CO2 Savings Research Articles

Transparent insulation integration in solar thermal collector: Advancing performance for domestic water heating in oceanic climates of Western Europe

Decarbonizing residential hot water demand requires efficient solar collectors. Conventional flat plate collectors are widely available but experience high heat losses in colder climates. This work investigates the performance of a modified flat plate collector that incorporates honeycomb transparent insulation to reduce convective heat loss, offering a cost-effective alternative to energy-efficient evacuated tube collectors. The thermal performance of the modified flat plate collector was obtained using the finite element method in COMSOL Multiphysics, revealing a significant reduction in convective heat loss. The obtained thermal performance was then incorporated into a transient simulation to assess the year-around performance of the modified flat plate collector in a solar domestic hot water system for Irish climate. The transient simulation accounted for variations in the transparent insulation’s transmission with incidence angle which was overlooked in previous studies. Over a year-long simulation, the modified flat plate collector generated a total useful energy of 532.45 kWh m−2, while requiring 1640 kWh of auxiliary energy to meet the hot water demand of a single-family house in Ireland. An economic analysis of solar domestic hot water system revealed that the modified flat plate collector could yield savings of 443.44 € more than the standard flat plate collector and 3281.03 € more than the evacuated tube collector for homeowners. Consequently, the simple payback period for the solar domestic hot water system decreased from 3.72 years with a standard flat plate collector and 8.37 years with an evacuated tube collectors to 3.56 years with a modified flat plate collector. In addition to its economic viability, the modified flat plate collector could result in a CO2 savings of 901.85 kgCO2 per year. The study concludes with a sensitivity analysis to identify the market conditions that maximize the profitability of the modified flat plate collector based solar domestic hot water system.

Empowering sustainable hotels: a guest-centric optimization for vehicle-to-building integration

In light of global warming, hotels account for one of the highest energy demands within the building sector, offering great decarbonization potential. As electrification increases, so does the demand for electric vehicles (EVs) charging stations at hotels and the proportion of Vehicle-to-Building-capable EVs. Therefore, the study explores the potential of guest-centric energy management. To accomplish this, we develop an optimization model for an energy management system that focuses on either cost-efficiency or carbon dioxide equivalents (CO2)-efficiency, grounded in a real-world case study. Through scenario analyses considering seasons as well as different guest mobility behaviors, this study discusses the expenses associated with CO2 savings using digital solutions. It emphasizes the currently perceived conflict between cost reduction and decarbonization goals to achieve a sustainable design of information systems. Thereby, this study highlights the critical importance of individual mobility behavior in enabling sustainable energy management for hotels.

Techno-economic and environmental assessment of green hydrogen and ammonia production from solar and wind energy in the republic of Djibouti: A geospatial modeling approach

This study conducts a thorough economic and technical analysis to assess the viability of green hydrogen and green ammonia production using renewable energy sources in the Republic of Djibouti. We explore the economic competitiveness of utilizing wind and solar power for sustainable energy production through various measures including levelized cost of energy (LCOE), hydrogen (LCOH), and ammonia (LCOA). Our analysis incorporates sensitivity assessments and Monte Carlo simulations to predict financial feasibility and environmental impact, focusing on CO2 emission reductions. A cost mapping of electricity, green hydrogen, and green ammonia from solar and wind resources was created to find Djibouti's most cost-effective production sites. The feasibility of exporting green ammonia to neighboring countries with high fertilizer demand was also evaluated using rail and truck transport scenarios. Key findings demonstrate that Moulouhlé, endowed with robust wind and solar resources, presents a strategic site for deploying renewable energy technologies. Wind energy, with a lower LCOE of 0.066 $/kWh compared to solar's 0.093 $/kWh, emerges as a more cost-effective solution for both hydrogen and ammonia production. Notably, wind-powered hydrogen production costs are 2.25 $/kgH2, significantly lower than solar-powered costs at 4.17 $/kgH2. In terms of green ammonia, wind power achieves production costs of 399.76 $/tonNH3, outperforming solar power which stands at 537.11 $/tonNH3. Additionally, our study evaluates the logistics of exporting green ammonia, determining rail transport as a more economically viable option than trucking. This research not only underscores Djibouti's potential as a leader in green energy exportation but also aligns with global decarbonization efforts, showcasing significant CO2 savings—154.94 Mt annually from wind. This work emphasizes the importance of strategic resource utilization in Djibouti, offering insights critical for stakeholders in making informed decisions about investing in renewable energy infrastructures. The outcomes suggest a promising future for regional energy sustainability and economic resilience, fostering a transition towards low-carbon energy systems.

