CO2eq Emissions Research Articles

Solid waste management in Ugandan developing cities: Material flow analysis and sustainable practices for reducing the global warming potential.

The introduction of appropriate solid waste management (SWM) strategies can foster the mitigation of waste open dumping and burning in low-income developing cities. In this work, the SWM system in Gulu (Uganda) has been studied, and a material flow analysis, also of informal flows of waste, has been carried out. Moreover, the effectiveness of the SWM system of St. Mary's Lacor Hospital in Gulu was evaluated. Waste has been characterized and a material flow analysis allowed to highlight the difference with the current situation in the remaining part of Gulu. The sustainable practices already implemented in the hospital compound were studied to be replicated in Gulu to mitigate SWM impact in terms of global warming potential. Inadequate financial resources pose a hurdle for Gulu municipality in managing municipal solid waste (MSW) effectively. The SWM system of the hospital demonstrated both financial and managerial competence, paving the way to promote waste recycling actions acting as a hub for fostering sustainable and health-conscious valourization technologies, while discouraging waste open burning and dumping. This study estimated that the total CO2-eq emissions from open dumping and open burning avoided in 2030-2050, if Gulu would appropriately dispose of MSW by 2030, are equal to about 17,000 metric tonnes per year (t year-1). This work suggests appropriate strategies to mitigate waste open burning in low-middle income countries. The results can be helpful for waste management planners and practitioners providing important information for the use of appropriate technologies in low-middle income developing cities.

Online exams in higher education: A possible solution to avoid unnecessary car trips

Distance learning represents a form of remote participation, resulting in avoidance of commuting trips. After the end of the pandemic emergency, the progressive return to in-person exams is expected to generate a significant volume of car trips, especially for those telematic universities that in the last few years have experienced an impressive growth in students’ enrolment. This research presents the case study from Universitas Mercatorum, the University of the Italian Chambers of Commerce. Through a survey-based methodology, this study aims at estimating the students’ travel demand to take exams in case of full return to traditional in-person format. Following a Well-to-Wheel approach, this study also performs a transport-related greenhouse gas (GHG) emissions assessment. Results show that car is the most used mode (51 %), and a total amount of about 40 million vehicle-kilometres travelled per year is expected. This translates into about 9 thousand tonnes of CO2eq emissions per year. However, the stated preference experiment highlights that 37 % of motorized private transport users (cars and motorbikes) might shift to rail and 37 % of car users are willing to carpool.

Environmental impact analysis of ajmaline challenge protocols: a comparative assessment of carbon footprint reduction in Brugada Syndrome diagnosis

Abstract Background Climate change is an urgent public health crisis that significantly impacts disease development and health outcomes. The 2022 Lancet Countdown Report revealed that healthcare contributes with 5.2% of global emissions, prompting a call for environmentally conscious approaches. In this context, we explored the environmental impact of different ajmaline challenge protocols, aiming to contribute to a more sustainable medical landscape. Purpose This study aims to compare the carbon footprint of two ajmaline challenge protocols commonly used in diagnosing Brugada syndrome, an inherited cardiac disorder associated with sudden cardiac death. Methods We performed a retrospective and observational analysis of adult patients (pts) who underwent ajmaline testing between March 2020 and June 2023 in two hospitals. In Group A (infusion protocol), 1mg/kg of ajmaline diluted in 50 mL of 5% glucose solution was infused in 10 minutes, up to the target dose, until a positive result or termination criteria ensued. In Group B (bolus protocol), 10 mg of ajmaline were administered every 2 minutes, again up to the target dose of 1mg/kg (maximum of 100 mg) or test interruption was indicated. Greenhouse gas emissions resulting from material processing were estimated based on life cycle analyses of each product's composition. Material consumption, waste production, and direct measurement of weights were considered. Results A total of 101 pts were included, 49 pts in group A with a mean age of 47.3±14.3 years old and 52 patients in group B with a mean age of 43.9±16.6 years-old. No complications were observed in either group. Test performance was not evaluated, since both protocols have been previously validated. Group A, utilizing the infusion method, exhibited a higher environmental impact, producing 18.19 kg CO2eq, compared to 6.23 kg CO2eq (p<0.001) in Group B (bolus protocol). Group B not only demonstrated a 66% reduction in CO2eq emissions but also used significantly less plastic (16g vs 102g per test) and glass (1.58 kg vs 1,79Kg), emphasizing its environmental superiority. Conclusions Shifting from infusion to bolus in ajmaline challenge protocols results in a substantial reduction in carbon footprint. Our findings emphasize the potential impact of adopting more dematerialized approaches in cardiac testing, urging healthcare professionals to embrace sustainable practices. Despite the study's limited sample size, the global adoption of such environmentally friendly strategies promises significant positive effects on healthcare's environmental footprint.

