Global Warming Potential Research Articles

High-Efficiency Electrocatalytic Reduction of N2O with Single-Atom Cu Supported on Nitrogen-Doped Carbon.

Nitrous oxide (N2O) is a potent greenhouse gas with a high global warming potential, emphasizing the critical need to develop efficient elimination methods. Electrocatalytic N2O reduction reaction (N2ORR) stands out as a promising approach, offering room temperature conversion of N2O to N2 without the production of NOx byproducts. In this study, we present the synthesis of a copper-based single-atom catalyst featuring atomic Cu on nitrogen-doped carbon black (Cu1-NCB). Attributed to the highly dispersed single-atom Cu sites and the effective suppression of the hydrogen evolution reaction, Cu1-NCB demonstrated an optimal N2 faradaic efficiency (82.1%) and yield rate (3.53 mmol h-1 mgmetal-1) at -0.2 and -0.5 V vs RHE, respectively, outperforming previously reported N2ORR electrocatalysts. Further, a gas diffusion electrode cell was employed to improve mass transfer and achieved a 28.6% conversion rate of 30% N2O with only a 14 s residence time, demonstrating the potential for practical application. Density functional theory calculations identified Cu-N4 as the crucial active site for N2ORR, highlighting the significance of the unsaturated coordination and metal-support electronic structure. O-terminal adsorption of N2O was favored, and the dissociative adsorption (*ON2 → *O + N2) was the rate-determining step. These findings reveal the broad prospects of N2O decomposition via electrocatalysis.

Circular And Sustainable: Evaluating Lithium-Ion Battery Recycling using a Combined Statistical Entropy and Life Cycle Assessment Methodology.

While there has been a growing interest on the concept of Circular Economy (CE), its correlation with sustainability remains controversial. In this work, the combination of Statistical Entropy Analysis (SEA) and Life Cycle Assessment (LCA) is proposed as a new methodology to evaluate recycling processes from the perspective of materials circularity and environmental impacts using a Li-ion battery recycling process as a case study. This work addresses the need of quantitative circularity indicators, as SEA evaluates the concentration of materials at a systems level, while LCA measures the environmental impact of recycling processes in comparison with virgin raw materials production. It was found that process optimization points can be found by simultaneously accounting for materials recovery and the LCA categories of global warming potential, ozone depletion and mineral resource scarcity. Furthermore, a strong correlation was found for the first time between the recovery of critical elements and the environmental impact of raw materials production. The proposed methodology thus offers a robust analysis of a product lifecycle that aids in its design and optimization from the CE perspective.

Sustainable Electrolytes: Design Principles and Recent Advances.

Today, rechargeable batteries are omnipresent and essential for our existence. In order to improve the electrochemical performance of electric fields, the introduction of electrolytes with fluorine (F)-based inorganic elemental compositions is a direction of exploration. However, most fluorocarbons have a high global warming potential and ozone depletion potential, which do not meet the sustainability requirements of the battery industry. Therefore, developing sustainable electrolytes is a viable option for future battery development. Although researchers have made much progress in electrolyte optimization, little attention has been paid to developing low-toxic and safe electrolytes. This review aims to elucidate the design principles and recent advances in this direction for solvents and salts. It concludes with a summary and outlook on future research directions for the molecular design of green electrolytes for practical high-voltage rechargeable batteries.

Life cycle assessment of cellulose nanocrystals prepared from crop straw by sequential periodate-chlorite oxidation

