Total Global Warming Potential Research Articles

Impact of waste processing byproducts on the carbon footprint of integrated waste-to-energy strategies

Resource recovery is a promising solution for multiple waste and economic challenges worldwide. Although the life cycle environmental performance of resource recovery systems has been widely studied, the impacts of their resultant waste processing byproducts remain unassessed. Depending on their management techniques and destinations, such large waste streams, such as non-recovered recyclables and anaerobic digestate, may significantly alter the overall environmental footprint of the integrated solid waste management (ISWM) strategy. This research aimed to assess the life cycle impacts of various ISWM strategies incorporating material recovery and waste-to-energy (WTE) systems. The examined strategies were based on combinations of incineration (INC) and anaerobic digestion (AD) plants, in addition to material recovery facilities (MRFs) and landfills. The study used eighteen scenarios to explore the effect of the potential pathways of waste processing byproducts on the overall carbon footprint of the strategies. The proposed lifecycle assessment framework was applied to an emerging metropolis. The highest energy recovery was achieved in the dual AD and INC scenarios, particularly when the digestate was incinerated, followed by the mono INC scenario. The highest material recovery, specifically recycled materials and digestate, was accomplished in the MRF+AD and MRF +AD+INC scenarios, in which digestate was marketed and non-recovered recyclables were incinerated. It was found that alternative pathways of waste-processing byproducts can reduce the overall global warming potential (GWP) of the base scenarios. Combining MRF and INC as well as MRF, AD, and INC while incinerating non-recovered recyclables, disposing ash, and marketing digestate (if any) were the optimum environmental options in terms of GWP. Incineration of non-recovered recyclables reduced carbon emissions by 29% compared to disposal, whereas marketing and incinerating the digestate positively impacted GWP compared to landfilling (83 and 77%, respectively). A breakdown of the sub-processes revealed that the energy recovery, recycling, and landfilling processes had the highest contributions to the total GWP (up to 88, 92, and 98%, respectively); the collection and transportation processes had the least impacts (2 and 13%, respectively). The more waste-processing byproducts were incinerated, the greater GWP contribution of energy recovery.

Eco-friendly yield-scaled global warming potential assists to determine the right rate of nitrogen in rice system: A systematic literature review.

Rice paddies are one of the largest greenhouse gases (GHGs) facilitators that are predominantly regulated by nitrogen (N) fertilization. Optimization of N uses based on the yield has been tried a long since, however, the improvement of the state-of-the-art technologies and the stiffness of global warming need to readjust N rate. Albeit, few individual studies started to, herein attempted as a systematic review to generalize the optimal N rate that minimizes global warming potential (GWP) concurrently provides sufficient yield in the rice system. To satisfy mounted food demand with inadequate land & less environmental impact, GHGs emissions are increasingly evaluated as yield-scaled basis. This systematic review (20 published studies consisting of 21 study sites and 190 observations) aimed to test the hypothesis that the lowest yield-scaled GWP would provide the minimum GWP of CH4 and N2O emissions from rice system at near optimal yields. Results revealed that there was a strong polynomial quadratic relationship between CH4 emissions and N rate and strong positive correlation between N2O emissions and N rate. Compared to control the low N dose emitted less (23%) CH4 whereas high N dose emitted higher (63%) CH4 emission. The highest N2O emission observed at moderated N level. In total GWP, about 96% and 4%, GHG was emitted as CH4 and N2O, respectively. The mean GWP of CH4 and N2O emissions from rice was 5758kg CO2 eq ha-1. The least yield-scaled GWP (0.7565 (kg CO2 eq. ha-1)) was recorded at 190kgN ha-1 that provided the near utmost yield. This dose could be a suitable dose in midseason drainage managed rice systems especially in tropical and subtropical climatic conditions. This yield-scaled GWP supports the concept of win-win for food security and environmental aspects through balancing between viable rice productivity and maintaining convincing greenhouse gases.

Does intensification with UV light and US improve the sustainability of electrolytic waste treatment processes?

