Greenhouse Gas Abatement Research Articles

Energy efficiency and greenhouse gas emission abatement opportunities for an existing gas treatment plant: a comprehensive technical and economic analysis

This research paper examined the operational performance and greenhouse gas (GHG) emissions of an existing gas treatment plant. Extensive data collection and analysis were undertaken to assess energy consumption and emissions and identify major emitter units. A GHG emission inventory was developed, and a benchmarking analysis was conducted. The gap analysis revealed excessive emissions, leading to the identification of potential GHG abatement alternatives for the turbo compressor and stabilizer heater. Technical feasibility assessments and economic evaluations were performed for the implementation of waste heat recovery systems, specifically an absorption chiller and a hot oil-driven re-boiler. The results demonstrated significant energy savings, emission reduction, and positive financial returns. The economic evaluation of the abatement opportunities revealed an estimated annual savings of $229,287 US with a simple payback period (SPBP) of 2.96 years and an internal rate of return (IRR) of 32%/year for the absorption chiller. The re-boiler heat system showed an estimated annual savings of $209,456 US with an SPBP of 5.14 years and an IRR of 14%/year. The total investment for both opportunities amounted to $1,755,773 US, with a total annual savings of $438,743 US. The combined SPBP for the opportunities was 4 years, with an IRR of 21%/year. Sensitivity analyses demonstrated the absorption chiller’s financial viability, while the hot oil-driven re-boiler opportunity proved more sensitive to variations in investment costs and savings. Therefore, it is recommended to implement both opportunities together.

The heterogeneous impact of geopolitical risk and environment-related innovations on greenhouse gas emissions: The role of nuclear and renewable energy in the circular economy

A transition to a circular economy (CE) has emerged as one of the most important worldwide endeavors in the pursuit of sustainable economic systems. However, the conceptual link between sustainable development and the circular economy is a subject of continuous discussion. Specifically, the degree to which CE activities contribute to the reduction of environmental pollution seems to be an unresolved topic. This study aims to develop possible mechanisms for perspectives of nuclear and renewable energy in a circular economy as solutions that may have economic, financial, social, and environmental co-benefits due to the effective use of environmentally connected technology, decreased emissions, and the promotion of innovation. This study utilizes continuously updated, fully modified and continuously updated, bias-corrected, newly advanced panel approaches; for robustness, a panel quantile regression was executed. The results indicate that nuclear energy, renewable energy, and environment-related technology facilitate greenhouse gas (GHGs) abatement, while the influence of geopolitical risk and economic growth are ineffective in reducing GHG emissions. These findings propose, several policy considerations are recommended to combat BRICS GHG emissions.

Assist in GHG Abatement of Offshore Ships: Design and Economic Analysis of an Integrated Utilization Model of hydrogen-powered Ship and Offshore Wind Power

As a hopeful solution to help the shipping sector achieve the greenhouse gas (GHG) abatement goal of the IMO by 2050, the application of hydrogen-powered ships has attracted more and more attention. To solve the problem of hydrogen supplement for offshore polymer electrolyte membrane fuel cell (PEMFC) ships, this paper presents a scenario design for the integrated application of coastal hydrogen-powered ships and offshore wind power, and analyzes its techno-economic feasibility. This model concept considers the problems in offshore hydrogen transportation and offshore wind power development together. It provides a feasible integrated scheme and operation mode for the combination of offshore wind power and hydrogen energy storage. A transformation scheme is also provided for the marine ranch ships, and these PEMFC-powered ships are combined with the hydrogen production of offshore wind farms. The analysis results show that the integrated utilization model is economically feasible and with a significant effect on decarbonization. It also shows great potential for further expansion to other coastal areas.

Comparing Life-Cycle Emissions of Biofuels for Marine Applications: Hydrothermal Liquefaction of Wet Wastes, Pyrolysis of Wood, Fischer-Tropsch Synthesis of Landfill Gas, and Solvolysis of Wood.