Life cycle assessment (LCA) of cellulose nanocrystals (CNC) prepared by sequential periodate-chlorite oxidation (SPCO) remains limited. In this study, the environmental impacts of CNC preparation at lab (LAB) and industrial (IND) scales were assessed based on the eFootprint system and data from the Chinese Life Cycle Database (CLCD). At the LAB scale, the global warming potential (GWP) reached 3410 kg CO2 eq/kg CNC. The contributions of the U2 (pulp making), U3 (periodate oxidation), U5 (concentration), and U6 (freeze-drying) unit processes were 42.9%, 22.8%, 21.3%, and 10.6%, respectively. At the IND scale, the GWP was reduced by one order of magnitude to 141 kg CO2 eq/kg CNC, and most of the other 13 category indicators of environmental impact (acidification, eutrophication, ecotoxicity, human toxicity, etc.) also showed the same trend. The contribution of the unit process U5 exceeded 50% in the 12 environmental impact indicators. The large contribution of U5 was attributable to the extensive use of ethanol. At the industrial scale, the GWP was reduced to 22.7 kg CO2 eq/kg CNC when the periodate was recycled, and an ultrafiltration membrane system was used to concentrate CNC solutions. The environmental impact of CNC prepared by SPCO was lower than that of CNC prepared by sulfuric acid hydrolysis. This study comprehensively assessed the potential environmental impacts of CNC production on an industrial scale and provided valuable data for future industrial-scale production of CNC and for comparison with alternative products.

Study of decomposition of R-1132(E) as ultra-low GWP refrigerants

The use of hydrofluorocarbons (HFCs) as refrigerants in air-conditioning and refrigeration systems is being re-examined globally due to their high Global Warming Potential (GWP) and large environmental load. Next-generation refrigerants with low GWP are currently attracting a lot of attention as a replacement for conventional refrigerants. Recently, we have developed a novel refrigerant, trans-1,2-difluoroethylene (R-1132(E)), which has similar saturated vapor pressure to R-32 and an extremely low GWP value of 0.0056. R-474A and R-479A, refrigerants containing R-1132(E), are already registered with ASHRAE standard 34 and ISO 817 and are expected to become next-generation refrigerants. However, due to chemical stability issues, a self-decomposition reaction of R-1132(E) can occur. For this study, both R-1132(E) and the blend of R-1132(E) and R-1234yf have been investigated. We have developed methods for evaluating the self-decomposition reaction for three ignition sources that may occur in air conditioners and clarified the conditions under which the self-decomposition reaction of R-1132(E) and R-1234yf blends does not occur.

Cellulose nanocrystal filled synthetic rubber: Sustainable production, environmental assessment and end-of-life biodegradation by polyphagous pests

Plastic and rubber productions have reached staggering levels, leading to environmental concerns and accumulation of microplastics (MPs) rising in ecosystems. Rubber tires, a major source of MPs, pose further challenges due to excessive use of carbon black (CB) nanofillers in their manufacturing process, stresses on adding the element of sustainability to these products. This study emphasizes on the production of bio-based cellulose nanocrystals (CNC) filled synthetic rubber with sustainability assessment through life cycle assessment (LCA). It investigates the end-of-life (EOL) biodegradation potentials of rubber waste using a polyphagous pest, fall armyworm (FAW) (Spodoptera frugiperda). The results revealed that the production of CNC filled rubber demonstrate enhanced modulus compared to CB nanofillers, while requires substantial resource consumption, impacting abiotic resource depletion–fossil fuels (ADPf), freshwater ecotoxicity (CTUe), global warming potential (GWP), particulate matter (PM) and other impact categories. Emissions associated with CNC filled rubber during EOL phase are comparatively lower than CB, rendering CNC based rubbers a potentially viable choice from an environmental sustainability perspective. EOL pest biodegradation of CNC filled rubber showed negligible to no discernible physiological effects, potentially attributed to the presence of a diverse gut microbiota community in FAW (S. frugiperda). These findings highlight the relationship between physiochemical properties and CNC biodegradability in synthetic rubbers, aiding the development of sustainable EOL strategies for rubber waste management.