Mathematical modeling for hydrogen blending in natural gas pipelines moving towards industrial decarbonization: Economic feasibility and CO2 reduction analysis

Hydrogen blending has proved to be a promising alternative to reduce CO2 emissions in current applications such as the industrial sector in which natural gas is the fuel source since it can mitigate GHG emissions and help to reach nation’s goal of decarbonization. This study explored the feasibility of different hydrogen blend compositions going from 1% to 30% hydrogen content (by volume) by computational simulations to determine the best performance of the system considering real operating conditions from Central Plant at UC Irvine. This work also performed an economic analysis as part of the implementation plan. It was determined that a blend of 19% H2 content could be implemented without any major renovation of utility infrastructure based on the operating conditions and change in the properties of the mixture. An addition of 30% H2 can reduce around 11% of the emissions produced by pure natural gas. This is equivalent to 1422 kg of CO2 in 1 h. It is evident that the higher the H2 content, the better the CO2 benefits that would be produced, but for the actual application of higher hydrogen content, there is a need for a better understanding of the effects of hydrogen in the current natural gas pipeline. Based on the CO2 savings, it was determined that a 30% blending of hydrogen may save about 22.2% of the economic cost compared to natural gas.

River water heat pumps to decarbonise district heating and promote the resilience of hydrosystems: Technico-economic, environmental and sociological challenges

The interdependence between water and energy (water-energy nexus) has been identified as one of the major challenges at European level, with roadmaps calling for the development of integrated approaches in this sector. The increase in river temperature is at the heart of this nexus, with anthropogenic thermal pollution adding to the effect of global warming. River Water Heat Pumps can play a major role by decarbonising district heating network (DHN) while actively cooling the aquatic resource. Hence, the objective of this short communication is to identify the scientific challenges to be met and the progress to be achieved considering the current state of the art. To illustrate the point, a rapid evaluation of the potential is performed for the city of Lyon in France resulting in an achievable cooling of ∼1.5 K which is above the minimum threshold to see an effect on aquatic ecosystem while the CO2 savings are significant for the DHN (∼ divided by a factor of 10). Because of its holistic nature, the impact assessment of such a system implies considering a wide diversity of indicators: energy, environmental, economics and sociological that need to be appropriately defined and quantified. In each field, progress beyond the state of the art to be performed has been identified, e.g. 4E analysis, cold water plume dispersion, integration of biodiversity in LCA.

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.

Synergizing renewable energy sources in building-integrated hybrid energy systems via niche-ant colony optimization

The rapid advancement of Building-Integrated Hybrid Energy Systems (BIHES), characterized by renewable energy sources with variable generation patterns, presents significant challenges for effective integration and utilization. This paper introduces an optimal economic dispatch strategy for commercial BIHES using a Niche-Ant Colony Optimization (NACO) Algorithm. BIHES integrates renewable sources such as 200 kW photovoltaic panels, 150 kW wind turbines, and 500 kWh energy storage systems within commercial buildings. A detailed mathematical model for economic dispatch leverages a multi-load demand of 1.2 MW and flexible adjustment capabilities. The model aims to maximize on-site renewable energy use while balancing grid interaction. The NACO Algorithm, tested through comprehensive simulations, demonstrated significant improvements, resulting in a 12.96 % reduction in environmental costs, an 18.4 % reduction in the Levelized Cost of Energy (LCOE), and a 14.25 % reduction in total operational costs compared to traditional methods. Additionally, the system achieved annual CO2 savings of 25,000 tons, increased renewable energy absorption by 22 %, reduced grid dependency by 30 %, and decreased energy purchase costs by 20 %. Energy storage optimization also extended the storage system's lifecycle by 15 %. These results highlight the enhanced synergy and complementarity of multiple energy sources within BIHES, showcasing its potential for substantial economic and environmental benefits.

