Cost Of CO2 Emissions Research Articles

Improvement of the monochlorobenzene separation process through heat integration: A sustainability-based assessment

Chlorobenzene is an important chemical intermediate in the production of commodities, such as herbicides, dyestuffs, and rubber. In this work, a heat integration was proposed for a monochlorobenzene separation process. The conventional process structure and the proposed integrated one were designed and simulated. An optimization focused on minimizing the cooling and heating costs was performed to obtain the best-operating conditions for the heat integration. The simulation of a utility plant, including cooling water and steam generation sections, was also carried out for more accurate estimations of CO2 emissions, water, energy consumption, and operating costs. The processes were evaluated and compared in terms of their sustainable performances using the eco-efficiency comparison index method and environmental and economic indicators, such as CO2 emission, water consumption, and utility cost, to assess the benefits of heat integration. The results demonstrated that the proposed strategy reduced around 57% of all environmental impacts and utility costs. As the composite evaluation index from the performance indicators showed, the proposed optimal heat integrated industrial plant significantly improved the initial processes? eco-efficiencies, up to 83%, proving a suitable strategy for a more sustainable process.

Techno-Economic Development Methodology for Mini-Environments in Battery Cell Production

Due to the rising interest in electric vehicles, the demand for more efficient battery cells is increasing rapidly. To support this transformation, battery cells must become cheaper and environmentally friendly. Energy consumption during production is a major driver of costs and CO2 emissions. To fulfill societal demand, higher gravimetric and volumetric energy density of lithium-ion battery cells are required. Since these materials are significantly more sensitive to moisture, the production conditions need to be adapted accordingly. Therefore, the preparation of clean and extremely dry atmospheric conditions is crucial for production of high-quality battery cells. The technology approach "Mini-Environment" enables the substitution of conventional clean- and dry-rooms for significant energy and cost savings. However, the diverse product- and process-specific characteristics along the value chain require individual solutions to enable Mini-Environments for highly automated battery cell production. Due to multiple interacting requirements and characteristics, such as operator interventions, logistics interfaces and air handling procedures, there is a very high diversity of variants for the machine equipment design. Moreover, typical methodological procedures for development of quality-oriented and energy efficient production machines remain less applicable to the early stages of technological development. Both issues lead to the research questions, how to identify the independencies between costs, air handling, product and process characteristics and how to reach the most techno-economical machine design. To answer these questions, a systematic techno-economic development procedure was conducted. Following a four-phase analytical approach, based on an extended morphological box, cost analysis, techno-economic utility analysis and sensitivity loop, different Mini-Environment concepts were constructed, analyzed and cross-evaluated. The study also forecasts the CO2 emission rate reduction and cost savings compared to alternative machine concepts. In summary, a fully interlinked system design was adapted on a cell assembly line with a cost-saving potential of 56% for future battery cell production.

Standalone hybrid system energy management optimization for remote village considering methane production from livestock manure

Recently, many efforts have been done to overcome increasing fuel consumption. One of the vital solutions is utilization of standalone renewable energy resources hybrid systems. This paper attempts to develop a cost-effective methodology to ascertain optimal design and energy management for a remote village. Different energy resources such as wind and solar, fuel cell, and energy storage systems are employed to satisfy total demands including agriculture, residential, school, and health center. Different hydrogen production methods are proposed to verify the efficiency of the developed methodology. In the proposed village, different waste types such as rice husk, maize straw, livestock, and residential wastes are used to generate the required hydrogen for fuel cells to generate electricity. The main objective of the proposed methodology is minimizing the total cost of the village including total costs of each Distributed Generation (DG), cost of natural gas consumption, penalty for interruption the demands, and cost of CO2 emission. A Particle Swarm Optimization (PSO) algorithm is employed to solve the optimization problem by minimizing the total system costs while the customers required Loss of Power Supply Probability (LPSP) is satisfied. The suggested hybrid system not only increases the renewable energy penetration but also decreases the natural gas consumption. The results achieved in the course of the present study depict that utilization of energy produced from different types of wastes plays a significant role in conserving fossil fuels and overcoming the fossil fuels depletion. It is concluded from the results that there is about a 17.46% reduction in natural gas consumption when all available waste is utilized. In addition, considering 100% availability for the animal manure reduces the natural gas consumption by reformer from 2.373 to 1.605 million liters which means reduction of the natural gas consumption is 32.35%. The results conclude that H2 produced by livestock waste is dominating among available wastes. However, there is about 18% reduction in the Cost of Energy (COE), when 100% availability is considered for this type of waste.

