Low-carbon Goals Research Articles

Low-carbon Transformation of Nankai Campus Based on Energy Audits Comprehensive utilization of New Energy

The existing campus has a large building area, a low level of energy saving, less renewable energy utilization, higher energy consumption, and obvious energy-saving space. Based on the energy audit of Nankai University, this paper proposes a low-carbon campus transformation technology system combining building energy saving, clean heat supply and distributed photovoltaic in view of its problems such as high municipal heating energy consumption, low comfort, high electricity bill, and tight electricity consumption. Because the campus has both winter holidays and there is tidal phenomenon in teaching buildings and dormitory buildings, etc., the heating demand is reduced, so its heating and energy-saving space is large. At the same time, the number of campus building floors is low, the roof is conducive to the installation of photovoltaic, it is estimated that the annual power generation of rooftop photovoltaic installation can reach more than 70% of the campus electricity consumption, combined with energy-saving transformation and smart energy management, it is easy to achieve its low-carbon goals.

Chemical kinetics properties and the influences of different hydrogen blending ratios on reactions of natural gas

Hydrogen is blended with natural gas to form hydrogenated natural gas (HCNG), which is a new, efficient and clean energy. CHEMKIN-PRO 19.0 software was combined with the GRI-Mech 3.0 mechanism to evaluate the capacity of H2 blending in reducing CO and CO2 emissions. Influences of H2 blending on combustion reactions of the CH4-air mixture were investigated. The results showed that the main reactants and products (CH4, CO, and CO2) decreased in gradient with increasing H2 blending ratio, accompanied by a shorter reaction duration and a faster reaction rate. After adding H2, important key radicals H, O, and OH increase significantly, so that the combustion reactions become more violent. Sensitivity analysis reveals that among relevant elementary reactions of CO and CO2, R38 (with its promotional effect) and R158 (with its inhibitory effect) show the greatest sensitivity. As the H2 concentration increases, the sensitivity of the two reactions (separately with promotional and inhibitory effects) decreases. Blending H2 in the natural gas can improve the combustion rate and reduce the generation of emissions CO and CO2, which is of important significance for realizing low-carbon goals and reducing air pollution.

Do smart cities promote a green economy? Evidence from a quasi-experiment of 253 cities in China

China's carbon neutrality target is not only a new requirement for energy development, but also a guide for the green and low-carbon development mode and direction of the whole economy. In order to achieve green and low-carbon goals, promote the construction of ecological civilization, and realize high-quality urban development, the Chinese government proposed the construction of “smart cities” in 2012. Using data from 279 cities in China from 2008 to 2020 and a multi-period difference-in-differences method, this paper empirically tested the impacts of the smart city constructions on the development of urban green economy. The results show that: the implementation of smart city has a significant impact in promoting the development of urban green economy, which is manifested in significantly reducing the pollutant emissions and energy intensity and has regional heterogeneity; Endogeneity issues arising from pilot selection are effectively addressed with the help of instrumental variables; Furthermore, the impact mechanism of smart city on green economy is also analyzed.

Green innovation of state-owned oil and gas enterprises in BRICS countries: a review of performance

ABSTRACT State-owned enterprises (SOEs) are a major force in energy markets in BRICS countries, including in national energy innovation systems. In this research, we investigate whether some of the largest oil and gas SOEs in BRICS countries – Brazil’s Petrobras, Russia’s Gazprom, India’s ONGC, China’s PetroChina, and South Africa’s PetroSA – are greening their innovation to foster low-carbon solutions in line with shifting government Nationally Determined Contributions (NDCs) on climate change. We compare the innovation priorities of oil and gas SOE firms in these countries, and specifically their efforts in clean energy from 2005 to 2020. Using an original data set, we set forth case studies on five SOEs and highlight differences in their approaches across a number of different features: the level of government ownership; firms’ revenues and financial health; national government policy; and global oil prices. We assess factors influencing performance in clean energy innovation and study each firm’s success in registering patents for specifically targeted energy technologies. Our findings show that all five SOEs demonstrate only modest efforts in greening of their energy innovation outcomes. We observe their heavy reliance on oil revenues to finance innovation and note how ongoing responsibility to avoid oil and gas shortages is stifling green innovation. We recommend policy avenues for governments to realign SOE practices with climate action and specifically NDCs.