Towards Sustainable Energy Communities: Integrating Time-of-Use Pricing and Techno-Economic Analysis for Optimal Design—A Case Study of Valongo, Portugal

This paper presents a comprehensive analysis of optimal energy community design, leveraging time-of-use pricing mechanisms and techno-economic parameters. Focusing on a case study of Valongo, Portugal, this study explores the intricate interplay between energy infrastructure planning, economic considerations, and pricing dynamics. Through a systematic approach, various factors, such as renewable energy integration, demand–response strategies, and investment costs, are evaluated to formulate an efficient and sustainable energy community model. Time-of-use pricing schemes are incorporated to reflect the dynamic nature of energy markets and consumer behavior. By integrating techno-economic analyses, this study aims to optimize energy resource allocation while ensuring cost-effectiveness and environmental sustainability. The influence of optimized sizes of photovoltaics (PV), battery storage, and electrical vehicles (EVs) on self-sufficiency rates, self-consumption rates and CO2 savings is analyzed. The findings offer valuable insights into the design and implementation of energy communities in urban settings, highlighting the importance of adaptive strategies in the transition towards a resilient and low-carbon energy future. The novelty of this paper lies in its comprehensive approach to energy community design, which integrates time-of-use pricing mechanisms with techno-economic parameters. By focusing on the specific case of Valongo, Portugal, it addresses the unique challenges and opportunities present in urban settings. Additionally, the analysis considers the interaction between renewable energy production, demand profiles and investment costs, providing valuable insights for optimizing resource allocation and achieving both cost-effectiveness and environmental sustainability.

Harnessing solar power: Innovations in nanofluid-cooled segmented thermoelectric generators for exergy, economic, environmental, and thermo-mechanical excellence

Addressing the imperative need for advancements in thermoelectric generation, this study pioneers an analysis of nanofluid-cooled solar segmented thermoelectric generators with non-uniform cross-sections. Insights into thermal management, structural integrity, and economic efficiency in thermoelectric systems are provided, employing a numerical model that accurately represents thermoelectric effects by accounting for temperature dependencies of semiconductor materials. Through research, exploration of diverse coolant strategies, including TiO2, Fe3O4, Al2O3, and graphene, offers key insights into their impact on cooling dynamics. Findings demonstrate that graphene nanofluid, operating at a flow velocity of 2 m/s, outperforms others, achieving optimal power generation of 221.77 mW and an exergy efficiency of 8.99 %. Additionally, at a concentrated irradiance of 595 kWm−2, graphene leads in environmental benefits, with the highest CO2 savings of 0.38 kgyr−1, and demonstrates economic advantages with a cost-effective dollar per mW value of 3.79×10−6 $mW−1. Furthermore, the study verifies the structural integrity of these systems, with graphene achieving an optimal von Mises stress of 1.35 GPa at a semiconductor height of 0.2 mm. These advancements contribute to environmentally friendly and high-performance generators for sustainable energy solutions, paving the way for future innovations in thermoelectric technology.

Green Nephrology - What does this mean for dialysis procedures?

In times in which climate change is becoming increasingly noticeable in the everyday lives of the global population, a rethinking towards an environmentally friendly and climate-neutral way of life is essential in all areas of human activity (including medicine). In the field of nephrology, a reorientation of resource-intensive renal replacement therapy is therefore absolutely necessary, keyword "green nephrology". To this end, awareness of the CO2 emissions caused in the field of nephrology must first be raised so that CO2 savings can then be implemented efficiently. Initially using the current conventional dialysis procedures. In addition, further technical developments such as portable and wearable haemodialysis and peritoneal dialysis machines will enable significant savings in energy and water consumption in the future. Furthermore, innovative research approaches are introducing new alternatives to organ transplantation, such as xenotransplantation, stem cell research and "artificial" organ replacement.A wide variety of promising approaches is therefore available for the renal replacement therapy of the future. The aim of nephrology must now be to drive forward further development and implement it in such a way that environmentally friendly patient care in nephrology is possible in the near future in order to make our contribution to climate protection while at the same time ensuring the treatment and its quality.

Reliable local renewable power decarbonising offshore energy

Reliable local renewable power generation enables more environmentally and economically viable operations, to meet with the challenge of renewable energy intermittency and energy security. The Renewables for Subsea Power (RSP) project support targets towards Net Zero Targets by providing a full solution to generate low carbon, cost-effective, power and communications to remote locations in the offshore energy industry. The development of the RSP system is a collaborative project led by three UK-based companies in partnership with wider industry engagement from operators and the Aberdeen-based Net Zero Technology Centre. Carbon capture, utilisation and storage (CCUS) is set to play a key role in the energy transition. CCUS developments will incorporate all-electric subsea systems that can benefit from the RSP solution. This first of a kind integrated solution will contribute significantly to the generation of clean energy in the petroleum industry using a Wave Energy Converter and seabed battery energy storage for production control applications. The various applications that would benefit from the cost and CO2 savings from deploying the system, compared to traditional methods, include umbilical remediation, brownfield expansion, long offsets, CCUS, and Autonomous Underwater Vehicle residency. For CCUS projects key advantages are a specific design catered towards simplified controls architecture (e.g. electric controls), and the ability to offer an alternative to direct current fibre-optic from shore. A full system demonstrator deployment commenced in Feb-23 and has demonstrated system capability to power subsea equipment and an Autonomous Underwater Vehicle (AUV). Trials continue through 2024.

