Indigenized Characterization Factors for Health Damage Due to Ambient PM2.5 in Life Cycle Impact Assessment in China.

Life cycle assessment (LCA) is a broadly used method for quantifying environmental impacts, and life cycle impact assessment (LCIA) is an important step as well as a major source of uncertainties in LCA. Characterization factors (CFs) are pivotal elements in LCIA models. In China, the health loss due to ambient PM2.5 is an important aspect of LCIA results, which, however, is generally assessed by adopting CFs developed by global models and there remains a need to integrate localized considerations and the latest information for more precise applications in China. In this study, we developed indigenized CFs for LCIA of health damage due to ambient PM2.5 in China by coupling the atmospheric chemical transport model GEOS-Chem, exposure-response model GEMM containing Chinese cohort studies, and the latest local data. Results show that CFs of four major PM2.5 precursors all exhibit significant interregional variation and monthly differences in China. Our results were generally an order of magnitude higher and show disparate spatial distribution compared to CFs currently in use, suggesting that the health damage due to ambient PM2.5 was underestimated in LCIA in China, and indigenized CFs need to be adopted for more accurate results in LCIA and LCA studies.

Research on sustainable development evaluation and improvement path of resource-based cities based on coupling of emergy and system dynamics.

The evaluation of the sustainable development of resource-based cities is still one of the hotspots in today's social research. Taking Jining, Shandong Province, as the research object, this work combines a relevant emergy evaluation index system with system dynamics, establishes a resource-based city emergy flow system dynamics model, and studies sustainable development path in the next planning year. In the work, the key factors affecting the sustainable development of Jining are obtained through the coupling of regression and SD sensitivity analysis, and some scenarios are set up by combining them with the local 14th Five-year plan. Besides, the appropriate scenario (M-L-H-H) for Jining's future sustainable development is chosen in accordance with regional circumstances. That is, during the 14th Five-year Plan period, the appropriate development ranges for the growth rate of social fixed assets investment, the growth rate of raw coal emergy, the growth rate of grain emergy and the reduction rate of solid waste emergy are 17.5-18.3%, - 4.0 to - 3.2%, 1.8-2.6% and 4-4.8%. The methodology system constructed in this article can serve as a reference for similar studies, and the research findings can aid the government in formulating pertinent plans for resource-based cities.

Estimation of Emission Factors from Purchased Electricity for European Countries: Impacts on Emission Reduction of Electricity Storage.

To evaluate the reduction brought about by energy storage technology, it is essential to first have accurate data on carbon emissions from electricity consumption. However, when gathering this data by evaluating marginal emission factors (MEFs), previous research measured only generation emissions and direct transfer emissions while ignoring the impact of embodied emissions from the cross-grid transfer. To gather more accurate data, this study constructs an electricity network composed of 28 European countries in 2019 and compares the difference between the MEFs when considering the network-wide emissions and the MEFs when only considering generation emissions and direct transfer emissions for electricity trade (neglecting the indirect emissions in purchased electricity). Three energy storage strategies are adopted to evaluate the carbon emission reduction benefits of energy storage. The results show that the errors in emission accounting and MEF calculation are 7% and 10%, respectively, if the impact of electricity trade is not taken into account. When disregarding the indirect emissions from electricity trade, the errors in emission accounting and MEF calculation are 1%. Implementing wind curtailment reduction strategies for energy storage systems could effectively reduce electricity carbon emissions, more than 200 gCO2/kWh in most countries with 100% storage efficiency. The accuracy of MEFs has a significant impact on the results of energy storage benefits, and the choice of storage strategies has different effects on electricity emissions in the same country. Our methods have general applicability for other regions and countries.

Recovery of CaO from CaSO4 via CO reduction decomposition under different atmospheres.

