Abstract

The flexible adjustment of the air conditioning system can help smooth the load curve and absorb renewable energy. However, the quantification of building air conditioning flexibility (Air-conditioning Virtual Energy Storage，AVES) is still in its early stages. This study takes the climate and architecture of Shanghai as an example to study the changes in VES characteristics of air conditioning under different fence structures. Based on regression analysis and correlation analysis, the main factors affecting the VES of air conditioning are analyzed and quantified. This study can provide theoretical reference for the study of flexible air conditioning regulation in specific regions.

Abstract

High-pressure environments have a significant impact on anaerobic oxidation of methane (AOM), increase in anaerobic methanotrophic euryarchaeota (ANME) growth rate at higher methane pressures. This study investigated the effect of temperature on the anaerobic methane-oxidizing and sulfate-reducing (AOM-SR) activities by a highly enriched ANME-2c community (high-pressure environments). The ANME-2c-enriched biomass was incubated at different temperature for 75 days. The most favorable condition for AOM-SR activity in the studied communities was set as the in situ temperature (4°C), suggesting that the studied ANME-2c is well adapted to conditions similar to those of its origins. Moreover, the dispersal process of the species is promoted by 4°C, whereas the symbiotic network is decreased.

Abstract

The coal-steam gasification method has been proven to be suitable for power generation. However, the low concentration of CO2 generated in the external coal combustion heating process causes significant CO2 capture energy consumption. As a carbon-neutral fuel, biomass combined with coal-steam gasification could contribute to a reduction in CO2 emissions. In this work, using the typical herbaceous biomass as the heating fuel, the energy efficiency and carbon emissions of the biomass-heating-coal-gasification power generation system (BHCG) are systematically studied. The results indicate that the coupling utilization of biomass and coal can significantly improve the emission reduction characteristics of fossil energy systems. In the no-carbon capture scenario, the power efficiency of BHCG is 50.66%, which is 5.31% higher than GE gasification power generation system. When the carbon capture process is introduced, the power efficiency of BHCG is 46.40% with -133.90 kg CO2/MWh. The biomass heating coal-steam gasification method can utilize the negative carbon utilization of fossil fuels and has high energy efficiency.

Abstract

Hydrogen is an ideal and potential energy carrier due to its high energy efficiency and low pollution. An alternative and promising approach to hydrogen generation is the chemical looping steam methane reforming (CL-SMR) over iron-based oxygen carriers. However, the process faces challenges such as high reaction temperature (>850°C) and low methane conversion. We demonstrate that Ni-mixed Fe-based oxygen carrier particles have significantly improved the methane conversion and hydrogen production rate in the range of 450-600°C under atmospheric pressure. The effect on the reaction reactivity of oxygen carrier particles with different Ni-based particles mixed mass ratios has been determined in the continuous unit. More than 85% of methane conversion has been achieved at 600oC, and hydrogen can be produced in both reduction and oxidation steps. Moreover, the iron-based oxygen carrier particles exhibited good cyclic performance during 150 consecutive redox cycles at 600°C. The mid-temperature iron-based oxygen carrier particles, integrated with a moving-bed chemical looping system, might provide a powerful approach toward more efficient and scalable hydrogen production.

Abstract

The bivalves in cold seep ecosystem can assimilate dissolves inorganic carbon (DIC) into their shell through extrapallial fluid (EPF) and methane through endosymbionts on their gills. Therefore, the DIC and methane released from cold seep can be decreased by the biological metabolism process of the bivalves, which can reduce such carbon enter into the atmosphere. Yet the contribution of cold seep bivalves are not considered hitherto. We choose three common bivalves from cold seep of South China Sea, Bathymodiolus platifrons, Gigantidas haimaensis, Archivesica marissinica and measure the carbon content as well as wet weight and dry weight. Comparing to five shellfish species the cold seep bivalves can store more carbon into their tissue. Combining the fact they feed on methane-oxidizing bacteria and sulfide-oxidizing bacteria, they can reduce the methane possibly released to the air. The Archivesica marissinica bivalves have the best carbon sequestration capacity for higher tissue weight.