This work aims to assess the influence of ultrasounds (US) application or ultraviolet (UV) light irradiation on the efficiency and sustainability of the treatment of wastes by conductive diamond electrochemical oxidation (CDEO). To do this, a life cycle assessment (LCA) is carried out in order to quantify the environmental impacts of the intensified CDEO processes. Inventories of three bench scale remediation plants (CDEO, Sono-CDEO and Photo-CDEO) in which the different technologies are implemented are performed by means of Ecoinvent 3.3 data base. AWARE, USEtox, IPPC and ReCiPe methodologies are used to quantify the environmental burden into 5 midpoint (water footprint, global warming 100a, ozone layer depletion, human toxicity, freshwater ecotoxicity) and 17 endpoint impact categories. Photo-CDEO attains the faster and more efficient removal in terms of energy consumed. All impact categories are lower in the case in which UV light irradiation is coupled to the CDEO treatment, particularly if the electrolyte does not contain chloride anions. From the point of view of toxicity and ecotoxicity, it is essential to achieve a complete mineralization, because of the intermediates generated into wastes containing chloride anions can become more hazardous than the initial pesticide. The operation of these technologies at large current densities shows positive results from the sustainability point of view, despite the huge environmental impact related to the energy production. Data notice that almost a 99.0% of the total global warming potential is mainly due to the electricity required during the electrochemical treatment, being higher by the sono and photo CDEO treatments because of the use of additional devices. Nevertheless, this issue can be overcome by means of using renewable energies as power sources of these remediation treatments. According to results, it can be claimed that the electrochemical technologies may successfully compete with other AOPs in terms of sustainability.

Comparison of Soil Greenhouse Gas Fluxes during the Spring Freeze–Thaw Period and the Growing Season in a Temperate Broadleaved Korean Pine Forest, Changbai Mountains, China

Soils in mid-high latitudes are under the great impact of freeze–thaw cycling. However, insufficient research on soil CO2, CH4, and N2O fluxes during the spring freeze–thaw (SFT) period has led to great uncertainties in estimating soil greenhouse gas (GHG) fluxes. The present study was conducted in a temperate broad-leaved Korean pine mixed forest in Northeastern China, where soils experience an apparent freeze–thaw effect in spring. The temporal variations and impact factors of soil GHG fluxes were measured during the SFT period and growing season (GS) using the static-chamber method. The results show that the soil acted as a source of atmospheric CO2 and N2O and a sink of atmospheric CH4 during the whole observation period. Soil CO2 emission and CH4 uptake were lower during the SFT period than those during the GS, whereas N2O emissions were more than six times higher during the SFT period than that during the GS. The responses of soil GHG fluxes to soil temperature (Ts) and soil moisture during the SFT and GS periods differed. During the SFT period, soil CO2 and CH4 fluxes were mainly affected by the volumetric water content (VWC) and Ts, respectively, whereas soil N2O flux was influenced jointly by Ts and VWC. The dominant controlling factor for CO2 was Ts during the GS, whereas CH4 and N2O were mainly regulated by VWC. Soil CO2 and N2O fluxes accounted for 97.3% and 3.1% of the total 100-year global warming potential (GWP100) respectively, with CH4 flux offsetting 0.4% of the total GWP100. The results highlight the importance of environmental variations to soil N2O pulse during the SFT period and the difference of soil GHG fluxes between the SFT and GS periods, which contribute to predicting the forest soil GHG fluxes and their global warming potential under global climate change.

Eating away at sustainability. Food consumption and waste patterns in a US school canteen