CaSO4 reduction decomposition for CaO preparation provides a theoretical basis for the utilization of the industrial byproduct, gypsum. In this study, the effects of temperature (950 °C-1150 °C), CO2/CO partial-pressure ratio (1-15), CO concentration (1%-5%), and O2 concentration (1%-7%) on the preparation of CaO from CaSO4 by CO reduction decomposition under different reaction atmospheres were investigated. The physical properties of CaO prepared by the decomposition of CaSO4 and CaCO3 were analyzed and compared. Finally, the reaction mechanism of the reduction decomposition of CaSO4 to CaO by CO was studied. The findings reveal that CaSO4 can be completely decomposed into CaO when the reaction temperature exceeds 1000 °C, CO% ≥ 2%, and P(CO2)/P(CO) ≥ 8. Furthermore, the addition of an appropriate amount of O2 can improve the yield of CaO in the products. In an O2-CO-N2 atmosphere, where O2% = 7% and CO% = 16%, CaSO4 can be completely decomposed into CaO without the addition of CO2. The physical properties of CaO prepared by the reduction and decomposition of CaSO4 are better than those prepared by the calcination of CaCO3. An analysis of the reaction mechanism of the reduction decomposition of CaSO4 by CO reveals that CaSO4 generates CaO and CaS simultaneously. In addition, CaS can react with unreacted CaSO4 to form CaO. Furthermore, it can react with CO2 to produce CaO if an appropriate amount of CO2 is added to the reaction atmosphere. The secondary interactions of CaS with CaSO4 and CO2 can significantly improve the yield of CaO in the product.

Environmental and human health risk evaluation of heavy metals in ceramsites from municipal solid waste incineration fly ash.

Municipal solid waste incineration (MSWI) for power generation can reuse waste effectively, but it generates a large amount of fly ash enriched with heavy metals. If this fly ash cannot be treated properly, it can cause ecological damage and human health risk. According to the production of ceramsites from MSWI fly ash, an evaluation methodology is established, in which the influence of heavy metal stability on the environment is considered for the first time, and the health risks of heavy metals via different exposure pathways are distinguished. The results show that heavy metals in MSWI fly ash have moderate potential environmental risks to environment and have strong non-carcinogenic and carcinogenic risks both to children and adults. By contrast, heavy metals in ceramsites pose little risk to environment and human health. This paper explains some reasons of heavy metal content and leaching ratio change in ceramsite and also illustrates why stability is a concern through comparing the potential risk index method and the improved evaluation method. This evaluation system can be applied to different production processes of building materials using solid hazardous waste and provides a quantitative evaluation method for reducing environment and human health risks of heavy metals.

Multicity comparative assessment and optimized management path of sustainability of the economy-energy-environment system: A case study of core cities in China's three major economic circles.

Coordinated and stable development of economy-energy-environment (3E) systems represents a long-term strategy for the sustainable development of humankind. Following the research idea of "indicator system construction-3E system evaluation-obstacles identification-optimization management," this article innovatively constructs a multiangle and comparable methodology system for evaluation and optimized management of the 3E system and considers the core cities of three economic circles in China as cases for empirical research. The results show that all the coordination degree levels were of good or high quality, which was at the highest level in the country. The sustainability degree of the three cities showed an upward trend; of these, Beijing had the highest sustainability degree, followed by Guangzhou and Shanghai. Obstacle degree analysis shows that technology investment and energy factors were common factors hindering sustainable development of the 3E systems of the three cities, and each city also had its own unique factors that acted as obstacles. On this basis, this article formulates region-specific policy recommendations in order to provide a useful reference for top-level design for the government. Integr Environ Assess Manag 2024;20:875-887. © 2023 SETAC.

Integrated assessment of environmental and economic impact of municipal solid waste incineration for power generation: A case study in China.

Municipal solid waste incineration for power generation is significant for reducing and reusing solid waste. The study conducted an integrated assessment of environment and economy on municipal solid waste incineration in China, from a "cradle to grave" perspective using 1 tonne of municipal solid waste incineration as the functional unit. The environmental impacts of each month are also calculated to analyze the dynamic change throughout one year. The results indicate that the environmental impacts are mainly concentrated in marine ecotoxicity, freshwater ecotoxicity, human carcinogenic toxicity, and human non-carcinogenic toxicity. Flue gas purification, waste incineration and transportation are the key processes, which account for 65.61 %, 18.50 %, and 11.93 % of the overall environmental impact, respectively. Urea, activated carbon, chelating agent (EDTA) and diesel fuel for transportation are key factors. The life cycle cost (LCC) is 132.26 RMB/t of waste, of which the initial capital causes the largest economic cost. When considering power generated from municipal solid waste incineration to replace electricity supply from the power grid, it achieves significant environmental benefits and the normalized environmental impact value changes from 0.85 to -12.19. The findings provide references for municipal solid waste treatment to mitigate the environmental impact and reduce the economic burden across the entire life cycle.

Is solar heating an appropriate choice in rural areas of northern China? Evidence from numerical simulation and life cycle assessment.

