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Background, aim, and scope: The expectations with respect to biomass as a resource for sustainable energy are sky-high. Many industrialized countries have adopted ambitious policy targets and have introduced financial measures to stimulate the production or use of bioenergy. Meanwhile, the side-effects and associated risks have been pointed out as well. To be able to make a well-informed decision, the Dutch government has expressed the intention to include sustainability criteria into relevant policy instruments. Main features: Among other criteria, it has been proposed to calculate a so-called life-cycle-based greenhouse gas (GHG) indicator, which expresses the reduction of GHG emissions of a bio-based fuel chain in comparison with a fossil-based fuel chain. Life-cycle-based biofuel studies persistently have problems with the handling of biogenic carbon balances and with the treatment of coproducts and recycling. In life-cycle assessments (LCAs) of agricultural products, a distinction between "negative" and "positive" emissions may be relevant. In particular, carbon dioxide, as a naturally occurring compound or an anthropogenic emission, takes part in the so-called geochemical carbon cycle. The most appropriate way to treat carbon cycles is to view them as genuine cycles and, thus, at the systems level, subtract the fixation of CO 2 during tree growth from the CO 2 emitted during waste treatment of discarded wood and to quantify the CH 4 emitted. In solving the multifunctionality problem, two steps may be distinguished. The first concerns the modeling of the product system studied in the inventory analysis. In this step, system boundaries are set, processes are described, and process flows are quantified. Multifunctionality problems can be identified and the model of the product system is drafted. The second step concerns solving the remaining multifunctionality problems. For this step, various ways of solving the multifunctionality problem have been proposed and applied, on the basis of mass, energy, economic value, avoided burdens, etc. As the GHG indicator may constitute the basis for granting subsidies to stimulate the use of bioenergy, for example, and as the method for the GHG indicator provides no guidelines on the handling of biogenic CO 2 and guidelines for solving multifunctionality problems such as with coproducts and recycling that leave room for various choices, this study analyzed whether the current GHG indicator provides results that are a robust basis for granting such subsidies. Results: For the robustness check, a hypothetical case study on wood residue-based electricity was set up in order to illustrate what the effects of different solutions and choices for the two steps mentioned may be. The case dealt with the production of wood pellets (residues of the wood industry) that are cofired in a coal-fired power plant. The functional unit is 1 kWh of electricity. Three possibilities for the places of the multifunctional process, two possibilities for whether or not to include biogenic CO 2 , and four possibilities for the allocation method were distinguished and calculated. Varying the options for these three choices in this way appears to have a huge effect on the GHG indicator, while no clear pattern seems to emerge. Discussion: The results found for this hypothetical case indicate that there are several methodological choices that have not sufficiently been fixed by the presently available standards and guidelines for LCA and GHG assessment of bioenergy systems. In particular, we have focused on issues related to biogenic CO 2 and allocation, two issues that play a prominent role in the assessment of bioenergy systems. Moreover, we have demonstrated with a small hypothetical case study that these are not only issues that might theoretically show up, but that they play a decisive role in practice. Conclusions: The present (Dutch) GHG indicator lacks robustness, which will raise problems for providing a sound basis for granting subsidies. This situation can, however, be improved by reducing the freedom of choices for the handling of biogenic CO 2 and allocation to an absolute minimum. Recommendations and perspectives: Even then, however, differences could appear due to different definitions, data sources, and method interpretations. It thus appears that two kinds of guidance are needed: (1) the LCA methodology itself should be expanded with guidelines for those issues that follow from science, logic, or consensus; (2) in the policy regulation that demands LCA to be the basis of the decision, additional guidelines should be specified that perhaps do not (yet) have the status of being scientifically proven or generally agreed upon, but that serve as a set of temporary extra guidelines.