Comprehensive methodology for the integrating of the organic rankine Cycle-ORC with diesel generators in off-grid areas: Application to a Colombian case study

Efficient fuel management in diesel generator sets for power generation in non-grid areas is a persistent concern. In this context, the use of an Organic Rankine Cycle (ORC) to recover heat from exhaust gases from diesel generator sets represents a promising route for additional power generation. To undertake such projects, it is necessary to understand the critical parameters related to diesel engines, including the specific fuel consumption, mass flow, and exhaust gas temperature. These parameters are fundamental to the sizing process of the ORC heat recovery system. This study introduces an innovative methodology for evaluating the operation of diesel-ORC systems based on the load demand of off-grid communities. The proposed system is a viable solution for the generation of additional power with the objective of improving the overall efficiency and meeting higher energy demands in isolated areas. Four organic fluids were selected for the ORC: R245fa, benzene, cyclopentane, and toluene. This selection was made based on many criteria, including global warming potential (GWP), ozone depletion potential (ODP), and safety classification (ASHRAE 34). In addition, the exergy behaviors of these fluids were reviewed. A comparative analysis was subsequently conducted for a non-interconnected region of Colombia to evaluate the performance of a diesel generator operating independently and in conjunction with the diesel ORC system. The key indicators employed were fuel consumption savings (L/year), energy produced (MWh/year), levelized cost of energy (LCOE, USD/kWh), and payback period (years). The results demonstrated that, over the course of a 1-year simulation period, the benzene ORC system exhibited the highest overall energy efficiency, achieving a value of 41.38%. The exergy analysis indicated that toluene had lower irreversibilities, achieving an exergy efficiency of 44.78%, followed by benzene (43.5%. Furthermore, the diesel-ORC system using benzene demonstrated a notable decrease in the specific fuel consumption from 0.282 to 0.247 L/kWh, signifying a 10.52% reduction in the annual CO2eq emissions. The cost of electricity generation decreased by 4.3%, with investment payback periods not exceeding 14 years.

The Environmental Kuznets Curve (EKC) Hypothesis on GHG emissions: analyses for transportation industry of South Africa

A series of energy-econometrics techniques were employed for a 5-year time span between 2016 and 2020. The tests of Environmental Kuznets Curve (EKC) hypothesis were conducted essentially to examine the significance of economic growth (GDP), energy consumption (EC), with energy intensity (EI), and on-road passenger vehicles (PV) as related to economic development on the mitigation of carbon emissions (CO2-eq) in the transportation industry of South Africa. The findings from the prevailing research imply that, with respect to South Africa’s transportation industry, CO2-eq emissions increased in the course of early phases of economic growth while it tends to decline at certain levels of economic threshold. Though the nation maintains the edge of turning points in both the industrial and circular economy. The results further indicate a nexus between GDP and EC, which consequently affect the CO2-eq emissions. The findings proffer the needs to monitor the EC from the long-run impacts alongside the short run impacts of the forecast. The per capita GDP from the short-run impacts of t-stat—(4.928) to the long run effects of t-stat—(5.033) rises, indicating its improper influence in the industry. To limit the use of fossil-based fuels, as demonstrated in the negative signal of EI for long-run impacts of a p-value (0.2835), then to the short run effects which possess a significant p-value. It also highlights the directional correlation surfacing between EC, EI and South Africa’s on-road PV. In the computation context, the series was determined to be stationary at its first differences, as evident by the R2 combined with the R2 (Adjusted) values of 0.9837 and 0.9827, respectively, for both long-run and short-run assessments. The indication of the research among others further reveals that public transportation systems of road and rail options, which have the potentials to incorporate alternative energy sources, can be the required efforts to mitigate climate change and global warming effects in the transportation industry.