In order to achieve a sustainable diet, perfect understanding and coordination of the production and consumption aspects of the food system need to be achieved, including inefficiencies as food waste. Food waste rates in developed countries are increasingly perceived as a failure in the system. Within school canteens high levels of food waste are generated, in a location where habits about sustainable consumption should be transmitted to the next generation. This gap between education on best practices and student behavior should be addressed by contextualizing and characterizing meal services within sustainable diets. This research assessed the impacts of food consumption and wastage, including the nutritional characteristics through a case study in a school canteen located in Columbia, Missouri, US. It combines life cycle assessment, environmental life cycle costing, nutritional evaluation, and a food waste audit using weighing, visual assessment, and sorting techniques to estimate the food waste of different canteen users (students and faculty members). The novelty of this research relies on the integration of recognized life cycle thinking methods, including the role of embedded impacts within environmental, cost, and nutritional attributes. Food wasted at the canteen represented between 28 and 53% (by weight) across canteen users of the food served as meals, accounting for 10–35% of nutrients. The highest environmental contribution occurred at the food procurement stage (85%), while the lowest occurred at food preparation (2%). The largest costs are associated with food preparation activities and food purchases (39% meal cost). The embedded food waste impact accounts for 40–57% of the total global warming potential and about 27% of the total cost. Interventions are proposed and evaluated to improve the diet performance, which could be extended to further canteen scenarios.

Effects of increased planting density with reduced nitrogen fertilizer application on greenhouse gas emission in double-season rice fields under water saving and simple cultivation mode

To clarify the effects of increased density and reduced nitrogen on greenhouse gas emission in double-season paddy fields under the water-saving and simple cultivation mode, we used Luliangyou 996 (early rice) and Fengyuanyou 299 (late rice) as materials to collect greenhouse gas by closed static box method, monitored the dynamics of CH4 and N2O emissions from different combinations of increased density and reduced nitrogen for early and late rice, and explored changes in cumulative CH4 and N2O emissions, global warming potential (GWP) and greenhouse gas intensity (GHGI) as affected by different combinations of increased density and reduced nitrogen from double-season rice fields. The results showed that the cumulative emissions of CH4 and N2O from different combinations were significantly different. Compared with the control (CK), cumulative CH4 emission, GWP and GHGI in the two seasons decreased by 50.8%, 37.3%, and 42.9% for the combination of increased density and reduced nitrogen IR2(the amount of nitrogen applied of early rice was 86.4 kg·hm-2, the density was 360000 holes·hm-2; the amount of nitrogen applied of late rice was 108 kg·hm-2, the density was 320000 holes·hm-2), respectively. IR2 of early rice had the lowest N2O cumulative emission, being 33.7% lower than CK. IR1(the amount of nitrogen applied of early rice was 103.2 kg·hm-2, the density was 320000 holes·hm-2; the amount of nitrogen applied of late rice was 129 kg·hm-2, the density was 280000 holes·hm-2) of late rice had the lowest N2O cumulative emission, being decreased by 94.9%. IR2 had the lowest annual total GWP and GHGI of double-season paddy fields. Compared with other treatments of increased density and reduced nitrogen, the IR2 treatment, where nitrogen fertilizer in both early and late rice was reduced by 28.0%, the density of early rice was increased by 28.6%, and the density of late rice was increased by 33.3%, was an effective and safe option for simultaneously ensuring high yield and reducing greenhouse gas emissions.

Fluctuating water level effects on soil greenhouse gas emissions of returning farmland to wetland

Future climate change is predicted to have an important impact on regional precipitation patterns. Water level is an important factor influencing soil greenhouse gas emissions. However, the effect of small-scale water level fluctuations on soil greenhouse gas emissions from returning farmland to wetlands has been little studied. We collected soils of three lands from returning farmland to wetland with different restoration years and a natural wetland at the Honghe National Nature Reserve in Sanjiang Plain, China. Through indoor simulation experiments, we explored the characteristics of soil greenhouse gas (CO2, CH4, and N2O) emissions under fluctuating water levels. When the water level fluctuated between − 8 and 8 cm, the CO2 and N2O emissions decreased as the water level increased, but the CH4 emissions were highest when water level fluctuated between − 3 and 3 cm. The CH4 emissions tended to increase as laboratory time extended. Different gases react differently to water level fluctuations. The CO2 emissions contributed 78.90–96.48% of the total global warming potential of the GHG emissions. The results of this study indicate that during the process of returning farmland to wetland, more attention should be paid to the effects of CO2 emissions. An appropriately raised water level can effectively suppress the global warming potential of greenhouse gas emissions.