Solar heating is generally regarded as a clean and low-carbon heating method, while its high initial investment hinders its promotion in economically underdeveloped areas. With the implementation of the clean heating policy and the proposal of the carbon neutralization target, rural bulk coal heating in northern China is restricted. The Chinese government proposes to widely adopt solar heating to meet the heating demands of rural residents. In this research, the application of solar assisted heat pump systems in Beijing, Tianjin, Hebei and its surrounding areas in China is numerically simulated. A new evaluation method under the same initial investment constraint is proposed to verify its benefits throughout the entire life cycle. The results indicate that although solar thermal heating has the lowest environmental impact and carbon emissions among various heating methods, it is not the best solution to rural clean heating. The reason is that equal investment in other projects can bring much more benefits, such as roof solar photovoltaic. In contrast to the air source heat pump and photovoltaic panel scheme with the same initial investment, solar heating has obvious negative environmental impact, 53.3 % higher economic cost, 35.9 tons more carbon emissions, and 105.9 % higher roof area occupation. The sensitivity analysis of solar fraction, geographical coordinates, and energy price also supports the above findings. The recommendation is proposed to promote air source heat pumps or solar photovoltaic, rather than solar thermal collectors, so as to reduce the cost of rural clean heating and carbon emission reduction.

The effect of optimizing chemical fertilizers consumption structure to promote environmental protection, crop yield and reduce greenhouse gases emission in China.

To ensure food security, simultaneously achieving environmental protection and greenhouse gas (GHG) emission reduction has become a significant challenge in the sustainable development of China's chemical fertilizers (CFs) industry. Hence, this work attempt to construct a multi-objective optimization model (MOOM) based on crop yield, environment protection, and GHG emissions to adjust and optimize China's CFs structure (nitrogen, phosphate, potash, and compound fertilizers). The findings revealed that it's impossible to achieve the coordinated development of the three objectives only through the adjustment of CFs structure. Different optimization measures were sequentially integrated with the MOOM to innovatively obtain the most suitable optimization schemes and the quantitative adjustment interval (which was compared with those in 2018) of the CFs structure. The following are the specific conclusions. First, compared with 2018, the appropriate increase interval for the total CFs consumption was 9 %-21 %, in which the proportion intervals of nitrogen, phosphate, potash, and compound fertilizers were 18 %-25 %, 12 %-18 %, 7 %-12 %, 48 %-60 %, respectively. Second, the reduction ranges of environmental impact and GHG emissions were 1.1 %-12 % and 12.2 %-16.4 %, respectively, under the optimal scheme (combination of the synergy of organic fertilizer substitution and technology improvement with the MOOM), and the growing range of crop yield was 0.2 %-52 %. The main contribution of this work is to build a methodology system for the adjustment and optimization of CFs consumption structure. The findings of the study could be used by the government to develop relevant policies and by other sectors to perform multi-objective optimization.

Coordinated effects of energy transition on air pollution mitigation and CO2 emission control in China.

China has made progress in energy transition to improve air quality, but still confronts challenges including further ambient PM2.5 reduction, O3 pollution mitigation, and CO2 emission control. To explore the coordinated effects of energy transition on air quality and carbon emission in the near term in China, we designed 4 scenarios in 2025 based on different projections of energy transition progress with varying end-of-pipe control level, in each of which we calculated emissions of major air pollutants and CO2, and simulated ambient PM2.5 and O3 concentrations. Results show that energy transition has disparate effects on emission reduction of different air pollutants and sectors, which largely depends on their current end-of-pipe control levels. The different effects on emission reduction may result in opposite variation tendencies of ambient PM2.5 and O3 concentration in a future scenario with aggressive energy transition policies and end-of-pipe control level in 2018. With the end-of-pipe control level strengthened in 2025, PM2.5 and O3 concentration could both reduce on the national scale, but the reduction of ambient O3 lags behind PM2.5, indicating the difficulty of O3 pollution control. As to CO2, national emission would go up in 2025 either implementing current or aggressive energy transition policies due to growing needs of electricity and on-road transportation, but emissions in most provinces could decline to below the 2018 level with aggressive energy transition policies because of substitution of clean energy in industrial, residential and off-road transportation sectors. The study results suggest strictly implementing restrictive end-of-pipe control measures along with energy transition to simultaneously reduce ambient PM2.5 and O3 concentration, and accelerating substitution of renewable energy in power sectors where electricity generation grows rapidly to synergistically control air pollution and CO2 emissions. Furthermore, the projection of CO2 emissions could provide references for short-term emission control targets from the perspective of air quality improvement.