Recent restrictions on marine fuel sulfur content and a heightened regulatory focus on maritime decarbonization are driving the deployment of low-carbon and low-sulfur alternative fuels for maritime transport. In this study, we quantified the life-cycle greenhouse gas and sulfur oxide emissions of several novel marine biofuel candidates and benchmarked the results against the emissions reduction targets set by the International Maritime Organization. A total of 11 biofuel pathways via four conversion processes are considered, including (1) biocrudes derived from hydrothermal liquefaction of wastewater sludge and manure, (2) bio-oils from catalytic fast pyrolysis of woody biomass, (3) diesel via Fischer-Tropsch synthesis of landfill gas, and (4) lignin ethanol oil from reductive catalytic fractionation of poplar. Our analysis reveals that marine biofuels' life-cycle greenhouse gas emissions range from -60 to 56 gCO2e MJ-1, representing a 41-163% reduction compared with conventional low-sulfur fuel oil, thus demonstrating a considerable potential for decarbonizing the maritime sector. Due to the net-negative carbon emissions from their life cycles, all waste-based pathways showed over 100% greenhouse gas reduction potential with respect to low-sulfur fuel oil. However, while most biofuel feedstocks have a naturally occurring low-sulfur content, the waste feedstocks considered here have higher sulfur content, requiring hydrotreating prior to use as a marine fuel. Combining the break-even price estimates from a published techno-economic analysis, which was performed concurrently with this study, the marginal greenhouse gas abatement cost was estimated to range from -$120 to $370 tCO2e-1 across the pathways considered. Lower marginal greenhouse gas abatement costs were associated with waste-based pathways, while higher marginal greenhouse gas abatement costs were associated with the other biomass-based pathways. Except for lignin ethanol oil, all candidates show the potential to be competitive with a carbon credit of $200 tCO2e-1 in 2016 dollars, which is within the range of prices recently received in connection with California's low-carbon fuel standard.

Resource efficiency and climate change policies to support West Asia's move towards sustainability: A computable general equilibrium analysis of material flows

The resources and energy sectors make a significant contribution to economic performance in the economies of West Asia. In this study we explore the effect ambitious policies for resource efficiency and greenhouse gas abatement would have on West Asian economies and what their contribution to environmental sustainability could look like. We employ the Global Trade and Environmental Resource Model (GTEM-Resource) to empirically assess the economic and environmental implications of global policy initiatives in the region. Results show that resource efficiency and greenhouse gas (GHG) abatement policies are complementary in their effects. Resource efficiency policies boost resource use productivity in the region, reduce all categories of material extraction based on sustainable consumption and production behaviour and also caused by trade, and foster economic performance. By contrast, GHG emission abatement policies have a small effect on resource productivity but drive significant GHG reductions that are accompanied by reduced economic performance. When these two policies are combined, real GDP in West Asia is projected to increase by 8% relative to business-as-usual by 2060, while resource extraction and GHG emissions levels in the region would decline dramatically by 40% and 50%, respectively. Saudi Arabia and the United Arab Emirates would be much better off, compared to other countries in the region, with large increases in real GDP and major reductions in GHG emissions and resource extraction levels. Findings suggest that technology development and climate mitigation policies would result in a win-win solution for all countries in West Asia, contributing to maintaining well-being and protecting the environment on regional and global scales. This shows that there is a pathway to economic prosperity for resource-rich countries and regions.

