Emission Savings Research Articles

Energy Use and Carbon Footprint Assessment in Retrofitting a Novel Energy Saving Device to a Ship

The Gate rudder system (GRS) was recently introduced as an innovative energy-saving device (ESD) for ships, and it is the most attractive ESD currently used in the market, with double figures of fuel savings in full-scale (>10–35%) compared with a ship with a conventional rudder system (CRS). Although there are few new ship applications of GRS, the recently completed EC-H2020 GATERS project successfully demonstrated its unique energy-saving and manoeuvrability benefits as a “retrofit” solution for an existing general cargo vessel for the first time. The project results suggested that the GRS holds significant potential for retrofitting existing ships to enhance fuel efficiency (~35%) and improve manoeuvrability. Nevertheless, the application was a comprehensive undertaking requiring various work tasks such as component manufacturing, removing existing systems, and modification and upgrading works, with substantial energy consumption and environmental impacts. Therefore, it was insightful to study energy use and environmental impacts in a GRS retrofit process. This study developed and implemented a comprehensive energy consumption and carbon footprint assessment framework for the GRS retrofit in the GATERS project. A detailed assessment of energy consumption and related carbon emissions was performed during the major stages of manufacturing, system removals, and modifications and assembly in the GRS retrofit. Also, the potential savings in energy use and emissions were addressed. The results demonstrated that the manufacturing stage was the most energy-intensive phase, being responsible for 91.4% of total electricity and 46.7% of fuel-based thermal energy use. The system removals accounted for 53.3% of the fuel-based thermal energy, whereas the modification and assembly work accounted for about 7.7% of the total electricity use. Additionally, various measures such as clean electrification, energy efficiency, mould/tool reuse, and component reuse to reduce the energy consumption and related carbon emissions in future GRS retrofit applications were addressed and discussed together with their reduction potentials.

Performance evaluation of a hybrid photovoltaic-vapor compression system serving a refrigerated van

The refrigerated transportation industry's growth necessitates addressing energy consumption and greenhouse gas emissions. This study estimates a photovoltaic system's energy and environmental benefits to power a vapour compression refrigeration (VCR) system serving a light-duty commercial refrigerated van. A comprehensive energy model encompassing thermal, electrical, and battery sub-models simulating the system's dynamic behaviour is calibrated with real-world data referring to an urban single-delivery mission. The potential benefits are estimated for a long-distance single-delivery mission starting from the University of Salerno (Italy) and ending at the Jaume I University in Castellon de la Plana (Spain). The results have shown that the system can reduce fuel consumption for refrigeration by more than 88 % during summer months and allows neutral refrigeration during winter months, leading to on-wheel emission savings between 4 and 8 gCO2,e/km. When considering total emissions, including electrical energy from the power grid and the increased weight due to the PV system, a 33–47 % reduction is obtained, corresponding to 1–5 gCO2,e/km. In detail, PV panels can cover up to 19 % of the total energy requirements. In economic terms, the system allows a cost-saving between 0.1 and 0.3 c€/km. The low complexity and promising results suggest the hybrid PV solution is a viable path towards decarbonising refrigerated transport.

Contribution of Onshore Power Supply (OPS) and Batteries in Reducing Emissions from Ro-Ro Ships in Ports

Increasingly restrictive environmental regulations for the maritime sector have led shipping companies to look for technological alternatives to reduce emissions. This article introduces a methodology to analyse emission reductions of ships in port by incorporating batteries into the ships or using an onshore power supply system. These have not yet been considered together for comparison or with a focus on ship operation. The aim is to avoid the use of auxiliary engines in ports. First, the cost calculation method to be used is specified; then, the engine’s behaviour and the established basic navigation criteria are analysed; and finally, different alternatives are considered. A methodology is afterwards defined for selecting alternatives, comparing their costs with those of using auxiliary engines in port. As an example, it is applied to a Ro-Ro route between the ports of Montoir (France) and Vigo (Spain). The results indicate that incorporating batteries into the ship produces greater savings in annual costs than onshore power supply. The cost savings from onshore power supply depend on the range of prices in each port. However, the greatest emission savings are obtained by using the onshore power supply. This methodology can be extrapolated to other routes and vessels by incorporating real operating data.

