Efficiency Emission Reduction Research Articles

Effect of flue gas condensing waste heat recovery and its pressure drop on energy saving and carbon reduction for refinery heating furnace

The refinery heating furnace has high energy consuming and high carbon emission, and the flue gas condensing waste heat recovery can achieve prominent results in saving energy and reducing emissions of petrochemical industry. Based on adding a flue gas condensing heat exchanger (FGCHE) at the rail of heating furnace, this paper investigates the effects of flue gas waste heat recovery and pressure drop on the energy saving and carbon reduction through theoretical and on-site testing methods. Flue gas heat recovery and pressure-drop characteristics of the FGCHE are analyzed to achieve maximum energy saving and emissions reduction under the normal operating conditions of heating furnace. Meanwhile, the effects of flue gas temperature and pressure drop on the energy saving and carbon reduction are derived under different combustion air temperature, humidity and excess air coefficient after fuel gas complete combustion. The results show that when the flue gas temperature is reduced from 180 °C to 20–40 °C, the energy saving efficiency, utilization ratio of flue gas waste heat, condensate recovery efficiency and carbon emission reduction ratio reach 12.5–16.9%, 74.4–98.1%, 58∼89.3% and 13.7–18.3%, respectively. Reducing the flue gas pressure drop can significantly improve the flue gas waste heat utilization ratio and carbon reduction.

Efficient emission reduction through dynamic supply mode selection

Reducing the carbon footprint of global supply chains is a challenge for many companies. Governmental emission regulations are increasingly stringent, and consumers are increasingly environmentally conscious. Companies should therefore integrate carbon emissions in their supply chain decision making. In this paper, we study the inbound supply mode and inventory management decision making for a company that sells an assortment of products. Stochastic demand for each product arrives periodically and unmet demand is backlogged. Each product has two distinct supply modes that differ in terms of their carbon emissions, speed, and costs. The company needs to decide when to ship how much using which supply mode such that total holding, backlog, and procurement costs are minimized while the emissions associated with different supply modes across the assortment remains below a target level. We assume that shipment decisions for each product are governed by a dual-index policy for which we optimize the parameters. We formulate this decision problem as a mixed integer linear program that we solve through Dantzig–Wolfe decomposition. We benchmark our decision model against two state-of-the-art approaches in a large test-bed based on real-life carbon emissions data. Relative to our decision model, the first benchmark lacks the flexibility to dynamically ship products with two supply modes while the second benchmark makes supply mode decisions for each product individually. Our computational experiment shows that our decision model can outperform the first and second benchmark by up to 15 and 40 percent, respectively, for moderate carbon emission reduction targets.

Can the Digitalization Reduce Carbon Emission Intensity?—The Moderating Effects of the Fiscal Decentralization

Carbon emission reduction is the top priority in improving green production efficiency and achieving sustainable development, while digitalization (Digi) is an important engine that drives efficient carbon emission reduction. However, in China, the government and the market jointly influence economic and social development, and the effectiveness of Digi in promoting carbon emission reduction is also influenced by the external fiscal system. In this study, we first establish a theoretical framework for digitalization that can reduce carbon emission intensity (CEI) and reveal the important role of fiscal decentralization (FD) on the impact of Digi on CEI and is based on the typical features of the Chinese FD system. Second, we investigate the relationship between Digi and CEI and the moderating effect of FD based on panel data from 30 Chinese provinces from 2011 to 2019, and we utilize a fixed-effects panel model that introduces moderating variables and a panel threshold model. By testing the econometric model, we observe that increasing the level of Digi significantly reduces CEI. FD reinforces this reduction effect, and Digi has a significant dampening effect on CEI only when the level of FD is higher than 0.84. Additionally, the inhibitory effect of Digi and positive moderating effect of FD are higher in the central and western regions of China. Finally, we suggest countermeasures to promote low-carbon development for accelerating digital transformation, thereby deepening the reform of “delegating power, improving regulation, and optimizing service” systems.