Projection of future carbon benefits by photovoltaic power potential in China using CMIP6 statistical downscaling data

Solar photovoltaic (PV) systems is an affordable solution that significantly contribute to climate adaptation and resilience, energy security and greenhouse gas abatement with respect to fossil fuel electricity generation. Currently, available studies on the benefits of PV power generation only consider the electricity consumption and do not account for the possible future benefits from carbon trading under the combined impacts of pollution emissions and socio-economic. In this study, the downscaling and bias correction were applied to the Coupled Model Inter-comparison Project Phase 6 (CMIP6) multi-model mean data based on the historical data from the China Meteorological Administration (CMA) stations. The corrected measurements of meteorology were used to explore the PV power potential and the environmental and economic benefits offset by solar power generation under SSP126, SSP245 and SSP585 in China during 2023–2100. We found that the annual mean PV power potential across mainland China ranged from 1 to 37 Wm−2 and demonstrated a decreasing trend in the Northwest China and an increasing trend in the Southeast China. Compared to thermal power generation, electricity from solar energy will counteract the total emissions of annual mean 139.54 × 105 t CO2, 1702 t SO2, 2562 t NO X and 3710 t dust in China in SSP126 scenario. The results of variable importance assessment showed that the West Texas Intermediate crude oil price (47.77%), coal price (41.76%), natural gas price (6.65%) and gross domestic product (2.44%) contribute the most to the carbon emissions allowances (CEAs) price. Against a ‘carbon peak’ background in China, the CEA price will reach 80 CNY/t CO2 by 2030 in China, with the carbon trading value potential ranging from 20 billion to 200 billion CNY of each pixel (10 km × 10 km) by 2030. This study would have important implications for the environmental construction and future investment and construction of PV systems in China.

Air quality and related health impact in the UNECE region: source attribution and scenario analysis

Abstract. The TM5-FAst Scenario Screening Tool (TM5-FASST) was used to study the influence of abatement policies within and outside the United Nations Economic Commission for Europe (UNECE) region on the exposure to O3 and PM2.5 and associated mortality in the UNECE countries. To that end, the impacts of pollutants derived from different geographic areas and activity sectors were evaluated using ECLIPSE V6b scenarios of air pollutant and greenhouse gas (GHG) emission reduction. The mortalities were attributed to O3 and PM2.5 following the Global Burden of Disease (GBD) approach and allocated to geographic areas (UNECE and non-UNECE) and activity sectors, including natural sources. In addition, a combination of runs designed for the purpose led to allocating exposure to O3 and related mortality to two families of precursors: NOx–VOC and CH4. In this study, the baseline scenario (current legislation scenario, CLE), which assumes that all air quality and greenhouse gas abatement measures adopted by 2018 are fully implemented, is compared with more ambitious scenarios (maximum feasible reduction, MFR). The findings from this comparison indicate that O3 exposure within the UNECE area is more sensitive to measures outside the UNECE region than PM2.5 exposure, even though the latter leads to higher mortality than the former. In the CLE, the mortality associated with O3 exposure in the UNECE region grows steadily from 2020 to 2050. The upward trend is mainly associated with the growing impact of CH4 emissions from areas outside UNECE. Also, the mortality related to NOx–VOC emissions outside UNECE increases in the same period. By comparison, a measurable decrease (13 %) is observed in the mortality attributable to NOx–VOC emissions within UNECE. In the same time window, the mortality associated with PM2.5 exposure in the UNECE region decreases between 2020 and 2040 and then rises until 2050. The PM2.5-related mortality in UNECE is mainly due to anthropogenic emissions within this region followed by natural sources (sea salt and dust) mainly located outside the UNECE region. Between 2020 and 2050, the impact of some UNECE anthropogenic sources on PM2.5-related mortality decreases progressively, in particular road transport, energy production and domestic combustion, while others, namely agriculture and industry, show an upward trend. Finally, the analysis of MFR scenarios confirms that abatement measures in line with UN Sustainable Development Goals (SDGs) and the Paris Agreement can lead to significant co-benefits between air quality and climate policies.

