Limit CO2 Emissions Research Articles

Impact of CO2 reduction targets on the integrated planning of municipal multi-energy carrier systems with grid infrastructures and energy conversion units

National climate protection goals require the emission reduction in municipal energy supply systems. Those systems include energy conversion units like heatings, energy storages, and grids for electricity, gas, and heat. This paper presents a mixed-integer linear optimization model for the integrated and multi-modal planning of such municipal energy systems to reach a defined CO2 emission limit with the least-cost system design. The exemplary application of the model to a study case with 3900 buildings shows that the flexible hybrid energy system resulting without emission restrictions gradually transforms into an inflexible system solely relying on pellet heaters and photovoltaic units when tightening the emission limit by just a few percentage points.

Water-Saving Tips With a Visualized Indicator Related to the Environment

Water-saving tips are information-based interventions aimed at managing water demand. Studies of the effectiveness of qualitative water-saving tips to explain why and how water should be saved have not always found significant changes in water consumption. Some studies indicate that the addition of quantitative tips and videos are effective for water conservation. This study adds to the literature by attempting to verify the effectiveness of water-saving tips that visualize the amount of water that can be saved using illustrations of bathtubs. Furthermore, as not all people are interested in water saving, we include tips with a visualized indicator related to the environment, which is of more general interest. These tips used CO2 emissions reductions to demonstrate the effect of water saving. As a result, for high-consumption households, it is more effective to present water-saving tips that present information on how their actions can limit CO2 emissions than to illustrate the reduction in water consumption directly. At the same time, for low-consumption households, none of the tips had neither water-saving nor boomerang effects (i.e., increased the consumption while planning to reduce). Households were divided into high-and low-consumption using baseline water consumption per capita for their household size. The results of this study could serve as a tool for water demand management that can be easily utilized in many parts of the world.

Impact of renewable and fossil fuel energy consumption on environmental degradation: evidence from USA by nonlinear approaches

ABSTRACT The study investigates impact of energy consumption on environmental degradation at aggregated and disaggregated levels. In this context, the study considers carbon dioxide (CO2) emissions as proxy of environmental degradation, and focuses on the United States of America (USA) as the biggest economy and highest second carbon-emitting country. Moreover, the study uses monthly data between 1989 January and 2021 September and performs nonlinear approaches as Wavelet Coherence (WC), Granger Causality-in-Quantiles (GCQ), and Quantile-on-Quantile Regression (QQR). Besides, Quantile Regression (QR) is used for robustness checks of the QQR. The results show that (i) energy consumption has an important impact on the CO2 emissions in the short, medium and long term, while the impact changes according to times and frequencies; (ii) causal effect exists in almost all quantiles excluding some lower (0.05, 0.25), middle (0.65, 0.70, 0.75, 0.80) and higher (0.95) quantiles, whereas indicator-based results change a bit; (iii) the QR results confirm that the QQR results are robust; (iv) overall, the effects of the energy consumption indicators change according to times, frequencies, quantiles, and aggregated/disaggregated levels. Hence, the empirical outcomes underline the significance of renewable energy consumption in improving environmental quality through limiting CO2 emissions at aggregated and disaggregated levels. The results imply that the USA policymakers should focus on the efforts the decreasing fossil sources and increasing renewable sources through conversion of energy systems to limit CO2 emissions while considering changing impacts of energy consumption at various times, frequencies, quantiles, and aggregated/disaggregated levels.

The effect of renewable energy development, market regulation, and environmental innovation on CO2 emissions in BRICS countries.

The relationship between energy, environment, and economic growth has been received a lot of attention recently among scientific studies, but environmental sustainability remains a global issue. Renewable energy development, green technological innovations, and regulatory policy mechanisms can all help to reduce greenhouse gas emissions and support environmental sustainability. The purpose of this study was to look at the influence of renewable energy development, market regulation, and environment-related innovation on CO2 emissions in the BRICS countries from 1990 to 2020. For empirical analysis, it uses second-generation panel unit root test and updated linear and nonlinear cointegration techniques. To this end, this study employs symmetric and asymmetric approach to linear and nonlinear relationship among study variables. The findings indicate that there is long-run symmetric and asymmetric relationship between renewable energy development, market regulation, environment-related innovation, and CO2 emissions. The market regulation plays significant mediating role in relation between renewable energy development, environment-related innovation, and CO2 emissions. Our findings suggest that BRICS countries need to more focus on the environment-related innovation and renewable energy development. They should design market-based environmental regulation policies, emphasize on environmental taxes, expand renewable energy development, and environment-related innovations. Such strategies are key to limiting CO2 emissions and gain environmental sustainable.