Event-driven low-carbon economic dispatch for multi-regional power grid considering power consumption behavior

The trend of low-carbon power puts forward new standards and challenges for the operation of power system, and also makes the optimal dispatching of power system more difficult. In order to better realize the low-carbon economic operation of the power system, this paper proposes a bi-level low-carbon economic dispatching (LCED) model for multi-regional power system. In the upper level, a carbon emission constraint based on event-driven mechanism tailored for coordinated operation of multiple regions is proposed, and the optimal objective is to minimize the total operating cost of the system. In the lower level, the reduction of carbon emission obligation on the load side is considered, and the optimal objective is to maximize the low-carbon utility on the load side. Thus, the synergy of the low-carbon goal on both source and load sides is achieved. Finally, through the simulation of the modified IEEE 39-bus system, it is verified that the proposed bi-level model can effectively reduce operating costs and reduce carbon emissions, and improve the level of renewable energy consumption.

Experimental study on the effect of the thermal barrier coated (TBC) piston on combustion of gasoline compression ignition (GCI)

Gasoline compression ignition (GCI) has the advantage in achieving high thermal efficiency and low emissions simultaneously. However, the difficulty in realizing stable compression combustion at low load is a major problem that GCI faces and needs to be addressed. In addition, improving thermal efficiency of internal combustion engine is also an important research topic, especially for satisfying low carbon goals in the future. Therefore, to explore strategies to improve combustion stability and thermal efficiency of GCI combustion, the low thermal conductivity ceramics (MgZrO3) was coated on the top surface and combustion chamber of the piston to reduce the thermal conductivity, then achieving the purpose of increasing the in-cylinder temperature and reducing the heat transfer. The experiment was conducted under different loads conditions to investigate the effect of thermal barrier coated (TBC) piston on GCI combustion. The result shows that the indicated thermal efficiency of GCI can be increased by 6.4% with the TBC piston at low load, meanwhile the THC and CO emissions are also reduced effectively. Furthermore, employing TBC piston can significantly improve the combustion stability of low load GCI combustion and therefore has great potential to extend lower load operation. However, the effect of TBC piston on improving indicated thermal efficiency decreases as engine load increases, and the difference in combustion between the TBC piston and piston without TBC is fairly small under high load condition. Compared to piston without TBC, the indicated thermal efficiency of TBC piston is higher and change slightly as EGR rate increases. With the TBC piston, lower NOx and soot emissions can be obtained while the indicated thermal efficiency remains at high value by introducing high EGR rate.

Sustainable Urbanism: Pathway to Resilient Strategies in Adapting Early Malay Town towards Low Carbon City

Due to an alarming rate on the impact of global climate change, the integration of low-carbon goal in regeneration of historic urban areas is regarded as a key part towards the implementation of sustainable urbanism practises based on Sustainable Development Goal (SDG). Much studies on the planning and design of low carbon strategies concerned overwhelmingly on the new planned cities without much emphasis given on the implemented at old town centre. In the context of Malay early town, the adaptation of the low carbon planning as shifting in environmental conditions is regarded as paramount importance particularly in the planning of the urban form to address the growing complexity of urban fabric at the town. This paper therefore explores the developed framework of Low Carbon City initiative and integration of resilience as an approach in urban transformation and regeneration of Malay early town to provide the platform for understanding the complexity of urban-natural environment from morphological perspective. The purpose of this research is two-fold; firstly, to examine the role of discourse in implementing Low Carbon City Framework (LCCF) in Malaysia at large. The second objective is to identify the place-specific mechanisms based on resilience approach to understand the capacity of urban form system to absorb, adapt or transform in ensuring the dynamic equilibrium of the urban-natural system. Considering Kota Bharu as representative of Malay town, a discursive-analytical perspective framed to examine the upsurge of the LCCF that helps to understand the pathway towards integration of framework at national, state and district level. Such comprehension on implementation measure formed a basis to identify the interactions between environmental performance and urban forms pattern as strategies for resilience. A case study with mapping analysis were employed that revealed significant relations between socio-cultural and environmental dimension which shaped the formation and transformation of urban morphology of the town. This study concludes with an examination of possible future directions for integration of space-morphological approach to general urban resilience for future adaptation planning of Malay towns towards Low Carbon City.