The future air quality impact of electric vehicle promotion and coordinated charging in the Beijing-Tianjin-Hebei region

The synergetic benefit of air quality improvements together with greenhouse gas (GHG) mitigations from fleet electrification can be maximized if the power used for electric vehicles (EVs) is from renewables. The worth-noting mismatch between renewable power generation and EV fleet charging demand requires appropriate coordination strategy. Here, we analyze the environmental benefits from increased EVs penetration in Beijing-Tianjin-Hebei (BTH) regions by integrating various scenarios of fleet electrification with coordinated charging strategies to examine the air quality improvement and GHG abatement. The study found that fleet electrification could bring substantial reduction on urban PM2.5 in BTH, especially in December by 0.8 ± 0.5 μg/m3. The coordinated charging strategy could further improve the air quality in BTH, albeit smaller than that of fleet electrification itself. PM2.5 reduction benefit from EV adoption could be significantly more pronouncing when ammonia emission reduction was considered, by more than 0.3 μg/m3 in both December and July, validating the great significance of vehicle NH3 emission control and the necessity of prioritizing the electrification of high ammonia emitting fleet. The outcome of this study helps to formulate the effective on-road transportation pollutant abatement strategies and offers technological support for policy makers to conduct more sensible sequence of future fleet electrification process.

Integration of the comprehensive Gorgon CO2 surveillance program for history matching of the Dupuy reservoir model

The Gorgon CO2 project (The Gorgon Project is operated by Chevron Australia and is a joint venture of the Australian subsidiaries of Chevron (47.3%), ExxonMobil (25%), Shell (25%), Osaka Gas (1.25%), Tokyo Gas (1%) and JERA (0.417%)) is the world’s largest operational Carbon Capture and Storage (CCS) project dedicated to greenhouse gas abatement. Since starting injection in 2019 it has successfully sequestered more than 7.5 million tonnes of CO2 equivalent (as at 31 January 2023). A comprehensive surveillance program – including reservoir pressure monitoring, 4D seismic, microseismic monitoring, distributed temperature and acoustic sensing, and InSAR surface displacement measurement – provides a wealth of data for developing history-matched static, dynamic and geomechanical models that are instrumental in the operation and development planning of the field. In comparison to modelling of conventional hydrocarbon reservoirs, in which maximising production and ultimate recovery are typically the focus, developing and selecting a suite of representative CCS models requires consideration of an additional set of factors. These factors include modelling CO2 plume movement, managing reservoir pressure at key locations and accommodating geomechanical constraints. This paper will explore these differences, and how the various sources of surveillance data have been integrated into the modelling process to better understand and predict the dynamic behaviour of the Dupuy reservoir.

Long-term onsite monitoring of a sewage sludge drying pan finds methane emissions consistent with IPCC default emission factor

As the wastewater sector moves towards achieving net zero greenhouse gas (GHG) emissions, quantifying and understanding fugitive emissions from various sewage treatment steps is crucial for developing effective GHG abatement strategies. Methane (CH4) emissions from a sludge drying pan (SDP) were measured at a wastewater treatment plant in Australia for more than a year, using a micrometeorological technique paired with open-path lasers. The emission rate was tightly associated with sludge additions, climatology, and operational processes. The mean emission rate during the 90 weeks after initial sludge addition was 2.3 (± 0.8) g m−2 d−1, with cumulative emissions of approximately 32 t of CH4. A dynamic temporal pattern of emissions was observed, highlighting the importance of continuous (or near-continuous) measurements for quantifying SDP emissions. A Methane Correction Factor (MCF) expressed as a fraction of the measured chemical oxygen demand of the sludge, was determined to be 0.17 after 63 weeks (the median operational cycle duration at the facility). This is broadly consistent with, albeit slightly less than, the IPCC default value of 0.2 for shallow anaerobic lagoons. These emission measurements will support wastewater utilities that employ open air sludge drying processes to develop effective GHG abatement strategies.