Abstract

The process of methane anaerobic oxidation coupled with sulfate reduction promotes alkaline conditions and the formation of carbonate minerals in cold seep environments. The existing studies on microbial communities inhabiting carbonate rock surfaces in cold seep environments primarily revolve around in situ investigations. In this study, high-pressure enrichment cultivation was conducted using methane as the sole carbon source, and periodic monitoring of community dynamics was performed. The results revealed a selective increase in the abundance of the ANME-2c group, which is a typical type of microorganism in methane utilization, anaerobic oxidation, and the synthesis of other nutrients. Additionally, temperature was identified as a crucial factor influencing microbial populations and carbonate processes. Higher temperatures stimulated microbial metabolism, resulting in the production of acidic substances and extracellular hydrolytic enzymes, potentially leading to carbonate dissolution. Conversely, lower temperatures had minimal impact. These findings reveal the significance of methane metabolism and temperature in microbial community dynamics and carbonate kinetics in deep-sea environment.

Abstract

The proper scheduling of residential demand-side flexible resources, such as static batteries and flexible loads, is crucial for mitigating the impacts of intermittent and fluctuating residential rooftop PV generation on utility grids. Previous studies have often overlooked the benefits of different stakeholders involved in the optimal scheduling process. To address these gaps, this study proposed a comprehensive framework for the many-objective optimal dispatch of residential PV-battery-flexible load systems, considering the interests of users, grid operators, and governments. Specifically, a day-ahead optimal dispatch model with six objective functions relevant to the three stakeholders’ benefits was developed. The effectiveness of the framework was validated through case studies, which demonstrated a significant improvement in system performance compared to the maximizing self-consumption strategy. The proposed framework can provide valuable guidance for the optimal scheduling of residential PV-battery-flexible load systems in practice.

Abstract

Renewable energy will be globally implemented through energy carriers in the low-carbon energy system. This paper first analyzes the chemical properties of methanol, methane, and ammonia, and then constructs detailed models of solid oxide fuel cells and homogeneous compression charge ignition engines. The lifecycle technical efficiency of methane, ammonia, and a combination of methane and ammonia is 30.8%, 30.7%, and 28.5%, respectively. The specific electric energy costs for methane, ammonia, and methanol are 1.64 CNY/kWh, 2.47 CNY/kWh, and 3.04 CNY/kWh, respectively. Currently, E-methane is more favorable compared to both ammonia and methanol, both in terms of efficiency and carbon emissions. In the future, the fuel costs for methanol, methane, and ammonia could be reduced to at least 1.02 CNY/kg, 2.47 CNY/kg, and 0.9 CNY/kg respectively. The electricity cost based on a hybrid SOFC-ICE system will be comparable to coal power generation.

Abstract

Demand response is an effective method for achieving energy flexibility. By utilizing the thermal properties of the building envelope, energy shifting can be achieved by preheating. In this study, a simulation-based method was used to quantify the energy flexibility of residential buildings in Kitakyushu City, Japan. A rule-based control method was used to control the heating systems, resulting in different heat energy reduction ratio after preheating at different start time during the day. Then, k-means clustering analysis was performed on the energy reduction of different buildings during January. The optimal number of clusters was determined to be two based on the Calinski-Harabasz and Davies-Bouldin indices. The results of the clustering analysis showed that the energy reduction was significantly affected by the thermal insulation properties of the building envelope compared to the thermal mass. In addition, weather conditions also had a significant impact on energy reduction, with higher solar radiation and lower humidity contributing to a significant enhancement of energy reduction effects.

Abstract

Geochemical characterization of seafloor sediment porewater as a rapid response to methane seepage and its biogeochemical processes to document methane seepage characteristics. In this study, methane seepage and geochemical indicators in porewater were investigated for five stations in “Haima” Cold Seep in the South China Sea. The results showed that the methane release in different stations was quite different, with the methane diffusion flux ranged from 0.3 to 168.3 μmol/(m²·a). However, there were some similarities in the geochemical indicators for every station. Correlation analysis indicated that methane seepage was positively correlated with depth and PO43-, and negatively correlated with TS, K+, Na+, Mg2+, Mn2+, Fe3+, and NO2-. The PCA cluster analysis results were similar to the classification of habitat characteristics observed during sampling. Therefore, it may be possible to provide an indication of methane leakage through habitat characteristics in future studies.