Net-Zero Target and Emissions from Land Conversions: A Case Study of Maryland’s Climate Solutions Now Act

Many climate change “solution” plans include net-zero goals, which involve balancing the anthropogenic greenhouse gas emissions (GHG) with their removal. Achieving net-zero goals is particularly problematic for soils because they are often excluded from GHG inventories and reduction plans. For example, Maryland’s Climate Solutions Now Act (Senate Bill 528) put forward the goal of lowering emissions of GHG to 60% under 2006 quantities by 2031 and with a target of net-zero emissions by 2045. To achieve these goals, the state of Maryland (MD) needs to quantify GHG emissions from various sources contributing to the state’s total emissions footprint (EF). Soils are currently excluded from MD’s GHG assessments, which raises a question about how the soil impacts the net-zero goal. This study examines the challenges in meeting net-zero goals using an example of carbon dioxide (CO2) as one of the GHG types (net-zero CO2 emissions). The current study quantified the “realized” social costs of CO2 (SC-CO2) emissions for MD from new land developments in the period from 2001 to 2016 which caused a complete loss of 2.2 × 109 kg of total soil carbon (TSC) resulting in $383.8M (where M = million, USD = US dollars). All MD’s counties experienced land developments with various emissions and SC-CO2 monetary values. Most of the developments, TSC losses, and SC-CO2 occurred near the existing urban areas of Annapolis and Baltimore City. These emissions need to be accounted for in MD’s GHG emissions reduction plans to achieve a net-zero target. Soils of MD are limited in recarbonization capacity because 64% of the state area is occupied by highly leached Ultisols. Soil recarbonization potential is further reduced by urbanization with Prince George’s, Montgomery, and Frederick counties experiencing the highest increases in developed areas. In addition, projected sea-level rises will impact 17 of MD’s 23 counties. These losses will generate additional social costs because of migration, costs of relocation, and damages to infrastructure. The state of MD has a high proportion of private land ownership (92.4%) and low proportion of public lands, which will limit opportunities for relocation within the state. Net-zero targets are important but meeting these targets without specific and integrative approaches depending on the source and type of emissions may result in failure. These approaches should also focus on the social costs of emissions, which raises the need for a new concept of integrating net-zero emissions and social costs.

How large is the mitigation potential of natural climate solutions in China?

China is facing a huge challenge in achieving its carbon neutrality goal by 2060 given that it is currently one of the world’s largest greenhouse gas (GHG) emitters and has set a very short timeline for going from peak emissions to carbon neutrality. Natural climate solutions (NCS) that protect, manage, and restore ecosystems have shown substantial potential for increasing carbon sinks or reducing GHG emissions to offset fossil fuel CO2 emissions. This study quantified the mitigation potential of 18 NCS pathways in China at 0.67–1.65 Gigatonne of CO2 equivalent (Gt CO2e) yr−1 averaged from 2020 to 2060, which is even larger than the size of the current national terrestrial carbon sink. Compared with a previous global estimate, our results show a lower mitigation potential in forest ecosystems but a much greater potential for cropland ecosystems in China. From 2020 to 2060, all 18 pathways combined can provide cost-effective mitigation compared to the global social cost of CO2 emission and carbon prices, and 98.6% and 83.3% mitigation potential are cost-effective, respectively. This study further showed that immediate action provides the greatest mitigation. Our estimates highlight the important role of NCS in achieving the national carbon neutrality goal because of their large mitigation potential and cost-effectiveness.

