Environmental and economic evaluation of silica nanoparticles grafted bio-polyols, according to different production scales, for the “green” construction sector

Introduction This work provides environmental and economic insight for the sustainable production of bio-polyols with grafted bio-nanofillers for the production of polyurethane (PUR) rigid foam, with applications in the “green” construction sector such as rigid insulating panels. The performances obtained from these materials makes them a valid solution for replacing synthetic counterparts. Silica nanoparticles grafted with different bio-polyols, based on lignin and cardanol, were selected as reactive fillers, imparting multifunctional properties to the designed PURs. The analysis follows a cradle-to-gate approach, examining polyols production processes on different scales, from the laboratory to pilot/industrial scale. Experimental Environmental impacts are assessed through Life Cycle Assessment - LCA, performed according to the ISO 14040 - 44 standards, with the Open LCA software, using Ecoinvent 3.7.1 database and CML 2001 method. The Life Cycle Costing analysis, for quantifying the cost, is performed by following the same framework of the LCA. Results and conclusions The LCA and LCC analyses allowed identifying the main, environmental and economic, hotspots in the synthesis process. Environmental impact categories were evaluated depending on each raw material option, waste and type of energy used during the production of fillers. The comparative research activity allowed optimising the formulation by reducing the environmental burden and production costs of bio-polyols for sustainable PURs panels. Multiscale analysis shown that at laboratory scale, energy consumption is dominating, whereas by scaling up the energy burden is reduced, and it is possible to better identify the specific impact of raw materials. At industrial scale the process enables a reduction of 30% for the environmental impact and 80% of cost compared to laboratory scale. The performances and features of the final rigid foam will be investigated by extending the analysis system boundaries encompassing the PURs production process itself and by suitably redefining the functional unit, compared to commercial solutions.