Global warming potential optimization of a turbofan powered unmanned aerial vehicle during surveillance mission

Gas emissions from all sources including air transport contribute to global warming. There are tremendous efforts to decrease the greenhouse gas emissions in all sectors. In this study, for a turbofan engine powered unmanned aerial vehicle, Global Warming Potential (GWP) calculations have been performed covering a range of flight Mach number and altitude. Unmanned aerial vehicles have different mission profiles and usage characteristics than manned aircraft. Therefore their emissions are also different than manned aircraft due to different flight altitude, loitering (surveillance) speed and engine power setting etc. Global warming potential was calculated with a genuine code combining aircraft performance, engine performance and exhaust gas emissions for all flight points during surveillance mission. Exhaust gases of CO2, H2O and NOx were calculated and at each leg of flight as they contribute to GWP. Results were presented to illustrate the GWP magnitudes for different flight speed and altitude in a comparative manner for the turbofan powered UAV. Optimization calculations were done by using genetic algorithm. For an investigated range of 6–16 km flight altitude and 0.25–0.75 flight Mach number, total surveillance mission GWP is lowest around 13 km and 0.37 Mach number as optimum values. However, GWP per hour during constant speed and altitude surveillance (loiter) is minimum around 15 km and 0.43 Mach number for assumed UAV flight mission profile.

Preliminary Study on the GWP Benchmark of Office Buildings in Poland Using the LCA Approach

The decarbonisation goal stated in the Energy Performance of Buildings Directive (EPBD) regarding the building sector will be achieved only if the whole building life-cycle is considered. To fulfil this requirement, a benchmark based on the life cycle assessment (LCA) must be integrated into the early planning phase of buildings by designers. The estimation of such indicators requires the development of a database of building assessments. In this study, an LCA of 11 office buildings in Poland was used to set average values that can be used as a benchmark. The LCA methodology based on the Building Research Establishment Environmental Assessment Method (BREEAM) certification was used. The analysis did not concentrate on one type of office building. The main objective was to investigate a possible range of total Global Warming Potential (GWP) index values normalized to the usable unit floor area. The importance of the GWP of individual life-cycle phases was also considered. The study shows that the used methodology is adequate for LCA benchmark estimation to set preliminary average values for office buildings in Poland.

Life-Cycle Assessment of the Use of Peach Pruning Residues for Electricity Generation

Biomass residues from permanent crops might be an alternative fuel for energy generation in a local market with limited transport distances. Moreover, as activities related to CO2 reduction are of special attention in the European Union (EU), sustainable use of resources plays an important role in climate change mitigation. In this paper, a life-cycle assessment (LCA) of the integrated value chain from peach pruning residues for electricity generation is presented and compared with the common practice including the mulching process of the pruned biomass in an orchard. It was shown that biomass harvesting, chipping and its delivery to a power plant—the Pruning-to-Energy (PtE) scenario—is feasible from an environmental point of view. The total global warming potential (GWP) of this value chain was 200 kg CO2 eq.·ha−1 (or 27 kg CO2 eq.·GJ−1). In turn, the mulching and leaving of the pruned biomass in an orchard—the pruning-to-soil (PtS) scenario—is characterized by a CO2 equivalent of 2360 kg·ha−1. Other impact categories showed a lower environmental impact for the PtE scenario as well. When considering the Spanish electricity-mix instead of coal-based electricity, the PtS scenario score better in most impact categories, but the GWP for the PtE scenario remains lower.

