LCA Mycelium-Based Composites

A cradle-to-gate LCA (A1–A3) was conducted by adhering to EN 15804:2012 + A2:2019 for a batch pilot production consisting of two 15*15*4 cm samples of rice straw MBCs, namely the S14_LC and the S14_HC, featuring respectively a density of 0.084 g/cm3 and 0.11 g/cm3 and a conductivity value of around 0.055 W/mK. The MBCs were produced through Solid State Fermentation (SSF). Specifically, the analysed composites were both made of rice straw mixed with water at a ratio of 200wt% inside autoclavable aerated bags. After being sterilised in the autoclave, the substrates, mixed with 10wt% of G. Lucidum spawn on a rye-grain basis, were incubated for 14 days at a constant temperature of 27°C and 60% RH, first in the bags and, after the first 7 days, in 3D-printed moulds made of PLA of 15*15*4 cm. Primary and secondary data have been collected through the direct fabrication of the MBC and literature sources as collected in the metadata folder. Quantities used for the production of 1 single sample of 15*15*4 cm have been scaled up to produce 1m2 of mycelium composite with a given thickness of 0.08 m. Mycelium spawn culture has been modelled as a subsystem of mycelium production based on literature data by (Leiva et al., 2015; Stelzer et al., 2021), as previously done by (Weinland et al., 2024). Concerning the modelling of rice straw, the study applied a zero-burden approach, as rice straw is a residual secondary flow coming from agro-industrial production of rice. Auxiliary materials, such as aerated bags and PLA moulds, have been taken into consideration and modelled based on (Livne et al., 2022; Stelzer et al., 2021). PLA moulds, which are potentially infinitely reusable, have been partially accounted for in the calculation, with 1/100 of the total quantity required for the production of 1 m2 of MBC included in the assessment. Disinfectant has been modelled as a solution made of 70% pure ethanol and 30% water. The environmental assessment of gloves has been omitted. The electricity needed for the operation of each production stage has been modelled by multiplying the process duration measured in the laboratory (in hours) by the power requirements (in kW) as provided in the manufacturers’ technical datasheets for the used equipment, considering the energy mix of Italy. To account for biogenic carbon, the -1/+1 approach was adopted, as addressed by the majority of the existing standards and guidelines, - ISO 14067 (2018), ISO 21930 (2017), EN 15804 + A2 (2019), PAS 2050 (2011). To adopt a conservative approach, the carbon potential of rice straw, 49 % of its Dry Weight (DW) (Weinland et al., 2024), with DW of rice being 95% of its weight, was considered solely, neglecting the potential CO2 storage of the mycelium strain of G. Lucidum. Moreover, the metabolic carbon of mycelium, stemming from mycelial respiration during the 14 days of incubation, was considered based on average respiration rates measured by (Pavlík et al., 2020) on a composite of Fagus sylvatica and G. Lucidum for two weeks of incubation, extrapolated for 24◦C based on the regression of emission rates in correlation with the ambient temperature (Alaux et al., 2024; Weinland et al., 2024).