Tracking Carbon and Ammonia Emission Flows of China's Nitrogen Fertilizer System: Implications for Domestic and International Trade.

China is the world's largest producer, consumer, and exporter of synthetic nitrogen (N) fertilizer. To assess the impact of domestic demand and international exports, we quantified the life-cycle CO2eq and ammonia (NH3) emissions by tracking carbon (C) and nitrogen (N) flows from coal/gas mining through ammonia production to N fertilizer production, application, and export. In 2020, China's N fertilizer system emitted 496.04 Tg of CO2eq and 3.74 Tg of NH3, with ammonia production and N fertilizer application processes contributing 36 and 85% of the life-cycle CO2eq and NH3 emissions, respectively. As the largest importers of N fertilizer, India, Myanmar, South Korea, Malaysia, and the Philippines collectively shifted 112.41 Tg of CO2eq. For every ton of N fertilizer produced and used in China, 16 t of CO2eq and 0.18 t of NH3 were emitted, compared to 9.7 t of CO2eq and 0.13 t of NH3 in Europe. By adopting currently available technologies, improving N fertilizer utilization efficiency and employing nitrification inhibitors could synergistically reduce CO2eq emissions by 20% and NH3 emissions by 75%, while energy transformation efforts would primarily reduce CO2eq emissions by 59%. The production of ammonia using green electricity or green hydrogen could significantly enhance the decarbonization of China's N fertilizer system.

Greenhouse gas and volatile organic compound emissions of additive-treated whole-plant maize silage: part A—anaerobic fermentation period

BackgroundSilage emits climate- and environment-relevant gases during fermentation and feed-out periods. This trial aimed to determine the unknown carbon dioxide (CO2), methane, nitrous oxide, ethanol, and ethyl acetate emissions of constant maize silage material over both periods. The results will be published in two consecutive articles (Part A: anaerobic fermentation period, Part B: aerobic storage period).MethodsThe untreated control (CON) was compared with the chemical additive treatment (CHE; 0.5 g sodium benzoate and 0.3 g potassium sorbate per kg fresh matter) and the biological additive treatment (BIO; 108 colony-forming units (CFU) Lentilactobacillus buchneri and 107 CFU Lactiplantibacillus plantarum per kg fresh matter). Barrel silos (n = 4) were connected to gas bags to quantify gas formation during anaerobic fermentation (30 or 135 ensiling days). Glass jar silos (n = 12) were used for laboratory silage analysis.ResultsCHE produced significantly (p < 0.05) less gas (6.7 ± 0.3 L per kg dry matter ensiled material (kgDM) until ensiling day 14.0 ± 0.0) and ethanol (8.6 ± 1.5 mg kgDM–1) than CON did (8.5 ± 0.2 L kgDM–1 until ensiling day 19.5 ± 6.4; 12.2 ± 1.5 (mg ethanol) kgDM–1). BIO indicates prolonged gas formation (9.1 ± 0.9 L kgDM–1 until ensiling day 61.3 ± 51.9; 12.0 ± 2.1 mg kgDM–1). CO2 is the main component of the gas formed. All treatments formed methane and nitrous oxide in small quantities. CON emitted significantly more CO2eq emissions than BIO and less than CHE (p < 0.05). Additives had no effect on ethyl acetate gas emissions. For BIO, ethanol concentrations in the material (rS = 0.609, p < 0.05) and gas quantities (rS = 0.691, p < 0.05) correlate with ethyl acetate gas quantities. All the treatments exhibited decreasing gas and CO2 quantities, and the dry matter mass increased between ensiling days 14 and 30 (− 0.810 ≤ rS ≤ 0.442; p < 0.05 to p = 0.20).ConclusionSilage generates climate- and environmental-relevant gases during fermentation and silage additives affect this pattern. Gas formation exceeds the fixation potential, and the carbon footprint of silage fermentation is negative.Graphical