A-198 ESG Opportunities Harnessed During Pathology Transformation

Abstract Background Synnovis (a SYNLAB business) is in the process of delivering one of the largest Pathology transformation programmes in the UK, moving to a seven-site hub and spoke model from 89 laboratories over a dispersed geography. This remit also presented an opportunity for SYNLAB to deliver on its Environmental Social Governance (ESG) ambitions, by embedding ESG principles into programme delivery. There are several examples within each ESG pillar that demonstrate the benefits to be leveraged during transformation. Methods SYNLAB’s vision is to deliver sustainable diagnostic services. The integration of ESG into both the decision-making process and transformation structure ties these ambitions into programme benefits realisation. As well as setting performance level targets, the delivery of ESG benefits provide measures of success throughout the transformation journey, motivating stakeholders and building confidence along the way. Results Environment: The efficient use of space and LEAN principle design has consolidated the fragmented laboratory services spanning 15,000m2 into a bespoke, cutting-edge Pathology Hub with 6 spokes (hospital based services). The new hub building was designed to achieve BREEAM Excellent standards which measure performance against criteria such as energy management and efficiency, sustainable design and materials. The hub’s energy is from renewable-backed sources, and we will achieve a 47% reduction in CO2 equivalent (CO2e) emissions by unifying a significant proportion of its legacy footprint in this way. Further energy savings will be achieved through the associated analytical equipment consolidation, including a decrease from 50 to 14 microtomes, a decrease of 29 to 15 ventilated benches and a reduction of over 200 fridges and freezers across the service. In addition, substantial CO2e emissions savings are also being delivered by moving to a greener logistics provider, utilising electric vehicles and bikes. 2023 saw such emissions fall by 60% across Synnovis, helping to keep London’s air cleaner. Social: The transformation programme enables the hand back of over 6,000m2 of real estate to Synnovis’ NHS partners to use for critical hospital services (the equivalent of over 150 operating theatres). Governance Both internally and externally, ESG is integrated within the Synnovis organisational culture. For example, internally it applies mandatory sustainability metrics to its solution selection processes. These influenced the selection of Abbott’s Indexor solution to support the transformation of Blood Sciences, delivering a saving of over 2.8 million plastic sample bags every year. Externally, SYNLAB works with its partners to manage this substantial and complex transformation programme. Risk management is assured through transparency, securing confidence in the good use of public funds, ensuring responsiveness to customer and partner feedback, and ensuring accountability for and the delivery of targeted healthcare outcomes. Conclusions The integration of SYNLAB’s ESG strategy within the transformation programme is delivering tangible benefits across all ESG pillars. It has highlighted that in addition to the core outcome of services transformation, there are many more opportunities that can be realised as a result of making ESG an integral part of the pathology transformation programme.

Remanufacturing Construction and Demolition Waste and Incineration Ashes into Eco-blocks: Quantitative Sustainability Assessment

This study performed a sustainability evaluation of a proposed business for remanufacturing concrete materials from construction and demolition waste (CDW) and ash from the combustion of municipal solid waste (MSW) to produce eco-blocks for construction applications. Six possible industrial remanufacturing alternatives are proposed based on commercially available industrial machinery and their economic sustainability was compared by a cost and profit feasibility study. Furthermore, the technical feasibility was evaluated by considering the maturity of the selected machinery based on the relationships among the cost–productivity, power–productivity, and number of workers–productivity pairs. The proposed remanufacturing business achieves a maximum profit of 17,643 USD/day with a minimum remanufacturing cost of 30.65 USD/t for the production of 529 t of eco-blocks in an 8-h factory shift. A quantitative environmental sustainability assessment was performed using the remanufacturing cost, profit, concrete savings, energy savings, CO2 emission savings, and eco-cost savings as criteria based on demographic statistics from the literature for current and predicted CDW and MSW generation. CDW and incineration ash are widely available, so the proposed process is viable worldwide. Based on the technical, economic, and environmental sustainability results, a final sustainability index of 0.874 was calculated, which exceeds literature thresholds for a sustainable business, indicating that the proposed eco-block remanufacturing process has the potential to generate substantial profits, while positively contributing to reducing waste and energy usage by recovering valuable resources and producing value-added products. The remanufactured eco-blocks are prepared in the same way as typical concrete blocks and can be used for all of the same residential, commercial, and industrial construction and landscaping applications. The remanufactured eco-blocks have several advantages over typical concrete blocks, including a much lower manufacturing cost (∼50% lower), significant environmental and resource savings by avoiding the use of new sand and gravel resources, and improved mechanical properties.