Performance study of thermal-nuclear co-generation system based on exergy and thermal economy analysis

The thermal-nuclear co-generation system realizes the effective complementarity of power generating efficiency and pollutant emission reduction while simultaneously reducing the consumption of fossil fuels and pollutant emissions. First, four potential combined thermal-nuclear power generation schemes are proposed in this research. The performance of each scheme is examined, and the system is compared and examined based on two indicators: nuclear energy share and nuclear energy generation efficiency. For the chosen ideal combination scheme, exergy analysis and a thermo-economic structural theory analysis are carried out. The examination of the assembly for the Direct heating scheme, which the study's findings indicated was the optimum option, revealed that the combined unit could achieve 38.14% assembly efficiency, which is 2.29% greater than that of the nuclear unit alone. The feasibility of combining thermal and nuclear power is demonstrated by the study of the influence of the key parameters on the cost per unit of assembly and the calculation that the co-generation system's economic efficiency is higher than that of nuclear or thermal power units built separately in terms of fuel economy.

Assessing the policy synergy among power, carbon emissions trading and tradable green certificate market mechanisms on strategic GENCOs in China

The establishment of carbon emissions trading (CET) and tradable green certificate (TGC) markets in China will cause great alterations in the bidding behavior for generation companies (GENCOs) and affect the low-carbon transformation of power industry. In this paper, a Nash bargaining game model is constructed to assess the synergy of power, CET and TGC markets on decision behavior of non-renewable energy GENCOs, renewable energy GENCOs and power purchasers. The simulation results show that there is transition incentive effect, price interaction effect and profit blocking effect between three markets. With the introduction of emissions trading scheme and renewable portfolio standard (RPS), the scheduled power of renewable energy GENCOs will increase by 21.43%, and transaction prices will reduce to 449.58 CNY/MWh; while the scheduled power of non-renewable energy GENCOs will reduce by 4.66%, and transaction prices will increase to 443.71 CNY/MWh, which make all power generation types compete at equivalent price level. Under the current installed capacity distribution and load demand, it is the critical point when RPS is 18.7% and the benchmark value of free carbon quota for units above and below 300 MW are 0.857 tCO2/MWh and 0.959 tCO2/MWh. Once exceeded, it will affect social benefits and emission reduction efficiency.

How do the carbon emission trading prices affect the financing decision of the supply chain considering carbon neutrality?

This paper considers a supply chain formed by a manufacturer with constrained capital and a retailer with sufficient capital. By using the Stackelberg game theory, we discuss the manufacturer's and retailer's optimization decisions for bank financing, zero-interest early payment financing, and in-house factoring financing under both normal and carbon neutrality scenarios. In the carbon neutrality scenario, numerical analysis shows that improving the efficiency of emission reduction drives manufacturers to switch from external to internal financing methods. The impact degree of green sensitivity on the supply chain's profit depends on the carbon emission trading prices. In the framework of green sensitivity of products and emission reduction efficiency, manufacturers' financing decisions are affected by carbon emission trading prices rather than by whether emissions exceed the standards or not. When the price is higher, internal financing is easier to obtain, whereas the space for external financing is constrained.

The Impact of Science and Technology Innovation on Carbon Emission Reduction Efficiency--Based on the input-output perspective

Using 30 provinces, municipalities and autonomous regions in China from 2013 to 2019 as the research objects, the dynamic benefits of emerging technologies and high technology on reducing carbon emission reduction efficiency was analyzed from the input-output perspective using the DEA-Malmquist method and by calculating the Malmquist index. Tobit regression analysis was also used to further investigate the factors influencing the differences in carbon emission reduction efficiency between different provinces and cities. The findings show that: i) science and technology innovation has a significant positive effect on reducing carbon emissions, and factors such as R&D funding have a positive effect on efficiency; ii) the regional tertiary industry share positively moderates this effect, while the regional Internet development level negatively moderates this effect. Finally, based on the results of the empirical study, we analyze the reasons for the changes of carbon emission reduction efficiency in each region and propose management suggestions to promote the improvement of carbon emission reduction efficiency.