Techno-economic assessment of hydrogen production from seawater

Population growth and the expansion of industries have increased energy demand and the use of fossil fuels as an energy source, resulting in release of greenhouse gases (GHG) and increased air pollution. Countries are therefore looking for alternatives to fossil fuels for energy generation. Using hydrogen as an energy carrier is one of the most promising alternatives to replace fossil fuels in electricity generation. It is therefore essential to know how hydrogen is produced. Hydrogen can be produced by splitting the water molecules in an electrolyser, using the abondand water resources, which are covering around ⅔ of the Earth's surface. Electrolysers, however, require high-quality water, with conductivity in the range of 0.1–1 μS/cm. In January 2018, there were 184 offshore oil and gas rigs in the North Sea which may be excellent sites for hydrogen production from seawater. The hydrogen production process reported in this paper is based on a proton exchange membrane (PEM) electrolyser with an input flow rate of 300 L/h. A financially optimal system for producing demineralized water from seawater, with conductivity in the range of 0.1–1 μS/cm as the input for electrolyser, by WAVE (Water Application Value Engine) design software was studied. The costs of producing hydrogen using the optimised system was calculated to be US$3.51/kg H2. The best option for low-cost power generation, using renewable resources such as photovoltaic (PV) devices, wind turbines, as well as electricity from the grid was assessed, considering the location of the case considered. All calculations were based on assumption of existing cable from the grid to the offshore, meaning that the cost of cables and distribution infrastructure were not considered. Models were created using HOMER Pro (Hybrid Optimisation of Multiple Energy Resources) software to optimise the microgrids and the distributed energy resources, under the assumption of a nominal discount rate, inflation rate, project lifetime, and CO2 tax in Norway. Eight different scenarios were examined using HOMER Pro, and the main findings being as follows:The cost of producing water with quality required by the electrolyser is low, compared with the cost of electricity for operation of the electrolyser, and therefore has little effect on the total cost of hydrogen production (less than 1%).The optimal solution was shown to be electricity from the grid, which has the lowest levelised cost of energy (LCOE) of the options considered. The hydrogen production cost using electricity from the grid was about US$ 5/kg H2.Grid based electricity resulted in the lowest hydrogen production cost, even when costs for CO2 emissions in Norway, that will start to apply in 2025 was considered, being approximately US$7.7/kg H2.From economical point of view, wind energy was found to be a more economical than solar.

Numerical analysis of thin building envelope-integrated phase change material towards energy-efficient buildings in severe hot location

Phase change materials (PCMs) have a great potential to enhance building thermal comfort and save energy towards energy-efficient buildings. The current study sheds light on employing PCM passively in a thin building envelope under a severely hot location using EnergyPlus software. The thermal contribution of PCM to indoor thermal comfort was evaluated considering the average temperature fluctuation reduction (ATFR), thermal load levelling reduction (TLLR) and operative temperature reduction (OTR). Besides, the total average heat gain reduction (AHGR) and equivalent CO2 emission and electricity cost saving (ECS) were discussed to quantify the energy-saving. Simulation results demonstrated PCM effectiveness during the hottest summer days. Quantitatively, the PCM contributed to the ATFR by 5 °C- 6 °C, along with TLLR and OTR by an average of 38%-59% and 6 °C, respectively. According to the energy-saving analysis, the daily total AHGR owing to PCM integration ranged between 66.6% and 76.5%, where the roof shared the most. The results also indicated environmental and economic benefits, attaining CO2 emission reduction by 2 kg/day and ECS by up to 250 IQD/day. Conclusively, the PCM can significantly improve building performance when integrated passively with thin envelope elements in severely hot locations.

Superefficient separation of HFC-245fa/HF using extractive distillation: From computational thermodynamics to process assessment

In this study, the applications of different extractants in the separation of 1,1,1,3,3-pentafluoropropane/hydrogen fluoride mixtures at the molecular level (including the extraction mechanism) and on a systematic scale (including extraction performance analysis) were investigated. The optimal extractant was screened, and 99.9 % 1,1,1,3,3-pentafluoropropane and hydrogen fluoride was obtained by an extractive distillation process. The extractant screening results indicated that ethyl acetate was the most promising extractant for 1,1,1,3,3-pentafluoropropane, followed by dimethyl sulfoxide. Analysis of the relative volatility also validated that ethyl acetate can be used as an extractant for separating 1,1,1,3,3-pentafluoropropane/hydrogen fluoride mixtures. The extractive distillation process results showed the optimal C01 and C02 parameters as determined by the sequential iterative optimization method. Economic analysis indicated that the annual operating costs and equipment costs are $ 0.70 × 106 and $ 2.01 × 106, of which the equipment costs of C01 and C02 are 33.03 % and 23.91 %, respectively. Environmental analysis demonstrated that the amount and cost of CO2 emissions for extraction distillation using ethyl acetate are 1.22 × 104 t/y and 6.34 × 104 $/y, respectively, which are 71.36 % lower than those of pressure swing distillation process. In addition, a reduction in the operating time results in a significant reduction in the emission costs.