Ethanol fuel in Brazil: policies and carbon emission avoidance

Since the launch of the first biofuel policy (Proalcool), in 1975, Brazil has developed a remarkable ethanol fuel industry which is now a major component of the country’s strategy to reduce greenhouse gas (GHG) emissions. In this paper we analyze how biofuel policies have affected the ethanol industry and how this industry has contributed to GHG emission reduction. Our study innovates by considering both Life Cycle Assessment (LCA) and Land Use Change (LUC) emissions and for covering the period from 1975 to 2022. We found that the use of ethanol fuel allowed significant emission savings for the transportation sector, causing GHG emission reductions of 39–46% compared with gasoline and a total avoided emission greater than 828 million metric tons of carbon dioxide equivalent. We identified that market drivers have been more decisive in fostering the ethanol industry, but biofuel policies also have a major influence on the development of the ethanol sector. Due to that, there are concerns about the environmental impact of the new biofuel policy (RenovaBio) as it ignores LUC emissions. To avoid adverse effects, we recommend that biofuel policies should consider all potential adverse impacts of LUC and should also involve strong actions aiming to halt deforestation.

Reducing the carbon footprint for a 30-bed haemodialysis unit by changing the delivery of acid concentrate supplied by individual 5 L containers to a central delivery system

BackgroundHaemodialysis treatments generate greenhouse gas (GHG) emissions mainly as a result of the equipment, consumables and pharmaceuticals required. An internal audit demonstrated a 33% wastage of acid concentrate when using individual 5.0 L containers at a 1:44 dilution ratio. We therefore investigated whether changing the delivery system for acid concentrate would reduce wastage and any associated greenhouse gas emissions.MethodsWe calculated the difference for a 30-bed dialysis unit between receiving acid concentrate in single-use 5.0 L plastic containers versus bulk delivery for a central acid delivery system connected to the dialysis machines. Estimates of carbon dioxide equivalent (CO2e) emissions were made using the United Kingdom government database and other sources.ResultsA 30-station dialysis unit functioning at maximum capacity (3 shifts and 6 days/week), switching to bulk delivery and central acid delivery could realise an approximate total reduction of 33,841 kgCO2e/year; in reduced product wastage, saving 6192 kgCO2e, 5205 kgCO2e from fewer deliveries, and 22,444 kgCO2e saving from a reduction in packaging and waste generated, which equates approximately to a one tonne reduction in CO2e emissions per dialysis station/year.ConclusionsSwitching from delivering acid concentrate in individual 5.0 L containers to a central acid delivery system can result in substantial reductions in CO2e emissions within a dialysis clinic. The emission savings from reducing the single-use plastic packaging greatly outweigh any gains from eliminating wastage of acid concentrate. Dialysis companies and clinicians should consider reviewing the design of current and future dialysis facilities and policies to determine whether reductions in CO2e emissions can be made.Graphical

A multi-life cycle assessment of external wall insulation strategies in an Irish domestic retrofit

European Union (EU) policy and initiatives are driving both building renovation and the uptake of low-embodied carbon and circular design in the construction sector. The European Performance of Buildings Directive (EPBD) recast (2021) introduces global warming potential (GWP) methodology, and the future state will likely be embodied carbon targets for which life cycle assessment (LCA) of buildings will be required. External wall insulation (EWI) will have an important role to play in meeting targets. In this context, this paper compares the carbon emission payoff of three alternative EWI strategies that address conventional, low-carbon and circular solutions to EWI respectively, in the retrofit of an existing dwelling. The circular strategy is based on design for disassembly (DfD). Whereas standard LCA is based on a single building life cycle, the literature reviewed shows that the environmental impact assessment of DfD requires a multi-life cycle approach. In the absence of standardised methods for assessment, four multi-cycle LCA methods are selected and applied holistically in a case study investigation. Three allocation methods, 100:0, linear degressive (LD) and enhanced linear degressive (CELD), provide a range of emissions from ‘conservative’ to ‘best case’ over three building life cycles and the fourth method, the Van Gulck method, assesses the benefits of circularity through the concept of ‘multi-cycling’ based on one building life cycle. As each method of assessment will deliver different results, carbon emission payoff is not a fixed value. Findings show that with multiple use, the circular strategy pays off due to avoided production emissions and benefits from end-of-life (EoL) processes that DfD facilitates, that the upfront carbon cost of the circular strategy is minor relative to the carbon emission savings that reuse brings, and that the margin of improvement relative to the alternative strategies increases with each subsequent reuse.