Towards a low-emission resource circulation of valuable metals from municipal solid waste incineration fly ash

The incineration fly ash (IFA) resulting from municipal solid waste combustion is laden with heavy metals, necessitating proper treatment not only for environmental management but also to reclaim the metal values. The surge in non-traditional metals like cobalt as emerging contaminant within IFA samples further attracts to address this issue. In response, the hydrometallurgical recycling of a cobalt-bearing IFA has been studied. Thereby, approximately 98 % zinc and 96 % cobalt were leached using a 1.0 mol/L H2SO4 solution at 90 °C and 1 h of leaching time. In-depth analysis of the leaching process unveiled metals' dissolution primarily via the ion-exclusion mechanism, as evidenced by lower diffusion coefficients (between 10−9 and 10−11 m2/s) and activation energies (9.6–14.9 kJ/mol). Above 99 % separation of zinc from the cobalt-bearing leach liquor was achieved by extraction with 1.0 mol/L D2EHPA at an equilibrium pH below 3.0, followed by stripping with a 2.0 mol/L H2SO4 solution. Cobalt, remained in the raffinate was efficiently precipitated by adding a 20 % excess dosage of oxalic acid to the stoichiometric ratio of C2O42−:Co2+, resulting in only 5 mg/L cobalt left in the solution when precipitation occurred at a pH of 2.8. Additionally, the conversion of CoC2O4 to high-purity Co3O4 was conducted through heat-treatment at 600 °C. The resulting Co3O4 was mixed with Li2CO3 at a Li/Co molar ratio of 1.1, yielding a LiCoO2 precursor that exhibited good electrochemical properties with a capacity of 128 mAh/g, thus affirming the high quality of the recycled cobalt. A comprehensive life-cycle assessment of the recycling process revealed that cobalt precipitation alone contributes approximately 50 % of the total global warming potential (GWP = 4.2624 kg CO2-eq). Notably, this value is remarkably lower than the GWP reported for primary cobalt production, highlighting the environmentally-friendly approach of this recycling endeavor.

Life Cycle Assessment Methodology Applied to a Wastewater Treatment Plant

Wastewater treatment plants are highly energy-intensive systems. This research uses Life Cycle Assessment (LCA) to determine the impacts generated during the operation of a wastewater treatment plant. Three different scenarios are analyzed: a baseline scenario that considers a conventional activated sludge treatment technology exploiting data from an existing plant located in central Italy, a second scenario that involves the implementation of MBR technology applied to the baseline scenario, and finally a third scenario that consists of the addition of an anaerobic digester that allows energy recovery from biogas production, followed by a photovoltaic plant capable of supplying the plant energy demand. Global warming potential, eutrophication, and acidification are the environmental categories considered most relevant to emissions. The results showed that the effluent had the highest impact in terms of CO2 equivalent in all three situations due to the presence of N2O. Since emissions from biological processes, transportation, and wastewater are almost similar in all three scenarios, it is preferable to focus on the environmental impacts associated with energy consumption. The third scenario involves careful resource management and the use of treatment technologies that allow for a reduction in the use of nonrenewable energy sources in favor of renewable ones.

Utilization of Biomethane to Support Energy Security in Indonesia, Riau Province: A Case Study

As the largest global palm oil producer, Indonesia contributes 59% to the world’s palm oil supply, producing 46.9 million tons of Crude Palm Oil (CPO) in 2021. However, this extensive production poses an environmental challenge through Palm Oil Mill Effluent (POME), estimated at 156 million m3 annually. POME treatment facilities release Biogas, predominantly Methane (CH4) at 50%–75%, a potent Greenhouse Gas (GHG) with 21 times the global warming potential of CO2. Conversely, Methane is a key component of widely used Natural Gas. Properly treated, POME-derived biogas can be upgraded to Biomethane, a clean and carbon-negative alternative for the Natural Gas Grid or fossil fuel substitution, estimated at 1,280 MWe, equivalent to 288 MMSCFD CH4. Despite Biomethane’s potential, its utilization remains limited to self-use in Palm Oil Mills or power plants, even in Riau Province, home to Indonesia’s largest oil palm plantation. PT Perusahaan Gas Negara Tbk survey identified potential customers in Riau willing to adopt natural gas, hindered by infrastructure and economic scale challenges. This research analyzes obstacles to biomethane business development in Indonesia, focusing on Riau Province, aiming to formulate an optimal distribution scheme and sustainable strategies. Methodologically, a mix of quantitative and qualitative data collection techniques, including literature studies, interviews, and questionnaires, informed a comprehensive analysis employing geographical, transportation cost, financial modeling, SWOT, and risk analyses. Findings suggest trucking as the optimal distribution mode for biomethane to scattered customers. Economic viability hinges on biomethane volume, necessitating stability and increased sales volume strategies. For Riau, four potential customers with a total daily demand of 11,248.93 m3 can be served affordably by selecting palm oil mills within a 76 km radius. Price and security supply considerations are crucial. This research provides insights into overcoming challenges and optimizing the biomethane business in Riau, offering a sustainable model for broader adoption in Indonesia.

