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

According to IPCC Annual Report (AR-5), environmental impact assessment of any product prototype is recommended before its large-scale commercialization; however, no environmental profile analysis of any biodiesel prototype has been conducted in Pakistan. Therefore, objective of this study was to conduct a comprehensive life cycle assessment (LCA), water footprint and cumulative energy demand (CED) of biodiesel production from Jatropha curcas L. (JC) seeds oil in Pakistan. A cradle-to-gate LCA approach was applied for 400 liter (L) JC biodiesel produced in Pakistan. JC biodiesel production chain was divided into three stages i.e., 1). cultivation of JC crop 2). crude oil extraction from JC seeds and 3). crude oil conversion to biodiesel. Primary data for all the stages were acquired through questionnaire surveys, field visits and measurements in the field. Potential environmental impacts were calculated in SimaPro v.9.2 software using Eco-indicator 99 methodology. Results showed that crude oil extraction stage accounted for highest emissions (77%) to the overall environmental impact categories evaluated, followed by oil conversion stage (21%) and JC cultivation stage (02%), respectively. The three stages of JC biodiesel production chain are major contributor to ecotoxicity with a contribution of 57% to this impact category. Higher contribution to ecotoxicity was due to agrochemicals used in the JC cultivation. Similarly, fossil fuels impact category was responsible for 38% of overall environmental impacts. In addition, water footprint of JC biodiesel production chain was 2632.54 m3/reference unit. Cumulative energy required for 400L JC biodiesel production chain was 46745.70 MJ in Pakistan. Fossil diesel consumption, synthetic fertilizers use and purchased electricity were major hotspot sources to environmental burdens caused by JC biodiesel production in Pakistan. By performing sensitivity analysis at 20% reduction of the baseline values of fossil diesel used, synthetic fertilizers and purchased electricity, a marked decrease in environmental footprint was observed. It is highly recommended that use of renewable energy instead of fossil energy would provide environmental benefits such as lower greenhouse gases and other toxic emissions as compared to conventional petroleum fuels. It is also recommended that JC as a biofuel plant, has been reported to have many desired characteristics such as quick growth, easy cultivation, drought resistance, pest and insect resistance, and mainly great oil content in JC seeds (27-40%). Therefore, JC plant is highly recommended to Billion Tree Afforestation Project (BTAP) for plantation on wasteland because it has multipurpose benefits.

Life cycle assessment of most widely adopted solar photovoltaic energy technologies by mid-point and end-point indicators of ReCiPe method.

The present article focuses on a cradle-to-grave life cycle assessment (LCA) of the most widely adopted solar photovoltaic power generation technologies, viz., mono-crystalline silicon (mono-Si), multi-crystalline silicon (multi-Si), amorphous silicon (a-Si) and cadmium telluride (CdTe) energy technologies, based on ReCiPe life cycle impact assessment method. LCA is the most powerful environmental impact assessment tool from a product perspective and ReCiPe is one of the most advanced LCA methodologies with the broadest set of mid-point impact categories. More importantly, ReCiPe combines the strengths of both mid-point-based life cycle impact assessment approach of CML-IA, and end-point-based approach of Eco-indicator 99 methods. Accordingly, the LCA results of all four solar PV technologies have been evaluated and compared based on 18 mid-point impact indicators (viz., climate change, ozone depletion, terrestrial acidification, freshwater eutrophication, marine eutrophication, human toxicity, photochemical oxidant formation, particulate matter formation, terrestrial ecotoxicity, freshwater ecotoxicity, marine ecotoxicity, ionising radiation, agricultural land occupation, urban land occupation, natural land transformation, water depletion, metal depletion and fossil depletion), 3 end-point/damage indicators (viz., human health, ecosystems and cost increases in resource extraction) and a unified single score. The overall study has been conducted based on hierarchist perspective and according to the relevant ISO standards. Final results show that the CdTe thin-film solar plant carries the least environmental life cycle impact within the four PV technologies, sequentially followed by multi-Si, a-Si and mono-Si technology.