Toward structure optimization for the mobile vehicle system based on multiconstraints

PurposeVehicle lightweight design has positive implications for reducing energy consumption and abating greenhouse gas emissions. The traditional trailer axle design mainly focuses on the overall performance of the trailer axle. Only when the local performance does not meet the requirements will local performance optimization be done, such as local heat treatment to improve local strength. Such a design results in an uneven distribution of axle performance and excess performance in some local structures. The purpose of this study is to investigate the weight reduction on the premise of ensuring the structural dimensions of the outer surface of the axle remain unchanged and the reliability of the axle.Design/methodology/approachThe axle is parameterized by computer aided design, and the optimized axle finite element model based on computer aided engineering is established and verified by taking the eight dimensions of the axle cavity structure which affect the performance as parameters. A genetic algorithm is used to optimize the axle cavity structure size and axle weight based on multiobjective optimization, and eight optimized size parameters of axle cavity structure are obtained.FindingsThe total weight of the optimized axle of TM1314 is reduced by 10.2 kg, and the weight reduction ratio reaches 10.7%. According to the optimized structural size of the axle, the specimen was trial-manufactured, and the bench tests of stiffness, strength and fatigue life were carried out according to the test requirements of the trailer axle standard (JT/T 475-2002). The test results show that the maximum deformation of the specimen is 2.46 mm, the strength safety factor of the specimen body and the steel plate spring seat are 6.71 and 6.86 and bear the alternating load more than 1.05 × 106 times, which meets the standard of the trailer axle and is better than the original design requirements of the trailer axle.Originality/valueIn this study, the multiobjective optimization model of the axle is established, the response surface is constructed by the Latin hypercube sampling design method and the optimal solution set is obtained by the multiobjective genetic algorithm. It has been verified by bench tests that it can achieve a weight reduction of 10.7% under the premise of the same structure and size of the outer surface of the axle. The lightweight method based on multiobjective optimization proposed in this paper can provide a reference for the lightweight design of other key vehicle components.

Using machine learning with case studies to identify practices that reduce greenhouse gas emissions across Australian grain production regions

It is difficult to identify farm management practices that consistently provide greenhouse gas (GHG) abatement at different locations because effectiveness of practices is greatly influenced by climates and soils. We address this knowledge gap by identifying practices that provide abatement in eight case studies located across diverse conditions in Australian’s grain-producing areas. The case studies focus on soil-based emissions of nitrous oxide (N2O) and changes in soil organic carbon (SOC), simulated over 100 years for 15 cropping management scenarios. Average changes in the balance of GHG from both N2O emissions and SOC sequestration (∆GHG balance) and gross margins compared to a high emissions baseline were determined over 25 and 100 simulated years. Because scenarios providing the greatest abatement varied across individual case studies, we aggregated the data over all case studies and analysed them with a random forest data mining approach to build models for predicting ∆GHG balance. Increased cropping intensity, achieved by including cover crops, additional grains crops, or crops with larger biomass in the rotation, was the leading predictor of ∆GHG balance across the scenarios and sites. Abatement from increased cropping intensity averaged 774 CO2-e ha−1 year−1 (25 years) and 444 kg CO2-e ha−1 year−1 (100 years) compared to the baseline, with reduced emissions from SOC sequestration offsetting increased N2O emissions for both time frames. Increased cropping intensity decreased average gross margins, indicating that a carbon price would likely be needed to maximise GHG abatement from this management. To our knowledge, this is the first time that the random forest approach has been applied to assess management practice effectiveness for achieving GHG abatement over diverse environments. Doing so provided us with more general information about practices that provide GHG abatement than would have come from qualitative comparison of the variable results from the case studies.

