Environmental sustainability assessment of biodiesel production from Jatropha curcas L. seeds oil in Pakistan

Optimization and characterization of biodiesel from waste cooking oil using modified CaO catalyst derived from snail shell

Currently, research has diverted toward generating renewable fuels due to the unreliable supply and rising cost of conventional fuels. Biodiesel is renewable fuel commonly obtainable via a simple process. Biodiesel was produced via the transterification of waste cooking oil (WCO) using heterogeneous catalysts. The aim of this study was to synthesis a ZnO and TiO₂-supported CaO catalyst from a snail shell for the transterification of waste cooking palm oil to produce biodiesel. Sol-gel and wet-impregnated methods were adopted to synthesize ZnO and catalyst, respectively. The physicochemical properties of waste cooking oil and biodiesel were characterized in accordance to AOAC and ASTMD standard methods. The FTIR and XRD analyses were carried out to characterize the biodiesel and the prepared catalysts. The result of this study revealed that CaO catalyst derived from snail shall, resulted to a WCO-derived biodiesel yield of 80%. The CaO catalyst modified with ZnO and TiO₂, further led to an increased biodiesel of 90% and 95%, respectively. The result of this study showed that the optimum conditions associated with highest biodiesel yield over the synthesized catalysts were at 3% catalyst weight, 65 °C, a 6:1 methanol-to-oil ratio and 3-h reaction time. The FTIR spectra also proved successful formation of biodiesel. Biodiesel was successfully synthesized from WCO, and the CaO catalyst synthesized from snail shells and modified with ZnO and TiO₂, showed potential to substitute for costly catalysts derived from chemical reagents for biodiesel production.

Life cycle environmental sustainability and cumulative energy assessment of biomass pellets biofuel derived from agroforest residues

This study was carried out to produce low-emitting biomass pellets biofuel from selected forest trees such as (Cedrus deodara and Pinus wallichiana) and agricultural crop residues such as (Zea mays and Triticum aestivum) in Gilgit-Baltistan, Pakistan using indigenously developed technology called pelletizer machine. Characterization, environmental life cycle impact assessment, and cumulative energy demand of biomass pellets biofuel produced from selected agriculture crops and forest tree residues were conducted. The primary data for biomass pellets production was collected by visiting various wood processing factories, sawmills, and agricultural crop fields in the study area. Biomass pellets are a type of biofuel that is often made by compressing sawdust and crushing biomass material into a powdery form. The particles are agglomerated as the raw material is extensively compressed and pelletized. Biomass pellets have lower moisture content, often less than 12%. Physically, the produced pellets were characterized to determine moisture content, pellet dimensions, bulk density, higher heating value, ash content, lower heating value, and element analysis. A functional unit of one kilogram (kg) biomass pellets production was followed in this study.The life cycle impact assessment of one kg biomass pellets biofuel produced from selected agro-forest species revealed environmental impact categories such as acidification (0.006 kg SO2 eq/kg pellets), abiotic depletion (0.018 kg Sb eq/kg pellets), marine aquatic ecotoxicity (417.803 kg 1,4-DB eq/kg pellets), human toxicity (1.107 kg 1,4-DB eq/kg pellets), freshwater aquatic ecotoxicity (0.191 kg 1,4-DB eq/kg pellets), eutrophication (0.001 kg PO4 eq/kg pellets), global warming (0.802 kg CO2 eq/kg pellets), and terrestrial ecotoxicity (0.008 kg 1,4-DB eq/kg pellets). Fossil fuel consumption was the hotspot source to all environmental impacts investigated. To measure the cumulative energy demand of biomass pellets made from different agroforestry species leftovers showed that the maximum cumulative energy was from wheat straw pellets (13.737 MJ), followed by corncob pellets (11.754 MJ), deodar sawdust pellets (10.905 MJ) and blue pine sawdust pellets (10.877 MJ). Among the various production activities, collection and transportation of primary raw material, crushing, screening, adding adhesives, pelletizing, cooling, final screening, and packing have the maximum contribution to the water scarcity index, followed by lubricating oil (0.00147m3). In contrast, the minimum contribution to water footprint was from electricity (0.00008m3) and wheat starch (0.00005m3). The highest contribution to the ecological footprint impact categories such as carbon dioxide, nuclear, and land occupation was lubricating oil and less contribution of wheat starch and electricity for manufacturing one kg pellets biofuel. It is concluded that physico-mechanical and combustion properties of the biomass pellets biofuel developed in the present study were following the Italian recommended standards. Therefore, it is strongly recommended that the Government of Pakistan should introduce the renewable biomass pellets industry in the country to reduce dependency on fossil fuels for cooking and heating purposes.

Environmental, Energy, and Water Footprints of Marble Tile Production Chain in a Life Cycle Perspective