Travel Distance Between Participants in US Telemedicine Sessions With Estimates of Emissions Savings: Observational Study.

Digital health and telemedicine are potentially important strategies to decrease health care's environmental impact and contribution to climate change by reducing transportation-related air pollution and greenhouse gas emissions. However, we currently lack robust national estimates of emissions savings attributable to telemedicine. This study aimed to (1) determine the travel distance between participants in US telemedicine sessions and (2) estimate the net reduction in carbon dioxide (CO2) emissions attributable to telemedicine in the United States, based on national observational data describing the geographical characteristics of telemedicine session participants. We conducted a retrospective observational study of telemedicine sessions in the United States between January 1, 2022, and February 21, 2023, on the doxy.me platform. Using Google Distance Matrix, we determined the median travel distance between participating providers and patients for a proportional sample of sessions. Further, based on the best available public data, we estimated the total annual emissions costs and savings attributable to telemedicine in the United States. The median round trip travel distance between patients and providers was 49 (IQR 21-145) miles. The median CO2 emissions savings per telemedicine session was 20 (IQR 8-59) kg CO2). Accounting for the energy costs of telemedicine and US transportation patterns, among other factors, we estimate that the use of telemedicine in the United States during the years 2021-2022 resulted in approximate annual CO2 emissions savings of 1,443,800 metric tons. These estimates of travel distance and telemedicine-associated CO2 emissions costs and savings, based on national data, indicate that telemedicine may be an important strategy in reducing the health care sector's carbon footprint.

Modelling and analysis of heat pump integrated Photovoltaics-Wind systems for an agricultural greenhouse in Turkey

This study focused on modelling and analysing photovoltaics and wind systems to meet the heating demand of a commercial greenhouse. The aim is to evaluate technical, economic, and environmental performances of the related systems and to determine the optimum configuration. A novel approach was introduced by integrating hybrid energy systems with large-scale wind turbines and developing a dynamic heat transfer model. A large commercial greenhouse with an area of 26,640 m2 located in Izmir, Turkey was selected for considering Mediterranean climate, and a detailed heat transfer model of the greenhouse were developed considering heat transfers by convection, radiation, ventilation, and infiltration. A combination of air source heat pumps, photovoltaic panels and wind turbines were used for meeting the heating demand of the related greenhouse. Five different on-grid energy systems scenarios, namely (i) Photovoltaics-Heat Pump, (ii) Photovoltaics-Wind Turbine- Heat Pump, (iii) Wind Turbine- Photovoltaics- Heat Pump (iv) Wind Turbine- Heat Pump, and (v) only Heat Pump were considered. The system modelling with a detailed heat transfer analysis of the greenhouse was made by MATLAB. The energy analysis of the systems was performed on an hourly basis for one calendar year. The annual heating demand and the corresponding electricity consumption of the greenhouse were calculated as 497.37 and 114.07 kWh/m2, respectively. Net Present Value, Levelized Cost of Energy and CO2 savings were used to evaluate economic and environmental performances of the systems. Among five on-grid energy system scenarios, the first scenario, consisting of 5271 photovoltaic panels and 20 heat pumps, emerged as the most economically attractive choice with Net Present Value and Levelized Cost of Energy of $547,440.40 and 0.080146 $/kWh, respectively. Critical parameters affecting the economy of this scenario were found to be electricity prices, tomato yield, and photovoltaic panel prices. For environmental evaluation the fourth scenario, integrating wind turbines and heat pumps, achieves the highest CO2 savings of 2,064.73 tons due to increased renewable electricity production and lower life-cycle CO2 emissions of wind turbines compared to photovoltaic systems. This analysis enhanced the understanding of energy dynamics in greenhouse environments, contributing to the advancement of sustainable practices in agriculture.