ZnO with engineered surface defects as a competent photocatalyst for CO2 photoreduction into valuable fuels under simulated solar light irradiation

Photocatalysis is one of the eco-friendly methods in greenhouse gases abatement by utilizing renewable resources such as sunlight. This study examined defective ZnO nanoparticles that serve as carbon dioxide (CO2) adsorption and activation sites in photocatalytic reactions. The defective ZnO nanoparticles were synthesized via a facile precipitation-hydrothermal method by only controlling the concentration of NaOH as the precipitating agent. The rough surface of ZnO were formed due to the heating treatment, where it conveniently removed the attached inorganic molecules on ZnO surfaces. The roughness surface of ZnO was observed by using Transmission Electron Microscopy (TEM) analysis, in which the pores with bright spot can be observed. Additionally, the defects originating from oxygen vacancies (VO), zinc interstitials (Zni) and carbonates groups (CO32−) was successfully optimized over variation of NaOH concentrations proven by Photoluminescence (PL) and X-Ray Photoelectron Spectroscopy (XPS) analysis. Here, 1 : 4 ZnO exhibited the highest CH4 yield (1.3 ×10-1 µmol) and 3-fold production than commercial ZnO (4.8 × 10-2 µmol). The reusability of 1 : 4 ZnO was demonstrated by conducting 4 cycles of stability test, which revealed a robust photocatalyst of 7.7% performance reduction after 4th cycle. A schematic mechanism pertaining to the novel defective ZnO nanoparticles in CO2 photoreduction to valuable fuels was proposed in this study, which undoubtedly will contribute a positive effect to industry’s long-term sustainability.

Causality analysis of the impacts of petroleum use, economic growth, and technological innovation on carbon emissions in Bangladesh

Bangladesh has traditionally relied on fossil fuels for meeting its energy demand whereby this South Asian nation has not been able to safeguard its environment from greenhouse gas emission-related adversities. Moreover, by ratifying several international environmental agreements, especially the Paris Accord and the Sustainable Development Goals, the government of Bangladesh has expressed its solidarity in abating greenhouse gas emissions through the deployment of relevant environmental policies. Hence, this study assesses the impacts of petroleum consumption, economic growth, and technological innovation on carbon emissions in Bangladesh using quarterly frequency data from 1972Q1 to 2020Q4. Overall, apart from confirming the cointegrating relationships among the variables, the regression findings reveal that higher petroleum consumption and economic growth stimulate environmental degradation by boosting carbon dioxide emissions while technological innovation reinstates environmental well-being by curbing the emission figures. Additionally, technological innovation is seen to moderate the relationship between petroleum consumption and carbon emissions by jointly reducing the emission with petroleum consumption. Lastly, the causality analysis shows that petroleum consumption, economic growth, and technological innovation causally influence carbon emissions. Based on these key findings, it is recommended that Bangladesh mitigates its petroleum dependency, blends environmental objectives into economic growth policies, and develops its technological stock.

Using a demographic model to project the long‐term effects of fire management on tree biomass in Australian savannas

AbstractTropical savannas are characterized by high primary productivity and high fire frequency, such that much of the carbon captured by vegetation is rapidly returned to the atmosphere. Hence, there have been suggestions that management‐driven reductions in savanna fire frequency and/or severity could significantly reduce greenhouse gas emissions and sequester carbon in tree biomass. However, a key knowledge gap is the extent to which savanna tree biomass will respond to modest shifts in fire regimes due to plausible, large‐scale management interventions. Here, we: (1) characterize relationships between the frequency and severity of fires and key demographic rates of savanna trees, based on long‐term observations in vegetation monitoring plots across northern Australia; (2) use these relationships to develop a process‐explicit demographic model describing the effects of fire on savanna tree populations; and (3) use the demographic model to address the question: to what extent is it feasible, through the strategic application of prescribed burning, to increase tree biomass in Australian tropical savannas? Our long‐term tree monitoring dataset included observations of 12,344 tagged trees in 236 plots, monitored for between 3 and 24 years. Analysis of this dataset showed that frequent high‐severity fires significantly reduced savanna tree recruitment, survival, and growth. Our demographic model suggested that: (1) despite the negative effects of frequent high‐severity fires on demographic rates, savanna tree biomass appears to be suppressed by only a relatively small amount by contemporary fire regimes, characterized by a mix of low‐ to high‐severity fires; and (2) plausible, management‐driven reductions in the frequency of high‐severity fires are likely to lead to increases in tree biomass of about 11.0 t DM ha−1 (95% CI: −1.2–20.8) over a century. Accounting for this increase in carbon storage could generate significant carbon credits, worth, on average, three times those generated annually by current greenhouse gas (methane and nitrous oxide) abatement projects, and has the potential to significantly increase the economic viability of fire/carbon projects, thereby promoting ecologically sustainable management of tropical savannas in Australia and elsewhere. This growing industry has the potential to bring much‐needed economic activity to savanna landscapes, without compromising important natural and cultural values.

