Near-zero Carbon Research Articles

Assessment of the polygeneration approach in wastewater treatment plants for enhanced energy efficiency and green hydrogen/ammonia production

Wastewater treatment plants (WWTPs) offer opportunities to optimize resource utilization and enhance energy efficiency. This study provides a comprehensive analysis of using the polygeneration approach in WWTPs to reduce grid energy dependence, optimize energy distribution, and utilize surplus energy for hydrogen (H2) and ammonia (NH3) production. Several models were employed, including photovoltaic (PV) cells, parabolic trough collectors (PTCs), steam methane reforming, and polymer electrolyte membranes, to assess the feasibility of this approach. Three scenarios were evaluated and compared: Scenario 1 (Baseline) represents the current situation, Scenario 2 maximizes the Net Present Value (NPV), and Scenario 3 minimizes NH3 production costs. Real data from As-Samra WWTP in Jordan was used to accurately assess the feasibility of each scenario. The results show that Scenario 2 offers the highest profitability and efficiency, with a NPV of 87.48 million USD and an annual NH3 production of 15,417 tons, reducing both grid dependency and biogas fuel consumption. Both Scenarios 2 and 3 demonstrate the ability to meet thermal demands efficiently while generating significant revenue from NH3 production. Scenario 3, in particular, achieves competitive H2 and NH3 production costs. Environmentally, Scenario 2 significantly reduces annual greenhouse gas emissions by 12.66 kilotons of CO2eq, with near-zero carbon intensity for thermal energy due to solar reliance. In conclusion, the polygeneration approach offers a promising pathway for WWTPs to achieve greater sustainability, economic gains, and reduced environmental impact, providing valuable insights for decision-makers.

Decision-making method for low-carbon transformation technology in existing residential areas based on knowledge graph and scenario analysis methods

ABSTRACT Cities are the main contributors to carbon dioxide emissions, and communities are crucial for implementing urban low-carbon emissions. As a result of the controversies surrounding existing transformation technologies and the varying conditions faced by different targets for transformation, an effective method is required for application in specific target communities to achieve good carbon reduction effects. We propose a method that utilizes the knowledge graph and scenario analysis to systematically screen and evaluate community low-carbon technologies. First, a comprehensive knowledge map spanning multiple fields was constructed, and the correlations were analyzed using CiteSpace. Additionally, we categorized the transformation technologies into nine scenarios to assess their effectiveness and feasibility across different community contexts. Finally, the near-zero carbon emission community pilot area of Shenzhen City was selected as a case study, and the method was applied as a demonstration. The total carbon emissions of the pilot community were reduced by 43% after applying the proposed method. This method is helpful for technical screening at the low-carbon transformation stage and also provides a useful reference for the low-carbon construction stage of communities.

4-E comparative analysis of two novel chemical looping hydrogen generation-based systems with near-zero carbon emissions

To achieve the near-zero carbon emissions from chemical looping hydrogen generation (CLHG) power plant, two novel systems were proposed in this study: one integrates CLHG with ammonia decomposition for hydrogen production (ADHP) and CO2 hydrogenation to methanol (CHM), while the other integrates CLHG with CHM and CO2 compression storage (CCS). The performance of these two integrated systems was evaluated through analyses of economy, energy, exergy, and ecology (4E). The findings reveal that the CLHG-CHM-CCS system is more economically competitive and environmentally favorable than the CLHG-ADHP-CHM system. Its maximum net present value increases by 2.373×108 $, and annual CO2 emissions decreases by 361.401 t. Meanwhile, the system's profitable allowable maximum purchasing price of natural gas increases by 0.036 $/Nm3, while its minimum selling price of methanol decreases by 47.583 $/t. However, the CLHG-ADHP-CHM system exhibits improvements in both energy efficiency and exergy efficiency, with improvements of 1.88% and 2.34%, respectively, compared to the CLHG-CHM-CCS system. Moreover, reactors within the CLHG subsystem account for 42.60% of its total exergy loss, offering a potential 3.275 MW improvement.