Effects of water management on greenhouse gas emissions from farmers' rice fields in Bangladesh

Alternate wetting and drying (AWD) irrigation in lowland rice cultivation increases water use efficiency and could reduce greenhouse gas (GHG) emissions compared to the farmers' practice of continuous flooding (CF). However, there is a dearth of studies on the impacts of water management on methane (CH4) and nitrous oxide (N2O) emissions in Bangladesh. Multi-location field experiments were conducted during the dry seasons of 2018 and 2019 to determine the baseline emissions of CH4 and N2O from rice fields and compare the emissions from AWD irrigation and CF. CH4 and N2O emissions were measured using the closed chamber technique and their concentrations were determined using a gas chromatograph. CH4 and N2O emissions varied across water management schemes and sites. AWD irrigation significantly (p < 0.05) reduced cumulative CH4 emissions (37%, average across sites) without affecting grain yields compared to CF. The CH4 emission factor for AWD was lower (1.39 kg ha−1 day−1) compared to CF (2.21 kg ha−1 day−1). Although AWD irrigation increased seasonal cumulative N2O emissions by 46%, it did not offset reduced CH4 emissions. AWD reduced the total global warming potential (GWP) by 36% compared to CF. Similarly, GHG intensity (GHGI) in AWD was 34% smaller compared to that in CF. Emissions varied across sites and the magnitudes of seasonal cumulative CH4 and N2O emissions were higher at the Gazipur site compared to the Mymensingh site. AWD, which saves irrigation water without any yield penalty, could be considered a promising strategy to mitigate GHG emissions from rice fields in Bangladesh.

Mechanism, kinetics, and environmental assessment of OH‐initiated transformation of CTDE in the atmosphere

AbstractThe transformation mechanism and kinetics of 2‐chloro‐1,1,2‐trifluoroethyl‐difluoromethyl‐ether (CTDE, CHF2OCF2CHFCl) triggered by OH radicals are studied by density‐functional theory methods and canonical variational transition state theory. The computational rate constant including small‐curvature tunneling correction is found to be in commendable agreement with the experimental data. Two hydrogen abstraction channels to form the alkyl radicals of C·F2OCF2CHFCl and CHF2OCF2C·FCl are observed, and the formation of CHF2OCF2C·FCl is found to be more favorable than C·F2OCF2CHFCl kinetically and thermodynamically. Subsequent evolution of CHF2OCF2C·FCl in the presence of NO and O2 indicates that the organic nitrate (CHF2OCF2CONO2FCl) is the stable product. The dechlorinate of alkoxy radical (CHF2OCF2C(O·)FCl) is the most favorable degradation channel, and the estimated ozone depletion potential for CTDE relative to chlorofluorocarbon‐11 is 0.0204, which could lead to ozone depletion as a consequence. The computed atmospheric lifetime for CTDE is found to be 3.69 years by considering the combined contributions from OH radicals and Cl atoms. The total radiative forcing and global warming potential of CTDE are, respectively, 0.547 W m−2 ppbv and 628.58 (100 years) at 298 K, suggesting that the contribution of CTDE to the greenhouse effect is moderate.

Control Effects of Chelonus munakatae Against Chilo suppressalis and Impact on Greenhouse Gas Emissions From Paddy Fields.

Field and pot experiments were conducted to investigate the control effects of parasitoid wasps (Chelonus munakatae Munakata) on striped rice stem borers and their impacts on N2O and CH4 emissions from paddy fields. Three treatments including no insect (NI), striped stem borer (CS) and parasitoid wasp + striped stem borer (CS+CM) were implemented. The abundance of GHG-related microorganisms in soils was determined by absolute real-time qPCR. Compared with NI, CS and CS+CM significantly increased the ratio of dead tillers, inhibited the growth and vitality of rice roots, and decreased the rice grain yield, while they significantly reduced the seasonal cumulative emissions of N2O and CH4 by 17.7–24.6 and 13.6–35.1%, and decreased the total seasonal global warming potential (GWP) by 13.6–34.7%, respectively. Moreover, compared with CS, CS+CM significantly enhanced the growth and vitality of rice roots, decreased the ratio of dead tillers, improved the rice grain yield, as well as increased the seasonal cumulative CH4 emissions and the total seasonal GWP. Principal component analysis indicated that the morphological features of rice roots play a more important role in regulating GHG emissions than GHG-related microorganisms. The results suggested that C. munakatae can effectively control the outbreak of C. suppressalis and alleviate crop damage with acceptably higher GHG emissions. It is concluded that it can be recommended as an effective, environment-friendly and sustainable approach to prevent and control C. suppressalis.