AbstractUnequal outcomes resulting from urbanization can pose a significant challenge to sustainable development. Vehicles are an important urbanization dimension as a critical component of urban infrastructure by providing mobility and accessibility to social services. China's vehicle ownership (referred to as in-use vehicle stocks) has been growing quickly since 2000, but its per capita stocks are still much lower than that in developed economies. This raises the question of whether and when China's vehicle stocks will reach a peak level close to that in the developed countries. By analyzing vehicle stocks in 283 Chinese cities during 2001–2018, we have the following findings: (1) vehicle stocks are predominantly distributed in northern and eastern coastal cities and provincial capital cities; (2) inequality in vehicle ownership rates between cities shows a declining trend at both national and region scales; (3) the growth of vehicle ownership rates follows an S-shape curve and most cities are still at the early stage of motorization; (4) China is likely to have a lower saturation level of vehicle ownership rate. These results could help to accurately forecast future vehicle demand in China, estimate the resulting environmental impacts, and explore strategies to achieve carbon neutrality in transportation.

This report summarizes the results of "Nanotechnology and Life Cycle Assessment," a twoday workshop jointly convened by the Woodrow Wilson Center Project on Emerging Nanotechnologies; the United States Environmental Protection Agency Office of Research and Development; and the European Commission, RTD.G4 "Nano S&T: Converging Science and Technologies." Held in October 2006, the workshop involved international experts from the fields of Life Cycle Assessment (LCA) and nanotechnology. The main program of the workshop consisted of introductory lectures, group discussions and a final plenary session. A writing group prepared the initial draft of this report based on workshop discussions, and the final report was reviewed by all workshop participants and outside experts. The contents are based on the results of the group discussions. The structure of this report follows the main topics identified and discussed by the groups. The purpose of the workshop was to determine whether existing LCA tools and methods are adequate to use on a new technology. This document provides an overview of LCA and nanotechnology, discusses the current state of the art, identifies current knowledge gaps that may prevent the proper application of LCA in this field and makes recommendations on the application of LCA for assessing the potential environmental impacts of nanotechnology, nanomaterials, and nanoproducts. For the purposes of this report, "nanoproducts" are defined as products containing nanomaterials. A short version of this report will be published in an appropriate LCA and/or a technical nanotechnology journal. The following presents a summary of the main conclusions and recommendations identified by the workshop participants and presented in this report. Main Conclusions · There is no generic LCA of nanomaterials, just as there is no generic LCA of chemicals. · The ISO-framework for LCA (ISO 14040:2006) is fully suitable to nanomaterials and nanoproducts, even if data regarding the elementary flows and impacts might be uncertain and scarce. Since environmental impacts of nanoproducts can occur in any life cycle stage, all stages of the life cycle of nanoproducts should be assessed in an LCA study. · While the ISO 14040 framework is appropriate, a number of operational issues need to be addressed in more detail in the case of nanomaterials and nanoproducts. The main problem with LCA of nanomaterials and nanoproducts is the lack of data and understanding in certain areas. · While LCA brings major benefits and useful information, there are certain limits to its application and use, in particular with respect to the assessment of toxicity impacts and of large-scale impacts. · Within future research, major efforts are needed to fully assess potential risks and environmental impacts of nanoproducts and materials (not just those related to LCA). There is a need for protocols and practical methodologies for toxicology studies, fate and transport studies and scaling approaches. · International cooperation between Europe and the United States, together with other partners, is needed in order to address these concerns. · Further research is needed to gather missing relevant data and to develop user-friendly eco-design screening tools, especially ones suitable for use by small and medium sized enterprises. Key Recommendations 1. Case-studies/prioritizing efforts With limited resources, a case-study research approach could be adopted to significantly enhance knowledge on environmental impacts of nanomaterials and nanoproducts. 2. LCA studies and presentations of results Any LCA study on nanoproducts and nanomaterials most likely suffers from high uncertainty issues. Therefore, the report recommends: · Do not wait to have near-perfect data. · Be modest about uncertainties; clearly state relevant uncertainty aspects and assumptions. · Draw conclusions in the case of major or significant improvements; otherwise, state that the nanoproducts and the conventional product are equivalent. · At this early stage, studies should focus on protecting humans and the environment. · Separate the category indicators, grouping them by relevance/uncertainty. · Avoid overselling the benefits of the new nanoproduct, since assessment methodologies will improve and might show "problems" in the future. · Work with toxicologists and other scientists (geographical and socio-economic impacts) to review data and bound the issue. · Make disaggregated data available for future LCA comparisons. 