Integrated Intelligent Energy

Strategic positioning of solar thermal power generation to promote technological progress

WANG Zhifeng, HE Yaling, KANG Chongqing, WANG Weisheng, DU Fengli

2021, 43(11): 1-4. doi:10.3969/j.issn.1674-1951.2021.11.001

Asbtract ( 557 )

HTML ( 10)

PDF (913KB) ( 380 )

References | Related Articles | Metrics

Being of high security, excellent power quality, large scale of energy storage and capability of bi-directional grid connection, the Concentrating Solar Power（CSP） technology is irreplaceable on the path to carbon peak and carbon neutrality. It will be the central pillar of the new power system construction taking new energy as the main body. After nearly 20-year growth, China's CSP industry is highly developed with a complete industrial chain. The localization rate of equipment for domestic projects in operation has exceeded 90%, which meets the requirement for large-scale application. By analyzing the breakthroughs of CSP technologies,significant cost reduction due to the scaling up of the industry,promotion of CSP industry made by the bundling of PV power, wind power and solar thermal energy on electric market, relevant proposals are put forward.

Background and routs of carbon neutrality and its nature-derived thermal solutions

LI Yang, WANG Heyang, WANG Yongzhen, ZHAO Jun

2021, 43(11): 5-14. doi:10.3969/j.issn.1674-1951.2021.11.002

Asbtract ( 320 )

HTML ( 7)

PDF (3912KB) ( 295 )

Figures and Tables | References | Related Articles | Metrics

Human activities have been the key inducement of global climate change, especially global warming, since industrialization. This has become the consensus of the scientific community in the world. Low-carbon energy, carbon emission reduction, carbon cycle and carbon storage are the four main technical routs for carbon peaking and carbon neutrality. In order to measure the contribution of different technologies to carbon neutrality accurately, 76 specific carbon reduction technologies given by the international organization Project Drawdown are analysed. The results show that carbon emission reduction related technologies will play the most important role; change of human behaviour will exert a greater impact than technological progress; the contributions of nature-derived technologies and thermal energy related technologies on carbon emission reduction potential are 45.9% and 35.5%, respectively. Then, based on the important role of nature in carbon cycle and abundant reserves of natural thermal energy resources in China, the concept of "nature-derived thermal solutions for carbon neutrality" is proposed, and its advantages are analysed by using underground heat storage as an example.

Status quo and prospects of geothermal energy in heat supply

WANG Guiling, YANG Xuan, MA Ling, ZHOU Jiaqi, SHEN Guohua, WANG Wanli

2021, 43(11): 15-24. doi:10.3969/j.issn.1674-1951.2021.11.003

Asbtract ( 410 )

HTML ( 18)

PDF (15363KB) ( 291 )

Figures and Tables | References | Related Articles | Metrics

The energy consumption in construction industry stays high.In 2019,global carbon emissions from construction industry accounted for 28% of the total CO₂ emissions.Nowadays,energy conservation and emission reduction for buildings has become a major problem for energy structure of China and even the world.In order to explore the heating potential of geothermal resources and its value in achieving emission peak and carbon neutrality,the endowment and distribution characteristics of geothermal resources in China is briefly described and the geothermal energy utilization modes suitable for different regions are obtained.Energy-saving and high-efficiency pipe burying ways for ground source heat pumps（GSHPs）have drawn great attention.Based on engineering cases,different heat-supply characteristics of shallow and medium-deep geothermal energy have been analyzed.According to the development in the past five years,the GSHP is of great development potential for being able to meet 19.25% of China's building energy supply demand by 2030. In terms of practical application and prospects,a variety of new underground heat exchangers,direct-expansion GSHPs,cross-season energy storage and multi-energy complementary geothermal energy utilization modes are proposed by considering the geothermal detection,geothermal extraction and geothermal utilization.These technologies can increase the utilization rate of renewable energy,reduce the fossil energy consumption and lower the energy consumption of buildings.