Pool boiling heat transfer characteristics of low-GWP refrigerants in a horizontal tube bundle configuration

Heat transfer enhancement techniques have been adapted on the shell side to improve the overall performance of the flooded evaporators, such as finned tubes. In recent years, it has been demonstrated that the metal foam structure can offer enhanced heat transfer performance under pool boiling conditions. However, there are not much research in the open literature that examine the feasibility of metal foam embedded tubes in horizontal tube bundle configurations. Therefore, this paper proposed a novel metal foam embedded tube (i.e., foam embedded outside the tube) to improve the heat transfer behavior of flooded evaporators. The experiments were performed on a horizontal tube bundle with a staggered arrangement. Moreover, the performance of low global warming potential (GWP) refrigerants (R-1234yf and R-1234ze(E)) is compared against R-134a for both plain tubes and metal foam tubes with porosities of 81%, 75%, and 62%. The results showed that a metal foam tube with a porosity of 62% showed a maximum heat transfer coefficient (HTC) enhancement of 291% compared to the plain tube. As compared with R-134a, the HTCs of R-1234yf and R-1234ze(E) are nearly 10% higher and 5% lower, respectively.

Molecular-level insight into the chlorofluorocarbons adsorption by defective covalent organic polymers.

Halocarbons have important industrial applications, howevertheycontributeto global warming and the fact that they can cause ozone depletion. Hence, the techniques that can capture and recover the used halocarbons with energy efficiency methods have recently received greater attention. In this contribution, we report the capture of dichlorodifluoromethane (R12), which has high global warming and ozone depletion potential, using covalent organic polymers (COPs). The defect-engineered COPs were synthesized and demonstrated outstanding sorption capacities, ~226 wt% of R12 combined with linear-shaped adsorption isotherms. We further identified the plausible microscopic adsorption mechanism of the investigated COPs via grand canonical Monte Carlo simulations applied to non-defective and a collection of atomistic models of the defective COPs. The modeling work suggests that significant R12 adsorption is attributed to a gradual increment of porosities due to isolated/interconnected micro-/meso-pore channels and the change of the long-range ordering of both COPs. The successive hierarchical-pore-filling mechanism promotes R12 molecular adsorption via moderate van der Waals adsorbate-adsorbent interactions in the micropores of both COPs at low pressure followed by adsorbate-adsorbate interactions in the extra-voids created at moderate to high pressure ranges. This continuous pore-filling mechanism makes defective COPs as promising sorbents for halocarbon adsorption.