An analytical solution to optimal heat pump integration

Heat pump integration has a large potential for reducing carbon emissions and operating costs of industrial processes. The Break-even COP method determines the maximum economically- or environmentally feasible heat pump temperature and the level of process heat electrification under specified economic conditions. However, this method fails to capture the optimal heat pump temperature and the possible emissions- and costs reduction in sensible heat processes. The present work introduces an analytical equation based on the Lorenz efficiency approach to determine the optimal heat pump sink temperature, maximizing the operating costs savings or the emission savings. Furthermore, it advances the break-even method to account for heat pumps with a temperature glide by applying a Lorenz efficiency approach. The method is applied to a spray-drier case study, showing a reduction on operation costs of 7.8 % and emissions by 11.9 % by a partial process electrification of 32 %. A parameter study is conducted, underscoring the importance of accurate predictions of the Lorenz efficiency factor and the electricity-to-fuel price and emissions ratios in heat pump integration studies.

Design and assessment of a concentrating solar thermal system for industrial process heat with a copper slag packed-bed thermal energy storage

Decarbonising the industrial sector is a key part of climate change mitigation targets, and Solar Heat for Industrial Process (SHIP) is a promising technology to achieve this. However, one of the drawbacks of SHIP systems is that they rely on an intermittent energy source. Therefore, sensible energy storage has emerged as a potential solution. In addition, solid byproducts have been proposed as a low-cost but effective material for thermal energy storage (TES). This work presents a SHIP system model coupled with a copper slag-packed-bed TES (PBTES) model using air as heat transfer fluid. The TES has been implemented to preheat the makeup water of the tank where steam is generated. A system design was carried out using a parametric analysis to find a solar field size and a corresponding TES volume. The resulting system was simulated, and the operating variables were analysed in detail. The results show that it is possible to generate 20% more energy due to the storage system. Additionally, a techno-economic analysis indicates that the SHIP with PBTES system results in a payback period of 14 years and a savings of CO2 emissions of 30tCO2.

Implementing Tri-Brid Energy Systems for Renewable Integration in Southern Alberta, Canada

The steep decline in the price of wind and solar photovoltaics provides a possibility to decarbonize electricity deeply and affordably. This study uses the HOMER Pro energy modeling tool to model an optimized grid-connected renewable energy system for a community in southern Alberta, Canada. The study’s goal is to identify the best renewable energy technology combinations that can provide electricity at the lowest levelized cost of energy (LCOE) and has lower greenhouse gas emissions as compared to the electricity produced by traditional fossil fuel. Gleichen is a small town in southern Alberta that is close to numerous commercial wind and solar projects given the region’s high quality renewable resources. “Tri-brid” systems consisting of wind turbines, solar photovoltaics, and battery energy storage systems (BESS) are considered and compared based on electricity prices, net present cost, and greenhouse gas emissions savings. This tri-brid system is connected to the grid to sell excess generated electricity or buy electricity when there is less or no availability of solar and wind energy. The tri-brid energy system has an estimated LCOE of 0.0705 CAD/kWh, which is competitive with the price of electricity generated by natural gas and coal, which is 0.127 CAD/kWh.

Estimation of wood biomass boiler use in cold climate regions on CO2 emissions of light-frame timber structure

Considering Nagano City, as the cold climate region of Japan, the annual heating load was simulated using a model of a two-story timber structure. The results of simulations were used to compare the CO2 emissions according to the energy consumption of five methods of heating as well as primary and secondary energy sources. Actual data from power and gas companies in Nagano and Japanese energy standards were used for the estimations of CO2 emissions of electric heat pump air conditioners, LNG-powered city gas boilers, LPG boilers, kerosene stoves, and wood biomass boilers using pellets as an energy source. Wood biomass boilers showed CO2 emission savings of up to 85 %, 75 %, 75 %, and 76 %, respectively. The operating and equipment costs were estimated based on secondary energy calculations. The kerosene stove had the lowest cost, but CO2 emissions were lowest in the case of using pellet boilers for 30 years. These results clearly show the potential and merit of pellets used in wood biomass boilers as a renewable energy source when compared to fossil fuels. In addition to the CO2 reduction capabilities, the low operating costs of wood biomass heating systems incentivize their use in cold climates.