3. Approaches · Critical review should always be done to ensure credibility of LCA studies. · An independent review should be made by an expert panel with balanced representation and wide range of expertise. · Data for the critical review or other supporting data should be published. · Panels of interested parties should be formed to establish rules for LCA of nanomaterials and nanoproducts. 4. Actions from stakeholders Different stakeholders/authorities can potentially support the application and use of LCA for nanoproducts and nanomaterials through a large set of actions. Government actions could include: · Setting up research frameworks and programs for the methodology development of LCA in the field of nanotechnology and with nanoproducts. · R&D activities, with special emphasis on multinational cooperation in fields related to health and environmental safety. · Use of LCA results to design adapted economic instruments. · Using LCA to help develop green purchasing and integrate nanotechnology criteria in green purchasing. · Allocating a portion of current nano research funding to nano/LCA research to make it more attractive to the private sector for further R&D. · Providing independent, standardized and reviewed LCA information that might be used by industry and other stakeholders. · Covering different nanotechnologies' flows of substances (air emissions, water releases etc.) into the European Commission's "European Reference Life Cycle Data System" (ELCD), and the US Life Cycle Impact database. · Working toward an international LCI database for nanomaterials. · Improving data coordination among different government agencies, e.g., agencies responsible for product consumer safety evaluations, workplace safety evaluations and environmental issues. Academia can potentially support the application and use of LCA to nanoproducts and nanomaterials through a large set of actions, including: · Setting up databases for LCA case studies on nanotechnology and nanoproducts. · Providing scholarships to the universities to hire Ph.D. students specifically for nano/LCA research. · Carrying out research in LCA methods applied to nanotechnology and nanoproducts. Industry can potentially support the application and use of LCA to nanoproducts and nanomaterials through a large set of actions, including: · Undertake R&D activities. · Use of LCA results to design improved products. · Co-funding research on developing LCA methods, impact characterization metrics specific to nanotechnologies. · Co-funding research on toxic effects of specific nanomaterials. · Co-funding social science research on public concerns about nanotechnology and on developing effective risk-communication strategies using LCA data. · Actively creating mechanisms for sharing confidential data without compromising competitiveness. The report also notes that the insurance industry should play a leading role in assessing life cycle risk assessments of nanoproducts. NGO and Consumer Associations can potentially support the application and use of LCA to nanoproducts and nanomaterials through a large set of actions, including: · Communicating LCA study results to the public to inform consumers. · Educating themselves and promoting LCA as a tool to assess nanotechnology.

The current study makes use of life cycle assessment to evaluate the potential greenhouse gas (GHG) savings in coal electricity generation by 5% co-firing with sorghum pellets. The research models the utilization of 100 thousand hectares of under-utilized marginal land in Flores (Indonesia) for biomass sorghum cultivation. Based on equivalent energy content, 1.12 tons of pellets can substitute one ton of coal. The calculated fossil energy ratio of the pellets was 5.8, indicating that the production of pellets for fuel is energetically feasible. Based on a biomass yield of 48 ton/ha·yr, 4.8 million tons of pellets can be produced annually. In comparison with a coal system, the combustion of only pellets to generate 8,300 GWh of electricity can reduce global warming impacts by 7.9 million tons of CO2-eq, which is equivalent to an 85% reduction in GHG emissions. However, these results changed when reduced biomass yield of 24 ton/ha·yr, biomass loss, field emissions, and incomplete combustion were considered in the model. A sensitivity analysis of the above factors showed that the potential GHG savings could decrease from the initially projected 85% to as low as 70%. Overall, the production of sorghum pellets in Flores and their utilization for electricity generation can significantly reduce the reliance on fossil fuels and contribute to climate change mitigation. Some limitations to these conclusions were also discussed herein. The results of this scenario study can assist the Indonesian government in exploring the potential utilization of marginal land for bioenergy development, both in Indonesia and beyond.