Green Supply Chain Coordination Considering Carbon Emissions and Product Green Level Dependent Demand

As traditional supply chains face increasingly severe environmental issues, and as countries promote green development and sustainable development policy concepts, cultivating green supply chain operation models is gradually coming to be highly valued by governments and enterprises. Generally speaking, the production of green products incurs higher additional costs, and thus, their total production costs also increase. In this work, we studied the coordination mechanism, by considering carbon emissions and product green level dependent demand, in which the product green level is related to the random demand. Under the green supply chain buyback contract with the green product R&D cost sharing between the manufacturer and the retailer, both the product green level and the order quantity need to be decided, to maximize the channel profit. In order to coordinate the green supply chain, the manufacturer needs to share both the risk of good salvage and the green product R&D cost with the retailer. We found that both the wholesale price and the buyback price increase in the manufacturer’s proposition of the green product R&D cost, but decrease in the emission reduction efficiency coefficient or carbon trading price. In addition, the product green level, the optimal order quantity and the channel profit increase in the emission reduction efficiency coefficient, but decrease in the R&D cost coefficient of the product green level. Interestingly, we found that if the carbon trading price is low, the manufacturer will set a low product green level, and the product carbon emission trading is a cost for the supply chain. The increment of the carbon trading price leads to a higher cost, such that the channel profit is decreased. However, if the carbon trading price is high, the manufacturer will set a high product green level, and the product carbon emission trading is a revenue for the supply chain. The increment of the carbon trading price leads to a higher revenue, such that the channel profit is increased.

Coordinated development of regional resources, environment, and economic growth under the background of low-carbon economy

IntroductionAt present, the rapid growth of social and economic development has also brought great challenges to the development of regional resources and environment. With the deepening of the concept of sustainable development, the coordinated development of regional resources, environment and economic growth has attracted more and more attention. The coordinated development of resources, environment and economic growth is not only the engine of industrial growth, but also the accelerator to promote industrial transfer and optimal allocation of resources, which has injected a strong impetus into social development. However, with the continuous upgrading of the industrial structure, environmental pollution, unbalanced economic development, resource shortage and other problems have gradually emerged in various important development areas.MethodsIn order to effectively solve this dilemma, this paper takes the Beijing-Tianjin-Hebei region (BTH) as an example, based on the analysis of the current situation of the economic and environmental development of BTH region and the influencing factors, combined with the background of low-carbon economy (LCE), effectively studies the coordinated development of its resources, environment and economic growth. In order to verify the effectiveness of low-carbon economic development, this paper, based on the actual development data of BTH region, tests the three dimensions of economic benefit index, environmental benefit index and emission reduction efficiency index.ResultsThe results show that the average environmental benefit index of 13 cities in the BTH region after the implementation of the target is about 0.457. The average benefit index before the implementation of the target was about 0.449.DiscussionFrom the final results of the test, it can be seen that the development of low-carbon economy has strong feasibility for promoting the coordinated development of regional resources, environment and economic growth.

Industrial Upgrading, Total Factor Energy Efficiency and Regional Carbon Emission Reduction in China

Industrial Upgrading, Total Factor Energy Efficiency and Regional Carbon Emission Reduction in China

A review of key issues in planning AC/DC distribution systems for renewable energy

New requirements have been put forward for the construction of an AC/DC power distribution system under the targets of carbon peaking and carbon neutrality. It is urgent to build a new AC/DC power distribution system featuring low carbonization to realize the coordinated, green development of a high proportion of renewable energy. The low carbonization of the power industry is the key to coping with global warming and realizing the sustainable development of China’s society and economy. The reasonable and effective system planning and operation method will be the powerful means to ensure the AC/DC distribution system attain efficient carbon emission reduction under the premise of safe and stable operation. This paper combines the connotation and characteristics of renewable energy interconnection and mutual benefit, analyses the key technology features of AC/DC distribution systems for renewable energy, establishes a complete overall research framework of key technology for planning and operation of AC/DC distribution systems for renewable energy from two aspects of system planning and system operation, and gives an overview and outlook on each key research direction.

