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We perform an ex-ante life cycle assessment, integrating cradle-to-gate greenhouse gas emissions into an off-grid energy system model. By applying a multi-objective optimization, minimizing both costs and carbon dioxide equivalent (CO 2 e) emissions, we find the Pareto boundary between these two goals. As a case study, we chose the power supply to an astronomical observatory in Chile, using mostly solar power and energy storage in batteries and hydrogen. We compare the ex-ante study to a prior ex-post life cycle assessment, and furthermore dive into sensitivities of our model regarding component lifetimes and costs. We find (i) low-hanging fruit in lowering emissions with small cost increases, (ii) ex-ante life cycle assessments' possibility to find less CO 2 e intensive power systems compared to ex-post conducted studies, (iii) a pronounced sensitivity of the optimization model on assumed lifetimes of energy storage components. This study shows the importance of including life cycle CO 2 e emissions into the optimization objective of energy system models. This method uncovers the environmental and economic trade-offs associated with high shares of renewable energies in off-grid energy systems. • We integrate life cycle assessment (LCA) into an off-grid energy system optimization. • The applied case study powers a remote astronomical telescope in Chile. • A multi-objective optimization finds Pareto curves at varying costs and lifetimes. • Low-hanging fruit shows low additional system costs to reduce CO 2 e impacts. • In contrast, a separate LCA did not find such trade-offs in costs and CO 2 e emissions. [ABSTRACT FROM AUTHOR]

Plastics account for 4.5% of global greenhouse gas (GHG) emissions, which are hard-to-abate due to the use of fossil fuels as feedstock. Our study develops a cradle-to-gate life cycle assessment of bioethylene production, exploring 33 pathways across Brazil, the EU, and the US. It aims to understand whether substituting fossil-based ethylene with bioethylene contributes to lowering carbon emissions, and in which of the relevant bioenergy-producing regions/countries the valorisation of biofuels as feedstocks would provide a less carbon-intensive bioethylene production. Results indicate that bioethylene production through catalytic dehydration of sugarcane bioethanol in Brazil presents lowest GHG emission. This pathway could deliver up to −2.1 kg CO 2 e/kg ethylene when accounting for biogenic carbon storage in long-lived applications such as infrastructure. In contrast, beef tallow performs the poorest as a raw material, regardless of whether land-use change (LUC) emissions are considered. When biogenic carbon storage is factored out, none of the pathways outperforms conventional fossil-based steam cracking; however, some are within the fossil-based range indicating potential indirect benefits through reduced refinery utilisation. Our study underscores that biomaterials production as a climate mitigation strategy must be on par with circular economy measures and the conservation of native forestry ecosystems. These results are particularly relevant to policymakers and industries seeking to align polymer manufacturing with sustainability objectives. • Bio-ethylene cradle-to-gate GHG emissions were assessed for 33 pathways. • Sugary, starch, lignocellulosic and oily crops are raw materials for bio-ethylene. • Local specificities such as biogenic carbon storage and land-use are critical to LCA GHG emissions. • Sugarcane bioethanol dehydration route yielded 2.1 kgCO 2 e captured per of kg ethylene. • Climate mitigation and circular economy policies must be designed coherently. [ABSTRACT FROM AUTHOR]

Anthropogenic greenhouse gas emissions (GHGE) are behind climate change. In Chile, food system is the second source of GHGE. Changing Chileans dietary patterns is key to reducing such emissions. There is geographic variability in terms of dietary patterns within the country. Here we investigated the dietary GHGE in five different geographical zones, along with the main contributing food groups and socio-demographic variables. Data for 4676 individuals were obtained from the 2010–2011 National Survey of Food Consumption. The carbon footprint value of each food was obtained from studies using life cycle assessment methodology. Median and percentiles of dietary GHGE were calculated, expressed in kilograms of carbon dioxide equivalent per person per day (kgCO 2 eq/person/d) and compared among zones by Kruskal-Wallis and Dunn's tests. Logistic regression models were fitted to analyzed associations among the variables of interest and quartiles of GHGE. Diet-related GHGE ranged from 3.50 (2.34–5.12) in the North-Central Zone to 4.66 (2.89–6.69) kgCO 2 eq/person/d in the South zone. Meat accounted for 53–58% of the GHGE in all the zones, followed by dairy products with 12–13%. Higher GHGE were significantly associated with energy intake (kcal/d) in all of the zones, with high socioeconomic level in the North-Central, South and Metropolitan zones, and with urban residence in the South-Central zone. Tailored policies considering geographic variability are warranted to promote healthy and sustainable diets among the Chilean population. • Differences in dietary greenhouse gas emissions were determined among five Chilean geographical zones. • South and Metropolitan region showed the highest GHGE while North showed the lowest. • Meat and dairy were the most contributing foods in all zones. • GHGE were positively associated with energy intake in all zones & with high socioeconomic level in three zones. • The promotion of sustainable diets in Chile must consider the geographical specificities. [ABSTRACT FROM AUTHOR]

