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Utilizing the thermal stratification of reservoirs to obtain cold water for cooling green data centers (GDCs) is a new mode of energy conservation and emission reduction. However, global warming is expected to alter this phenomenon in deep reservoirs and thus may affect the digitalization process. While the frequency and intensity of extreme climate (EC) events are increasing under a changing climate, the impacts of these highly destructive events on thermal stratification and the related cascading effects on GDC cold-water supplies are still unclear. A two-lateral-dimensional thermohydrodynamic model was established to determine the characteristics of reservoir thermal stratification changes and its potential water environment impacts based on the heat extreme experienced by the Jinshuitan Reservoir, a large, pumped storage power station (PSPS) with a GDC in southeastern China. Fourteen different PSPS inlet/outlet schemes under 2 climate scenarios were designed, and two new indexes, namely, the risk index of cold-water shortage and the index of thermal stratification, were proposed to explore the impact of extreme climates on GDC water extraction. The results showed that compared to the present climate conditions, the reservoir experienced stronger thermal stratification with a 20.6 % average increase in thermal stability, a longer thermal stratification duration with a transitional trend from seasonal to permanent stratification, and a thinner cold-water layer with a 15-m average decrease. Changes in the thermal stratification of reservoirs under EC conditions will benefit some species, such as diatoms (except for early July and the period from mid-August to early October), green algae and cyanobacteria and the migration of warm-water fish, but adversely impact dissolved oxygen, diatoms and cold-water fish. Furthermore, the risk of cold-water shortages under EC conditions was consistently greater than that under average climate (AC) conditions (traditional assessment) when the elevation of pumped storage intake/outlet was less than 145 m. According to the traditional assessment method, the intake/outlet elevation of pumped storage reservoirs resulted in a 60.27 % increase in the risk of cold-water shortages during climate extremes. Furthermore, the demand for green cold-water withdrawal and optimal pumped storage power generation benefits were met when the PSPS intake/outlet elevation was 145 m. Beyond solving this specific case, this study elucidates the importance of linking the thermal stratification and data center of cold-water withdrawal to ECs. These findings provide new insights for increasing climate change resilience. [Display omitted] [ABSTRACT FROM AUTHOR]

Spatiotemporal variations of ozone (O 3) taken from the Copernicus Atmosphere Monitoring Service (CAMS) and the second Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) were intercompared and evaluated with ground and ozone-sonde observations over China in 2018 and 2019. Intercomparison of the surface ozone from CAMS and MERRA-2 reanalysis showed significant negative bias (CAMS minus MERRA-2, same below) at Tibetan Plateau of up to 80 µg/m3, and the average R 2 was about 0.6 across China. Evaluated with the ground observations from China National Environmental Monitoring Center (CNEMC), we found that CAMS and MERRA-2 reanalysis were capable of capturing the key patterns of monthly and diurnal variations of surface ozone over China except for the western region, and MERRA-2 overestimated the observations compared to CAMS. Vertically, the CAMS profiles overestimated the ozone-sonde from the World Ozone and Ultraviolet Radiation Data Center (WOUDC) above 200 hPa with the magnitude reaching up to 150 µg/m3, while little bias was found between the reanalysis and observations below 200 hPa. Intercomparison drawn from the vertical distribution between CAMS and MERRA-2 reanalysis showed that the negative bias appeared throughout the troposphere over China, while the positive bias emerged in the upper troposphere and lower stratosphere (UTLS) with high order of magnitude exceeding 100 µg/m3, indicating large uncertainties at higher altitudes. In summary, we concluded that CAMS reanalysis showed better agreement with the observations in contrast to MERRA-2, and the large discrepancy especially at higher altitudes between these two reanalysis datasets could not be ignored. [Display omitted]. [ABSTRACT FROM AUTHOR]