Impact of NOx and NH3 Emission Reduction on Particulate Matter across Po Valley: A LIFE-IP-PREPAIR Study

Air quality in Europe continues to remain poor in many areas, with regulation limits often exceeded by many countries. The EU Life-IP PREPAIR Project, involving administrations and environmental protection agencies of eight regions and three municipalities in Northern Italy and Slovenia, was designed to support the implementation of the regional air quality plans in the Po Valley, one of the most critical areas in Europe in terms of pollution levels. In this study, four air quality modelling systems, based on three chemical transport models (CHIMERE, FARM and CAMx) were applied over the Po Valley to assess the sensitivity of PM2.5 concentrations to NOx and NH3 emission reductions. These two precursors were reduced (individually and simultaneously) from 25% up to 75% for a total of 10 scenarios, aimed at identifying the most efficient emission reduction strategies and to assess the non-linear response of PM2.5 concentrations to precursor changes. The multi-model analysis shows that reductions across multiple emission sectors are necessary to achieve optimal results. In addition, the analysis of non-linearities revealed that during the cold season, the efficiency of PM2.5 abatement tends to increase by increasing the emission reductions, while during summertime, the same efficiency remains almost constant, or slightly decreases towards higher reduction strengths. Since the concentrations of PM2.5 are greater in winter than in summer, it is reasonable to infer that significant emission reductions should be planned to maximise reduction effectiveness.

A theoretical study of the effect and mechanism of FeN3-doped biochar for greenhouse gas mitigation

Paddy fields are a major emission source of greenhouse gases (GHGs) [for instance, methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2)] among agricultural fields. Biochar has been deemed a potential candidate for the reduction of GHGs in paddy fields. However, there is no consistent conclusion that biochar can simultaneously reduce emissions of CH4, N2O, and CO2. Herein, we proposed the FeN3-doped biochar (FG) as an excellent material for GHGs restriction in paddy fields via the first-principles calculation. The computation results indicated that the FG exhibited satisfactory adsorption ability for CH4, CO2, and N2O, which improved the adsorption energies to −1.37 , −1.54, and −2.91 eV, respectively. Moreover, the density of state (DOS) analyses revealed that the factor responsible for FeN3-doped biochar to exhibit excellent adsorption ability was the occurrence of drastic energy up- or down-shift of the electron for Fe d, C p, O p, or N p orbital upon adsorption of CH4, CO2, or N2O. Our study suggested an advanced modified biochar material for reducing the GHGs emissions in paddy fields, in addition to exploring the adsorption properties and mechanisms of FeN3-doped biochar for GHGs mitigation, which provided a strategy to explore biochar modification and efficient emission reduction materials.Graphical

ENGINE PERFORMANCE ANALYSIS OF PALM KERNEL OIL-BASED BIODIESEL BLENDS ON SPEED VARIATIONS OF A 4-CYLINDER ENGINE AT CONSTANT TORQUE

Biodiesel made from the transesterification of plant-derived oils is an important alternative fuel source for diesel engines. Several disparate studies have emphasized the significance of biodiesels in emission reduction and engine efficiency. The present study examined the effect of using palm kernel oil (PKO), pure petroleum diesel, and its blends on the fuel consumption rates, energy expended, brake-specific fuel consumption, and brake thermal efficiency of a four-cylinder tractor under varying operating speeds (700 – 1900rpm) at constant torque. The study was conducted at a large farming site in Anambra State, Nigeria. The findings indicated that PKO biodiesel blends had the overall optimum energy output, fuel consumption rates, and brake-specific fuel consumption, respectively, at the highest engine speed of 1900. Although B10's rating of 60.6% for thermal brake efficiency was impressive, it was lower than B100's 66.95 %. Based on the results, B10 is the best gasoline for testing and may be used as a replacement fuel in four-cylinder farm tractor engines with no modifications. The study concludes that biodiesel blends showed potential as an alternative to fossil diesel.

