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The possibility of recovering energy from biomass residues has attracted a lot of research interest due to the environmental problems associated with burning coal. Wood wastes generated from construction and demolition activities and other wood product wastes can be a good potential source of renewable energy. The present study was conducted by using Hong Kong as an example to assess the environmental sustainability of converting recycled wood wastes (from construction and demolition activities and other wood product wastes) to produce wood pellets for direct energy generation. The chemical and physical characteristics of different types of wood product wastes were tested. An attributional lifecycle assessment approach was used to assess and compare the environmental impacts and sustainability for heat generation from the pelletized bio-fuel and coal. The test results showed that the energy content, chemical compositions and the trace metal concentrations all met the relevant standards. The results also showed that significant impacts on health, ecosystem, climate change and resources damage can be potentially avoided by using wood pellets instead of coal for energy generation. The overall findings demonstrated that the proposed “energy recovery” approach for using wood pellets as a bio-fuel in Hong Kong is environmentally sustainable, which can provide an alternative route for managing wood product wastes with the added benefits of energy recovery, and may be more applicable in mega cities especially when city-based incineration is a concern. [ABSTRACT FROM AUTHOR]

• Evaluated the techno-environmental feasibility of using natural pozzolana in concrete production, • Comparable compressive strength was found for the use of VA against conventional SCMs, • VA significantly reduced environmental impacts of concrete compared to OPC and other SCMs, • 11–30% lower GHG emissions was found for VA concrete compared to other cementitious materials. With increasing environmental sustainability concerns in the construction industry and a demand for producing more durable and sustainable concrete, effort is devoted to producing concrete with Ordinary Portland cement (OPC) being substituted by alternative binder materials. By considering the compressive strength, the comprehensive environmental performance of natural pozzolana in concrete was evaluated comparatively by developing six mix-designs of concrete with OPC, and commonly used industrial by-products as supplementary cementitious materials such as fly ash (FA) and ground granulated blast furnace slag (GGBS) based on the lifecycle assessment (LCA) approach. The results show that comparable compressive strengths can be achieved for the use of 20% and 30% volcanic ash (VA) against conventional SCMs. Using the volume as functional unit, the LCA results have demonstrated that higher environmental savings are associated with VA concrete compared to that of OPC, GGBS (30%) and FA (25%), but almost similar when 50% GGBS is used. For example, 15–24% and 10–19% lower global warming potential are associated with VA concretes compared to that of OPC and FA concretes, respectively, but much higher saving is found when considering the strength of the concrete, as they are about 11–12%, 10–11% and 29–30% compared to that of GGBS, FA and OPC concretes, respectively. The results can be used as valuable guidelines for VA-based in sustainable concrete production, which would further enhance the sustainability of the concrete industry. [ABSTRACT FROM AUTHOR]