Application status and perspectives of air-source heat pump air conditioning technology

CHEN Jianyong, LI Hao, CHEN Ying, ZHAO Jun

2021, 43(11): 25-39. doi:10.3969/j.issn.1674-1951.2021.11.004

Asbtract ( 606 )

HTML ( 15)

PDF (1922KB) ( 471 )

Figures and Tables | References | Related Articles | Metrics

Air source heat pump air conditioning systems are widely used in heating, hot water supply and drying,due to their advantages of high efficiency, energy saving and environmental protection. Researches on the circulation construction, defrosting mechanism and control strategy of the air conditioning system are made at home and abroad,and the advantages and disadvantages of the various technologies are analyzed. The typical application scenarios of air source heat pump air conditioning systems in different industries are introduced,and attention is paid to the contributions to "coal-to-electricity" projects in northern China made by the systems. The COP of the system can reach 2.13, which indicates a significant energy saving. Finally, the challenges faced by the promotion of air source heat pump air conditioners are illustrated, including deficient policy and low public acceptance. Corresponding improvement should be made on the components, cycles, defrosting and control mechanisms. Moreover, the further advancement for the system can made by integrating thermal storage, big data and artificial intelligence technologies, which will facilitate the realization of carbon peaking and carbon neutrality under the new situation.

Progresses and applications of solar air conditioning and heat pump technologies

CHEN Erjian, JIA Teng, YAO Jian, DAI Yanjun

2021, 43(11): 40-48. doi:10.3969/j.issn.1674-1951.2021.11.005

Asbtract ( 223 )

HTML ( 1)

PDF (2456KB) ( 406 )

Figures and Tables | References | Related Articles | Metrics

The increasing energy consumption by buildings runs counter to the goal of carbon neutrality and carbon peaking.Consequently,it is imperative to reduce building energy consumption through new energy-saving technologies.Solar air conditioning and heat pump technologies integrating solar power and energy supply for buildings provide a potential development path to large-scale application of solar energy.They can be subdivided into heating and cooling technologies driven by solar energy or photovoltaic power.The main technical routs of solar air conditioning and heat pump technologies are enumerated,including thermally driven absorption cooling /heating pumps,adsorption cooling,desiccant air conditioning,air conditioners driven by electricity and PV power,direct expansion heat pumps and photovoltaic/thermal （PVT） heat pumps.The progresses of the related technologies are also briefly introduced.The solar air conditioning and heat pump technologies have made progress in improving energy efficiency,broadening the driven temperature range and enhancing environmental adaptability.Considering the energy demand of buildings,the technologies can advance the energy supply diversity and promote the green transformation of building energy.

Review and prospect of underground thermal energy storage technology

ZHANG Yuanyuan, YE Cantao, GONG Yulie, MA Jiuchen, HUANG Yonghui, ZHAO Jun, PANG Zhonghe

2021, 43(11): 49-57. doi:10.3969/j.issn.1674-1951.2021.11.006

Asbtract ( 216 )

HTML ( 2)

PDF (1855KB) ( 530 )

Figures and Tables | References | Related Articles | Metrics

In order to mitigate global warming,achieve "emission peaking and carbon neutrality" and utilize new energy resources efficiently,the power system taking new energy as the main part and power storage industry have to develop in coordination.As one of the key technologies for the joint development,the seasonal underground thermal energy storage,especially Aquifer Thermal Energy Storage（ATES）,is difficult to be transformed from theory to engineering cases.Summarizing the methods and principles of underground thermal energy storage,the theoretical research progress of ATES system in numerical simulation and testing are analyzed.Then,the key technologies and bottlenecks in practical engineering cases are deeply analyzed.The evaluation standards for thermal performance,economic and environmental benefit of ATES systems are compared.On this basis,the prospect of the new power system coupled with ATES technology is made,which can provide reference for the following researches.