Energy and Carbon Savings in European Households Resulting from Behavioral Changes

The study evaluates the impact of behavioral changes resulting from climate awareness on energy consumption and carbon emissions in European households based on the results of a two-stage survey addressed to individuals manifesting pro-ecological attitudes. In the first stage, the author analyzed 67 pro-environmental behaviors declared by the participants, identified a set of new sustainable choices, and compared them to the conservation habits used in Rasch and Campbell’s models. The 10 most popular initiatives undertaken by over 50% of participants were selected for further analysis. The influence of these initiatives on energy consumption and CO2 emissions was assessed. A total of 24 impact indicators were identified at the building scale. Energy and carbon savings were calculated for 500 participants from 28 European countries and compared to the results computed for the 100 households used as a reference. The main conclusions from the research concern the significance of individual decisions at the building scale in the context of their actual environmental impact calculated for a larger scale. The comparative analysis showed that the highest annual energy (2292.1 MWh) and emission (267.02 tons of CO2) savings resulted from the car-to-bicycle (or walking) transition on short-distance trips (declared by 79%) and from the transition from non-renewable to renewable energy sources (PV panels installed by 65% of respondents). Annual energy and emission savings reached, respectively, 1300 MWh and 262.6 tons of CO2. The research findings help explain the critical importance of transforming the built environment towards renewable energy sources and supporting pedestrian and sustainable transportation.

A modular framework to assess biological resource utilization impacts (BIORIM)

The strong influence of biological processes and site conditions, the large diversity in management, compositional changes of agricultural produce, and the circularity of processes challenge the assessment of environmental impacts of the bioeconomy. This paper introduces a novel sustainability assessment and material flow model to study biological resource utilization impacts (BIORIM) which aims to address these challenges. The model represents important bioeconomic production systems (e.g. arable land, dairy farm, biogas plant) and considers input properties, production parameters such as site conditions or management, and different emission factors when calculating products and emissions. For this reason, the functions that represent the conversion processes need to be executed in the correct order when analysing larger production networks. The model keeps full track of mass, carbon and nitrogen flows, and therefore allows assessing how much is lost during processing, ending up in the produce and is recycled. The modelling approach is illustrated at the example of a dairy farm where dairy manure is used as an organic fertilizer for fodder crop production in the following year. This is compared to a scenario that includes a biogas plant. The comparison of manure storage to biogas production reveals that this change does not only affects direct emissions. Biogas production leads to higher carbon losses and thus negatively affects the humus balance. The manure storage, on the other hand, leads to higher nitrogen losses, which result in a lower fertilization value of the manure, and therefore a higher amount of mineral fertilizer is required in the following year. Together with the emission savings from the energy production, this results in a lower global warming effect of the biogas scenario. The study shows that it is important to consider the interplay of processes when assessing impacts of bioeconomic production systems.

Green mechanism: Opportunities for corporate investment in PV/battery/diesel hybrid systems with techno-economic and environmental analysis

In rural areas, diesel generators are prevalent due to their lower initial cost, despite inefficiencies and carbon emissions. Transitioning to PV/Battery/Diesel systems offers a solution by reducing costs and emissions. However, the high upfront expenses present a significant barrier, particularly for rural communities, necessitating external financial support. This study evaluates the benefits of adopting a PV/Battery/Diesel hybrid system over traditional diesel generators in a rural community with 25 customers and a daily demand of 50 kWh. The proposed system includes a 12 kWp photovoltaic array and a 48 kWh battery bank, simulated using Hybrid Optimization of Multiple Energy Resources (HOMER) software. Results indicate a 91% renewable fraction and a cost of energy of 0.279 USD/kWh, substantially lower than the 1.05 USD/kWh of diesel-only systems, with CO2 savings of 25 t per year. The paper advocates for a case study approach to green mechanism, urging energy and environmental companies to invest in these systems. By replacing diesel generators with hybrid PV/Diesel/Battery systems, companies can offer electricity at a reduced cost, driving adoption. Selling carbon credits from emission savings can generate additional income, leveraging CO2 tax incentives. Under scenarios where investors cover 50% of diesel costs, selling electricity yields 9581 USD annually, and selling CO2 credits generates 500 USD annually. This leads to a payback period of 9.83 years without CO2 credits and 9.18 years with CO2 credits, totaling 46,848 USD without CO2 credits and 52,927 USD with CO2 credits over the project's lifespan. Meanwhile, adjusting electricity pricing to 75% of diesel costs, this increases annual income from electricity sales to 14,372 USD. This reduces the payback period to 5.89 years without CO2 credits and 5.66 years with CO2 credits, totaling 105,094 USD without CO2 credits and 111,174 USD with CO2 credits at the end of the project.