Novel Use of Concentrated Solar Thermal Energy for Producing Highly Thermal Activated Materials for CCUS via Mineral Carbonation of Mine Waste

An assessment of the levelised cost and associated CO2-eq emissions for the thermal activation of serpentine mine tailings to be used as activated feedstock for CCUS processes via mineral carbonation, is reported here for the first time. Two main technological scenarios were assessed, based on either direct fuel sources heating (natural gas and hydrogen) or indirect, CST-based heating with a back-up burner and storage to provide continuous operations, for a 200 ton/hr of processed ore and a targeted roasting ore temperature of 700°C. For CST-based systems, 3 different solar input scales, namely 50, 150 and 450 MWth, were considered, and simulations performed over a year timeline with a 10 minutes time step, using Mt Keith Nickel mine in Western Australia as the reference location. The analysis highlighted that the proposed CST-hybrid plant layout can achieve similar cost to that of fuel-only cases with current Australian fuel prices for natural gas and hydrogen, with lower CO2-eq emissions, and a parity cost with fuel-only scenarios of some 16 USD/GJ. The proposed CST-hybrid plant layout was also identified as the potential, preferred route over direct CST routes to achieve 24/7 continuous heat supply while retaining fine tuning of activation temperature, given a very narrow temperature window of activation for the chosen mine tailings for mineral carbonation processes.

The future of single-use plastics in life science: Sterile printing of PLA reduces greenhouse gas emissions by 80% and enables carbon neutrality

The European Union’s Green Deal emphasizes life science and biotechnology as key drivers for achieving a circular economy. However, the prevalent use of non-sustainable single-use plastics derived from petrochemical sources in life science research and development contradicts this ecological goal. This study presents a viable alternative through on-site sterile 3D printing of single-use plastics using poly(lactic acid) (PLA). The sterile printing of PLA demonstrates a substantial reduction in CO2eq emissions per shake flask, decreasing from 260 g CO2eq to 145 g CO2eq. Suitability for cell culture was demonstrated for sterile printed PLA, autoclaved high-temperature PLA and for suspension cell cultures in shake flasks using CHO and insect cells as well as adherent Vero cell cultures in cell culture wells. Further optimization of sustainable shake flasks is achieved by utilizing recycled PLA, resulting in a remarkable reduction to 73 g CO2eq, constituting a 72% decrease in CO2eq emissions compared to conventional single-use plastics. Moreover, by employing geometric optimization to minimize material usage, emissions can be further reduced to 44 g CO2eq, representing an 83% reduction in CO2eq emissions. Anticipated advancements in PLA production suggest future carbon net negative PLA production, potentially achieving zero carbon emissions for single-use plastics using PLA. The exceptionally cost-effective nature of 3D printed single-use plastics, coupled with negligible capital costs for implementation, positions sterile 3D printing as a practical solution aligned with the 2030 Green Deal goals. Moreover, ongoing improvements in bioplastic production underscore the feasibility of meeting the 2050 targets of carbon neutrality for single-use plastics in life science research and development.