Least-cost pathways to net-zero, coupled energy systems: A case study in Australia

This paper investigates the least-cost greenhouse gas (GHG) abatement pathway for a coupled energy system. We consider the roles of diverse abatement technologies, such as renewable electricity generation, biomass and carbon capture and storage (CCS), as well as sources of operational flexibility, such as peaking generators, electricity storage, transmission and electrolysis. Scenario and sensitivity analyses are applied to explore plausible pathways to energy system decarbonization. All modelled pathways to a zero-emissions energy system feature an accelerating transition from fossil fuels to renewable energy with diverse technologies playing a role. This includes variable renewable generators (VRG), CCS, and sources of operational flexibility on different timescales. Specifically, synchronous condensers appear to be a cost-effective option to control system frequency, inter-seasonal hydrogen storage in engineered caverns can play a significant and complementary role to that of pumped hydro and battery storage, and technologies that capture and sequester atmospheric carbon, including biomass-to-CCS and direct air capture (DAC), can also play a significant role in the transition to net-zero emissions.

Multifunctionality of temperate alley-cropping agroforestry outperforms open cropland and grassland

Intensively managed open croplands are highly productive but often have deleterious environmental impacts. Temperate agroforestry potentially improves ecosystem functions, although comprehensive analysis is lacking. Here, we measured primary data on 47 indicators of seven ecosystem functions in croplands and 16 indicators of four ecosystem functions in grasslands to assess how alley-cropping agroforestry performs compared to open cropland and grassland. Carbon sequestration, habitat for soil biological activity, and wind erosion resistance improved for cropland agroforestry (P ≤ 0.03) whereas only carbon sequestration improved for grassland agroforestry (P < 0.01). In cropland agroforestry, soil nutrient cycling, soil greenhouse gas abatement, and water regulation did not improve, due to customary high fertilization rates. Alley-cropping agroforestry increased multifunctionality, compared to open croplands. To ameliorate the environmental benefits of agroforestry, more efficient use of nutrients is required. Financial incentives should focus on conversion of open croplands to alley-cropping agroforestry and incorporate fertilizer management.

Greenhouse gas balances and yield-scaled emissions for storage and field application of organic fertilizers derived from cattle manure