Near-zero carbon emission power generation system enabled by staged coal gasification and chemical recuperation

Generating clean, efficient, and low-carbon electricity from coal is imperative for limiting the global temperature rise to 1.5 °C. This study presents a near-zero-carbon-emission power generation system that utilizes staged coal gasification. The innovation of this system is the division of coal gasification into two stages: intermediate-temperature pyrolysis, followed by high-temperature gasification. This process begins with utilizing waste heat from the exhaust of a gas turbine to drive the partial gasification of coal during pyrolysis. The nongaseous products from this stage are then completely gasified in the gasifier, and chemical recuperation is performed, in which heat from the syngas at the gasifier's outlet preheats the reactants at the inlet and aids in reforming pyrolysis gas. For CO2 capture, an oxyfuel combustion strategy is used. Our system produced net electricity and exergy efficiencies of 43.01 and 47.57 %, respectively, surpassing both pre-combustion CO2 capture systems based on staged coal gasification (improvements of 3.04 and 5.37 %, respectively) and coal-water slurry gasification (improvements of 3.55 and 5.8 %, respectively). Moreover, the carbon emissions from our system are approximately 90 g/kWh lower than those from these systems. Thus, this study offers an environmentally sustainable approach to utilizing coal that may facilitate achieving global environmental goals.

Biogas reforming as a sustainable solution for hydrogen production: Comparative environmental metrics with steam-methane reforming and water electrolysis in the Portuguese context

This study delves into the dynamics of hydrogen production, with a specific focus on biogas reforming (BGSMR) for hydrogen generation. It compares the environmental impact of this solution with hydrogen production from natural gas-steam reforming (NGSMR) and commercial electrolysis in the Portuguese context. Various metrics, including carbon footprint, water depletion, energy utilization, and waste valorization are employed for a comprehensive comparison. The assessment explores the impact of operational parameters and different off-gas combustion scenarios, incorporating water recycling practices. Due to challenges in obtaining detailed data on the actual reforming process, the study relies on process simulation techniques, primarily using DWSIM. Commercially available data for water electrolysers were used for comparison. In the context of decarbonizing power systems, hydrogen from water electrolysis emerges as a competitive option only in a scenario where the power system is 100% reliant on renewable sources, particularly with respect to the carbon footprint metric. Biogas systems, characterized by near-zero carbon emissions, stand out as a favourable option from the near future to the long run. This research contributes valuable insights into the dynamics of hydrogen production, shedding light on environmentally viable alternatives across a range of power system scenarios.

A Brief theoretical approach on Green Hydrogen Production

Many different technical techniques can be used to manufacture hydrogen from both renewable and nonrenewable feed supplies while reducing greenhouse gas emissions. Hydrogen is employed in upcoming low-carbon energy systems since it emits relatively little carbon. The bulk of the present green hydrogen activities are geared toward the possibility of a green hydrogen market. Green hydrogen and origin guarantees have been defined using various approaches. These vary according on the following: the carbon financial statements' characteristics; the emission threshold at which hydrogen is classified as green; the plan's feedstock and production techniques; and whether or not sustainable hydrogen must be produced through the use of renewable energy. To overcome obstacles and improve green hydrogen production's viability as a sustainable energy source, research is always moving forward. To hasten green hydrogen's integration into clean energy transitions and slow down global warming, research efforts are concentrated on increasing its efficiency, cutting prices, and broadening its applications. A study that focused on the near-zero carbon production method of green hydrogen by electrolysis using renewable energy sources underscored the advancements and prospects of this field of study. This article describes the current techniques for creating hydrogen from sustainable and renewable energy sources. Keywords: Green Hydrogen, Biomass, Efficiency, Renewable, Hydrogen production.

Environmental impact evaluation of low-carbon concrete incorporating fly ash and limestone

This work examines the environmental impact of low-carbon concrete that incorporates supplementary cementitious materials (SCMs). After reviewing near-zero carbon SCMs and low-carbon concrete, a life cycle assessment (LCA) was undertaken for concrete mix designs with normal-to-high compressive strengths, incorporating limestone and fly ash as cement replacements. The analysis includes relevant region-specific life cycle inventory parameters for raw materials, energy production, and transportation. A comparative assessment between embodied carbon emissions and the material mechanical performance is then made. The results of this paper indicate that incorporating limestone and fly ash in concrete can reduce carbon emissions, yet at a proportional decrease in mechanical properties compared to conventional cement concrete. The combination of cement and fly ash produced, on average, a higher strength concrete by 20.5% and lower CO2-eq values by 21.1% when compared to limestone cement blends. The CO2-eq emissions associated with transportation of the main constituents for concrete production were on average below 4% of the total CO2-eq per mix. In addition to eco-mechanical quantitative assessments, the study offers insights and recommendations for the development of concrete materials considering global resource availability of near-zero carbon concrete constituents.