Transforming Turkish electricity system in the context of circular economy and green deal: impacts on steel and agricultural production

ABSTRACT Two important but conflicting goals in Turkey’s energy policy have been ensuring energy security through increased indigenous energy resource utilization and meeting the 2053 net zero emission commitment. Based on this, this work explores emission mitigation pathways for Turkey’s electricity system through circularity approaches of CO2 utilization and framework material recycling (FMR). Using mathematical models, eight life cycle impact potentials are evaluated including global warming potential (GWP). The extended impact on steel and agricultural production was also examined in the Green Deal context. The circularity approaches investigated showed that the GWP of Turkey’s wind, solar, and lignite energy sources reduce from the base values of 7.3 gCO2eq./kWh, 29.5 gCO2eq./kWh and 1130 gCO2eq./kWh to 2.72 gCO2eq./kWh, 21.08 gCO2eq./kWh and 241.26 gCO2eq./kWh, respectively. Fifty percent recycling ratio is also determined as the optimum for CO2 utilization and FMR. With this ratio, 21.84% CO2 emission reduction corresponding to 0.083 GT annual CO2 savings is achieved in the Turkish electricity mix. The decarbonization of electricity results in 25.0% and 27.0% GWP impact reductions in the agricultural and steel sectors, respectively. Hence, the decarbonization of electricity mix can significantly ease the negative impacts of the Green Deal on Turkey’s economy. Additionally, promoting and increasing the share of renewable energy sources in the electricity mix can further enhance these environmental benefits.

LOW CARBON FOOTPRINT ALUMINIUM COMPONENTS FOR E-MOBILITY

In the fast-evolving E‐mobility transformation, the circular economy is one of the key factors to make Europe carbon neutral by 2050, together with sustainability, achievable only with a synergic approach, from raw material choice to recycling, through product design for re‐purposing. Secondary aluminium alloys have a twenty times lower carbon footprint than primary metals, leading to significant CO2 savings. Their properties can satisfy engineering targets through optimized product design. Adopting a smart system layout, in which functions are assigned to assemblies, some of the low‐end mechanical properties of secondary alloys can be offset. Design for easy disassembling can then guarantee a selective re‐purposing and, finally, an environmentally friendly recycling of components. Innovative products in this field have been developed and successfully produced by means of an optimized high-pressure die casting (HPDC) technology, adopting low carbon footprint raw materials supplied in alternative to ingot format. In this work, the characterization of a component for e-mobility has been conducted, evaluating both the characteristics of the scrap alloy used to produce the castings and the casting itself. The results demonstrate a fine and high-quality microstructure of the casting, proving the feasibility of the production process using exclusively scrap alloy.

An Opportunity for Coal Thermal Power Plants Facing Phase-Out: Case of the Power Plant Vojany (Slovakia)

The study deals with the possibilities of using alternative types of fuels to produce electricity. Power Plant Vojany (PPV) is a thermal power plant (TPP) in eastern Slovakia, which is part of the company Slovenské elektrárne, a. s. (SE). PPV primarily used black coal to produce electricity, which had to be imported from abroad (the Russian Federation). This activity has become inefficient both economically and environmentally, due to the high price of CO2 permits and the high emission factor of this type of fuel. PPV decided to co-combust biomass and refuse-derived fuel (RDF), which resulted in much better economic conditions due to their price, economic efficiency, and partly closed CO2 cycle. The aim of the paper is to explore the possibilities related to the production of energy in the cleanest possible way and with the least possible damage to the environment in coal thermal power plants using the example of operating Power Plant Vojany located in eastern part of Slovakia and to inspire each other for the modern transformation. For the purposes of hypothesis verification, analytical methods focused on overview studies of average fuel prices, comparisons, and the balance of fuels in connection with eliminated CO2 emissions, as well as municipal waste (MW) management in the EU and V4 countries, were used. The authors also focused on the energy recovery and combustion of MW and tracking the achieved CO2 savings in connection with the development of fuel sources in PPV. The results point to the fact that PPV is one of the power plants that could use biomass and RDF as fuel, which confirms the economic advantages of this procedure. The results confirm that the potential of RDF production in Slovakia is sufficient to ensure the operation of PPV at planned, even higher volumes of electricity production. The transformation to cleaner operation of coal thermal power plants represents a significant contribution of this study.