Recently, more and more global attention has been paid to data centers' energy consumption and climate impact. Serving as the backbone of the digital world, the energy and carbon-intensive data centers have to find a green expansion way to fulfill their obligations in building a carbon-neutral society. Therefore, this paper proposes a net-zero carbon operation oriented data center expansion scheme for the central government to formulate incentive policies. The economic expansion model minimizes newly established data centers' investment and electricity consumption costs. Geographical location, on-site renewable utilization, and green certificate purchase are integrated and considered to achieve net-zero carbon operation by reducing total electricity consumption, increasing green power consumption, and offsetting inevitable carbon emissions. A case study in China is conducted, and results under different geographical location scenarios, power supply mix scenarios, and green certificates market scenarios are analyzed and compared. It is found that the zero-carbon operation of new data centers mainly relies on clean main-grid power, but a more decentralized layout and a provincial green certificate market can increase the contribution of on-site renewable energy. Lastly, four detailed policy implications for stimulating China's data center expansion are discussed. • A data center expansion scheme considering net-zero carbon operation is proposed. • Expansion model minimizes newly established data centers' expansion costs is built. • Three measures are integrated to achieve data centers' net-zero carbon operation. • Case study in China is conducted and core findings and key implications proposed. [ABSTRACT FROM AUTHOR]

• Combined macro-level CO 2 models with empirical data for a holistic carbon emissions view in China's data centers. • Identified expansive computing scale as a primary driver for CO 2 emission surge across Chinese provinces (2017–2021). • Projected tripling of data center CO 2 emissions by 2050, reaching 430 million tons if trends persist. • Demonstrated 'net-zero emissions' strategy's potential to restrict 2050 CO 2 emissions between 11 and 29 million tons. Increased emissions related to China's burgeoning digital economy pose significant challenges. Using a Kaya–LMDI model, this study investigates the driving factors of data-center CO 2 emissions in China from 2017 to 2021, highlighting the roles of computing scale, energy intensity, power usage effectiveness, and emission intensity. We find a marked increase in emissions across various Chinese provinces, largely driven by computing scale. While projections suggest that data-center emissions could reach 430 million tons by 2050 (three times greater than 2021 levels), such emissions could potentially be reduced to 11–29 million tons under the "net-zero emissions" scenario. Highlighting the need to mitigate data-center emission intensity, our findings underscore the recalibrations in operational methods, technology, and energy sourcing needed to expedite the transition to net-zero emissions. [Display omitted] [ABSTRACT FROM AUTHOR]

• The two sets of switch conditions and three working modes for the unit applied to data center was proposed. • The energy-saving ratio of the unit in the actual data center for the whole year in China was simulated by DeST. • The energy consumption characteristics and its influencing factors of the unit were investigated. To reduce the power consumption of the cooling system in the data center effectively, a prototype of the integrated cooling unit with rotary booster and compressor was developed, and the operating characteristics were tested comprehensively according to its cooling requirements throughout the year. A data center model reflecting the characteristics of energy consumption and environmental requirements was established, the energy consumption characteristics and influencing factors of the model data center when the integrated unit was used to meet its yearly cooling requirements in the typical climate zones in China were simulated by DeST software based on the measured characteristics of the integrated cooling unit. The results showed that compared with the traditional computer room air conditioner, the energy-saving ratio of the integrated system can be as high as 39.55% for the whole year, and the energy-saving effect is remarkable. The energy-saving potential of the integrated unit becomes more significant while the heat transfer coefficient of the envelope structure becomes larger, and the load rate of IT equipment and the annually-averaged ambient temperature lower. [ABSTRACT FROM AUTHOR]