CO2 Emission Costs Due to the Production and Use of Vehicles in the Context of Automotive Development

Abstract The aim of this article is to assess the carbon dioxide (CO2) emissions of three types of cars: two internal combustion cars and one Fuel Cell Electric Vehicle (FCEV), measured on the basis of type approval regulations. The article also assesses the CO2 emission costs resulting from the production of fuel and the production of the car. It was assumed as a research hypothesis that the development and growing serial production of vehicles with different power systems will bring measurable changes in CO2 emissions from road transport. Based on their own research, the authors also analyzed the credibility of the assumptions made about the benefits related to emissions resulting from replacing the classic vehicle with hydrogen one. They estimated the duration and intensity of use of a hydrogen vehicle that offers CO2 benefits compared to a conventional vehicle.

Optimal fresh-air utilization strategy for constant temperature and humidity air-conditioning system based on isocost line

The constant temperature and humidity air-conditioning systems extensively applied in buildings and spaces, such as clean rooms and manufacturing facilities, are considerably energy intensive. To provide thermal comfort, ensure working efficiency, or maintain positive pressures in a workshop, a large amount of fresh air must be supplied indoors. The reasonable use of fresh air can reduce the cost (such as energy, CO2 emission, or money cost) of the air-handling process. An optimal fresh-air utilization strategy was developed to minimize the cost of operation based on considerations of the different costs for different handling processes in all working conditions. Straightforward isocost lines were developed to determine the optimal fresh-air ratio. Using this method, the performances of heating, ventilation, and air-conditioning systems in a workshop were simulated and tested. Results demonstrate that the proposed optimal strategy exhibits superior performance in terms of cost savings. Compared with commonly used strategies, the optimal strategy can reduce the total annual primary energy consumption by 8.3%–9.7%; and the reduction can be as high as 35% in the transition seasons. When the optimal fresh-air utilization strategy is applied in the field, the primary energy consumption is reduced by 6.4%–9.8% on typical days.

A Robust Possibilistic Bi-Objective Mixed Integer Model for Green Biofuel Supply Chain Design under Uncertain Conditions

In recent years, concerns regarding issues such as climate change, greenhouse gas emissions, fossil reserve dependency, and petroleum price fluctuation have led countries to focus on renewable energies. Meanwhile, in developing countries, designing an appropriate biofuel supply chain network regarding environmental competencies is an important problem. This paper presents a new bi-objective mixed integer mathematical model aiming to minimize CO2 emission and total costs in the process of the biofuel supply chain, creating a suitable green supply chain network. In this respect, CO2 emission and biofuel demand are regarded as uncertain data to address the real complex cases. Moreover, the SAUGMECON approach was implemented to construct a single objective model, and the obtained Pareto optimal points were depicted and analyzed. Thereby, a robust possibilistic programming approach was implemented to the proposed model to handle existing imprecise data. Furthermore, the applicability and performance of the proposed model were demonstrated based on an experimental example. In this respect, the obtained results from the proposed robust possibilistic programming model were compared with its crisp form to show the robustness and reliability of the proposed uncertain mathematical model.