Plasma atomic layer etching of SiO2 with a low global warming potential fluorocarbon precursor (C6F6)

Reducing greenhouse gas emissions from semiconductor manufacturing has been attracting enormous interest in both industry and academia as global warming issues have increased in significance year by year. Among various strategies, the search for etch precursors that have low global warming potential is actively underway worldwide to reduce the use of conventional precursors with high global warming potential. In this paper, we explore the use of C6F6, a promising candidate to replace the widely utilized perfluorocarbon precursor C4F8, for plasma atomic layer etching (ALE) of SiO2. In situ ellipsometry results indicated that acceptable ALE characteristics were obtained with C4F8 and C6F6 each in their own specific ALE window, while C6F6 showed superior ALE performance. Investigation into the ALE performance with different precursors was then conducted based on plasma diagnostics for radical density, electron density, and plasma potential, and the results of which showed that the difference in the radical composition between precursors significantly affected the resulting ALE trends and also that the excellent ALE performance with C6F6 might originate from its significant polymeric characteristics. We expect the present findings to contribute to the wider adoption of low global warming potential precursors in the etching process.

Mitigating methane emissions and global warming potential while increasing rice yield using biochar derived from leftover rice straw in a tropical paddy soil

The sustainable management of leftover rice straw through biochar production to mitigate CH4 emissions and enhance rice yield remains uncertain and undefined. Therefore, we evaluated the effects of using biochar derived from rice straw left on fields after harvest on greenhouse gas emissions, global warming potential (GWP), and rice yield in the paddy field. The experiment included three treatments: chemical fertilizer (CF), rice straw (RS, 10 t ha−1) + CF, and rice straw-derived biochar (BC, 3 t ha−1 based on the amount of product remaining after pyrolysis) + CF. Compared with CF, BC + CF significantly reduced cumulative CH4 and CO2 emissions, net GWP, and greenhouse gas emission intensity by 42.9%, 37.4%, 39.5%, and 67.8%, respectively. In contrast, RS + CF significantly increased cumulative CH4 emissions and net GWP by 119.3% and 13.8%, respectively. The reduced CH4 emissions were mainly caused by the addition of BC + CF, which did not increase the levels of dissolved organic carbon and microbial biomass carbon, consequently resulting in reduced archaeal abundance, unlike those observed in RS + CF. The BC + CF also enhanced soil total organic carbon content and rice grain yield. This study indicated that using biochar derived from leftover rice straw mitigates greenhouse gas emissions and improves rice productivity in tropical paddy soil.

Reliable Physics Demand Revision of the IPCC Global Warming Potentials

The Global Warming Potentials (GWP) of the Intergovernmental Panel on Climate Change (IPCC) in Table 2.14 of the Fourth Assessment Report (AR4) show the increase in warming by methane (CH4) and nitrous oxide (N2O) is 21 and 310 times respectively that of CO2. There has been wide acceptance of these values since publishing in 2007. Nevertheless, they are inaccurate. This study uses accurate methods to calculate the impacts of CO2, CH4, and N2O on the warming of the atmosphere. For example, this quantitative analysis from reliable physics shows the contribution of CO2 to warming at Amsterdam is 0.0083oC out of a difference of 26oC. The warming effect of CH4 on the Earth’s atmosphere is 0.408% of that of CO2, and the warming by N2O is 0.085% of that of CO2. Thus, the warming effects of CO2, CH4, and N2O are too small to measure. The invalidity of the methane and nitrous oxide values indicates the GWPs of the remaining approximately sixty chemicals in the Table 2.14 list are also invalid. A recommendation is that the IPCC consider revising or retracting the GWP values in Table 2.14.

The hydrometallurgical recovery of critical and valuable elements from WEEE shredding dust: Process effectiveness in a life cycle perspective