Decarbonization of the Indian electricity sector: Technology choices and policy trade-offs

SummaryIndia is the third largest CO2 emitter worldwide, and its electricity demand, which is primarily supplied by coal-fired generation, is expected to increase almost threefold over the next twenty years. Here, we simulate 40 scenarios for the 2040 Indian electricity sector, considering uncertainty in future natural gas prices and costs for batteries and variable renewable energy (VRE) technologies, under different CO2 emissions limits and renewable portfolio standard (RPS) targets. We find a large-scale expansion of VRE, particularly, solar PV, in most scenarios. Furthermore, energy storage competes with natural gas and coal to provide flexibility to integrate VRE. Given a set of technology assumptions, policies that explicitly limit CO2 emissions are more cost-effective at reducing emissions than RPS policies. The former are also more effective at reducing air pollution than RPS policies by explicitly penalizing CO2 emissions, thereby reducing coal generation more substantially than RPS policies.

Sustainable digital economy and trade adjusted carbon emissions: Evidence from China’s provincial data

The importance of the digital economy and trade adjusted emissions is of great importance to study, especially in case of China. Since China is the leading exporter of the world and achieving high economic growth consecutively for the last 2-3 decades, this study, unlike past studies, evaluates the importance of digital economy, exports, imports and gross domestic product on trade adjusted carbon emissions for China. This is the only study that incorporates the importance of digital economy on trade adjusted carbon emissions for provincial data of China. This study determines whether the digital economy is a viable source of green economy. Research and development will simply replace a physical resource, flows through energy and transportation networks? This question is answered by using updated data, especially for digital economy. This study uses panel data for the Chinese provinces to investigate the impact of the digital economy in limiting CO2 emissions, taking into account GDP, exports and imports as control variables. Using method of moments quantile regression, we find a negative impact of digital economy and exports on consumption-based carbon emissions. Moreover, we find that GDP, and imports amplify consumption-based carbon emissions.

Energy assessment strategies in carbon-constrained industrial clusters

With the increasing climate change concerns, governments around the world are working on setting targets to mitigate its upsurge. Greenhouse gases (GHG), more specifically carbon dioxide (CO2), are the highest contributors to global warming. As a result, strict regulations for GHG emissions are being enforced, worldwide. Industrial sectors rely extensively on fossil fuels, the highest carbon emitters, and in turn face many challenges towards the compliance of the set emission standards. Therefore, finding solutions that would both meet the environmental requirements while satisfying the industries’ energy and fuel demands has been the focus of several studies over the years. This paper proposes a carbon reduction optimisation-based technique that assesses more than one source of energy with carbon utilisation technologies and assesses both its economic and environmental feasibilities. A systematic optimization-based model is introduced to develop sustainable utilization strategies to meet a cluster’s product requirements, while meeting the set CO2 emission limits and maximizing associated financial returns. A Mixed Integer Nonlinear Program (MINLP) was developed to select the optimal allocation of the different fuels, the optimal source to sink mapping and carbon utilization configuration to meet the mentioned targets. Even though the integration of biomass, or a renewable source of energy as an alternative to fossil fuels, has been previously investigated by many, there exist no studies that targeted more than one type of fossil fuel in carbon constrained industrial cluster. Four different case studies consisting of a natural gas cluster, a coal cluster, a biomass cluster, and a blended fuel cluster, were analysed to illustrate the proposed model.