Future of hydrogen in the U.S. energy sector: MARKAL modeling results

Hydrogen is an attractive energy carrier which could play a role in decarbonizing process heat, power or transport applications. Though the U.S. already produces about 10 million metric tons of H2 (over 1 quadrillion BTUs or 1 % of the U.S. primary energy consumption), production technologies primarily use fossil fuels that release CO2, and the deployment of other, cleaner H2 production technologies is still in the very early stages in the U.S. This study explores (1) the level of current U.S. hydrogen production and demand, (2) the importance of hydrogen to accelerate a net-zero CO2 future, and (3) the challenges that must be overcome to make hydrogen an important part of the U.S. energy system. The study discusses four scenarios and hydrogen production has been shown to increase in the future, but this growth is not enough to establish a hydrogen economy. In this study, the characteristics of hydrogen technologies and their deployments in the long-term future are investigated using energy system model MARKAL. The effects of strong carbon constraints do not cause higher hydrogen demand but show a decrease in comparison to the business-as-usual scenario. Further, according to our modeling results, hydrogen grows only as a fuel for hard-to-decarbonize heavy-duty vehicles and is less competitive than other decarbonization solutions in the U.S. Without improvements in reducing the cost of electrolysis and increasing the performance of near-zero carbon technologies for hydrogen production, hydrogen will remain a niche player in the U.S. energy system in the long-term future. This article provides the reader with a comprehensive understanding of the role of hydrogen in the U.S. energy system, thereby explaining the long-term future projections.

Hydrogen production system with near-zero carbon dioxide emissions enabled by complementary utilization of natural gas and electricity

The complementary utilization of different energy sources is a promising strategy for consuming excess electricity and improving system efficiency. In this study, complementary utilization of electricity and natural gas is proposed for a hydrogen production system based on chemical recuperation. The system uses electrolysis technology to convert excess electricity generated from intermittent and fluctuating renewable energy into green hydrogen. It also utilizes the by-product oxygen for oxy-fuel combustion to achieve near-zero carbon dioxide emissions after subsequent compression, transportation, and storage. The system uses natural gas for steam methane reforming to generate hydrogen. A portion of flue gas generated by the combustor is introduced into the reformer, replacing high-temperature steam for reforming with methane. In addition, the waste heat from the flue gas is introduced into the electrolysis cell to save electricity. Energy and exergy analyses of the proposed and reference systems were performed. The results revealed that the energy and exergy efficiencies of the proposed system are 81.20% and 73.29% at near-zero carbon dioxide emission, representing an improvement of 7.09 and 6.41 percentage points, respectively, compared to the reference system. It also appeared that 98.68% in situ oxygen consumption was achieved. The hydrogen mass flow generated by the proposed system is 33.83 kg/h, which is 8.78% higher than the 30.88 kg/h of the reference system. This study introduces a promising method for developing a hydrogen production system with high efficiency and near-zero carbon dioxide emissions.

Room-temperature photooxidation of low-concentration coalbed methane to methanol over CuOx/D-WO3 combined with gas-solid-liquid interface: From pollutant to clean fuel