Manure treatment such as anaerobic digestion and solid-liquid separation has shown a potential to abate greenhouse gas (GHG) emissions, but few studies have considered GHG emissions from both storage and field application regarding crop yield. In this study, four different organic fertilizers were studied: untreated cattle manure (CA); digestate of cattle manure anaerobically co-digested with grass-clover (DD); a liquid fraction from the separation of DD (LF); and a liquid fraction derived from a biogas desulfurization biofilter enriched with sulfur and ammonium (NS). The CH4, N2O and NH3 emissions during storage of CA, DD and LF between August and November 2020 (11 weeks) were quantified. Storage continued until April 2021 when these materials, as well as the NS fertilizer and a mineral NKS fertilizer, were applied at a rate of 100 kg total N ha−1 to spring barley. N2O emissions and soil mineral N content were monitored during the growing season. Overall, CH4 emissions during storage were the main source of GHG emissions independent of treatments, accounting for 85 %, 40 % and 11 % of total GHG emissions (based on field application of 100 kg ha−1 total N) from treatments CA, DD and LF, respectively. Anaerobic digestion and separation significantly reduced CH4 emissions during storage due to the diminished content of degradable organic matter available for methanogens. The N2O emissions from treatments CA, DD, and LF during storage were not significantly different. Treatments DD and LF emitted more NH3 than CA during storage, presumably because of higher pH and ammonium content. In the field experiment, the dilute solution of NS emitted the most N2O, while emissions from treatments CA, DD and LF were comparable. Yield-scaled GHG emissions for treatments CA, DD, LF and NS during both periods of storage and field were 44.4, 17.1, 8.5 and 24.3 kg CO2 eq hkg−1 grain yield, respectively. Anaerobic digestion with or without separation were thus effective strategies for the mitigation of GHG emissions from cattle manure in this study. Yields and nitrogen use efficiencies of the processed manure materials were not significantly different from those observed with the same N application rate as inorganic fertilizer, and hence anaerobic digestion with or without separation were promising GHG mitigation strategies.

Greenhouse gas abatement via repurposing computers

The purpose of this research is to generate findings to support the reduction of computer supply chain greenhouse gas emissions. This is achieved by answering the question, ‘can greenhouse gas abatement be delivered by alternative computer operating system displacement strategies?’ We hypothesised that extending the useful lifespan of end user computing devices to 8 years by repurposing a device with a new operating system can reduce scope 3 supply chain emissions, which account for 73% of an end user computing device's carbon footprint. To test the hypothesis, we measure the carbon footprint reduction delivered by repurposing 3,150 obsolete desktop computers, which were installed with a Linux based operating system to become thin clients and support a remote working solution for a major financial institution during the recent Covid-19 pandemic. We calculate scope 3 supply chain emissions avoided by not purchasing new thin client solutions. Legacy device power consumption is also measured and extrapolated to represent the one-year period of use and compared with that of new devices to calculate the excess scope 2 emissions of the former. We find that while new devices reduce scope 2 emissions, this gain is outweighed by the reductions in scope 3 emissions from not replacing the legacy devices. Furthermore, we find that the new Linux based operating system reduces energy consumption by 22% compared with Microsoft Windows. We also calculate the financial gains from the repurposing strategy to test the perception that sustainable information technology adoption is costly. Finally, the impact of remote working on commuting emissions is estimated. In conclusion, the findings show that repurposing end user computing devices contributes meaningfully to sustainability strategies from both an environmental and financial perspective.

Land use and environmental quality in Ireland over two decades of contrasting agricultural trends

Global awareness and scrutiny of food production systems, including competition for land between agriculture and nature-based solutions to climate change, has increased immensely recently. In Ireland, around 70% of land area is used for agriculture, mostly pasture-based livestock production. Cattle numbers began to decline in the late 1990s, as milk productivity per cow increased along with the European Union policy of intensification implemented in 1998. Phasing out of the EU milk quota system from 2011 onwards initiated an increase in dairy cow numbers, which rose by 46% by 2020. This development has reversed environmental progress. This study outlines the impact of contrasting policies that have contributed to abatement and intensification of greenhouse gas and ammonia emissions from Ireland’s agriculture, forestry and other land use (AFOLU) sector, along with impacts on water quality effects. Ireland achieved most environmental targets during the 2000s. However, between 2010 and 2019, agricultural greenhouse gas emissions increased by 12% and annual ammonia emission ceilings exceeded the national limit in seven of those years. Around 6% of rivers lost their good or high ecological water quality status. These developments jeopardise compliance with contemporary environmental targets, such as achieving a 25% reduction in greenhouse gas emissions from agriculture by 2030, and AFOLU climate neutrality by 2050. Achieving environmental quality targets will necessitate far-reaching and immediate development of policy for the land use sector beyond the implementation of currently proposed mitigation measures.