Relationship between Soil Organic Carbon, Soil Nutrients, and Land Use in Linyi City (East China)

The distribution characteristics of soil organic carbon (SOC) and soil nutrients under different land-use types in Linyi City, East China, were studied. The spatial distribution of SOC under different land-use types and the relationship between SOC and soil nutrients were analyzed using remote sensing interpretation and soil sample analyses. The results showed that SOC in Linyi was mainly stored in drylands and paddy fields. SOC and total nitrogen (TN) levels were positively correlated for most land use types. There was a positive linear correlation between SOC and total K in the paddy fields. The coefficients of variation for SOC and TN differed greatly among the land use types studied. Total SOC storage was 8772.73 × 103 kg in the surface 0.2 m soil layer. The order of total SOC storage was drylands (6771.45 × 103 ton) > paddy field (764.67 × 103 ton) > nurseries (510.79 × 103 ton) > forest land (413.49 × 103 ton) > low-cover grasslands (238 × 103 ton) > bare land (74.35 × 103 ton). With the largest SOC storage, and C density, respectively, drylands and paddy fields are conducive to enhancing soil C sequestration, achieving low-carbon goals, and mitigating climate change.

Investigating cooperative strategies in low-carbon public–private partnership projects through evolutionary game

PurposePromoting low-carbon in the construction industry is important for achieving the overall low-carbon goals. Public–private partnership is very popular in public infrastructure projects. However, different perceptions of low-carbon and behaviors of public and private sectors can hinder the realization of low-carbon in these projects. In order to analyze the willingness of each stakeholder to cooperate towards low-carbon goals, an evolutionary game model is constructed.Design/methodology/approachAn evolutionary game model that considers the opportunistic behavior of the participants is developed. The evolutionary stable strategies (ESSs) under different scenarios are examined, and the factors that influence the willingness to cooperate between the government and private investors are investigated.FindingsThe results illustrate that a well-designed system of profit distribution and subsidies can enhance collaboration. Excessive subsidies have negative impact on cooperation between the two sides, because these two sides can weaken income distribution and lead to the free-riding behavior of the government. Under the situation of two ESSs, there is also an optimal revenue distribution coefficient that maximizes the probability of cooperation. With the introduction of supervision and punishment mechanism, the opportunistic behavior of private investors is effectively constrained.Originality/valueAn evolutionary game model is developed to explore the cooperation between the public sector and the private sector in the field of low-carbon construction. Based on the analysis of the model, this paper summarizes the conditions and strategies that can enable the two sectors to cooperate.

Regional inequality in the carbon emission intensity of public buildings in China

Driven by urbanization and the growth of residents’ income, CO2 emissions from energy consumption in public buildings have gradually become an important source of CO2 emission growth in China. There is an obvious phenomenon of carbon emission inequality, and there is still a research gap. This study explores the inequality in the carbon emission intensity of public buildings and its drivers on two scales—carbon emissions per capita and per unit of floor area—using provincial panel data for public buildings in China from 2010 to 2019 by Kaya-Theil model. The following results are obtained: (1) The carbon emissions per capita increased from 415 kg to 605 kg, those per unit of floor area decreased from 70.67 kg to 62.16 kg, and those from public buildings in hot summer and cold winter regions and cold regions were significantly higher than those in other regions. (2) The overall regional variation in the carbon emission intensity of public buildings mainly consists of intra-regional variations, ranging mainly from 70% to 90%. The role of building climate zones in the spatial difference in carbon emissions per capita is gradually increasing. (3) The added value of the tertiary sector per capita is the main factor contributing to the inequality in the carbon intensity of public buildings, with a contribution of approximately 70% (±5%), and energy consumption per unit of floor area gradually contributes to the increase in carbon inequality. Our findings provide practical guidance for reducing the carbon emission intensity, thereby further promoting the development of global low-carbon goals.