How has China's low-carbon city pilot policy influenced its CO2 abatement costs? Analysis from the perspective of the shadow price

Extant studies mainly focus on the emissions reduction effect of environmental regulations, ignoring their influences on the costs of reducing emissions. This study takes the low-carbon city (LCC) pilot project in China as a quasi-natural experiment and examines its impact on the marginal abatement cost (MAC) of CO2 emissions. Based on city-level data from 2003 to 2018, it first utilizes a dual model of non-linear programming to estimate the shadow price of CO2 emissions, which is applied to measure the MAC. Then, it employs the difference-in-differences (DID) approach to estimate the causal impact. The results suggest that the LCC project has increased the MAC of CO2 emissions of pilot cities by 5.27% through two opposite effects: (i) The green technology progress effect, which decreases the MAC; (ii) The emissions intensity effect, which increases the MAC. The results are robust after accounting for heterogeneous treatment effects, omitted variables, sample selection bias, potential outliers, and confounding factors. Besides, the heterogeneity analysis suggests that the LCC project has a greater impact on small and medium-sized cities and non-resource-based cities. The findings of this study provide a more thorough knowledge of the policy effects of the LCC project and demonstrate the importance of green technology progress in reducing CO2 emissions.

An efficient Energy Management System for long term planning and real time scheduling of flexible polygeneration systems

The ever-increasing participation of new energy sources, storage systems and controllable loads to electricity markets has introduced more complexity in the operation of power plants, microgrids (MGs) and networks. To face these issues, it is often necessary to design Distributed Energy Systems to optimize the power exchange. Usually, MG operation is managed by an Energy Management System (EMS) dealing with large amounts of parameters to be taken into account and that may drive to problems difficult to be faced and requiring long computational timings. In this direction, this paper describes the Mixed Integer Linear Programming MATLAB Based Energy Management System (MB-EMS) developed at the University of Genoa, aimed at optimizing the operating costs of a generic polygeneration system, considering different electrical and thermal production units, energy storage systems, non-programmable loads and flexible loads. Many important technical details are accounted: the duration and costs related to maintenance interventions and CO2 emissions costs are considered for all production units as well as constraints and incentives related to the High-Efficiency Cogeneration systems. Constraints related to the minimum and maximum State-Of-Charge of energy storage systems, plus their deterioration, with the consequent optimization of their utilization, are also modelled. Specific test cases for all functionalities are presented. Moreover, a test related to a real MG performed over a time horizon of one year with a time step of 1 h is performed and solved in a short computational time. The linearization of constraints reduces the computational effort, avoiding the need of clustering or averaging parameters for similar production units. Consequently, calculations are rapidly performed, also when dealing with long term planning problems (a realistic test case with time horizon of one year and time step of 15 min can be simulated in some seconds). In this sense, the developed tool can be used both in real time operation and in long term planning problems.

Environmental thermoeconomic performance analysis of gas turbine combined cycle under off‐design conditions

AbstractAlthough the gas turbine combined cycle (GTCC) system has better environmental performance, it still emits pollution gases such as CO2 and NOx. It is reasonable and necessary to add the environmental cost to the power production cost of the GTCC system. Based on the structure theory of thermoeconomics, through the reasonable pricing of pollutants (considering the environmental costs of CO2 and NOx emission), the system environmental thermoeconomic cost (ETC) model is developed in this study, which achieves absolute internalization of environmental costs. Taking GTCC with different gas turbine (GT) operation strategies as the research object, the influences of different operation strategies and environmental conditions on the GTCC system ETC are studied. The results of this study show that it is beneficial to maintain higher turbine inlet temperatures (T3) and turbine outlet temperatures (T4), thus ensuring better GTCC environmental thermoeconomic performance, and GTCC with the operation strategy (using inlet guide vane (IGV) control to maintain T3 at the design value and then to keep T4 at its maximum value (IGVT3‐650‐F) has the lowest ETC, which are 0.09429 $/kW·h at 75% gas turbine load rate (GTLR) and 0.10079 $/kW·h at 50% GTLR, respectively; reducing the emission of pollutants can reduce the unit ETC; for the combustion chamber, as the pollutant generation component of GTCC unit, it is most affected by the environmental damage cost; reducing the inlet air temperature can improve the system environmental thermoeconomic performance.