• Performances of present water source heat pump (WSHP) unit were compared. • Three types of WSHP heating system using data center waste heat are proposed. • Thermal and energy characteristics of three proposed systems were studied. • Matching rule of data center waste heat, ending user and WSHP system is obtained. The number and scale of data centers (DCs) in China are constantly expanding with the advancement of networking and informatization. A large amount of waste heat is dissipated at its end. If this waste heat can be recovered, then achieving carbon neutrality in DCs can be effectively accelerated. At present, water source heat pump (WSHP) are widely used in air-cooled and liquid-cooled DCs of different sizes for waste heat recovery. This study analyzes the equipment type and heating capacity of different brands of WSHP units. Three WSHP heating systems are proposed according to the different locations of waste heat enhancement (SE, TDE, UE). The coupling and matching relationship between user-side heat load demand, DC waste heat load, and energy efficiency of WSHP units under different systems is also investigated. Moreover, the law of energy consumption and energy efficiency changes is analyzed. Thus, this study provides a reference for the DC waste heat recovery system design and equipment development. The results show that the coupling matching relationship between user-side heat load demand, DC waste heat load, and heating COP of WSHP units is Q. N / Q. S = C O P ′ / C O P ′ - 1 = φ , where φ ranges from 1.1962 to 1.3642. The heating COP of the SE system is the greatest when user-side heat load demand is between 0 and 120 kW. The heating COP of the TDE system is the highest when the user-side heat load demand is between 1750 and 70000 kW. Furthermore, the heating COP of the three WSHP heating system types is related to unit brand when user-side heat load demand is between 120 and 1750 kW. [ABSTRACT FROM AUTHOR]

Multiple geographically dispersed data center buildings have been increasingly positioned in renewable-rich areas due to their high energy consumption. This paper proposes an optimal multi-energy portfolio for zero carbon data center buildings in the presence of proactive demand response programs. In the data center buildings, the complementarities of hydro-solar-wind hybrid renewable energy sources (RESs) are fully exploited via multi-energy conversion and storage devices, which are modeled as 100% renewable energy hubs for zero carbon multi-energy supplies. In order to exploit the hub-internal operational dispatchability and flexibility, a comprehensive energy consumption model of data center buildings is proposed to facilitate the demand response in terms of available serves, while the variable speed pumped storage (VSPS) is modeled to capture its dynamic operational characteristics. The energy‑carbon production, conversion, storage, and consumption are formulated as an energy‑carbon matrix, which are solved via a two-stage method to obtain the optimal portfolio. Case studies on southwest China data center buildings are implemented to demonstrate the effectiveness and superiority of the proposed methodology on cost-effective accommodation of RESs. Simulations results show that the system portfolio cost can be reduced by at most 17.8% with a higher operational flexibility. • A cost-effective data center building is proposed to accommodate zero carbon targets. • Hydro-solar-wind 100% renewables are formulated for multi-energy supplies. • VSPS and data center energy consumption are modeled to exploit inherent flexibility. • The energy-carbon production, conversion, storage, and consumption are optimized. [ABSTRACT FROM AUTHOR]

With the increasing penetration of renewables, load flexibility is crucial to balance the power system in China. Data centers are rapidly growing energy consumers and their flexible operations could make them a potential source of load flexibility. However, there have been no large-scale attempts to apply this concept in China. This paper utilizes a hybrid research method to explore the flexibility potentials, identifying key technical, financial, policy, and institutional barriers. The study quantifies the flexibility potential of data centers in China and provides solutions for addressing the identified solutions. • A hybrid research method of literature review, questionnaire, and semi-structured interviews is employed. • Potentials, barriers, and possible solutions for data centers in China to provide flexibility are analyzed in four parts. • Power flexibility potentials of data centers in China is quantified. [ABSTRACT FROM AUTHOR]

In recent years, water-side free cooling has been broadly applied in data centers to lessen the high cost of energy consumption. The energy-saving opportunities of free cooling have been recognized by numerous studies across the world. In this paper, the field test and energy performance evaluation were performed in an operational data center with water-side free cooling, located in Chongqing, China. Existing problems were found during tests, including the insufficient cooling capacity of towers in wintertime and the inability to activate partial-free cooling. The results of the tests show that the reduction in Power Usage Effectiveness (PUE) is much lower than the expected. To understand the marked discrepancies, the performance of the cooling tower was discussed in terms of the approach temperature and actual cooling capacity. The maximum cooling capacity in winter is only about 50 % of the rated. With the consideration of the cooling tower configuration performance in different climate conditions, the conservative energy effects were calculated in 34 provincial cities of China. To prolong the hours available, optimized operation schemes of cooling towers are presented. The available hours for free cooling could be increased from 730 h to 1300 h when operating at 67 % of rated flow rate, resulting in a decrease in the energy saving of chillers between 8.44 % and 21.05 %. [ABSTRACT FROM AUTHOR]