Investigation of a high-temperature combination heat pump for lower-cost electrification in multifamily buildings

The development of space and water heating combination heat pumps capable of generating water temperatures high enough for convective heat emitters will enable more cost-effective and equitable decarbonization solutions for electrifying multifamily buildings. In this paper, multifamily building models and a charge-sensitive mechanistic cycle model of a combination heat pump are developed, and the system performance is predicted based on the models. Unlike other state-of-the-art residential heat pumping equipment, the modeled combination heat pump using an economized, fluid-injected variable-speed compressor can achieve higher temperature lifts of 40° – 85°C, with lower installation costs and complexity. The model predicted heating coefficient of performance (COPh) is 2.1 at an ambient temperature of −15°C with a high-temperature lift of nearly 85°C, and a seasonal coefficient of performance in heating mode (SCOPh) ranges from 2 – 4 for different locations. The system shows 30% – 90% lower CO2eq emissions over a condensing gas boiler and 9% – 13% lower projected installation costs than two separate space and water heat pumping appliances.

Regional drivers of industrial decarbonisation: a spatial econometric analysis of 238 EU regions between 2008 and 2020

ABSTRACT The European context of socio-economic integration and physical proximity likely plays an essential role in explaining the decarbonisation outcomes of industrial sectors. However, there is hardly any spatial regional analysis on CO2 emissions drivers in European countries. This study investigates the role of geographical space and regional determinants in industrial decarbonisation by analysing how socio-economic drivers and their interregional relationships impact industrial carbon emissions in European regions. We employ a spatial panel data econometric model to a novel panel dataset comprising 13 years (2008–20) of carbon emissions from hard-to-abate industrial sectors from 238 NUTS-2 regions across 27 European Union countries. Results indicate the presence of endogenous spatial interactions and high-time persistence between CO2-eq emissions in European Union regions. As such, industrial carbon emissions of regions follow similar patterns to their neighbours, supporting the evolutionary economic geography and growth theory assumptions of the spatial interaction of carbon emissions between regions. Furthermore, the use of a spatial econometric model illustrates the negative direct and spillover effects that higher levels of education and regional investment in research and development have on industrial CO2-eq emissions.

Harnessing offshore wind for decarbonization: A geospatial study of hydrogen production and heavy industry utilization in Mexico

This study comprehensively examines the techno-economic potential of utilizing offshore wind resources for hydrogen production in Mexico. Through the integration of geospatial analysis techniques with energy generation and economic models, the research estimates hydrogen production, CO2eq emissions reduction potential, Levelized cost of electricity (LCOE), and Levelized cost of hydrogen (LCOH). The analysis highlights Mexico’s capacity to produce up to 217.33 million tons of hydrogen annually, predominantly from the Gulf of Mexico. Centralized offshore hydrogen production demonstrates significant cost advantages, being up to 0.92 USD/kg cheaper than onshore production. The study also underscores the economic benefits of repurposing existing oil and gas infrastructure, which can reduce LCOH by up to 11%. Environmental benefits are substantial, with hydrogen use in ammonia production potentially reducing CO2eq emissions by 82.5%. Additionally, the study identifies highly suitable offshore areas for hydrogen production, particularly near existing oil infrastructure, facilitating the integration of new renewable energy projects with minimal additional infrastructure development. These findings provide valuable insights for policymakers and stakeholders, emphasizing the economic viability and environmental benefits of offshore wind hydrogen production as a strategic pathway for Mexico’s energy transition and decarbonization efforts.

Carbon emission reductions in the University of São Paulo’s transportation sector using hydrogen-powered vehicles

The transportation sector, especially diesel-powered buses in Brazil, faces a significant decarbonization challenge, contributing with 19.76 million tCO2-eq GHG emissions. Therefore, this study aims to calculate the achievable GHG emission reductions by implementing renewable hydrogen vehicles at the University of São Paulo. The methodological approach considers low-carbon hydrogen production using the ethanol steam reforming route, where energy and mass balances are performed throughout the hydrogen chain. Two models are developed to calculate CO2-eq emissions. Results show that replacing the current fleet of conventional internal combustion engine buses with hydrogen-based options leads to a significant annual reduction of 2658 tCO2-eq, approximately an 83% reduction as compared to the conventional one. Moreover, the total energy conversion efficiency, well-to-wheel, reaches 26.9% and 11.8% for hydrogen and conventional vehicles, respectively, without air-conditioning system, or 21.9% and 9.9% when air-conditioning is coupled, respectively. Notably, CO2-eq emissions increase by at least 38.3% and 15.5% due to the presence of that equipment, respectively. Finally, the results of total cost of ownership (TCO) showed that CAPEX represents only 7.14% of the TCO, being the fuel cost the major proportion for both technologies.