Intermodal Green p-Hub Median Problem with Incomplete Hub-Network

In the literature, hub-networks have often been modeled such as only one mode is considered for all transportation. Also, the consolidated demand flows are assumed to be transferred directly between each origin-destination hub pairs. The previous assumptions impose restrictions on the practical applications of such hub-networks. In fact, various transport modes are usually retained for freight transport, and intermodal terminals (e.g., rail terminals) may not realistically be fully connected. Thus, to assist decision makers, we investigate if the appropriate use of more eco-friendly transportation modes in incomplete networks may contribute to the accomplishment of the significant global reduction goals in carbon emissions. In this paper, we study the intermodal green p-hub median problem with incomplete hub-network. For each p located hub nodes, the hub-network is connected by at most q hub-links. The objective is to minimize the total transportation-based CO2 emission costs incurred through the road- and rail-transportation of each o-d demand flows. We present a MILP formulation for the studied problem and propose a novel genetic algorithm to solve it. A penalty cost is considered on solutions where train capacity is exceeded. Additionally, we present a best-path construction heuristic to generate the initial population. Furthermore, we develop a demand flows routing heuristic to efficiently determine the partition of demand flows in the incomplete road-rail network. And we implement novel crossover and mutation operators to produce new off-springs. Extensive computational experiments show that the proposed solution approach outperforms the exact solver CPLEX. Also, we perform a comparison between the unimodal and intermodal cases, and offer a discussion on the tuning of freight trains.

CO2 emission and construction cost reduction effect in cases of recycled aggregate utilized for nonstructural building materials in South Korea

The construction industry is a major consumer of natural resources and a major waste generator. The use of recycled aggregate is important for the environmental sustainability of the construction industry because it can not only reduce the need for waste landfills, but can also reduce the depletion of natural aggregates. Although there are many studies on the environmental effects of recycled aggregate, there are few studies on its practical effects as applied to real buildings. Recycled aggregates have not been widely used owing to a lack of user trust. Generally RCA has been commonly used in nonstructural materials (such as pavements or filling materials) owing to its inherent properties. Due to inferior characteristics of RCA, there is a limit to being widely used as a structural material immediately. Therefore, to expand the use of recycled aggregate, it is necessary to study the economic and environmental benefits from using recycled aggregate as a nonstructural material for buildings. In this study, the cost and potential embodied CO 2 (ECO 2 ) emission benefits were analyzed by using recycled aggregates as the nonstructural materials in four types of buildings, including apartments with 31 different characteristics. When applied RCA to the apartments, the cost savings are -$122,057 which is 10% reduction compared to original material. And the ECO 2 emissions cost savings amount to -$2,958 which is 5% reduction compared to original material; these represent the most effective case and reflect a −0.158% change in the total construction cost.

Green building envelope designs in different climate and seismic zones: Multi-objective ANN-based genetic algorithm

In recent years, the major component of green building designs adopted by governments in order to reduce CO2 emissions as well as energy consumption is the green building envelope. The green envelope has the most important share in terms of thermal energy consumption, environment, and indoor comfort criteria. Determining the most suitable building envelope combination in the building life cycle is an important problem for designers. This study presents a new multi-objective approach that determines the most suitable green envelope designs for the buildings in different climate and earthquake zones, taking into account CO2 emissions, heating/cooling energy consumption, and material cost in terms of life cycle cost analysis. To this end, EnergyPlus building performance simulation program, artificial neural network (ANN), and genetic algorithm are used together. After the heating and cooling energy consumption, CO2 emissions, and material cost values are obtained for a certain number of the envelope alternatives with the EnergyPlus, ANN models that learn the working mechanism of EnergyPlus are trained according to these values. An ANN-based genetic algorithm procedure is developed to search the whole envelope alternative space by using the trained ANN models with EnergyPlus. The proposed approach allows searching in a very short time the whole alternative space, which is almost impossible to scan with EnergyPlus by reducing the time spent and the number of alternatives required for the design and simulation processes of the green building envelope. The proposed approach is performed for a design-stage city hospital structure in Turkey. Window type, the internal/external plaster, wall, and insulation materials along with the thicknesses of these materials, which consist of 46 different variables, are determined as envelope attributes for four different climate and seismic zones. The green building envelope designs obtained with the proposed approach are entered into EnergyPlus and the consistency of the results is compared. ANN models with an average accuracy of over 97% are developed. Without the CO2 emission cost in the life cycle cost, the mean absolute percent error (MAPE) values for each region are 0.67%, 0.6%, 0.58%, and 1.78%, respectively. With the CO2 emission cost in life cycle cost, the MAPE values for each region are 0.96%, 0.88%, 0.86%, and 0.43%, respectively. According to the obtained results, there is a consistency of over 99% between EnergyPlus and the proposed approach.