Waste electrical and electronic equipment (WEEE) recycling stands as a crucial opportunity to get critical resources while managing a waste stream in accordance with the circular economy principles. Recently, a two-step hydrometallurgical process has been successfully investigated to treat the dust originating from the mechanical processing of WEEE. The best operating conditions selected in this study were used to further investigate the recovery of precious metals and critical elements, achieving extraction yields of approximately 77.7 % and 53.1 %, respectively; base metals (i.e. aluminum, zinc, copper, ..) were also leached from dust up to 96 %. A life cycle approach was also applied to preliminary assess and compare the potential environmental impact of the proposed process with respect to the manufacturing process of the virgin material. The analysis focused on standard environmental indicators (i.e. global warming potential, acidification, …), human toxicity and eco-toxicty and a set of five different characterisation models for abiotic depletion of resources. Four scenarios, differing for allocation criteria (mass/economic) and the possible recovery of metals along with REEs, were compared. Among the recovered products, the greates potential benefits were found in the case of rare earth elements, in the scenario considering the complete recovery of base and precious metals and performing an economic allocation. Impacts on abiotic depletion and toxicity account for the highest benefits from maerial recovery. Nevertheless, the recovery of sulphuric acid would allow a further reduction also in other impacts, strengthening the potential competitiveness of REE recovery against the manufacturing of virgin materials.

Renewable methyl acetate production from dimethyl ether carbonylation in a fluidized bed reactor

The carbonylation of bio-based dimethyl ether (DME) using ferrierite offers a renewable approach to methyl acetate (MA) production with a potential reduction in carbon emissions. This work showcases the feasibility of employing fluidized-bed reactors in this process, leveraging benefits such as effective solid mixing, uniform temperature distribution, and facile catalyst purge and makeup. Through parametric studies, the impact of operating conditions on the reaction kinetics and reactor hydrodynamics was elucidated. Both physical and chemical catalyst deactivation were found to be dependent on the fluidization regime. Numerical models based on experimental results enabled the prediction of reaction yield and selectivity in the process simulation and optimization. Preliminary techno-economic analysis (TEA) and life cycle assessment (LCA) showed the potential for a 40% reduction in production costs and an 8% reduction in the global warming potential compared to the fossil-based benchmark. Overall, this study highlights the operation simplicity, cost competitiveness, and environmental benefit of MA production from DME carbonylation in a fluidized-bed reactor, providing insights for process scale-up and feedstock sourcing.

LCA of recycling aluminium incineration bottom ash, dross and shavings in a rotary furnace and environmental benefits of salt-slag valorisation

Recycling aluminium in a rotary furnace with salt-fluxes allows recovering valuable alloys from hard-to-recycle waste/side-streams such as packaging, dross and incinerator bottom ash. However, this recycling route generates large amounts of salt-slag/salt-cake hazardous wastes which can pose critical environmental risks if landfilled. To tackle this issue, the metallurgical industry has developed processes to valorise the salt-slag residues into recyclable salts and aluminium concentrates, while producing by-products such as ammonium sulphate and non-metallic compounds (NMCs), with applications in the construction or chemical industries. This study aims to assess through LCA the environmental impacts of recycling aluminium in rotary furnaces for both salt-slag management routes: valorisation or landfill. It was found that this recycling process brings forth considerable net environmental profits, which increase for all the considered impact categories if the salt-slag is valorised. The main benefits arise from the production of secondary cast aluminium alloys, which is not unexpected due to the high energy intensity of aluminium primary production. However, the LCA results also identify other hotspots which play a significant role, and which should be considered for the optimisation of the process based on its environmental performance, such as the production of by-products, the consumption of energy/fuels and the avoidance of landfilling waste. Additionally, the assessment shows that the indicators for mineral resource scarcity, human carcinogenic toxicity and terrestrial ecotoxicity are particularly benefited by the salt-slag valorisation. Finally, a sensitivity analysis illustrates the criticality of the metal yield assumptions when calculating the global warming potential of aluminium recycling routes.