Direct transformation of CH4 in low-concentration coalbed methane (LC-CBM) to clean fuel methanol is a more sustainable route as industrial CH4 transformation is usually energy-intensive. Solar-driven photocatalysis with near-zero carbon emissions can activate and transform CH4 at ambient temperatures, whereas the reported methanol productivities of traditional solid-liquid photocatalysis are still far from satisfactory. Herein, amorphous CuOx decorated defective WO3 nanocomposites (CuOx/D-WO3) were first synthesized and used as full-spectrum responsive photocatalysts for selective oxidation of LC-CBM to methanol. Introducing oxygen vacancies endows CuOx/D-WO3 with near-infrared (NIR) response. Loading CuOx boosts the separation of photogenerated charge carriers and the generation of ·OH via H2O2 reduction by photoelectrons on CuOx sites, confirmed by photoelectrochemical characterizations and in-situ XPS. Under simulated solar light irradiation, CuOx/D-WO3 exhibited significantly promoted activity of CH4 oxidation compared with the counterpart D-WO3. Even under NIR illumination, the optimal 3.0 % CuOx/D-WO3 showed a methanol production of 1.57 mmol·gcat−1 with selectivity of 79.8 %. Furthermore, a gas-solid-liquid triphase interface was constructed by immobilizing hydrophilic 3.0 % CuOx/D-WO3 on superhydrophobic carbon fiber paper (CFP) to promote methanol generation through strengthening CH4 mass transfer. This triphase photocatalysis exhibited a methanol production of 25.42 mmol·gcat−1, which was ∼4 times higher than solid-liquid diphase catalysis. Methanol selectivity of CuOx/D-WO3/CFP triphase photocatalysis was up to 95.3 %. It was mainly due to enhanced mass transfer of CH4 from gas phase to photocatalysts layer through hydrophobic-hydrophilic wettability abrupt interface of CuOx/D-WO3/CFP, which could be evidenced by significantly increased ·CH3 radicals from in-situ EPR spectra. This work broadens the avenue toward cleaner and efficient utilization of LC-CBM in a sustainable way.

Air change per hour improvement for positive and negative pressure mechanical ventilation facilities systems

Ventilation reduces indoor pollutants, and this issue has recently received attention. Most scholars adopt ventilation strategies to reduce energy consumption. While natural ventilation does not require ventilation facilities, it also brings many challenges, such as lack of external openings and insufficient air change per hour. Therefore, it is necessary to rely on mechanical ventilation to increase indoor air change per hour. However, mechanical ventilation comes with increased energy consumption, which poses a significant challenge to reducing energy usage at present.To improve energy usage, increase air changes per hour, and reduce the number of fans by half, we propose implementing positive and negative pressure ventilation indoors at the same airflow rate (3000 CMH). The research results showed that positive and negative pressure ventilation increased air changes per hour by 94 % and 62 %, respectively, while also reducing fan energy usage by 50 %. Through visualization, we also discovered the uneven distribution of indoor carbon dioxide levels. This breakthrough is of significant importance for current indoor mechanical ventilation systems and contributes greatly to future near-zero carbon emissions.

Effects of Injection Parameters and EHN Mixing on the Combustion Characteristics of Fueling Pure Methanol in a Compression Ignition Engine

As one of the most ideal alternative fuels for internal combustion engines, methanol can achieve near-zero carbon emissions. The main problem of methanol application in compression combustion engines is the phase lag caused by its poor combustion characteristics, but under low load conditions, the fuel activity can be improved by adding the cetane number improver EHN (Isooctyl nitrate), and the dependence on intake heating can be reduced to a certain extent. Based on a three-dimensional CFD simulation, the effects of methanol injection parameters and the addition of EHN on the combustion characteristics of a four-stroke exhaust turbocharged diesel engine were studied in this paper. With or without EHN, the increase in injection pressure and the advance in injection timing lead to an increase in the peak temperature, pressure, and heat release rate, as well as a shortening of the combustion duration. Adding EHN witnesses reduced requirements for methanol ignition, including a decreased peak temperature, pressure, and heat release rate, a significantly shortened ignition delay period, and an extended combustion duration, which thus results in a reduced indicated thermal efficiency. This study innovatively develops a 3D model of a compression combustion engine applicable to in-cylinder direct injection pure methanol fuel and EHN under small load conditions, which provides a reference for future research and development of small-load pure methanol compression combustion engines and has certain guiding significance.