Are EU environmental regulations consistent with the concept of internalisation of externalities – the case of Polish electricity sector

The article’s goal is to examine whether the existing EU environmental regulations implemented in the Polish electricity sector are consistent with the concept of internalisation of external costs. The tool used in the research is the partial equilibrium model of the mid-term development of the Polish power sector. There are two scenarios. The first ‘base’ scenario assumes gradual decarbonisation of the Polish energy sector. In the ‘int’ scenario, the structure of energy production results from the full internalisation of external costs. The structural changes in the ‘base’ scenario are a significant challenge. All coal-based technologies are being drastically phased out and will be replaced by RES and nuclear technologies. The climate policy leading to a gradual reduction of CO2 emissions in Poland makes sense, assuming much higher external costs of CO2 emissions (€65/Mg CO2 ) than those assumed in this study.

Optimal design of hybrid grid-connected photovoltaic/wind/battery sustainable energy system improving reliability, cost and emission

In this paper, the optimal designing framework for a grid-connected photovoltaic-wind energy system with battery storage (PV/Wind/Battery) is performed to supply an annual load considering vanadium redox battery (VRB) storage and lead-acid battery (LAB) to minimise the cost of system lifespan (CSLS) including the cost of components, cost of purchasing power from the grid and cost of CO2 emissions and the reliability constraint is defined as energy not supplied probability (ENSP). The optimal configuration of the system is found via an artificial electric field algorithm (AEFA). The capability of the design framework with the VRB is evaluated on sizing, CSLS, ENSP and cost of energy (COE) and in achieving a reliable and economical energy system in comparison with design based on the LAB. The results demonstrated that the CSLS (0.7–1%) and COE (0.87–1.2%) are reduced and reliability (7–10%) is improved more in the grid-connected designing framework for 1% of maximum ENSP (ENSPmax = 1%) in comparison with the stand-alone framework due to power purchasing capability from the grid and minimising the CO2 emission. The results cleared that the CSLS (32.7%), and COE (32.8%) are decreased and reliability (2–4.3%) is improved more for ENSPmax = 1% in system design with VRB than the system design using LAB storage due to higher depth of discharge and further efficiency. The results proved that increasing the ENSP constraint causes decreases in the CSLS and COE and enhances the reliability. The better performance of the proposed multi-criteria design framework via the AEFA is confirmed in comparison with the particle swarm optimisation (PSO) and grey wolf optimiser (GWO) to obtain the best configuration of the hybrid system with the lowest CSLS and COE and more reliability.

How does the marginal abatement cost of CO2 emissions evolve in Chinese cities? An analysis from the perspective of urban agglomerations

Lowering the cost of reducing carbon emissions is of great significance for the low-carbon development of urban agglomerations. This study aims to investigate the dynamic characteristics of the marginal abatement cost (MAC) of CO2 emissions (measured by its shadow price) in China's eight major urban agglomerations. Based on the data from 135 cities from 2003 to 2018, this study uses a dual model of nonparametric linear programming to calculate the shadow price of CO2 emissions, which is used to measure the MAC and estimate the marginal abatement cost curve (MACC). Subsequently, it uses the Dagum Gini coefficient to examine the regional differences in the MAC and corresponding sources and uses the spatial convergence model to examine the convergence trend of the MAC within and between urban agglomerations. The results reveal a U-shaped relationship between carbon emission intensity and the MAC, and the MAC increases gradually with the decrease in carbon intensity. Barring the Beijing–Tianjin–Hebei region, differences in the MAC within other urban agglomerations are narrowing, and the regional difference is the main source of the overall difference. The convergence analysis suggests that the MACs of the eight urban agglomerations as a whole and within each urban agglomeration are changing toward their respective steady-state levels, and spatial correlation is one of the reasons for the convergence within some urban agglomerations. Finally, it is recommended that the technology spillover and scale effect of the agglomeration economy should be explored fully to lower the costs of emissions reduction and promote the low-carbon development of urban agglomerations.