Evaluation of regional sustainability through emergy analysis: a case study of nine cities in the Yellow River Basin of China.

The Yellow River is an important ecological shelter zone and economic belt in China. However, rapid urbanization and industrialization has produced a fragile ecological environment conditions and unbalanced economic development in the Yellow River Basin (YRB). Ecological protection and high-quality development of the YRB has been China's national strategy since 2019. As the only coastal province with the largest economy and population in the YRB, the sustainable development of Shandong Province is of great importance in the region. This study evaluated the dynamic trend of sustainability levels of the nine cities in Shandong Province in the YRB through emergy analysis. Emergy-based indicators were established and analyzed from 2010 to 2019, taking account of the ecological service emergy (ESE) needed to dilute pollutants and emergy equivalent loss (EEL) on ecosystem quality and human health damage. Results showed that emergy sustainable indicators (ESI) in Tai'an, Heze, Dezhou, and Liaocheng ranged from 1 to 10, which had the potential for sustainable development. The ESI value of Jinan, Jining, Zibo, Dongying, and Binzhou was less than 1, which indicated that these cities were under great ecological pressure. The value of emergy indicators for sustainable development (EISD) of the nine cities all declined from 2010 to 2016, but remained stable from 2017 to 2019. Based on findings from the emergy analysis regarding policy implications and local conditions, the study concludes by providing proposals to improve regional sustainability.

Carbon footprint and embodied carbon transfer at the provincial level of the Yellow River Basin.

The ecological conservation and high-quality development of China's Yellow River Basin is a national strategy proposed in 2019. Under China's goal of achieving a carbon peak by 2030 and carbon neutrality by 2060, clarifying the carbon footprint of each province and the transfer paths of embodied carbon emissions is crucial to the carbon reduction strategy for this region. This paper uses input-output model and multi-regional input-output model to account for the carbon footprint of nine provinces in the Yellow River Basin, and to estimate the amount of embodied carbon transfer between provinces and industrial sectors. Social network analysis is applied to identify the critical industries in the inter-provincial embodied carbon emission transfers from the three major industries. We found that the per capita carbon footprint of the Yellow River Basin decreased by 23.4% in 2017 compared to 2012. Among the sectoral composition of the carbon footprint of each province, "Processing and manufacturing of petroleum, coking, nuclear fuel, and chemical products", "Construction", "Other services", and "Metal processing and metal, non-metallic products" are the four sectors with a higher proportion of emissions. The embodied carbon emission transfer between the provinces in middle and lower reaches of the Yellow River Basin is much higher than that between the upstream provinces. Among carbon emission transfer network of three major industries in nine provinces，the secondary industry in Shaanxi has the highest centrality and is the most critical industry. This study provides a theoretical basis and data support for formulating carbon emission reduction plans in the Yellow River Basin.

Reducing the life cycle environmental impact of electric vehicles through emissions-responsive charging.

Electric vehicles (EVs) are currently being promoted to reduce transport emissions. We present a life cycle assessment of EV charging behaviors based on marginal emissions factors. For Great Britain, we find that electricity consumption accounts for the highest proportion of life cycle carbon emissions from EVs. We highlight the potential life cycle carbon emissions reduction brought by charging during periods when the grid mix produces relatively low emissions. While our study focuses on Great Britain, we have applied our methodology to several European countries with contrasting electricity generation mixes. Our analysis demonstrates that countries with a high proportion of fossil energy will have reduced benefits from deploying EVs, but are likely to achieve increased benefits from smart charging approaches. We conclude that using marginal emissions factors is essential to understanding the greenhouse gas impacts of EV deployment, and that smart charging tied to instantaneous grid emissions factors can bring benefits.

A comparative study of EOF and NMF analysis on downward trend of AOD over China from 2011 to 2019.