The carbon footprint of external beam radiotherapy and its impact in health technology assessment

BackgroundThe major drivers of carbon dioxide (CO2eq) emissions of external beam radiation therapy (EBRT) are not well known and limit our ability to initiate mitigation strategies. Material and methodsWe describe the carbon footprint of four typical centers. We explore direct EBRT associated factors such as the impact of fractionation and use of MRI-LINAC, as well as indirect factors (e.g. patient rides). Treatment strategy related CO2eq emissions are included in a health technology assessment analysis that takes into account CO2eq emissions. ResultsA typical EBRT treatment emits from 185 kgCO2eq to 2066 kgCO2eq. CO2eq emissions are mostly driven by (i) accelerator acquisition and maintenance (37.8 %), (ii) patients and workers rides (32.7 %), (iii) drugs and medical devices (7.3 %), (iv) direct energy consumption (6.1 %), and (v) building and bunker construction (5.6 %) with a substantial heterogeneity among centers. Hypofractionation has a strong impact to mitigate emissions. MRI-LINAC is associated with a substantial increase in CO2eq emissions per fraction and requires ultra hypofractionation in 5 fractions to achieve a similar carbon footprint compared to 20 fractions treatment schemes. The expected limited small increase in toxicities due to hypofractionation (when existing) are in the same range as avoided detrimental effects to future people’s health thanks to CO2eq mitigation. ConclusionCarbon footprint of EBRT is not neglectable and could be mitigated. When safely feasible, hypofractionation is one of the main factors to decrease this impact. Taking into account CO2eq emissions has a substantial impact on the health technology assessment of EBRT, favoring hypofractionated regimens.

The Potential of Fiber-Reinforced Concrete to Reduce the Environmental Impact of Concrete Construction

Material optimization was one of the challenges for achieving cost-competitive solutions when concrete was introduced in construction, leading to new structural shapes for both civil works and buildings. As concrete construction became dominant, saving material was given less significance, and the selection of the structural typology was mostly influenced by construction or architectural considerations. Simple and non-time-consuming methods for building thus arose as the dominant criteria for design, and this led to the construction of less efficient structures. Currently, the awareness of the environmental footprint in concrete construction has brought the focus again to the topic of structural efficiency and material optimization. In addition, knowledge of material technology is pushing the use of cements and binders with lower environmental impact. Within this framework, Fiber-Reinforced Concrete (FRC) has been identified as a promising evolution of ordinary concrete construction. In this paper, a discussion is presented on the structural properties required for efficient design, focusing on the toughness and deformation capacity of the material. By means of several examples, the benefits and potential application of limit analysis to design at the Ultimate Limit State with FRC are shown. On this basis, the environmental impact of a tailored mix design and structural typology is investigated for the case of slabs in buildings, showing the significant impact that might be expected (potentially reducing CO2-eq emissions to half or even less in slabs when compared to ordinary solutions).