Alternative uses for urban autumn tree leaves: A case study in profitability and greenhouse gas emissions for the city of Berlin

Autumn tree leaves collect as waste on many city streets every year. In the city of Berlin, they are usually collected and transported for composting as their final treatment, which emits greenhouse gases (GHG) into the atmosphere. This study assesses alternative end uses of autumn tree leaves in order explore the potential of reducing GHG emissions while producing electric energy from residual biomass. It uses a combination of partial life-cycle assessments and net present value (NPV) to explore the different net GHG emissions and economic benefits of using autumn tree leaves for the following scenarios: anaerobic digestion (biogas), gasification, and co-firing. Assuming the use of 36,000 tonnes of leaves per year, co-firing in existing power plants shows the highest NPV, of between 10.3 million and 12.1 million euros for a 10-year lifetime, in line with the phase-out of coal combustion in Germany. It also results in the lowest net GHG emissions, with savings of between 252,000 and 144,000 tonnes of CO2eq. Gasification in new plants resulted in similar NPVs, estimated at between 9.80 and 9.86 million euros over a 20-year investment horizon, but lower emissions savings of 178,000 to 127,000 tonnes of CO2eq. Biogas production showed high emissions savings of 204,000 to 203,000 tonnes of CO2eq, but a much lower NPV of between 2.3 and 2.5 million euros. Composting was the only scenario with positive net GHG emissions. The amount of energy retrieved from the conversion technologies and the electrical tariff applied were the main drivers of these results. Other aspects that can shape the results include the availability of infrastructure and transport distances. The results are highly sensitive in both cases to the dryness of the leaves, while electricity tariffs influenced the economic performance considerably.

Replacing Gray Hydrogen with Renewable Hydrogen at the Consumption Location Using the Example of the Existing Fertilizer Plant

The production and use of hydrogen are encouraged by the European Union through Delegated Acts, especially in sectors that are difficult to decarbonize, such as the industrial and transport sectors. This study analyzes the possibility of partial decarbonization of the existing plant in the petrochemical industry, with a partial transition from natural gas to renewable hydrogen, as a precursor to the adoption of the hydrogen economy by 2050. This study was based on the example of a plant from the petrochemical industry, namely an existing fertilizer plant. Namely, in the petrochemical industry, hydrogen is produced by steam-reforming natural gas, which is needed in the process of producing ammonia, one of the basic raw materials for mineral fertilizers. By building an electrolyzer at the location of the existing fertilizer plant, it is possible to obtain renewable hydrogen, which enters the ammonia production process as a raw material. The electricity from which hydrogen is produced in the electrolyzer is provided through Power Purchase Agreement contracts concluded with electricity producers from 12 wind power plants. The results of this study show that the production of renewable hydrogen at the location of the analyzed plant is not profitable, but due to the specificity of the process of such an industry, the high consumption of natural gas, and large savings in CO2 emissions which can be achieved by the production of renewable hydrogen, investment is needed. With a 370 MW electrolyzer, about 31,000 tons of renewable hydrogen is produced, which represents about 50% of the hydrogen needs of the analyzed plant. By producing renewable hydrogen for part of the needs of the analyzed plant, a saving of about 300,000 tons of CO2 emissions is achieved in relation to the production of gray hydrogen, which contributes to the partial decarbonization of the analyzed plant. The authors are aware that the current market opportunities do not allow the profitability of the investment without subsidies, but with the advancement of technology and a different price ratio of electricity, natural gas, and CO2 emissions, they believe that such investments will be profitable even without subsidies.