In recent decades China has experienced high-level PM2.5 pollution and then visible air quality improvement. To understand the air quality change from the perspective of aerosol optical depth (AOD), we adopted two statistical methods of Empirical Orthogonal Functions (EOF) and Non-negative Matrix Factorization (NMF) to AOD retrieved by MODIS over China and surrounding areas. Results showed that EOF and NMF identified the important factors influencing AOD over China from different angles: natural dusts controlled the seasonal variation with contribution of 42.4%, and anthropogenic emissions have larger contribution to AOD magnitude. To better observe the interannual variation of different sources, we removed seasonal cycles from original data and conducted EOF analysis on AOD monthly anomalies. Results showed that aerosols from anthropogenic sources had the greatest contribution (27%) to AOD anomaly variation and took an obvious downward trend, and natural dust was the second largest contributor with contribution of 17%. In the areas surrounding China, the eastward aerosol transport due to prevailing westerlies in spring significantly influenced the AOD variation over West Pacific with the largest contribution of 21%, whereas the aerosol transport from BTH region in winter had relative greater impact on the AOD magnitude. After removing seasonal cycles, biomass burning in South Asia became the most important influencing factor on AOD anomalies with contribution of 10%, as its interannual variability was largely affected by El Niño. Aerosol transport from BTH was the second largest contributor with contribution of 8% and showed a decreasing trend. This study showed that the downward trend of AOD over China since 2011 was dominated by aerosols from anthropogenic sources, which in a way confirmed the effectiveness of air pollution control policies.

Evaluation and optimization of blanket production from recycled polyethylene terephthalate based on the coordination of environment, economy, and society.

The recycling of waste polyethylene terephthalate (PET) is widely regarded as an eco-friendly and cost-effective technology and has been gradually developed into an important direction for the utilization of solid waste resources. However, the integrated evaluation research on this technology from the environmental, economic, and social aspects are still not in place. Based on the theory of collaborative entropy, this study constructs an integrated evaluation and optimization methodology system for the environmental, economic, and social impacts of blanket production from recycled PET, using environmental life cycle assessment, life cycle cost assessment, social life cycle assessment, and sensitivity analysis. The study assessed the environmental load, economic cost, and social impact of blanket production from recycled PET, and then identified the key processes through sensitivity analysis. In addition, the graphical method and the principle of collaborative entropy model are applied to evaluate two of the environmental load, economic cost, and social impact in the blanket production from recycled PET. The results of the two methods are consistent, which indicates that to carry out multi-objective integrated evaluation with collaborative entropy model have good reliability. Moreover, the quantified results of collaborative entropy showed that the key processes that affected the coordinated development of the environment, economy, and society were organic chemicals usage process, electricity generation process, and direct air emission process. Based on the "Reduce-Reuse-Recycle" theory and the position of key processes in the system, feasible optimization suggestions were proposed. The establishment of this methodology system could provide theoretical and practical references for other waste utilization industry.

Evaluation and optimization of a circular economy model integrating planting and breeding based on the coupling of emergy analysis and life cycle assessment.

The sustainable development of agriculture is facing problems such as high resource consumption and serious environmental pollution. The development of the circular economy model integrating planting and breeding (CEMIPB) has become an effective way to realize the sustainable development of agriculture. Due to the great difference of natural resource attributes in different regions of China, CEMIPB shows diverse characteristics on the whole. Based on this, this paper constructs a coupling model based on emergy analysis (EMA) and life cycle assessment (LCA) called EM-LCA model and conducts an empirical analysis using a typical CEMIPB in Fujian Province, China, as a case. By comparing the results of the EM-LCA and EMA models, the former effectively compensates for the deficiencies of the latter in terms of economic and environmental impact assessment, and the evaluation results can better reflect the actual situation of the system. Furthermore, sensitivity analysis is introduced to identify key processes and substances. Based on the reduce-reuse-recycle (3R) principle, several optimization suggestions, such as reducing the input of corn and veterinary drugs, are put forward. The construction of the aforementioned methodology system can provide a new perspective for research in similar fields and provide a scientific basis for local government decision making.

Integrated assessment of the environmental and economic effects of "coal-to-gas conversion" project in rural areas of northern China.

Northern China suffers from serious air pollution especially in winter, much of which derives from solid fuel used for domestic heating in rural areas. In order to reduce pollution emissions in the heating season, the Chinese government has introduced a "coal-to-gas conversion" policy, promoting a switch to natural gas which is much cleaner than the coal normally used for winter heating. The "coal-to-gas conversion" project will cover more than 1.8 billion m2 of heated built floor area and affect more than 12 million heat users in Beijing, Tianjin, Hebei, and the surrounding areas. Life cycle assessment and life cycle cost methods are applied to compare and analyze the environmental impact and economic cost of household energy usage for the whole year under 5 scenarios before and after "coal-to-gas conversion." In the three scenarios after "coal-to-gas conversion," the environmental impact decreases by around 50% while the total economic cost increases by around 80%. Particulate emissions responsible for air pollution are considerably reduced with accompanying benefits for human health, though significant, but reduced, impacts on freshwater and marine ecotoxicity remain. Improving thermal efficiency through natural gas utilization, implementing an energy-saving retrofit of rural housing, and promoting straw utilization yield benefits for people and the environment in rural areas of northern China.