Modeling the environmental impacts of Asparagopsis as feed, a cow toilet and slurry acidification in two synthetic dairy farms

Intensive dairy farming, particularly enteric fermentation and manure management, is a major contributor to negative impacts on the local and global environment. A wide range of abatement measures has been proposed to reduce livestock-related emissions, yet the individual and combined effects of these innovations are often unknown. In this study, we performed an attributional life cycle assessment of three innovative measures modeled in two synthetic German dairy farm systems: Feeding of the seaweed Asparagopsis, installing an in-house cow toilet system, and performing on-field slurry acidification. These measures were modeled both individually and in combination to account for single and cumulative effects and compared to a reference scenario under current practices. Our results showed that feeding high levels of Asparagopsis and the combination of all three measures were most effective at reducing global warming potential (20–30 %), while only the latter mitigated eutrophication (6–9%) and acidification potential (14–17 %). The cow toilet required additional adapted manure management (separated storage and injection of urine) to effectively reduce eutrophication (8–10 %) and acidification potential (19–23 %) and to decrease global warming potential (3–4%) and abiotic depletion (4–5%). Slurry acidification slightly affected all considered environmental impact categories. All three measures involved trade-offs, either between LCA impact categories (global warming potential vs. abiotic depletion), the location of impacts (off- vs. on-farm), or the emission reduction in individual gases (ammonia vs. nitrous oxide). Measure combinations could compensate for the observed trade-offs. Our study highlights the potential of novel abatement measures but also shows the interdependencies of measures in different stages. This calls for a revisiting of current priorities in funding and legislation, which often focus on single objectives and measures (e.g. ammonia reduction) toward the preferential use of measures that are effective without driving trade-offs or improving resource efficiency.

Greenhouse gas and ammonia emissions in modelled cereal crop production under Polish agricultural conditions: An example spring barley

Based on the analysis of statistical data, the average area under cultivation and average yields of barley in Poland in 2010–2020 were calculated. Barley is one of the most important cereals grown in Poland. Its cultivation area occupied an average of 920,595 ha in these years, with average yields of 3.66 Mg∙ha−1. Barley is a cereal grown mainly as a spring cereal. The average area under spring species in these years accounted for 95% (875,771 ha) of the total area under this cereal, and the average yield of spring varieties was 3.60 Mg∙ha−1. In order to estimate emissions of greenhouse gases (GHG) and ammonia (NH3), the sources of emissions – inorganic fertilisers, fuel consumption – were analysed for selected barley cultivation technologies, differentiated by yield level, and variant model production technologies were developed to obtain projected yields. Emissions were calculated for individual greenhouse gases (N2O, CH4 and CO2) and they were recalculated according to the greenhouse potential of each gas (GWP – global warming potential) to be able to compare the total amount of greenhouse gas emissions for the analysed variants. Greenhouse gas emissions for cultivation technology ranged from 134.53 to 136.48 kg CO2eq for 1 Mg yield. A more accurate Tier 2 method was used to estimate NH3 emissions, taking into account soil conditions and climate zone. The estimated ammonia emissions from the application of mineral fertilisers were from 0.99 kg to 2.35 kg for 1 Mg yield.

Helping the climate by replacing liquefied natural gas with liquefied hydrogen or ammonia?

The war in Ukraine caused Europe to more than double its imports of liquefied natural gas (LNG) in only one year. In addition, imported LNG remains a crucial source of energy for resource-poor countries, such as Japan, where LNG imports satisfy about a quarter of the country’s primary energy demand. However, an increasing number of countries are formulating stringent decarbonization plans. Liquefied hydrogen and liquefied ammonia coupled with carbon capture and storage (LH2-CCS, LNH3-CCS) are emerging as the front runners in the search for low-carbon alternatives to LNG. Yet, little is currently known about the full environmental profile of LH2-CCS and LNH3-CCS because several characteristics of the two alternatives have only been analyzed in isolation in previous work. Here we show that the potential of these fuels to reduce greenhouse gas (GHG) emissions throughout the supply chain is highly uncertain. Our best estimate is that LH2-CCS and LNH3-CCS can reduce GHG emissions by 25%–61% relative to LNG assuming a 100 year global warming potential. However, directly coupling LNG with CCS would lead to substantial GHG reductions on the order of 74%. Further, under certain conditions, emissions from LH2-CCS and LNH3-CCS could exceed those of LNG, by up to 44%. These results question the suitability of LH2-CCS and LNH3-CCS for stringent decarbonization purposes.