A Supervised-Learning Assisted Computation Method for Power System Planning

To achieve a low-carbon economy, the comprehensive planning of the early retirement of coal-fired power plants (CFPPs), the construction of renewable energy plants, and the investment in energy storage systems (ESSs) are critical. However, the nonlinear characteristic of the alternating current power flow (ACPF) brings difficulties in solving the long-term planning problem efficiently. Hence, in this article, a learning and optimization integrated framework is presented to help the power sector to reach the emission reduction goal economically while guaranteeing system security and reliability. First, the electricity network transition from the fossil fuel-dominated system to the low-carbon-oriented system is planned. Then, a data-driven method is utilized to regress the power flows, and a method is proposed to integrate the data-driven model into an optimization problem to alleviate the heavy computational burden. Because the penetration of intermittent renewable energy is high in a low-carbon energy system, the security and reliability of the planning decisions are verified in the second level by the N-1 security check. Simulation results reveal that the data-driven method can calculate power flows more accurately than direct current power flow (DCPF) and linearized ACPF models. Also, the supervised-learning method can help reduce computing time. The proposed planning model is verified on the IEEE 30-bus system. Through case studies, it can be concluded that our proposed method can reach the low-carbon goals with the lowest cost, and reliability can be ensured at the same time. Because of the coordinated retirement of CFPPs and the proper planning of ESS, the planned electricity system can cope with uncertainties better.

Potential for CO2 mitigation and economic benefits from accelerated carbonation of construction and demolition waste

Transitioning to zero-waste cities may help achieve low-carbon goals. The unprecedented generation of construction and demolition (C&D) waste poses a significant obstacle to the sustainable development of the built environment, particularly for megacities in emerging economies. Among the common C&D wastes, concrete debris has high alkalinity and can be used for CO2 sequestration via mineralization. However, previous studies have almost exclusively considered the CO2 uptake potential, while ignoring the emissions associated with the energy and material consumption for carbonation. The lack of understanding in this domain poses a great challenge to industrial applications due to environmental and economic uncertainties. Thus, this study aims to evaluate the net emission reduction and economic efficiency of using concrete debris in 14 global regions via life cycle assessment and life cycle costing to fully consider the inputs and outputs in carbonation systems, which can compensate for the biased results of historical studies. The results show that the average unit net CO2 benefits and economic benefits from the industrialization of carbonated recycled concrete aggregates (cRCA) technology vary considerably between countries, with CO2 benefits (ton CO2 emission/ton CO2 uptake) ranging from 0.7 in Brazil to 2.6 in Pakistan and economic benefits (USD/ton concrete debris) ranging from 18.5 in the USA to −5.6 in Pakistan. We found that, even with cRCA technology, only a few countries can obtain net negative CO2 emissions and positive economic value simultaneously, which indicates that the production process should be further adjusted to reduce avoidable emissions and increase potential economic benefits before it is promoted. Given the heterogeneity of economic and spatial contexts across countries, the study proposes targeted strategies for the transport, production, and trade processes of various types of regions to optimize the situation. But in general, restructuring the transportation network and relocating recycling plants are the most effective options for improving economic and environmental benefits. CO2 sequestration via concrete debris carbonation will become promising when strategies are tailored to local conditions.

How the perceived value of green creativity influences employees’ green creativity: the dual promotion–prevention path

Employee green creativity is a key aspect of achieving low-carbon goals. Yet the proximal driving factors related to the creators of underlying green creativity have been largely understudied. Based on regulatory focus theory, we introduce the concept of perceived value of green creativity (PVGC) to explore how it affects employee green creativity. Using a time-lagged research design, 311 paired datasets were collected from front-line managers and employees of Chinese luxury hotels. The results show that PVGC significantly enhances employee green creativity. Green creativity intrinsic motivation (GCIM, promotion focus) and green image preservation motivation (GIPM, prevention focus) mediate the relationship between PVGC and employee green creativity. We further find that the mediating role of promotion focus is stronger than that of prevention focus. The moderating effect of green mindfulness is apparent in the PVGC–GCIM relationship but not the PVGC–GIPM relationship. The novel concept of PVGC can extend research on perceived value to the green management field and even deepen the investigation of the factors that drive employee green creativity. The results have important implications for the promotion of hotel employee green creativity in response to the ongoing green transformation.