The marble industry is growing in Pakistan, and Khyber Pakhtunkhwa province is the largest producer of marble tiles in Pakistan. Marble production consumes a considerable amount of water during its life cycle stages and impacts various environmental compartments, such as air, water, and soil; therefore, this study aimed to quantify the environmental impacts, water footprint, and cumulative energy demand of one-tonne marble tile manufactured in a small industrial estate Mardan (SIEM), Pakistan, and provide recommendations to improve its environmental impact profile. The study covers water consumption, energy use, and associated environmental impacts of raw materials and processes through different stages of the marble life-cycle during 2017–2018. The cradle-to-gate (extraction to factory gate or store house) life cycle assessment approach was followed in this study. The functional unit for the current study was one tonne of finished marble tile produced. Primary data from the field surveys and secondary data were modeled using the water scarcity index (WSI), CML 2000 v.2.05 methodology, and the cumulative energy demand indicator present by default in SimaPro v.8.3 software. The total water footprint required for one tonne of finished marble tile was 3.62 cubic meters per tonne (m3/t), with electricity consumed at processing units contributing to environmental burdens the most. Similarly, electricity consumed (at processing units and during polishing) and transportation of finished marble tile to the local market were responsible for global warming potential (388 kg CO2 eq/tonne tile), human toxicity (84.34 kg 1,4-DB-eq/tonne), freshwater aquatic ecotoxicity (94.97kg 1,4-DB eq/tonne) and abiotic depletion (7.1 × 10−5 kg Sb eq/tonne). The results of our study follow other marble tile LCA studies conducted globally (such as in Turkey and Italy), which also reported a high contribution to GWP, AP, EP, and HT due to electricity and fossil fuels consumption. The total cumulative energy demand (CED) was calculated as 5863.40 MJ (Mega Joule), with most energy usage associated with non-renewable fossil fuel sources. The results indicated that reducing electricity (using standard automatic machinery) and waste materials, especially paper and plastic wastes, can reduce environmental impacts. Most of the surveyed industrial units did not have wastewater treatment and recycling plants, and wastewater directly flows to nearby freshwater bodies and terrestrial ecosystems. These wastewaters should be adequately treated before being discharged into freshwater aquatic bodies. Environmental impacts must be improved by using the latest automatic machinery, reducing waste materials generation, reducing the distance between processing units and the market, and installing wastewater recycling plants.

Life Cycle Environmental Sustainability and Energy Assessment of Timber Wall Construction: A Comprehensive Overview

This article presents a comprehensive overview of the life cycle environmental and energy assessment for all residential and commercial constructions made of timber walls, globally. The study was carried out based on a systematic literature analysis conducted on the Scopus database. A total of 66 research articles were relevant to timber wall design. Among these, the residential construction sector received more attention than the commercial sector, while the low-rise construction (1–2 stories) gained more attention than high-rise construction (>5 stories). Most of these studies were conducted in Canada, Europe, Malaysia, and the USA. In addition, the end-of-life phase received limited attention compared to upstream phases in most of the studies. We compared all environmental and energy-based life cycle impacts that used “m2” as the functional unit; this group represented 21 research articles. Global warming potential was understandably the most studied life cycle environmental impact category followed by acidification, eutrophication, embodied energy, photochemical oxidation, and abiotic depletion. In terms of global warming impact, the external walls of low-rise buildings emit 18 to 702 kg CO2 kg eq./m2, while the internal walls of the same emit 11 kg CO2 kg eq./m2. In turn, the walls of high-rise buildings carry 114.3 to 227.3 kg CO2 kg eq./m2 in terms of global warming impact. The review highlights variations in timber wall designs and the environmental impact of these variations, together with different system boundaries and varying building lifetimes, as covered in various articles. Finally, a few recommendations have been offered at the end of the article for future researchers of this domain.

Characterization and Life Cycle Exergo-Environmental Analysis of Wood Pellet Biofuel Produced in Khyber Pakhtunkhwa, Pakistan

Major objectives of this study were to produce low-emitting wood pellet biofuel from selected agro-forest tree species, i.e., Kikar (Acacia nilotica), Oak (Quercus semicarpifolia), and Mesquite (Prosopis juliflora), grown in the southern part of the Khyber Pakhtunkhwa (KP) province of Pakistan using indigenously developed technology (pelletizer machine). Primary raw material, such as sawdust of the selected agro-forest tree species, was obtained from sawmills located in southern part of KP. Life cycle inventory (LCI) was sourced for entire production chain of the wood pellet biofuel by measuring quantities of various inputs consumed and output produced. In addition, the wood pellets were characterized to examine diameter, length, moisture content, ash content, bulk density, high heating value (HHV), low heating value (LHV), as well as nitrogen and sulphur contents. A comprehensive life cycle assessment was performed for wood pellet biofuel production chain using SimaPro v9.1 software. A functional unit of one (01) kilogram (kg) wood pellet biofuel was applied following a gate-to-gate approach. The results of the present study were in accordance with the recommended Italian standard CTI-R 04/5 except for pellet bulk density and nitrogen content. The bulk density for all wood pellets, manufactured from the saw dust of three different agro-forest tree species, were lower than the recommended Italian standard, while for nitrogen content, the results were higher than the recommended Italian standard. Among the environmental impacts, Kikar (Acacia nilotica) wood pellets were the major contributor to fossil fuel depletion, followed by ecotoxicity, mineral depletion and acidification/eutrophication. This was primarily due to lubricating oil and urea-formaldehyde (UF) resin used as inputs in the wood pellets biofuel manufacture. Likewise, human health and ecosystem quality was also affected by lubricating oil, UF resin, and saw dust, respectively. In cumulative exergy demand of 1 kg wood pellets biofuel, the highest impact was from Kikar wood pellets for non-renewable fossils, mainly due to lubricating oil used. Difference in environmental impacts, damage assessment, and exergy were examined in three different scenarios for major hotspot inputs by reducing 20% lubricating oil in case 1, 20% UF resin in case 2, and without usage of UF resin in case 3, while marked reduction was observed in ecotoxicity, fossil fuel, and mineral depletion, as well as acidification/eutrophication impact category. Moreover, a pronounced reduction was also noted in the non-renewable fossil fuel category of cumulative exergy demand of one kg of wood pellets biofuel produced.