Serving as the information backbone of an increasingly digitalized world and energy-intensive, the data center industry has to seek low-carbon developing way to properly meet the rapidly rising service demand. This paper designs 45 kinds of configuration choices for each decision units by integrating three data centers, three cooling technologies, as well as five energy supply mixes. The model is formulated as a bi objective optimization problem for the decision maker to decide newly established data location and configuration with objective of reducing data center expansion costs and well as minimizing power utilization associated with carbon emissions from a country level. The pilot study in China under the scenarios of different carbon emissions limitation and propagation delay that China can reduce at least 25% of newly established data center related emissions from 2020 to 2023. It further shows that future expansion can be focus on Inner Mongolia and Ningxia for the north, Hubei for the middle, and Yunnan and Guangxi for the south. This paper provides a fresh perspective and makes a valuable attempt at the low-carbon development of data centers. • Carbon awareness based integrated optimization model for data center in China is proposed. • Layout, scale, cooling technology and power supply mix are simultaneously considered. • 25% of newly established data center electricity related emissions in China can be avoided. [ABSTRACT FROM AUTHOR]

It is important to cool data centers for improving IT equipment reliability through indoor temperature control. The air conditioning energy consumption is almost 38% of the total energy consumption. Free cooling in cool days is a promising technology for energy conservation. A pump-driven loop heat pipe (PLHP) system for free cooling was developed and installed in a data center project, which has a high energy efficiency ratio (EER) compared to air conditioners. The running performance of the PLHP system in the case project was tested and studied. The fitting rule of EER and outdoor temperature was obtained. The hourly energy savings and payback periods of the PLHP system for different cities of different climate regions in China were analyzed basing on the fitting formula compared to air conditioners. A national distribution map was developed to show the annual energy saving ratio in China. Results show that the PLHP system provides remarkable energy savings and the indoor temperature is remained at 18°C to 25°C. About 74.2% of Chinese cities lie in regions suitable for applications, and the annual energy saving ratio is over 30%. The average payback period for most cities in China is about 3.9 years. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is to research energy efficiency by using free cooling in data centers. The upper limit of wet bulb temperature of free cooling is obtained and the recommended value is 16 ℃ in the way of indirect cooling by open cooling tower. The concept of sensitivity of the natural cold resource is proposed for the first time. The natural resource utilizing potential of main climate zones of China is analyzed. The analysis indicates that natural resource utilizing ratio is over 50% in most regions. The improvement of the upper limit of wet bulb temperature is most beneficial to Moderate area. Finally, a data center in hot-summer and warm-winter region is analyzed. The results show that the annual synthesized COP value increased by 23.7% and the energy saving rate is about 19.2% after full use of free cooling. [ABSTRACT FROM AUTHOR]

The high energy consumption of data centers (DCs) has become a global issue that needs to be addressed, and as a result, their development of green rating systems (GBRSs) has been widely emphasized. Although GBRSs have been the subject of many studies for various building types, there has been few studies for DCs. This is the first study to comprehensively analyze GBRSs for DCs. The study established nine categories of standardized overall indicators and seven categories of standardized energy indicators, and furthermore reformatted and aligned the GBRS items accordingly. The study first compared GBRSs for DCs and other non-residential buildings to find out main concerns for a green DC, second compared different GBRSs for DCs to identify regional differences, and finally investigated GBRSs for DCs in China where digital infrastructure is booming. Power usage effectiveness (PUE) as a key indicator of DC energy efficiency was further analyzed. The results highlighted the importance of energy related criteria to DCs and discussed how to use the assessment criteria to appropriately guide and promote green DCs in future work. It also discussed the constraint for energy efficiency in DCs and the best practices that should be encouraged in the category of Innovation for green DCs. This study fills the gap in existing studies of GBRSs for DCs and contributes to the development of green buildings and the refinement of assessment criteria in DCs. [ABSTRACT FROM AUTHOR]