Sustainable composites based on carbon fiber recycled for the automotive sector

In the automotive sector, lightening weight is a key issue in the designing of vehicle components, to reach the CO2 emission limits that have been defined in Europe for the year 2020. That is why the strategy in the sector is to use fiber-reinforced composites, that allow to lighten the metal structures between 15 and 40% depending on the type of fiber. On the other hand, the recyclability is another important point, since the directives on the end of the useful life of the vehicles, stipulates that will be obligatory the recycling of 85% of the vehicle, not contemplating the "recovery of energy" of polymers as a means for its recycling. Composites, although they are lightweight and have a high resistance, have the disadvantage of their recyclability, and the reality is that environmental legislation is becoming increasingly restrictive, and it is urgent to find solutions to landfill. This is one of the reasons why the pyrolysis of carbon composites for the recovery of carbon fiber, and its reuse in the form of non-woven MAT, and the thermostable resins that can be recycled and reprocessed, can lead to a new generation of sustainable and recyclable composites in the automotive sector.

Cheaper or eco-friendly cars: What do consumers prefer? An experimental study on individual and social preferences

The importance of preserving the environment by limiting CO2 emissions is an issue crucial to the modern era. One sector that contributes greatly to the increase in CO2 emissions is transport. In this paper, we assess the importance that consumers attach to the environment when buying a car. Cars are categorized by lifespan and associated production and operating costs. It is well known that consumers pay particular attention to their choices regarding these aspects. Using a laboratory experiment, we aimed to find out whether consumers prefer eco-friendly products over less expensive and non-eco-friendly ones. We analysed whether the results are different when considering individual choices versus social choices. We found that the electric car is preferable to the gasoline car, especially when the charging position is well located, and the possibility exists for rapid recharging. Furthermore, consumers seem to be sensitive to the degree of eco-friendliness. They do choose the more ecological of two electric cars with different environmental impacts, and the public economic incentive positively influences this choice. Concerning the experimental methodology applied, we found a difference in behaviour between “paid” and “unpaid” groups and between social and individual choices.

Impact of the porosity and moisture state of coarse aggregates, and binder nature on the structure of the paste-aggregate interface: Elementary model study

The preservation of natural resources and the limitation of CO2 emissions contribute to sustainable development. In the context of concrete design, this contribution is achieved by using local or recycled aggregates. However, such aggregates can be porous and of low quality, adversely affecting the compressive strength and the durability of concrete. To gain a preliminary understanding, an experimental programme was designed for an elementary model (EM) composed of paste and gravel. This paper analyses the impact of the nature (highly or only slightly porous), the moisture state (saturated surface dry (SSD) or oven dry (OD)) and the volume content of aggregates, together with the binder nature, on i) the water porosity of the EM (WP EM), and ii) the structure of the paste-aggregate interface. The results indicate that volume and water porosity of the aggregate are the two most important factors affecting WP EM. In order to better highlight the coupling between the nature of the aggregate and the nature of the binder, the porosity of the paste in the EM (WP PEM) is calculated. This calculation shows that it is the nature of the binder (water retention capacity and reactivity) rather than the aggregate porosity that mainly controls the variations of WP PEM, in comparison with the porosity of the paste hydrated (WP BP) without any aggregates. The representation of the difference between WP PEM and WP BP by a three-phase model makes it possible to assess the extent of the aggregate disturbance in the arrangement of hydration products (physical thickness of the interfacial transition zone (ITZ)). In most cases this is greater than the chemical disturbance measured with a scanning electron microscope (SEM) in combination with energy-dispersive spectroscopy (EDS). The increase in the aggregate volume content accentuates WP PEM and the ITZ physical thickness when porous aggregates (natural or recycled) in the SSD moisture state are inserted.

Does financial inclusion and education limit CO2 emissions in China? A new perspective.

China is the second-largest economy in the world after the USA and the largest contributor of CO2 emissions in the globe followed by the USA. In this study, we have included two factors that could affect the CO2 emissions in China i.e. financial inclusion and education. Five different proxies of financial inclusion have been estimated through the ARDL technique and four of them have confirmed the favorable impact of financial inclusion on the environmental quality in China. Similarly, the role of education proved to be beneficial in reducing CO2 emissions in China. Among the control variables, GDP and population also exerted a negative impact on CO2 emissions, whereas, the research and development activities encourage carbon emissions. Our findings suggest that financial inclusion and education can play an important role in the fight against global warming. Funds should be transferred to those firms, businesses, and individuals who are involved in eco-innovations. Government should try to educate people on the environment and the harmful effects of global warming. Knowledge helps to build up technology that is more energy-efficient; hence, innovation through knowledge should be promoted to fortify the positive impacts of education on the eco-system.

