of waste wood. Only the second hotspot in this category is the use of electricity in the final mix. For terrestrial ecotoxicity, the solid medium also accounts for the main hotspot, but the main contributor in this case is the use of wheat bran, and once again, only the second hotspot is the use of electricity in the final mix.

4 Recommendations and Conclusions of the Study

The objective of this LCA was to define the environmental profile of the impacts of the product system thermo-acoustic panel and suggest measures that could lower the environmental impacts of the system. A few improvement measures can be drawn from those results and suggested to Organization Z, based on the hotspots found during the LCIA phase.

The main hotspots for the product system assessed in this LCA were the use of electricity, and the solid medium. In the solid medium, the components which contributed the most to environmental impacts of the system were the consumption of electricity and the use of wheat bran.

Overall, it is observed that solely reducing the consumption of electricity at the final stage of the production of the panels can contribute to reducing the environmental impacts of the system to a large extent. It is noted that scaling-up the production and using less energy-intensive equipment, or sharing equipment/facilities at this stage, might be able to reduce the net energy consumption and lower the need for energy per product unit.

It is suggested that the company investigate the possibility of replacing the equipment used in the manufacturing facilities aiming at greater energy efficiency, and/or replacing the energy source used to power these pieces of equipment in order to reduce the environmental impacts. Another alternative would be to partner with another organization in order to either share more energy-efficient equipment or establish collaboration to produce their energy from a cleaner source, with lower environmental impacts. Lastly, the company could also buy a specific mix from the energy carrier or a third party. On top of that, it was also suggested the use of different feedstock throughout the year, thus accounting for seasonality of agricultural byproducts, to investigate the environmental impacts (but also impacts on technical quality and market implications) of different byproducts in the production of the thermoacoustic panel.