A life cycle carbon dioxide equivalent emissions assessment of zero carbon building in hot semi-arid climate region: Case study

As societies are shifting toward carbon neutral environments, they are beginning to account for their carbon emissions. One of the primary contributors of greenhouse gas emissions and global warming is the building industry; therefore, Life Cycle Assessment (LCA) is one of the instruments that allows an assessment of the energy and the energy-related environmental impacts of the buildings from cradle to grave, according to ISO 14040. In this context, the aim of this research study is to assess the Life Cycle carbon dioxide (LC CO2eq) emissions over a 50-year-lifespan of a zero-carbon solar-powered earth-based building, built with carbon-free adobe bricks, in the hot semi-arid climate of Morocco. While research on the carbon dioxide equivalent (CO2eq) emissions across the life cycle is crucial to determine the energy-intensive stages, this study looks into global tendencies of CO2eq emissions arising during the cradle-to-gate embodied (A1-3) and operational (B6) phases of a Zero Carbon Building (ZCB) case study, and which should be offset by carbon-free energy in order to abide by the ZCB definition. Results show that the LC CO2eq emissions of the eco-friendly zero-carbon residential building falls in 48.62 Kg CO2eq/m2.y., with an operational phase that has a share of around 93 % of global LC CO2eq emissions. In addition, when conventional construction materials such as concrete, bricks, and insulation materials are used as an alternative, embodied carbon emissions accounts for 6.3 kg CO2eq/m2.y. and is 85 % higher than the eco-friendly building, and it constitutes approximately 12.5 % of the overall carbon footprint. Moreover, the annual embodied and operational CO2eq emissions are offset by the 3.3-kWc-building-added-photovoltaic system. Hence, the conducted case study offers valuable insight into the good practices for decarbonization of Morocco's building stock.Through that case study, we aim to generate knowledge of net zero carbon buildings within the African continent, promoting the perks of decentralized solar energy in leaping forward a carbon-free electrified continent and valorizing the local construction techniques and knowhow in the building sector.

Lifetime optimisation of integrated thermally and electrically driven solar desalination plants

We compare the performance of photovoltaic (PV), flat-plate and evacuated-tube solar-thermal (ST), and hybrid photovoltaic-thermal (PV-T) collectors to meet the energy demands of multi-effect distillation (MED) desalination plants across four locations. We consider three scales: 1700 m3day−1, 120 m3day−1 and 3 m3day−1. We find a strong dependence of the capacity and configuration of the solar collectors on both the cost of sourcing electricity from the grid and the specific collector employed. We find specific costs as low as 7.8, 3.4 and 3.7 USDm−3 for the three plant capacities. We find that solar-driven systems optimised for the lowest specific cost result in CO2eq emissions equal to, or higher than, those from grid-driven reverse osmosis (RO) and in line with PV-RO. This highlights the need to consider the environmental footprint of these systems to ensure that desalination is in line with the United Nations’ Sustainable Development Goal 6.

The levelized cost of carbon abatement (LCCA) in substituting conventional ammonia production with power-to-ammonia for fertilizer, hydrogen and export

The production of ammonia using the conventional Haber-Bosch technique produces significant CO2 emissions, largely owed to the fossil fuel-based hydrogen production. To reduce these emissions, low-carbon ammonia production with hydrogen from water electrolysis (i.e., power-to-ammonia, P2A) is being developed. This study compares P2A with the methane-fed Haber-Bosch process by performing a time-based levelized cost of carbon abatement (LCCA) analysis, considering technology development and adoption, and the mismatch between production capacity and ammonia demand over time. The LCCA results quantify the cost and potential carbon reduction simultaneously and provide the cost to reduce one unit of CO2-eq emissions using P2A. Various scenarios in multiple sectors are considered in different regions in Canada from 2027 to 2050, such as low-carbon fertilizer, ammonia as a hydrogen carrier for domestic use and energy export, and their dynamics over-time were studied and compared. Results show that under the base case with conservative assumptions, the LCCA is higher than the proposed carbon price in Canada, except when low-carbon ammonia demand is low, e.g., domestic hydrogen use. Yet sensitivity analyses suggest that the LCCA can approach the carbon price with technical improvements and increased adoption over time. The electricity generation mix also has great impacts on the LCCA. Regions with abundant low-carbon electricity sources, e.g., Quebec, Prince Edward Island, Nova Scotia, Manitoba, and British Columbia can benefit from P2A on both environmental and economic perspectives. Some of these regions are connected to the coast, so there is also great potential for ammonia-shipping corridors in both the Atlantic and Pacific Oceans.