Immunization Information Systems (IIS) are computerized population-based systems with individual-level vaccination-related information used to help ensure protection from vaccine preventable diseases. The Chinese Center for Diseases Control and Prevention (China CDC) conducted a survey of the 32 mainland China provincial CDCs to determine IIS coverage and implementation of key functions: individual vaccination records, vaccine management, cold-chain management, and school entry vaccination status verification. Twenty-seven IISs collectively managed 252 million immunization records, 43.8% for children under 6 years; 20 could exchange records with other IISs. The within-province duplicate-record rate varied from 0.3% to 4.0%, but compared with National Statistical Bureau's census estimates, 138.0% of births from 2012 to 2017 were represented in the IISs, implying significant across-province record duplication. China CDC should consider developing a national-level IIS center for data exchange and analysis. [ABSTRACT FROM AUTHOR]

The volume of landfill gas (LFG) produced during municipal solid waste (MSW) decomposition in local landfills has increased rapidly in recent years. To promote circular economy (CE) applications through resource recovery, this article investigates the feasibility of utilizing LFG as a sustainable energy to power data centers (DCs) in Xiamen (China) and evaluates the implications of waste heat reuse on the energy consumption of DC. The objective of this study was to investigate the environmental impacts and economic benefits of this scheme based on a SFC model. With respect to its novelty, LFG is utilized as an energy supply to DCs, while the waste heat generated in the energy production is recovered. The socio-economic benefits generated in this process are also elaborated. It was found that a large number of MSW was completely recycled to generate energy. The LFG enterprise could benefit from energy sale, while the energy satisfied the annual demand for DC power consumption. Utilizing this energy output resulted in the reduction of primary energy and less CO₂ emissions. By reusing the waste heat for domestic heating, the energy efficiency could be improved, while primary energy could be further saved, avoiding more CO₂ emissions. This implies that utilizing LFG output and waste heat to power DCs not only facilitate resource recovery from unused resources to improve energy efficiency and obtain socio-economic benefits, but also promote the digitalization of DCs and sustainable development of urban cities in the framework of CE. [Display omitted] • LFG can be used to power data centers (DCs) in order to promote CE. • The recovery of waste heat from LFG generation reduced CO 2 emission of 8.46 × 108kg. • Within 15 years, 4.97 × 10 10 kg of MSW can generate 4.65 × 109 kW ⋅ h of electricity. • The recovery of waste heat benefited landfill operators and DC firms financially. [ABSTRACT FROM AUTHOR]

Loop thermosyphon system is an efficient cooling system for energy saving in data center. It is necessary to investigate the performance of the loop thermosyphon system filled with alternative refrigerants to prompt its application. In this paper, a R32 loop thermosyphon system is experimentally investigated in an enthalpy difference laboratory for its performance. R22 and R134a are also used for comparison. The results show that the optimal filling ratio of R22, R134a and R32 is the same (37.3%). At the optimal filling ratio, the flow stability of R32 is obviously better than those of R22 and R134a. When cold water temperatures are 10–22 °C, the cooling capacity of R32 is 5.4–15.6% higher than those of R22 and R134a. After controlling extractor fans, the energy efficiency ratio of R32 is 4.9–206.6% higher than those of R22 and R134a. Moreover, the free cooling potentials of the three refrigerants in five typical climate cities across China are analyzed and compared. Compared with R22 and R134a, R32 has 3.6–11.0% and 18.5–26.7% higher free cooling percentages and annual energy efficiency ratio, respectively; and its annual average partial power usage effectiveness is 0.0012–0.0017 lower than that of other two refrigerants. [ABSTRACT FROM AUTHOR]

