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This study assesses possible biodiesel pathways for the Spanish transport sector, representing the current situation. Life Cycle Assessment was carried out for two scenarios: Scenario 1, where 1 MJ of soybean biodiesel was imported from Argentina, and Scenario 2, where 1 MJ of biodiesel from used cooking oil (UCO) was manufactured in Spain. System expansion was performed to include the marginal products involved and additional functions were considered under a consequential approach. Scenario 1 included the production of palm oil in Malaysia (+25.27 g), as the marginal supplier in the global market. This also implied a decrease in the production of soybean meal in Brazil (-3.44 g). In Scenario 2, interactions in the global oil market led to changes in the opposite direction: the production of palm oil decreases in Malaysia (-26.31 g), whereas the production of soybean meal increases in Brazil (+3.58 g). Without considering emissions from Land Use Change (LUC), UCO biodiesel produced in Spain performed better than imported biodiesel from Argentina in all the analyzed impact categories but Global Warming (GW), which was 138.9% lower in Scenario 1, mainly due to the carbon uptake by soybeans in Argentina and palm trees in Malaysia. Since these results could be misleading, GHG emissions from LUC in each country were included. Indirect functions of the expanded systems appeared to have a great contribution in the overall GW impact, especially in Scenario 2. Results show that there are clear environmental benefits arising from the use of UCO biodiesel in Spain to meet the European targets, as compared to the use of imported soybean biodiesel from Argentina. The Monte Carlo simulation for both scenarios also reinforces confidence in the comparative assessment. [ABSTRACT FROM AUTHOR]

Expanding the production of fuels and fibres based on traditional food crops can put additional pressures on ecosystems and natural resources, with potential spillover effects through induced land use change (iLUC). Computable General Equilibrium (CGE) modelling provides a systematic framework for ex-ante sustainability analysis, capturing the complex interactions between land uses, agri-food markets, and international trade. This study applies an integrated CGE framework that considers loss of natural vegetation to derive quantitative indicators on the sustainability of manufacturing bioplastics from arable crops in five major producing regions (Brazil, China, the European Union, United States and Thailand). The approach consists of increasing bioplastics production at the cost of conventional plastics in each of these regions separately by means of a production subsidy, simulating bioplastic production targets. In order to assess the uncertainty in sustainability metrics, different levels of market penetration are considered, as well as variability in key model parameters. Increasing bioplastics production in Thailand is in general associated with more favourable metrics, although this is related to the relatively small size of the sector, which triggers minor market-mediated effects. When iLUC is included, increased bioplastics production in China is, on average, associated with the largest land footprint (16.93 ha t–1); whereas the highest CO 2 emission intensity is estimated for bioplastics produced in the European Union (10.41 t CO 2 -eq. t–1). Emissions from iLUC outweigh potential greenhouse gas (GHG) savings from fossil fuel substitution, except for Thailand, where increasing bioplastics production from sugarcane and cassava saves on average 2.0 kg CO 2 -eq. t–1. This translates into decades of carbon payback time and high abatement costs even for Thailand, while trade-offs arise among the metrics proposed. Other impacts besides deforestation and GHG emissions should ideally be considered to examine further interactions within the Water-Food-Energy nexus, though this may require combining global with regionalized approaches, with the associated challenges. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Power-to-Fuel (PtF) systems use carbon dioxide and hydrogen as feedstock together for renewable fuel production and can hence contribute to climate change mitigation. This study assesses the environmental performance, from cradle to gate, of an innovative PtF system for synthetic methanol production, which integrates a biogas plant based on manure and straw residues as well as a combined heat and power unit. Under this concept, the residual carbon dioxide from biogas production is used for the synthesis of methanol, whereas hydrogen is obtained via wind-based electrolysis. A life cycle assessment (LCA) is carried out here for 1 kg of methanol produced with the integrated system proposed, operated on a small scale. In view of the multi-functionality of the process, the uncertainty in LCA outcomes is assessed by considering different assumptions on co-product credits for both the electricity from cogeneration and the digestate from the anaerobic digestion of organic raw materials. Additionally, a sensitivity analysis is performed to examine the influence of variability in life cycle inventory data on the results. All the analysed scenarios show significant improvements compared with conventional methanol production from fossil resources (with only a few exceptions for acidification and eutrophication). The sensitivity analysis shows that parameters determining the overall energy requirements as well as methane losses from anaerobic digestion in the PtF system greatly influence its environmental performance, and should be carefully considered in process design and upscaling. In spite of the uncertainty inherent in LCA, the system is presented as an interesting option to produce renewable methanol while contributing towards a circular economy, provided that the economic performance is also beneficial relative to the fossil alternative. Image 1 • Life cycle assessment of Power-to-Fuel system to obtain methanol from organic waste. • 9 scenarios with assumptions on co-product credits under system expansion approach. • The system yields environmental gains compared to fossil-based methanol production. • Results greatly depend on choices of co-product credits besides data variability. • Energy demand and CH 4 losses are critical to overall environmental performance. [ABSTRACT FROM AUTHOR]