Exploring the implementation feasibility of the sol-char sanitation system using machine learning and life cycle assessment

Globally, 1.5 billion people still lacked access to safe sanitation facilities in 2022, which exacerbated health risks and environmental degradation. To address this, we created the Sol-Char sanitation system, a potential solution for expanding secure sanitation alternatives. This study aimed to develop a machine learning model that could evaluate the viability of implementing the Sol-Char system in 76 countries with high rates of open defecation in 2022. Using the Random Forest model, we identified suitable locations considering factors such as solar energy availability and economic feasibility. The model successfully identified 42 countries (55 %), mainly in Sub-Saharan Africa and South Asia, as appropriate candidates for implementing the system. In addition, a framework was developed to guide solar technology suitability prediction using our machine learning model. Furthermore, we conducted an ex-ante life cycle assessment (LCA) study to evaluate the environmental impacts across different implementation scenarios. The baseline scenario (Scenario 1) produced the least emissions, with 299 kg CO2-eq. In contrast, the scenario (Scenario 2) involving international transportation had the highest emissions at 395 kg CO2-eq (32 % higher), while the localized scenario (Scenario 3) landed in between with 337 kg CO2-eq emissions. The LCA and contribution analysis highlighted that optimizing materials and design was essential to reduce emissions across these scenarios. Local manufacturing, particularly in high-transportation scenarios like Scenario 2, could reduce emissions from logistics but required careful consideration of local resources and energy structures, as demonstrated in Scenario 3.

Water-energy-food-greenhouse gas nexus: An approach to solutions for water scarcity in agriculture of a semi-arid region

CONTEXTAgricultural systems involve intricate interdependencies among water, energy, and food. Increasing understanding of these linkages, along with implications for greenhouse gas (GHG) emissions and developing new assessment approaches are critical for achieving key sustainability goals. OBJECTIVES1) Evaluation of the impacts of tillage, irrigation and residue management practices on water and energy consumption, and GHG emission in the cultivation of irrigated wheat and rapeseed, 2) Developing a novel Water-Energy-Food-Greenhouse gas (WEFG) nexus index to provide a holistic assessment of the linkages among water, energy, food, and GHG emissions in agriculture, and 3) Assessing the sustainability of irrigated wheat and rapeseed cultivation under different methods of tillage, irrigation and residue management applying the WEFG nexus index. METHODSThis study formulated a new WEFG nexus index applying eight indicators of water and energy consumption, CO2-eq (CO2 equivalent) emission, water and energy mass productivity, water, energy and CO2-eq economic productivity to evaluate the sustainability of wheat and rapeseed cultivation under two field management practices: 1) furrow irrigation with conventional tillage (FICT), and 2) center pivot irrigation with no-tillage (CPNT), within a semi-arid region in northeastern Iran. Irrigation in both systems was done by applying a deficit irrigation approach. RESULTS AND CONCLUSIONSCPNT resulted on average in 46% and 53% energy consumption reductions from water and diesel usage, respectively, compared to FICT. The mean CO2-eq emission under CPNT was 26% lower than that recorded under FICT. Furthermore, the WEFG nexus index score for wheat and rapeseed under CPNT was 0.91 and 0.73, respectively, out of 1, compared to 0.18 and 0.12 for FICT. These scores suggest that the CPNT approach is a more appropriate strategy than FICT, as it effectively reduced water and energy consumption while aligning better with long-term environmental and economic aims. SIGNIFICANCEThe study applies more accurate GHG emission-based indicators to introduce a new WEFG nexus index, and it uses these for evaluation of different field management at the farm level to reduce the uncertainties in the large-scale studies. The proposed methodology for assessing multiple aspects of the WEFG nexus can change previous perceptions about agricultural management in other regions confronting multiple resources and environmental crises.