Orientation and participation mode of geothermal power generation in the new power system

WANG Yongzhen, HAN Kai, ZHAO Jun, WANG Jianxiao, GONG Yulie, FAN Yifan

2021, 43(11): 58-65. doi:10.3969/j.issn.1674-1951.2021.11.007

Asbtract ( 152 )

HTML ( 1)

PDF (1251KB) ( 217 )

Figures and Tables | References | Related Articles | Metrics

The construction of a new power system with new energy as the main body is the key path to achieve carbon peak and carbon neutrality in China. The role that geothermal power generation technology, which is famous for its stability and cleanness, plays in protecting ecology of the new power system brings challenges and opportunities to this technology. Based on the concept of "systematization" of Energy Internet,we tentatively analyze the thermal,economic and environmental benefits of the new power system with grid-connected geothermal power,wind power and PV power, as well as the participation mode and mechanism of geothermal power in the new system. From the perspective of power system balance and the LCOE the whole system, geothermal power can participate in the new power system as a secured and flexible power source and an auxiliary service provider by means of replacing coal power and realizing carbon capture and storage （CCS）,which supports the schedule and operation. The IEEE-118 node system that represents a wind-PV-geothermal power system was studied. The results show that replacing 20% of coal power by geothermal power, the total economic cost of the whole system will be reduced by about 14% in 30 years. However, the lack of top-level design and geothermal power evaluation mechanism, and the underdeveloped medium-low temperature hydro-geothermal power generation,CO₂-enhanced geothermal power generation and thermo-economic analysis technologies are restricting the development of the geothermal power generation technology in China.

Low-cost and sustainable utilization of geothermal resources in oilfields to achieve carbon neutrality

SONG Chaofan, ZHAO Jun, YIN Hongmei, LI Yang, WANG Guiling, ZOU Hongli

2021, 43(11): 66-73. doi:10.3969/j.issn.1674-1951.2021.11.008

Asbtract ( 169 )

HTML ( 6)

PDF (1202KB) ( 230 )

Figures and Tables | References | Related Articles | Metrics

Carbon neutrality and carbon peaking will bring extensive and profound systematic transformations to economic and social fields and limits to conventional fossil energy development as well.As a clean,low-carbon,stable and sustainable non-carbon energy,geothermal energy is indispensable to achieve the goal of carbon peak and carbon neutrality. There are a large number of inactive oil wells in China,and some of them are of abundant hydro-geothermal resources expecting to be explore scientifically,economically and sustainably.The exploration will be of great significance to realizing carbon neutrality.By summarizing the transformation ways of inactive oil wells into geothermal wells,and analyzing the existing engineering examples of transformed geothermal wells in China and the advantages and bottlenecks of geothermal energy utilization in oil fields,the application prospect of this transformation is made,which provides a reference for subsequent engineering researches.

Efficiency enhancement technology and carbon emission prediction of refrigeration system taking CO₂ natural refrigerant in supermarkets

DAI Baomin, LIU Shengchun, CAO Yu, YANG Haining, FENG Yining, XIAO Peng

2021, 43(11): 74-84. doi:10.3969/j.issn.1674-1951.2021.11.009

Asbtract ( 114 )

HTML ( 1)

PDF (2281KB) ( 241 )

Figures and Tables | References | Related Articles | Metrics

China formally accepted the Kigali Amendment to the Montreal Protocol on September 15th,2021.For the frozen and refrigeration equipment in supermarkets,CO₂ is a reliable substitute for regular synthetic refrigerants.However,high-pressure operation of CO₂ refrigeration systems leads to huge throttling losses,resulting in low energy efficiency of the system.The configurations of the CO₂ refrigeration systems applied in supermarkets are introduced,and the latest technology to improve the energy efficiency and their status quo at home and abroad are summarized.At present,only a few demonstration supermarkets in China are using CO₂ refrigeration equipment.According to the actual energy consumption of CO₂ refrigeration equipment,the life cycle climate performance（LCCP） is calculated.Compared with the carbon emission of the existing equipment taking refrigerant R404A,the carbon emission reduction realized by the equipment taking new technology is predicted.Analyzing the factors restricting the CO₂ technology promotion in China,it is suggested that the energy efficiency of the refrigeration system can be enhanced by taking climatic conditions,differences between peak electricity price and off-peak electricity price and the site condition around the supermarket into consideration.It is recommended that the exorbitant price of the equipment should be lower by policy subsidies,and the acceptance of CO₂ refrigeration system on the market can be improved by promoting the of alternative refrigerants,the goals of carbon peaking and carbon neutrality and awareness of energy conservation and emission reduction.The suggestion will provide a reference for the optimization design and low-carbon and efficient operation of the refrigeration equipment.