Wood and other bio-based building materials are often perceived as a good choice from a climate mitigation perspective. This article compares the life cycle assessment of the same multi-residential building from the perspective of 16 countries participating in the international project Annex 72 of the International Energy Agency to determine the effects of different datasets and methods of accounting for biogenic carbon in wood construction. Three assessment methods are herein considered: two recognized in the standards (the so-called 0/0 method and −1/+1 method) and a variation of the latter (−1/+1* method) used in Australia, Canada, France, and New Zealand. The 0/0 method considers neither fixation in the production stage nor releases of biogenic carbon at the end of a wood product's life. In contrast, the −1/+1 method accounts for the fixation of biogenic carbon in the production stage and its release in the end-of-life stage, irrespective of the disposal scenario (recycling, incineration or landfill). The −1/+1 method assumes that landfills offer only a temporary sequestration of carbon. In the −1/+1* variation, landfills and recycling are considered a partly permanent sequestration of biogenic carbon and thus fewer emissions are accounted for in the end-of-life stage. We examine the variability of the calculated life cycle-based greenhouse gas emissions calculated for a case study building by each participating country, within the same assessment method and across the methods. The results vary substantially. The main reasons for deviations are whether or not landfills and recycling are considered a partly permanent sequestration of biogenic carbon and a mismatch in the biogenic carbon balance. Our findings support the need for further research and to develop practical guidelines to harmonize life cycle assessment methods of buildings with bio-based materials. [Display omitted] • Life cycle assessments of the same multi-residential building were carried out by experts from 16 countries. • Effects of methods and datasets of biogenic carbon accounting in wood construction were identified. • Different end-of-life scenarios (incineration, landfill, recycling) cause variations in the results. • Different interpretations of the permanence of storing biogenic carbon in landfills also cause variations in the results. • The input and output flows of biogenic carbon must be balanced to correctly assess its climate change impacts. [ABSTRACT FROM AUTHOR]

The ever-increasing anthropogenic greenhouse gas (GHG) emissions worldwide make it quite challenging to meet country-specific Nationally Determined Contributions (NDC) targets. Therefore, it is evident that the existing emissions abatement measures need to be taken a step further. Internationally Transferred Mitigation Outcomes (ITMOs) are allowed in Article 6.2 of the Paris Agreement as a cooperative approach to achieving NDC goals. There is a potential to create ITMOs between Canada and China by replacing coal use in China with British Columbia (BC)'s liquefied natural gas (LNG) supply. Replacing coal with LNG in energy generation applications is a promising approach to mitigate emissions. With global and national pressures to reduce emissions, China has created a market for LNG imports to cater to its rising natural gas (NG) consumption due to the coal-to-gas source switching strategy. However, the terms under Article 6.2 requires generated ITMOs to ensure environmental integrity, support sustainable development goals, and have a robust accounting system. Therefore, the current study aims to quantify the life cycle environmental outcomes of generating ITMOs by exporting LNG from BC to Chinese end-users while integrating uncertainties and to provide policy recommendations in adherence with the requirements of Article 6.2. Different LNG export scenarios were generated in the study and environmental impacts of each scenario were assessed and compared using a life cycle assessment (LCA) framework developed by the authors. Sensitivity and uncertainty analyses were conducted to understand the impacts created by the data uncertainties in the final result. By replacing conventional coal with NG, approximately 40–45% and 26%–32% emissions reductions can be obtainable for Chinese textile and chemical industries, respectively. The highest emissions reduction of approximately 60% was observed when coal is replaced with NG for district heating. The life cycle emissions (LCE) quantification framework provided in the study provides stakeholders with a systematic approach to determine the total GHG emissions and emissions reduction potential of different LNG export scenarios. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emissions from energy consumption have become a major focus all over the world. Cities, especially, are playing an important role in responding to the challenges of global climate change. However, there is still a lack of case studies on the whole life stage (including energy import, production, and consumption) at the city level. This is the first study to systematically estimate the whole lifecycle GHG emissions of urban energy consumption in Macau using the life cycle assessment (LCA) method. It identifies the main contributors, draws the balance framework diagram of energy GHG emissions, and proposes the effective reduction measures through a scenario analysis. The results show that the total GHG emissions of energy consumption in Macau increased from 2.10 × 103 kt CO 2 eq. in 2000 to 5.34 × 103 kt CO 2 eq. in 2018. In 2018, the energy-related GHG emissions in the import phase, production phase, and consumption phase were 3.37 × 103, 4.08 × 102 and 5.34 × 103 kt CO 2 eq., respectively. Since the return of Macau from Portugal to China (December 20, 1999), its GHG emissions from energy import have come to depend more on Mainland China, increasing from 71% in 2000 to 98% in 2018. For the consumption phase, indirect GHG emissions are more important, accounting for 75.3% of total GHG emissions in Macau. From the final consumption perspective, the gambling industry results in the largest GHG emissions (38.07% in 2018), followed by the transportation industry; while for the final energy consumption types, electricity consumption has become the predominant source. The scenario analysis shows that under an ideal scenario, the GHG emissions can be slowed down and will peak in 2033. [Display omitted] • It firstly estimates the whole lifecycle GHG emissions from Macau urban energy consumption. • The GHG emission dependence on the mainland China increases from 71% to 98% since 2000. • It draws the balance framework diagram of energy GHG emissions. • Gambling industry results in the largest GHG emissions in Macau. • Under ideal scenario, the GHG emissions will peak in 2033. [ABSTRACT FROM AUTHOR]