• K-means clustering was used to map diurnal cycles of precipitation amount. • Precipitation events with different durations were mapped separately. • Results can characterize regions of irregular shapes and show more spatial details. • Regional characteristics of diurnal cycles of precipitation in China were revealed. The diurnal cycle of precipitation is a fundamental mode of climatic variability. Based on an hourly 0.1° × 0.1° gauge-satellite merged precipitation dataset, which is provided by the China Meteorological Data Service Center, this study used the K-means clustering algorithm to map the diurnal cycles of precipitation in summer over China. The obtained maps can objectively delineate irregular regions with similar patterns of diurnal cycles, and many of these regions resemble large-scale geomorphic units such as the North China Plain and the valley of the Yarlung Zangbo River, which verifies the importance of macroterrain for diurnal cycles of precipitation. In addition to total precipitation, precipitation events with different durations, which are often related to different types of precipitation (e.g., convective precipitation and stratiform precipitation), were analyzed separately. Compared with the previous studies using predefined region boundaries, the main advantage of this study is that the obtained maps can show more spatial details, through which we can get intuitive and in-depth understandings of the regional characteristics and spatial patterns of the diurnal cycles of precipitation over China. [ABSTRACT FROM AUTHOR]

In the era of big data astronomy, next generation telescopes and large sky surveys produce data sets at the TB or even PB level. Due to their large data volumes, these astronomical data sets are extremely difficult to transfer and analyze using personal computers or small clusters. In order to offer better access to data, data centers now generally provide online science platforms that enable analysis close to the data. The Chinese Virtual Observatory (China-VO) is one of the member projects in the International Virtual Observatory Alliance and it is dedicated to providing a research and education environment where globally distributed astronomy archives are simple to find, access, and interoperate. In this study, we summarize highlights of the work conducted at the China-VO, as well the experiences and lessons learned during the full life-cycle management of astronomical data. Finally, We discuss the challenges and future trends for astronomical science platforms. [ABSTRACT FROM AUTHOR]

In data centers, a large number of IT sever racks with different heat dissipation rates are arranged in multiple rows, leading to much higher per-unit heat release and therefore more uneven temperature distribution than in general buildings. This paper chooses a small-scale data center located in China to analyze the thermal environment for the operation of these critical equipments. The wind speed and temperature in the data center were measured, and a corresponding computer room model was established via computational fluid dynamics (CFD) simulation software. Based on it, the characteristics of flow field and temperature field of the data center were analyzed. The optimization methods for problem of uneven temperature distribution and chaotic air supply in the data center were proposed and verified by evaluation index. Furthermore, the return temperature index(RHI) increased from 0.918 to 0.93, the return heat index(RTI) increased from 0.222 to 0.342. • The thermal environment of a small-scale data center in Wuhan, China was measured. • The data center model was established via numerical simulation software. • The optimized schemes for the thermal environment in the data center were proposed. • Optimization of data center can provide reference for construction and operation. [ABSTRACT FROM AUTHOR]

• An overview of utilization of mined underground space over the world is presented. • Classification, development, advantages and identification of mined underground space are explored. • Future demands for mined underground space and directions of development and utilization are discussed. The mined underground space is formed by the exploitation of resources and minerals. On the basis of review analysis of experiences of utilization of mined underground space over the world, suitable conditions of surrounding rocks for mined underground space are clarified to various functions of development and utilization of mined underground space. A method is proposed for identifying and estimating the scale of mined underground space, and this is used to obtain an estimate of the volume of available underground space in mines in China and to construct distribution maps of mined underground space available in the country. In order to improve comprehensive utilization of mined underground space, combined with current foundation of underground space utilization and future strategic demands, nine types of functional utilization are proposed systematically, including underground pumped-storage power stations, deep underground medicine and rehabilitation, the storage of strategic energy and resource reserves, underground data centers, domestic and industrial waste disposal, intelligent vertical parking systems, cutting-edge scientific facilities, underground agriculture, and underground ecological cities. [ABSTRACT FROM AUTHOR]