Natural working fluids transformation and carbon emission reduction potential on the path to carbon peaking and carbon neutrality

AN Qingsong, YAN Ruoxue, SUN Boyang, MA Yitai

2021, 43(11): 85-90. doi:10.3969/j.issn.1674-1951.2021.11.010

Asbtract ( 220 )

HTML ( 1)

PDF (2079KB) ( 188 )

Figures and Tables | References | Related Articles | Metrics

Working fluids,so-called the "blood" of thermal cycle systems, play vital roles in the cycles. At present, with the establishment of the carbon peaking and carbon neutrality goals and the entrance into force of The Kigali Amendment to the Montreal Protocol in China, our coordinating responses to ozone layer depletion and climate change start a new chapter,which make higher requirements on working medium selection. The development history of working fluids and the main challenges at this stage are briefed, and the physical properties and applications of natural working fluids are elaborated. Natural working fluids, such as R744（CO₂）, R718（H₂O）, R717（NH₃） and hydrocarbons（HCs）,are more environmental and expected to be the alternative for the traditional working fluids（HFCs） and play key role in refrigerant revolution. The ways to replace the traditional working fluids by natural working fluids in refrigeration and heat pump systems, and the matchability between working fluids and different systems and technologies need more attention. Finally, the carbon emission reduction in various scenarios is measured. It is expected to provide reference for natural working fluids replacement and their emission reduction potentials on the path to carbon peaking and carbon neutrality.

Utilization of marine renewable energy resources under the goal of carbon peaking and carbon neutrality

WANG Xiangnan, MA Changlei

2021, 43(11): 91-96. doi:10.3969/j.issn.1674-1951.2021.11.011

Asbtract ( 275 )

HTML ( 12)

PDF (10536KB) ( 333 )

Figures and Tables | References | Related Articles | Metrics

The development and utilization of marine renewable energy exerts key potential influence on promoting energy conservation,emission reduction and countermeasure for climate change.The reserves of marine renewable energy in China are abundant,and its exploitable amount in offshore waters goes as high as hundreds of GW.In recent years,marine renewable energy development and utilization technology has made rapid development in China,and its installed capacity ranks among the best in the world. The implementation of the energy green transformation strategy under the goals of carbon peaking and carbon neutralization provides a vital opportunity for the development and utilization of marine renewable energy resources in China.Based on the study and important progress made in the development and utilization of marine renewable energy in China,the existing problems and the potential of marine renewable energy in emission reduction are analyzed.Then,the medium and long-term development goals of marine renewable energy in China under the background of carbon peaking and carbon neutrality are made,and its short-term technology development goal and key points in large-scale utilization are proposed.

Review and prospects of carbon capture technology assisted by renewable energy,waste heat and combination of them

LU Junhui, WANG Suilin, TANG Jinjing, REN Kexin

2021, 43(11): 97-109. doi:10.3969/j.issn.1674-1951.2021.11.012

Asbtract ( 190 )

HTML ( 3)

PDF (1762KB) ( 388 )

Figures and Tables | References | Related Articles | Metrics

Carbon capture and storage technology（CCS）and its utilization are important for achieving near-zero CO₂ emissions and carbon neutrality.However,the boost of cost and energy consumption of carbon capture will lower the energy efficiency of power systems.The innovation of low-energy carbon capture technology and development of carbon capture technology assisted by high-efficiency renewable energy are important ways to reduce the energy consumption in carbon capture and improve the energy efficiency of the system.The technologies of using renewable energy,waste heat and the combination of them to assist carbon capture are summarized.The status quo and problems of carbon capture technologies assisted by solar energy,wind energy,biomass energy,waste heat and multi-energy combination are analyzed and their development trends are foreseen.The review indicates that,with the innovation and development of renewable energy and waste heat utilization,the cost of CCS can be reduced and the energy efficiency of the system can be improved.Coupling the cooling,heating,powering and lighting by solar energy with chemical conversion in assisting CCS technology can explore the potential in solar energy efficient utilization.The key points of the carbon capture technology assisted by renewable energy,waste heat and combination of them focus on the process match,optimized cascade unitization of energy and the refining of comprehensive evaluation and index system.