Carbon Metabolism in Urban “Production–Living–Ecological” Space Based on Ecological Network Analysis

To understand the changing pattern of urban carbon metabolism from the perspective of urban “production–living–ecological” (PLE) space, taking Suzhou City as an example, this study constructed a carbon metabolic network model in urban PLE space, analyzed the changes of horizontal carbon flow, and evaluated the comprehensive effect of the PLE space changes using the ecological network analysis method. The results showed that the total carbon sequestration showed a fluctuating change of increasing and then decreasing, while the total carbon emissions grew dramatically. Production spaces were the key nodes for the generation of horizontal carbon flow. The exploitation relationship was the dominant ecological relationship in the network, the mutualism relationship was abundant from 2005 to 2010 and gradually decreased from 2010 to 2018, and the frequency of competition relationship appeared gradually increased. The ecological network hierarchy evolved from an irregular shape dominated by primary consumers in 2000–2005 to a pyramidal shape dominated by producers in 2010–2018 at the driving weight end, and the pull weight showed a declining trend, with pull weight of producers increasing from 1.72% to 24.33%. The results can provide a theoretical basis for planning adjustments to the city’s PLE space structure to achieve low-carbon goals.

How Can the Layout of Public Service Facilities Be Optimized to Reduce Travel-Related Carbon Emissions? Evidence from Changxing County, China

With the developments in urbanization and motorization, travel-related carbon emissions are increasing rapidly. The layout of public service facilities (LPSF) has a direct impact on travel-related carbon emissions. However, existing public service facility planning methods focus on population, economy, and other aspects, ignoring the environmental impact. So, how do we optimize the LPSF to reduce carbon emissions? This paper proposed a method to optimize the LPSF under the constraint of travel carbon emissions. We selected medical facilities in Changxing County, China, and applied the method we proposed. We found that (1) the carbon reduction effect was significant—the total monthly emissions in Changxing were reduced by 26.10%, and the area covered by high emissions was reduced; (2) the medical facilities in Changxing under a low-carbon goal should be distributed in the county center and surrounding urban areas in a multi-center form; and (3) improving the accessibility of facilities can help to form a low-carbon facilities layout. This paper provides a spatial planning method to guide the specific locations of facilities under low-carbon goals. It also provides scientific suggestions for low-carbon land-use policies at the county level in China.

Renewable Energy Communities as a New Actor in Home Energy Savings

Renewable energy communities (RECs) might be an interesting new stakeholder in stimulating home energy-saving efforts by tenants and homeowners due to their potential of raising awareness locally and gaining public support for low-carbon energy and energy-savings projects, because RECs are often locally sited, in close social proximity of residents, and are already part of local structures and share local institutions. This comes with many benefits since they already have a reputation locally, a social history with the local community, and can be trusted by the latter. This makes them potentially better suited than other—often less-trusted—parties (i.e., government and business companies) to use their agency to encourage sustainable change. The article builds on empirical data from the EU Horizon 2020 project REScoop Plus, using a mixed-methods research approach, including desk research, expert interviews, validation workshops, and multiple surveys among RECs in six EU member states about energy-saving actions implemented, and their effectiveness in terms of raising awareness, influencing the intention to save energy, and actual energy-saving behaviour. This article provides more insight into the assessment of actions and measures for coaching householders to achieve energy savings and low carbon goals. In addition, it shows the potential of using RECs as a new strategy to address home energy savings in the current housing stock, including options to improve the energy performance thereof.