Economic transition and industrial sulfur dioxide emissions in the Chinese economy.

China transitioned into "new normal phase" during 2007 to 2017, shifting from pursuing rapid GDP growth to a win-win state of economic development and environmental improvement. Using the input-output (IO) table for 2007-2012 and the latest IO table for 2012-2017, an IO model of China's industrial SO2 emissions is established and structural decomposition analysis (SDA) is applied to examine the changes in industrial SO2 emissions resulting from this economic transition. Five influencing factors (emission intensity, production technology, final demand expenditure, final demand structure and economic scale) are taken into consideration. The analysis shows that emission intensity and economic scale are the most influential factors on SO2 emissions. Emission intensity reduced SO2 emissions by 16,560,886 t in 2012-2017 whilst economic scale increased SO2 emissions by 473,490 t. Compared with the period 2007-2012, the contribution rate of emission intensity increased from -82.3% to -189.2%, while that of economic scale decreased from 131.8% to 54.1%. The total contributions of 5 factors to SO2 reduction increased from -5,249,417 t to -12,783,248 t, and the contribution rate increased from -24.8% to -146%. China's energy conservation and emission reduction has achieved remarkable results between 2007 and 2017. In "new normal phase", the slowing of China economic growth, the transition of economic development, industrial structural adjustment and rational consumption habits have had significant effects in reducing environmental pollution.

Life cycle assessment of ultra-low treatment for steel industry sintering flue gas emissions.

The largest contributor to pollutant emissions is the sintering process in steel industry. Ultra-low emission policy for the Chinese steel industry states that emission concentrations of particulate matter, SO2 and NOx should not exceed 10, 35 and 50 mg/m3 respectively. The emission concentrations of the steel industry are the same as the ultra-low emission policy for the coal-fired power industry, but the pollutant control technologies of the two industries are different. Life cycle assessment method is applied to analyze the latest ultra-low treatment process for sintering flue gas emissions which includes electrostatic precipitation, ozone oxidation, wet desulfurization, wet denitration, condensation dehumidification and wet electrostatic precipitation. Following this novel ultra-low emission treatment, the concentrations of particulate matter, SO2, NOx, and PCDDs in the sintering flue gas decreased very significantly, attaining the new emission standard. With 1 ton of sinter as the functional unit and "cradle to gate" as the system boundary, the environmental impact of the process is 0.1811 and the total economic cost is 172.79 RMB, of which internal cost is 34.64 RMB and external cost is 138.15 RMB. The main environmental impacts result from applying the wet denitration and ozone oxidation processes. Sodium sulfite in the wet denitration process, and electricity and liquid oxygen in the ozone oxidation process are the key inputs that cause environmental impact. These findings are useful for a further optimization of the ultra-low emissions process from both the environmental and economic perspective, which is applicable in other regions of the world.

Life cycle assessment of autoclaved aerated fly ash and concrete block production: a case study in China.

With the rapid development of construction industry, consumption of concrete block has increased rapidly in China. As a kind of green building material and resource comprehensive utilization product, autoclaved aerated fly ash and concrete block have better performance in terms of heat preservation, sound insulation, and fire resistance. However, some typical issues are associated with autoclaved aerated fly ash and concrete block production process such as energy and material consumption as well as pollutant emissions. To examine the environmental and economic impacts of its production process is imperative. Choosing 1 m3 of autoclaved aerated fly ash and concrete block product as functional unit and "cradle to gate" as system boundary, a life cycle inventory is developed. The key processes and key materials with significant environmental impact are identified. Results show that the top four environmental impact categories are marine ecotoxicity, freshwater ecotoxicity, freshwater eutrophication, and human toxicity. Key processes are fly ash slurry production, lime grinding, and steam curing processes. These processes account for 46.58%, 26.00%, and 19.62% of the total environmental load respectively. The key materials are cement, lime, and natural gas, which account for 44.91%, 22.79%, and 20.61% respectively of overall environmental impact. Sensitivity analysis shows that the fly ash slurry production should be optimized preferentially, followed by lime grinding and steam curing processes. These findings are helpful to facilitate the sustainable production of autoclaved aerated fly ash and concrete block.