Waste heat recovery from a green ammonia production plant by Kalina and vapour absorption refrigeration cycles: A comparative energy, exergy, environmental and economic analysis

The production of green ammonia involves significant energy penalties due to heat losses. Recovering this heat can enhance the sustainability of ammonia production. However, this area remains largely unexplored, making it unclear which approach to waste heat recovery is best suited. Therefore, this paper investigates two methods of waste heat recovery in a green ammonia production plant: the Kalina Cycle (KC) and the Vapour Absorption Refrigeration Cycle (VARC). The underlying processes are simulated, and an analysis is conducted covering energy, exergy, environmental, and economic aspects. The results show that integrating the system with KC yields a marginal energy efficiency improvement of about 1%. However, when the conventional ammonia production system is integrated with VARC, the improvement in energy efficiency reaches 8%, while exergy efficiency improves by 11%. An environmental assessment estimates the greenhouse gas emissions saved by each heat recovery method, revealing that VARC achieves almost four times the emission savings compared to KC. Economically, integrating KC increases the levelized cost of ammonia (LCOA) by over 18%, whereas adding VARC has almost no impact on the LCOA. Overall, the co-production of refrigeration using VARC is identified as a superior heat recovery technique for green ammonia plants.

Wire arc additive manufacturing of a high-strength low-alloy steel part: environmental impacts, costs, and mechanical properties

Additive manufacturing (AM) technologies have demonstrated a promising material efficiency potential in comparison to traditional material removal processes. A new directed energy deposition (DED) category AM process called wire arc additive manufacturing (WAAM) is evolving due to its benefits which include faster build rates, capacity to build large volumes, and inexpensive feedstock materials and machine tools compared to more technologically mature powder-based AM technologies. However, WAAM products present challenges like poor surface finish and lower dimensional accuracy compared to powder-based processes or machined parts, prevalence of thermal distortions, residual stresses, and defects like porosity, cracks, and humping, often requiring post-processing operations like finish machining and heat treatment. These post-processing operations add to the production cost and environmental footprint of WAAM-built parts. Therefore, considering the opportunities and challenges presented by WAAM, this paper analyses the environmental impact, production costs, and mechanical properties of WAAM parts and compares them with those achieved by laser powder bed fusion (LPBF) and traditional computer numerical control (CNC) milling. A high-strength low-alloy steel (ER70S) mechanical part with medium complexity was fabricated using WAAM. Based on the data collected during this experiment, environmental impact and cost models were built using life cycle assessment and life cycle costing methodologies. WAAM was observed to be the most environmentally friendly option due to its superior material efficacy than CNC milling and has a better energy efficiency than LPBF. Also, WAAM was the most cost-friendly option when adopted in batch production for batch sizes above 3. The environmental and cost potential of WAAM is amplified when used for manufacturing large products, resulting in significant material, emission, and cost savings. The fabricated WAAM part demonstrated good mechanical properties comparable to that of cast/forged material. The methodology and experimental data presented in this study can be used to calculate environmental impacts and costs for other products and can be helpful to manufacturers in selecting the most ecofriendly and cost-efficient manufacturing process.

Man versus machine: cost and carbon emission savings of 4G-connected Artificial Intelligence technology for classifying species in camera trap images

Timely and accurate detection and identification of species are crucial for monitoring wildlife for conservation and management. Technological advances, including connectivity of camera traps to mobile phone networks and artificial intelligence (AI) algorithms for automated species identification, can potentially improve the timeliness and accuracy of species detection and identification. Adoption of this new technology, however, is often seen as cost-prohibitive as it has been difficult to calculate the cost savings or qualitative benefits over the life of the program. We developed a decision tool to quantify potential cost savings associated with incorporating the use of mobile phone network connectivity and AI technologies into monitoring programs. Using a feral cat eradication program as a case study, we used our decision tool to quantify technology-related savings in costs and carbon emissions, and compared the accuracy of AI species identification to that of experienced human observers. Over the life of the program, AI technology yielded cost savings of $0.27 M and when coupled with mobile phone network connectivity, AI saved $2.15 M and 115,838 kg in carbon emissions, with AI algorithms outperforming human observers in both speed and accuracy. Our case study demonstrates how advanced technologies can improve accuracy and cost-effectiveness and improve monitoring program efficiencies.