Review and prospects of two-step solar thermochemical cycle for preparing fuels based on metal oxides

MA Tianzeng, FU Mingkai, REN Ting, LI Xin

2021, 43(11): 110-127. doi:10.3969/j.issn.1674-1951.2021.11.013

Asbtract ( 124 )

HTML ( 1)

PDF (5902KB) ( 264 )

Figures and Tables | References | Related Articles | Metrics

Clean fuels can be prepared by two-step solar thermochemical cycle based on metal oxides. This method is expected to be an effective way to carbon neutrality for its high theoretical efficiency and zero CO₂ emissions. However, its energy conversion efficiency from solar energy to chemical energy is unsatisfactory. The analysis on the method is made from the oxide pairs, reactor design and optimization of multi-energy complementation systems, and focuses on the factors affecting the conversion efficiency of solar energy to chemical energy. In terms of materials, we expound the development history of oxide pairs and point out the importance of DFT and machine learning in oxide pairs screening. Considering the characteristics of different materials, the application scope, advantages and disadvantages of foam ceramic/honeycomb-structure reactors, particle reactors and membrane reactors are analyzed. Proper porosity and particle radius can speed up the heating rate of the oxide pairs, and effectively reduce heat loss. At the same time, large-scale continuous design can also improve the efficient use of solar energy. In terms of system optimization, the roles of new technologies,such as digital twins,in multi-energy complementary systems are comprehensively analyzed. In the end, the prospects of high-temperature solar thermochemical cycle for preparing fuels and the suggestions for the technology are put forward.

Advances of composite membranes in CO₂ separation

LIAN Shaohan, LI Run, ZHANG Zezhou, LIU Qingling, HAN Rui, ZHAO Jun, SONG Chunfeng

2021, 43(11): 128-137. doi:10.3969/j.issn.1674-1951.2021.11.014

Asbtract ( 121 )

HTML ( 2)

PDF (1030KB) ( 157 )

Figures and Tables | References | Related Articles | Metrics

In order to achieve carbon peak and carbon neutrality, it is necessary to develop CO₂ capture, storage and resource utilization （CCUS） technology to control CO₂ emissions. As one of the most common gas separation technologies, membrane-based separation has been widely used in the CO₂ capture of flue gas from power plants and the purification of natural gas. It has the advantages of low energy consumption, easy operation, small site area, easy expansion and low operating costs,compared to absorption, adsorption and cryogenic methods. However, pure inorganic membranes and polymer membranes can hardly be used in large-scale applications for their own shortcomings. The development of composite membranes with superior gas separation performance has become the hotspot.The research progress of composite membranes on CO₂ capture was reviewed. Being sorted by their structures,composite membranes include mixed-matrix membranes and supported liquid membranes. The separation performances of different composite membranes were compared. Based on their advantages and disadvantages,the key issues restricting the development of composite membranes were analyzed and discussed. Finally, the development direction of composite membrane-based gas separation technology was also prospected.

Application of radiative sky cooling in achieving carbon neutrality

ZHOU Zhihua, ZHANG Ji, ZHANG Yunfei, LIU Junwei

2021, 43(11): 138-148. doi:10.3969/j.issn.1674-1951.2021.11.015

Asbtract ( 154 )

HTML ( 8)

PDF (5182KB) ( 218 )

Figures and Tables | References | Related Articles | Metrics

Carbon neutrality should be achieved as soon as possible with regard to curbing global climate change. It is our common pursuit to accelerate the green and low-carbon transformation of the whole society. In this regard, the refrigeration technology faces major change on its development path. As a completely passive cooling technology, radiative sky cooling does not consume any energy or produce any environmental pollutant, which is extremely prospective. On the basis of introducing the fundamental theory of radiative cooling technology, the typical technologies and cooling effects of radiative cooling materials in recent years have been summarized. Then, we elaborate the current research status of radiative cooling materials in different fields. Finally, we analyze the application scenarios of the technology in the carbon neutralization, as well as its development trends and problems that radiative cooling materials have encountered. The development and application of radiative cooling materials make great contributions to energy conservation and emission reduction for China.

Table of Content