Investigation into the Effects of Straw Retention and Nitrogen Reduction on CH4 and N2O Emissions from Paddy Fields in the Lower Yangtze River Region, China

Straw retention is a widely used method in rice planting areas throughout China. However, the combined influences of straw retention and nitrogen (N) fertilizer application on greenhouse gas (GHG) fluxes from paddy fields merits significant attention. In this work, we conducted a field experiment in the lower Yangtze River region of China to study the effects of straw retention modes and N fertilizer rates on rice yield, methane (CH4) and nitrous oxide (N2O) emission fluxes, global warming potential (GWP), and greenhouse gas intensity (GHGI) during the rice season. The experiments included six treatments: the recommended N fertilizer—240 kg N·ha−1 with (1) no straw, (2) wheat straw, (3) rice straw, and (4) both wheat and rice straw retentions; in a yearly rice–wheat cropping system (N1, WN1, RN1, and WRN1, respectively); as well as both wheat and rice straw retentions with (5) no N fertilizer and (6) 300 kg N·ha−1 conventional N fertilizer (WRN0, WRN2). The results showed that CH4 emissions were mainly concentrated in the tillering fertilizer stage and accounted for 54.2%–87.5% of the total emissions during the rice season, and N2O emissions were primarily concentrated in the panicle fertilizer stage and accounted for 46.7%–51.4% total emissions. CH4 was responsible for 87.5%–98.5% of the total CH4 and N2O GWP during the rice season, and was the main GHG contributor in the paddy field. Although straw retention reduced N2O emissions from paddy field, it significantly increased CH4 emissions, which resulted in a significant net increase in the total GWP. Compared with the N1 treatment, the total GWP of WN1, WRN1, and RN1 increased by 3.45, 3.73, and 1.62 times, respectively; and the GHGI increased by 3.00, 2.96, and 1.52 times, respectively, so the rice straw retention mode had the smallest GWP and GHGI. Under double-season’s straw retentions, N fertilizer application increased both CH4 and N2O emissions, and the WRN1 treatment not only maintained high rice yield but also significantly reduced the GWP and GHGI by 16.5% and 30.1% (p &lt; 0.05), respectively, relative to the WRN2 treatment. Results from this study suggest that adopting the “rice straw retention + recommended N fertilizer” mode (RN1) in the rice–wheat rotation system prevalent in the lower Yangtze River region will aid in mitigating the contribution of straw retention to the greenhouse effect.

Comparison of global-warming potential impact of food waste fermentation to landfill disposal

Food waste (FW) has been identified as a critical global issue. The generation of FW is challenging to control because it is driven by various factors. Landfills, the most common final destinations for FW, are often associated with negative economic and environmental impact. Most previous studies have found that FW could also contribute to global warming due to GHG emission from decomposition of organic waste, so it is important to divert FW from landfills and find a better option such as using it to produce other value-added products. Depending on the particular FW composition, such waste has potential to be used in fermentation technology, so the primary objective of this study is to compare the global-warming potential (GWP) impact of FW fermentation and landfill disposal methods. Life-cycle assessment (LCA) was conducted to determine the effect on environmental of four scenarios: (i) FW fermentation without enzymes and a 2-step distillation system, (ii) FW fermentation without enzymes and a membrane distillation separation process, (iii) FW fermentation integrated with combined heat power (CHP), and (iv) FW in landfills. As expected, all FW fermentation options produced lower GWP impact values than a landfilling method. From the overall fermentation process, the lowest total GWP value was 164.1 kg CO2-eq/1 Mg of FW for the second scenario. Membrane distillation is an environmentally sound process, and suggesting that FW can be utilized to produce value-added products in fermentation while minimizing the environmental burden.