Study on the Retrofit of Near-Zero Carbon Lighting in Existing Office Buildings

<p>在建築領域中，照明被視為能源消耗的主要貢獻者之一。透過適當的設計來降低照明需求，實現照明的能源效益，對於照明改造項目而言是一項至關重要的策略。本研究的目標是探討既有辦公建築中近零碳照明改造的評估方法。透過研究各燈具同時符合照度需求及能耗上限之面積-盞數對照圖，以及統計計算各對照圖之單盞服務面積，提供一種更快、更簡單和更準確的方法，用於既有辦公建築中的近零碳照明改造，最終降低改造成本。本研究顯示，在現有辦公建築中進行近零碳照明改造，有三種簡單直接的方法可以確定需要改造的照明設備數量，第一種為光通量計算法，第二種為模擬照度對照圖法，第三種則為單盞服務面積法。研究結果顯示，當在「112年度公有既有建築物能效評估補助作業及淨零示範計畫」中使用本研究提出的評估方法時，可以確保改造空間的照明需求和節能標準，實現快速而準確地確定所需的照明設備數量，從而降低整體改造預算。以該淨零示範計畫為例，整體照明改造預算可以減少60％，節省高達19,238,000元的費用。此外，對於使用LED照明設備進行現有辦公建築中的近零碳照明改造，本研究建議將其容許耗用能源標準（MEPS）值應訂為100lm/W以上，且改造之燈具應採用有節能標章的燈具，以確保改造既滿足節能要求，也滿足照度需求，從而實現近零碳照明改造的目標。</p> <p> </p><p>In the field of architecture, lighting is regarded as one of the primary contributors to energy consumption. Achieving energy efficiency in lighting through appropriate design is a critical strategy for lighting retrofit projects. The goal of this study is to investigate evaluation methods for near-zero-carbon lighting retrofits in existing office buildings. By examining area-lamp count charts that simultaneously meet illuminance requirements and energy consumption limits and statistically calculating the single-lamp service area for each chart, a faster, simpler, and more accurate method is provided for near-zero-carbon lighting retrofits in existing office buildings, ultimately reducing retrofit costs. This study demonstrates that there are three simple and direct methods for determining the necessary number of lighting fixtures to be retrofitted in existing office buildings for near-zero-carbon lighting retrofits. The first method is the luminous flux calculation, the second is the simulated illuminance chart method, and the third is the single-lamp service area method. The research results indicate that when the evaluation methods proposed in this study are applied in the "Energy Efficiency Assessment Subsidy Operation and Net-Zero Demonstration Program for Existing Public Buildings in the 112th Fiscal Year," they can ensure that the lighting requirements and energy-saving standards in retrofit spaces are met, allowing for a rapid and accurate determination of the required number of lighting fixtures, thus reducing the overall retrofit budget. Using the Net-Zero Demonstration Program as an example, the overall lighting retrofit budget can be reduced by 60%, saving up to 19,238,000 yuan. Furthermore, for near-zero-carbon lighting retrofits in existing office buildings using LED lighting fixtures, this study recommends setting the Minimum Energy Performance Standards (MEPS) value at 100lm/W or higher and using energy-efficient certified fixtures to ensure that the retrofit meets both energy-saving and illuminance requirements, thereby achieving the goal of near-zero-carbon lighting retrofits.</p> <p> </p>

Evidence for high-frequency oxygenation of Ediacaran shelf seafloor during early evolution of complex life

Increasing oxygenation of the early Ediacaran Ocean is thought to have been responsible for the emergence of early animals. Although geochemical studies have suggested periods of oceanic oxygenation in the Ediacaran, direct evidence for seafloor oxygenation has been lacking. Here, we report frequent occurrences of distinctive, sub-millimetric, and early diagenetic pyrite-marcasite rosettes in phosphorites from the lower Ediacaran Doushantuo Formation (Weng’an, South China). They typically consist of a nucleus of framboidal pyrite, a cortex of radiating marcasite blades intergrown with quartz, and a rim of second-generation pyrite, recording partial oxidative dissolution of pyrite and co-precipitation of marcasite and quartz. This inference is further supported by near-zero carbon isotope values of the host dolostone, similarly low sulfur isotope values for pyrite and marcasite, and evident Fe-isotope fractionation between marcasite and pyrite. Collectively, our findings reveal intermittent bottom-water and porewater oxygenation events, providing direct evidence of high-frequency oxygenation of Ediacaran continental shelves.