Achieving co-benefits by implementing the low-carbon city pilot policy in China: Effectiveness and efficiency

Cities are the main emitters of CO2 and air pollutants, and the main drivers of addressing climate change. The implementation of the low-carbon city pilot (LCCP) policy has achieved carbon emission reduction, but further research is needed to determine whether the synergistic reduction of CO2 and PM2.5 can be effectively implemented, and the efficiency of the synergistic reduction can be improved. Panel data belonging to 279 Chinese cities are selected. We assess the effectiveness and efficiency of the implementation of the LCCP policy to achieve co-benefits of CO2 and PM2.5 emission reduction, using the time-varying difference-in-differences model. We evaluate the synergistic emission reduction efficiency and its decomposition by the super-efficiency slack-based measure model with CO2 and PM2.5 as undesirable outputs. The results show that the LCCP policy reduces 3.55% of CO2 and 2.18% of PM2.5 respectively, and enhances the effectiveness of coordinated emission reduction governance. The LCCP policy also improves the synergistic emission reduction efficiency, moves the input–output model towards the “optimal production frontier”. We form policy recommendations for encouraging technological innovation and optimal resource allocation to achieve “net zero emissions”. Most importantly, policymakers should incorporate synergistic emission reduction efficiency into the process of policy evaluation, and establish a low-carbon economic development model tailored to local conditions.

Carbon Emission Efficiency, Technological Progress, and Fishery Scale Expansion: Evidence from Marine Fishery in China

China’s technical progress on emissions and vast ocean area make the study for CO2 emission reduction suitable in a marine fishery. This study uses the slack variables of SBM and the Malmquist index to analyze the CO2 emission efficiency of Trawler, Seine net, Drift net, Fixed net, and Angling, along with their efficiency values, distinguishing the impact of technological progress, scale expansion, and technological efficiency. Results show that the CO2 emission efficiency of the Angling and Seine industry is high with the development potential of the low-carbon fishery. Moreover, China’s technological progress is increasing, but the technical efficiency of CO2 emission reduction is declining. Lack of pure technical efficiency is the primary constraint of low-carbon capture fishery, making changes in efficiency show a downward trend. These results expand the research depth of the efficiency impact of technological progress and reveal that technological progress keeps increasing, but the CO2 emission reduction efficiency is decreasing. This indicates that emission reduction requires both technological growth and the technology’s capacity to reduce CO2 emissions efficiently.

Research on the articulated coupling effect of carbon tax policy under resource endowment in China

The carbon tax is a policy tool that internalizes external costs through a tax mechanism, which helps to reduce the consumption of fossil energy and lower carbon dioxide emissions. China, as the largest carbon emitter, introducing a carbon tax can further enhance the effectiveness of emission reduction. However, the introduction of a carbon tax may exacerbate contradictions in other aspects of the social system. To this end, the paper establishes a dynamic model of the carbon tax system by combining grey system theory and the IPAT model and then explores the coupling effect of the carbon tax on the economy, energy, and environment under the premise of China's resource endowment. It is found that carbon tax will not only distort consumer behavior but also aggravate the degree of capital market distortion. In the time-series simulation, it is found that the emission reduction efficiency of the carbon tax will show an oscillation decline. The carbon tax undermines the carbon peak target by dampening demand for energy consumption. In addition, we also find that the change of energy structure is the root of driving the failure of the "Jevons Paradox" and the realization of the "environmental Kuznets curve," and the panel data of energy and economy are only the manifestation of these two phenomena. China needs to adjust its energy structure to achieve its carbon peaking target. These results are helpful for policymakers to rationally view the carbon peaking target and formulate reasonable emission reduction policies.