A dynamic analysis of the global warming potential associated with air conditioning at a city scale: an empirical study in Shenzhen, China

Heating, ventilation and air conditioning (HVAC) systems are a major source of energy consumption in buildings, directly and indirectly contributing to greenhouse gas (GHG) emissions. In the urban environment, and depending on local climatic conditions, air conditioning units attribute to these high energy demands. This study analyzes the use of residential air conditioning units and their associated global warming potential (GWP) between 2005 and 2030 for the city of Shenzhen, a fast-growing megacity located in Southern China. A life cycle assessment approach was adopted to quantify the GWP impacts which arise from both direct (refrigerant release) and indirect (energy consumption) sources, in combination with a materials flow analysis approach. The results show that the total GWP (expressed as carbon dioxide equivalents, CO2 eq.) from residential air conditioning systems increased from 2.2 ± 0.2 to 5.1 ± 0.4 million tonnes (Mt) CO2 eq. between 2005 and 2017, with energy consumption and refrigerant release contributing to 72.5% and 27.5% of the total demands, respectively. Immediate measures are required to restrict refrigerant release and reduce the energy consumption of air conditioning units, to help mitigate the predicted additional total emissions of 36.4 Mt. CO2 eq. potentially released between 2018 and 2030. This amount equals to approximately New Zealand's national CO2 emissions in 2017. The findings proposed in this study targets air conditioning units to reduce the GWP emissions in cities, and provide useful data references and insights for local authorities to incentivise measures for improving building energy efficiency management and performance.

How are annual CH4, N2O, and NO emissions from rice–wheat system affected by nitrogen fertilizer rate and type?

Although the effect of controlled-released fertilizer (CRF) on methane (CH4) and nitrous oxide (N2O) emissions has been investigated from many rice–wheat rotation systems, most studies were conducted either in the rice or in the wheat seasons. Few studies measured CH4, N2O, and nitric oxide (NO) emissions from rice–wheat rotation systems simultaneously. In this study, one-year outdoor pot experiments and two-year field experiments were conducted to investigate the effects of altering nitrogen (N) fertilizer type from traditional fertilizer (TF) (e.g., compound fertilizer and urea) to CRF and reducing 30% of the local conventional N application rate on CH4, N2O, and NO emissions from a typical Chinese rice–wheat rotation system. Results showed that the annual cumulative N2O emissions and EFN2O in the CRF treatment decreased by 3.91%–16.7% and 9.23%–20.7% compared with the TF treatment, respectively. These emissions also significantly decreased by 26.0%–34.4% and 18.1%–28.5% when local conventional N fertilizer application rate was decreased by 30% (P < .05). However, neither altering fertilizer type nor reducing 30% N fertilizer application rate affected CH4 emissions (P > .05), and the reduction effect of CRF on NO emissions could only be detected at the CRF fertilization rate at 270 kg N ha−1 per season but not at 190 kg N ha−1 per season. The annual total global warming potential in CRF treatment decreased by approximately 1.47%–9.17% compared with that in TF treatment. Moreover, this potential decreased by 8.29%–15.4% when 30% of the N application rate was reduced. Therefore, altering N fertilizer type from TF to CRF and applying optimal N rate should be encouraged as a partial substitution N fertilizer management strategy for the sustainable development of rice–wheat rotation systems.

Energy Consumption, Carbon Emissions and Global Warming Potential of Wolfberry Production in Jingtai Oasis, Gansu Province, China