Holistic life-cycle accounting of carbon emissions of prefabricated buildings using LCA and BIM

Prefabricated concrete building (PCB) can save resources, reduce construction, improve quality, and reduce pollution. Understanding PCB environmental benefits versus traditional buildings could reinforce relevant policies and adoption. This study aimed to develop a holistic life-cycle accounting system based on BIM technology to calculate carbon emissions of PCB accurately and efficiently, and verify the effects of energy saving and emission reduction. Existing international and national databanks allowed the compilation of carbon emission factors. Five representative residential PCB projects were enlisted to calculate carbon footprints in six individual life-cycle construction stages. In most stages, carbon emissions were reduced with an increasing prefabrication rate. In the operation and maintenance stage, carbon emissions accounted for approximately 91% of the total, and the building materials production stage accounted for about 11%. The “negative carbon emission” in the demolition and recycling stage was about −4%. Carbon emissions of the remaining three stages were minimal at about < 2%. This study established the whole life-cycle carbon-emission indices of residential prefabricated buildings, with average annual carbon emission per unit area at around 105.88 kgCO2/(m2.a), and computed values for individual building stages. For comparison, a completely cast-in-place building was studied, with average annual carbon emission per unit area at around 130.79 kgCO2/(m2.a), significantly higher than the PCB. The study contributed to knowledge by furnishing the holistic carbon footprint calculation method and establishing the empirical patterns and trends of carbon emissions of PCB. The findings could inform construction projects' carbon-emission control and achieve the construction industry's green and low-carbon goals.

Interaction and mediation effects of economic growth and innovation performance on carbon emissions: Insights from 282 Chinese cities

China is under rapid urbanization and consequently facing increasing carbon emissions (CE). Economic growth (EG) and innovation performance (IP), as two critical indicators of urbanization, are considered the driving forces of CE. Although economy and innovation are entangled and can jointly affect CE in reality, the measured effects of economy and innovation on CE are often treated separately in traditional studies. We adopted a three-part research framework including the total, interaction and mediation effect tests to elucidate how EG and IP affected CE in China from 2005 to 2015 based on insights from 282 Chinese cities. The empirical results showed that both economy and innovation contributed to CE, although the contribution has reduced over the 11 years. In particular, the interaction effect between economy and innovation for North China, Northeast China, and Southwest China was −4.201, −8.442, and − 3.897, respectively, in 2015, meaning that these regions adversely affect CE. In addition, we found that the economy helps reduce CE via innovation. When considering the changes of economy and innovation, their mediation effect on CE changes varied in different regions, attributable to the level of economy and innovation as well as the stocks of energy resources. Therefore, future planning for low-carbon transition should regard the economy and innovation together. Based on this principle, we propose five detailed policies. Overall, this study is valuable not only for further understanding the triangle relationship among economy, innovation, and CE, but also for reaching low-carbon goals.

What if carbon drives our design from the outset?

This article considers the implications of adopting a carbon-driven design approach – with the express intent of limiting the embodied carbon of the structure. It examines the impact this approach will have on a number of key design decisions – material choice, grids and spans, loads, structural system, foundations, serviceability requirements, facade type and method of construction – and highlights the tensions that may arise between these and the low-carbon goal. The article argues that opting for timber as the initial material choice will likely offer greater flexibility and leave open the option of switching to another material later in the design process should the need arise.

Regulation capacity evaluation for air conditioners considering operating status and occupant comfort

In recent years, the load peak-valley difference is increasing rapidly and needs more regulation capacity to reduce it. However, traditional generating units are phasing out for low carbon goal and cannot provide enough regulation capacity for the power system. Besides, Air conditioners (ACs) account for about 40% of the electricity consumption of the power system during peak period in summer. Due to the thermal inertia of rooms, indoor temperature will not be greatly affected, when ACs are controlled temporarily to provide regulation capacity. To fully realize the regulation potential, it is of significantly importance to accurately evaluate the regulation capacity of ACs, where the real-time operating status and occupant comfort are two key factors. Therefore, this paper proposes a regulation capacity evaluation method for ACs considering operating status and occupant comfort. The equivalent thermal parameter (ETP) model based on the AC operating characteristics is developed firstly. On this basis, the regulation capacity for the individual AC is evaluated considering operating status and user comfort, and the regulation capacity of aggregated ACs can be obtained by summing. Finally, the effectiveness of the proposed method is proved by cases.