Engineering application of BIM in saving water and energy conservation

With the improvement of living standards, people are more and more eager to improve the efficiency of energy conservation and emissions reduction of buildings. Pursuant to this, the application of BIM technology in the water supply and drainage engineering of green buildings is proposed. Firstly, the BIM model is built to draw the axis network and axis height and transform the spatial position of family components, which is conductive to addressing the problem of the loss of engineering information. Then, the energy-saving pathways of green building water supply and drainage projects are analyzed, Concretely, the drainage energy consumption can be reduced by decreasing the overall head of the water pump. The pipe resistance and drainage efficiency can be respectively reduced and improved through reasonable selection of parallel drainage pipelines. Also, the principle of "avoiding the peak and filling valley" can be adopted to reduce pump operation in peak period and water draining in valley period, thereby saving drainage cost. By optimizing the control strategy of the drainage system and improving the utilization rate of water resources, the final results of the study show that BIM technology can realize 69% energy saving of the total savings in water supply and drainage engineering of green buildings, decrease cost consumption and improve the quality of water supply and drainage system, so as to make full use of limited water resources to achieve the effect of energy conservation and emission reduction.

Bamboo as a sustainable construction material for residential buildings in the cold and severe cold regions of China

ABSTRACT bamboo is a construction material with excellent mechanical and thermal properties. It also has excellent carbon storage capacity and is already widely recognized as a sustainable construction material. This study quantifies the bamboo’s potential for energy efficiency and carbon emission reduction throughout the building life cycle in the cold and severe cold regions of China. A six-storey residential building is applied as a case study for a comparison between reinforced concrete (RC) and laminated bamboo lumber (LBL) construction in five representative cities. The comparison considers the inventory analysis of the materialization, operation, and end-of-life (EoL) stage, energy consumption as simulated by the commercial software IES-VE, and carbon emissions assessed by a process-based method. The results for the five cities show that the use of bamboo instead of the conventional reinforced concrete structure would reduce energy consumption by 3%∼5% and reduce CO2 emissions by 7%∼20%. The analyse of results demonstrates that bamboo residential buildings are more carbon-efficient in cold climates. Furthermore, this study clarifies the applicability and sustainability of bamboo construction materials and contributes to suggesting alternatives for the life cycle carbon reduction for residential buildings.

Tower yarder powertrain performance simulation analysis: electrification study

Radical changes are necessary to address challenges related to global warming and pollution. Ever-tightening emission standards for combustion engines have already led to a drastic reduction in the amount of harmful gas and matter emitted. Drivetrain hybridization and electrification, which are becoming increasingly popular in all sectors, are two additional ways to achieve that goal. However, within the forestry sector most of the equipments still rely on conventional mechanic or hydraulic drivetrains. An example of this is tower yarders, the workhorse of the alpine logging industry. This work simulates the duty cycle and energy flow of tower yarders in logging operations, both with conventional diesel–hydraulic configuration and a proposed hybrid configuration. The objective is to determine the potential of hybridized drivetrains for tower yarder applications. Detailed models are developed to describe the cable-based extraction of timber and tower yarder internal processes. Extensive simulations were performed to determine force, power and energy components during the harvesting operation for both the diesel–hydraulic and hybrid drivetrains. Results confirm the large potential of the hybrid configuration for efficiency improvement and emission reduction, with estimated fuel savings of 45% and 63% in the uphill and downhill configurations, respectively. Extensive sensitivity analysis further demonstrates that the hybrid concept remains effective across a wide range of cable setup and transport characteristics. This confirms the large potential of electrified drivetrains, especially in the presence of very dynamic duty cycles, as is the case in cable-based logging equipment.