During the last decade, China's agro-food production has increased rapidly and been accompanied by the challenge of increasing greenhouse gas (GHG) emissions and other environmental pollutants from fertilizers, pesticides, and intensive energy use. Understanding the energy use and environmental impacts of crop production will help identify environmentally damaging hotspots of agro-production, allowing environmental impacts to be assessed and crop management strategies optimized. Conventional farming has been widely employed in wolfberry (Lycium barbarum) cultivation in China, which is an important cash tree crop not only for the rural economy but also from an ecological standpoint. Energy use and global warming potential (GWP) were investigated in a wolfberry production system in the Yellow River irrigated Jingtai region of Gansu. In total, 52 household farms were randomly selected to conduct the investigation using questionnaires. Total energy input and output were 321,800.73 and 166,888.80 MJ ha−1, respectively, in the production system. The highest share of energy inputs was found to be electricity consumption for lifting irrigation water, accounting for 68.52%, followed by chemical fertilizer application (11.37%). Energy use efficiency was 0.52 when considering both fruit and pruned wood. Nonrenewable energy use (88.52%) was far larger than the renewable energy input. The share of GWP of different inputs were 64.52% electricity, 27.72% nitrogen (N) fertilizer, 5.07% phosphate, 2.32% diesel, and 0.37% potassium, respectively. The highest share was related to electricity consumption for irrigation, followed by N fertilizer use. Total GWP in the wolfberry planting system was 26,018.64 kg CO2 eq ha−1 and the share of CO2, N2O, and CH4 were 99.47%, 0.48%, and negligible respectively with CO2 being dominant. Pathways for reducing energy use and GHG emission mitigation include: conversion to low carbon farming to establish a sustainable and cleaner production system with options of raising water use efficiency by adopting a seasonal gradient water pricing system and advanced irrigation techniques; reducing synthetic fertilizer use; and policy support: smallholder farmland transfer (concentration) for scale production, credit (small- and low-interest credit) and tax breaks.

Experimental Investigation on Compressive Properties and Carbon Emission Assessment of Concrete Hollow Block Masonry Incorporating Recycled Concrete Aggregates

In this paper, the compressive strength experiment for three groups of recycled aggregate concrete (RAC) specimens with different replacement ratios of recycled aggregate (0%, 50%, 100%) was carried out. The mechanism of the block and mortar properties on the compressive strength of block masonry was investigated by means of a static loading test. The formula for calculating the compressive strength of a recycled concrete block was obtained based on experimental data. Moreover, the global warming potential (GWP) of recycled aggregate concrete (RAC) block masonry was evaluated by life cycle assessment (LCA) methodology. The feasibility for application of RAC block masonry was discussed combined with environmental impact data analysis. The results show that the strength of RAC blocks is the principal element affecting the compressive strength of block masonry, and the strength of mortar also has a certain impact for the compressive of RAC block masonry; the sub-coefficient of material performance should be enhancive appropriately for ensuring the construction quality of RAC block masonry; the total GWP of RAC block is lower than that of natural aggregate concrete (NAC) block. The environmental benefits of the promotion and application of RAC block masonry are inspiring.

How has LCA been applied to 3D printing? A systematic literature review and recommendations for future studies

Abstract Previously perceived as a rapid prototyping technique, additive manufacturing (AM) has evolved into a fully developed manufacturing process, with growing accessibility to different industrial sectors. Its technological and economic advantages are frequently documented, but AM’s environmental performance is seldom investigated. Not long ago discrete initiatives to assess AM’s applicability for building large-scale structures started to arise. Mostly focused on technical and economic feasibility, these studies pave the way for the process’s consolidation in the construction sector. This paper aims to systematically and critically assess the available literature on AM’s life cycle environmental impacts and to identify the main challenges and trends on loads measurements. The findings help feed recommendations to perform life cycle assessments (LCA) in AM initiatives, with a special focus on the construction sector. A systematic search led to the careful analysis of 52 papers, out of 353 that matched our search protocol. In terms of LCA methods’ robustness, a lack of transparency stood out in many papers, suggesting that authors were most likely non-LCA experts, applying the tool without much knowledge of requirements and modelling intricacies. In terms of documented global warming potential (GWP) values in comparison to conventional manufacturing (CM), AM processes were portrayed as beneficial in most cases. Most papers documented results ranges, which represented different printing, production or distribution strategies, in which AM’s performance varied considerably. LCA played a significant role in finding an optimum production approach and seems to be a valuable lens to assure 3D printing’s environmental competitiveness. A contribution analysis showed that there is a shift between materials vs. production processes contribution in the life cycle GWP loads of systems manufactured with AM and CM. 3D printing processes account for almost 80% of AM’s total GWP, while for CM that position is held by the material-related loads. For construction related AM processes, the material intensity is, however, still by far the largest contributor to building systems’ GWP, maintaining the impact distribution as in typical manufacturing processes.