Modeling and analysis of air combustion and steam regeneration in methanol to olefins processes

Light olefins is the incredibly important materials in chemical industry. Methanol to olefins (MTO), which provides a non-oil route for light olefins production, received considerable attention in the past decades. However, the catalyst deactivation is an inevitable feature in MTO processes, and regeneration, therefore, is one of the key steps in industrial MTO processes. Traditionally the MTO catalyst is regenerated by removing the deposited coke via air combustion, which unavoidably transforms coke into carbon dioxide and reduces the carbon utilization efficiency. Recent study shows that the coke species over MTO catalyst can be regenerated via steam, which can promote the light olefins yield as the deactivated coke species can be essentially transferred to industrially useful synthesis gas, is a promising pathway for further MTO processes development. In this work, we modelled and analyzed these two MTO regeneration methods in terms of carbon utilization efficiency and technology economics. As shown, the steam regeneration could achieve a carbon utilization efficiency of 84.31%, compared to 74.74% for air combustion regeneration. The MTO processes using steam regeneration can essentially achieve the near-zero carbon emission. In addition, light olefins production of the MTO processes using steam regeneration is 12.81% higher than that using air combustion regeneration. In this regard, steam regeneration could be considered as a potential yet promising regeneration method for further MTO processes, showing not only great environmental benefits but also competitive economic performance.

Investigation on decontamination kinetics of metallic radionuclides in irradiated graphite by chlorination roasting

Irradiated graphite used as moderator and reflector material in reactor core in nuclear industry is an important radioactive waste after reactor decommissioning. Treatment of irradiated graphite waste has been a challenge for IAEA member states. Chlorination roasting was proposed in order to remove the metallic radionuclides in irradiated graphite waste. The promising advantages of the proposed method include that the category of graphite waste can be reduced with near-zero carbon emission, and it can lead to potentially the recycling of irradiated graphite and metallic radionuclides. The decontamination kinetics of metallic radionuclides was evaluated based on a lab-scale tube furnace combined with density functional theory (DFT). 56Fe ions were implanted into nuclear graphite to simulate metallic radionuclides derived by neutron radiation. Decontamination efficiencies of Fe at 900, 1000, 1100, and 1200 °C for the retention time of 210 min were 42.6%, 81.6%, 94.4%, and 96.7%, respectively. Fe could volatilize from graphite in the form of complex metal chloride with retaining a large amount of graphite inert matrix. The decontamination process was described by the second order reaction model. Through DFT evaluation, Fe was chlorinated via Fe → FeCl → FeCl2 reaction pathway. This decontamination process is efficient, cost-effective, and reliable, which provide a valuable contribution to managing irradiated graphite.

Study on optimal allocation of solar photovoltaic thermal heat pump integrated energy system for domestic hot water

In recent years, solar photovoltaic thermal heat pump has become a highly concerned near-zero carbon energy technology for domestic hot water. In order to facilitate the optimal configuration design of the system for domestic hot water, following studies were carried out in this paper: Firstly, the photovoltaic thermal heat pump integrated energy system was established and the operation study of the system was carried out. During the operation, the average coefficient of system heating performance was 2.76 in winter, 3.55 in transition season and 4.10 in summer. Afterwards, the prediction model of system operation performance was established and hourly system performance prediction of the system in the whole year was conducted. Then, the system for domestic hot water with a total installed photovoltaic capacity of 1 MW was taking as a case study to establish the calculation model. Finally, the optimal allocation of the system was carried out with the goal of minimizing the dynamic investment payback period, then the standard cell method was proposed to facilitate the optimal allocation design. The results showed that the minimum dynamic investment payback period of the system was 3.9 years and the daily hot water supply of the standard cell was 9.2tons.

Experimental Study on the Impact of Hydrogen Injection Strategy on Combustion Performance in Internal Combustion Engines.