Renewable Energy Source (RES)-Based Polygeneration Systems for Multi-Family Houses

This research work synthetizes the energy, economic, and environmental aspects of a novel configurational analysis of four polygeneration schemes designed to fulfill the demands of a multi-family building that includes 12 dwellings. The design aims to meet the requirements (water, electricity, heat and cold air) from Renewable Energy Sources (RESs), in particular by selecting photovoltaic and photovoltaic-thermal panels, thermoelectric generators, and biomass as auxiliaries. Electricity is available from the grid, and no electrical storage is planned. Water and cooling may be produced by alternative technologies that configure the polygeneration alternatives. The case study is in Valencia, a coastal Mediterranean city in Spain. The Design Builder Clima estimated demand calculations, and the system performance was modeled in TRNSYS. Desalination was linked by using EES models. Results show that the suggested schemes offer substantial energy and CO2 savings. The innovative life-cycle analysis applied further enhances the cumulative CO2 savings across the four configurations if the impact of the installations is compared with the conventional external supply. The electric option (combining heat pump and reverse osmosis for cooling and desalination) emerged as the most appealing solution due to its reliability, lower investment cost, and environmental impact.

Suggestions and Solutions for Enhancing Active Commuting to the University of Maribor and Advancing CO2 Emission Reduction

This study investigated commuting behavior at four technical faculties (BCTF) in Maribor. The main aim was to provide suggestions and solutions for challenges related to active commuting to the BCTF, while promoting advancements in CO2 emission reduction. The research methodology was based on analyses of a questionnaire survey and calculations of CO2 emissions. The results indicate that implementing measures to promote walking, bicycling and the use of city and regional public transport, in conjunction with supportive housing and parking policies, has the potential to eliminate car trips within 0–1 km of the BCTF and reduce car trips from other zones in favor of active commuting by 30% to 50%. These proposed transport scenarios could lead to an annual reduction in CO2 emissions ranging from 17% to 29%. The greatest potential for CO2 savings is observed within 0–5 km of the BCTF, where a shift to walking and bicycling could reduce emissions by up to 44%. The results also highlighted a notable disparity, indicating that students with term-time accommodations emitted 3.5 times and 4.1 times less annual CO2 within 0–5 km of the BCTF compared to students and staff commuting daily from their permanent residences in the city.

Comparison of solar district heating and renovation of buildings as measures for decarbonization of heat supply in rural areas

In this study two different decarbonization strategies for rural heat supply are compared on the example of 180 buildings located in a small village in Germany with about 860 inhabitants and typically mainly old buildings, partly in half-timbered construction. The comparison shows that erection of a solar district heating system with solar fraction of about 67 % leads to similar heating costs as an energy efficient renovation followed by installation of decentralized air source heat pumps for most of the buildings. Both concepts aim to achieve a heat supply that is free from the local use of fossil fuels. While the solar district heating system can probably be realized within a few years and therefore achieves the full CO2 savings promptly, this would take decades for the implementation of energy efficient renovation and heat pumps due to low renovation rate. Reaching climate-neutrality for the heat supply could thus be accelerated significantly by the construction of a solar district heating system. Moreover, the two decarbonization approaches do not appear to be fundamentally mutually exclusive: subsequent steady renovation of connected buildings will either increase solar share in heat supply or enable connection of new consumers at similar solar coverage rate. However, it should be also noted that with solar district heating alone, not always the same thermal comfort as with reinforced building renovation is achieved.

Analysis and optimization of a hybrid system for the production and use of green hydrogen as fuel for a commercial boiler

This study analyzes a hydrogen-methane thermal power plant installed in a high school. In this plant, photovoltaic energy is used to produce hydrogen through two alkaline electrolyzers. The hydrogen is stored under pressure and utilized as fuel, mixed with methane in a commercial boiler for heating purposes. A digital twin of the hybrid system was developed, and simulations were conducted using Matlab/Simulink software. The study compares two possible system configurations: in the first one, the energy produced by the photovoltaic array is sufficient to meet the required amount of hydrogen throughout the simulation year; in the second one, the electrolyzers come into operation only when green electricity is available. For each configuration, several simulations were performed, considering variable sizes of the photovoltaic array, hydrogen storage capacity, and hydrogen-to-methane ratio to determine the optimal plant configuration from an economic perspective. Results indicate that, with current operating expense and capital expenditure costs, the system can achieve a payback time of 16 years with 100 % hydrogen combustion, provided the photovoltaic array and hydrogen storage subsystems are sized appropriately. In terms of environmental benefits, the optimized system configuration enables an annual CO2 savings of 155 tons.