Hydrogen is an ideal alternative fuel for internal combustion engines due to its fast combustion rate and near-zero carbon emissions. To further investigate the impact of the injection strategy on combustion performance under various excess air coefficients and loads, experimental methods were employed to systematically study injection timing, injection pressure, and dual injection. The results demonstrate that appropriately delaying hydrogen injection timing can improve the thermal efficiency by up to 2.6% and reduce NOx emissions of equivalent combustion by nearly 88%. While increasing the hydrogen pressure to 8 MPa does not directly enhance the thermal efficiency and emissions, it can reduce the injection pulse width by approximately 75%, allowing for more flexibility in delaying the injection timing. Delaying the secondary end of injection (SEOI) leads to a reduction of over 47% in NOx emissions for λ (excess air coefficient) values of 1.5 and 1.0. The combustion duration and ignition delay initially increase and then decrease with the delay in SEOI, depending on the movement state of the fuel jet. With the increase in secondary injection proportion (SIP), brake thermal efficiency increases by no more than 1%, but NOx is reduced by more than 43% for λ values of 1.5 and 1.0. In the case of ultralean conditions (λ = 2.3), increasing the SIP from 0 to 30% results in a nearly 14% increase in the peak heat release rate (HRR) and a 19% reduction in combustion duration.

The clinical use of stress echocardiography in chronic coronary syndromes and beyond coronary artery disease: a clinical consensus statement from the European Association of Cardiovascular Imaging of the ESC.

Since the 2009 publication of the stress echocardiography expert consensus of the European Association of Echocardiography, and after the 2016 advice of the American Society of Echocardiography-European Association of Cardiovascular Imaging for applications beyond coronary artery disease, new information has become available regarding stress echo. Until recently, the assessment of regional wall motion abnormality was the only universally practiced step of stress echo. In the state-of-the-art ABCDE protocol, regional wall motion abnormality remains the main step A, but at the same time, regional perfusion using ultrasound-contrast agents may be assessed. Diastolic function and pulmonary B-lines are assessed in step B; left ventricular contractile and preload reserve with volumetric echocardiography in step C; Doppler-based coronary flow velocity reserve in the left anterior descending coronary artery in step D; and ECG-based heart rate reserve in non-imaging step E. These five biomarkers converge, conceptually and methodologically, in the ABCDE protocol allowing comprehensive risk stratification of the vulnerable patient with chronic coronary syndromes. The present document summarizes current practice guidelines recommendations and training requirements and harmonizes the clinical guidelines of the European Society of Cardiology in many diverse cardiac conditions, from chronic coronary syndromes to valvular heart disease. The continuous refinement of imaging technology and the diffusion of ultrasound-contrast agents improve image quality, feasibility, and reader accuracy in assessing wall motion and perfusion, left ventricular volumes, and coronary flow velocity. Carotid imaging detects pre-obstructive atherosclerosis and improves risk prediction similarly to coronary atherosclerosis. The revolutionary impact of artificial intelligence on echocardiographic image acquisition and analysis makes stress echo more operator-independent and objective. Stress echo has unique features of low cost, versatility, and universal availability. It does not need ionizing radiation exposure and has near-zero carbon dioxide emissions. Stress echo is a convenient and sustainable choice for functional testing within and beyond coronary artery disease.

Energy consumption characteristics and rooftop photovoltaic potential assessment of elevated metro station

The current trend of urbanization has spurred the growth of the urban railway transportation sector, leading to increased carbon emission and environmental challenges. Applying renewable energy assisted power supply systems into metro stations is a feasible method for achieving decarbonization in urban transit systems. This study comprehensively reveals the real energy profile of a metro station on an hourly scale and establishes a multi-objective model to investigate the energy flexibility of the metro station with integrated battery energy storage for on-site renewable electricity consumption maximization. The results show that the elevated station has a photovoltaic potential of 20 %–25 %, in terms of self-sufficiency rate, when the rooftop of the station is fully utilized for photovoltaic array installation. Moreover, a photovoltaic-battery system in addition to a multi-objective mixed inter linear programming model is presented for the circumstance, there existing idle land around the station, to achieve a near-zero carbon station. It is indicated that the near-zero carbon station can be achieved with a minimum payback period of 11.5 years by optimizing the photovoltaic array size and battery storage capacity, leading to the annual carbon emission reduced from 457.1 to 91.4 tons. It is anticipated this study could provide reference for clean electrification and decarbonization in urban metro system.