Exploring the Relationship between Foreign Investments and Carbon Emission: A Bound Test Analysis for Pakistan

In this study, the theoretical and empirical effects of foreign investment, openness to trade, urbanization, and economic development on carbon dioxide emission levels (CO2) in Pakistan were examined. Annual time series for 38 years 1970-2018 were utilized. The Auto Regressive Distributed Lag (ARDL) bound test has been used to estimate the model which indicates the presence of cointegration among the variables. Long-run and short-run relationships were observed between Foreign Direct Investment (FDI) and CO2 emission levels revealing that increase in FDI results in increased CO2 emission levels contributing to environmental degradation. This endorses the theory of Pollution Haven Hypothesis (PHH) in the case of Pakistan. To achieve the goal of sustainable economic development, it is imperative to consider the possible negative effects of foreign investment on the environment. The study suggests limiting CO2 emissions by adopting more advanced low carbon technologies to ensure growth and a sustainable environment. Strict implementation of environmental laws for foreign and domestic firms both by defining CO2 emission limits, installation of proper waste management plants, and imposing a pollution tax are crucial steps for the improvement of environmental quality.

Quantitative validation of an in-flow water condensation model for 3D-CFD simulations of three-way junctions using indirect condensation measurements

The usage of three way junctions to merge fluid streams is widely extended. For certain applications, such as refrigeration systems or internal combustion engines, the mixing of humid gaseous flow leads to bulk condensation, which compromises the integrity of the downstream elements. In this work, a test bench is adapted to manage the mixing of wet streams and a novel experimental technique is developed to measure condensation indirectly. Well-resolved temperature distributions are measured by means of a rotating array of thermocouples at experiments with and without humidity. Enthalpy balances using temperature distributions of both cases allow to infer the condensation mass fraction field. 3D CFD simulations with an in-flow condensation sub-model are compared with these measurements for two junction geometries and two operating conditions, with an average agreement of 11% in terms of condensation mass flow rate. The three-way junction design and its ability to reduce mixing is found to be of paramount importance to reduce bulk condensation. This validated model is therefore suitable for optimizing the junction geometry in terms of condensation reduction. With limited water condensation, NOx, CO2 and particulate matter emissions can be strongly abated for internal combustion engines by extending the usage of low-pressure exhaust gas recirculation to cold conditions.

Medium-term planning of active distribution systems considering voltage-dependent loads, network reconfiguration, and CO2 emissions

This work proposes a novel mixed-integer linear programming model to address the medium-term reinforcement planning for active distribution networks, taking into account multiple investment options and CO2 emission limits. The investment plan jointly includes (i) the replacement of overloaded conductors, (ii) the installation of voltage control equipment such as voltage regulators and capacitor banks, and (iii) the installation of distributed energy resources, such as dispatchable and non-dispatchable renewable generators, and energy storage units. Uncertainties associated with the demand for electricity, energy prices at the substation, and non-dispatchable distributed generation are addressed through scenario-based stochastic optimization. In contrast to conventional planning methods, the proposed approach models the load as voltage-dependent in order to achieve substantial reductions in energy consumption. As another outstanding feature, network reconfiguration, which is an operational planning alternative that is normally addressed independently, is incorporated within the planning options. The objective function of the model is aimed at establishing an investment strategy with minimal total costs, but that satisfies the operational restrictions of the network and CO2 emissions cap. A 69-node system was used to test the proposed model and, the results show that modeling the load as voltage-dependent and integrating network reconfiguration into the medium-term planning actions helps to achieve an effective network that, in addition to being environmentally friendly, has low total planning costs. Finally, the scalability of the proposed method was evaluated using a real 2313-node system.

Impact of the Energy Sector on the Quality of the Environment in the Opinion of Energy Consumers from Southeastern Poland

Limiting CO2 emissions has been adopted as a contemporary challenge and introduced into numerous global and regional policies. The measures taken to reduce greenhouse gas emissions largely relate to the decarbonization of the economy. Changes in the Polish energy sector are a huge challenge because the energy mix is dominated by the energy derived from coal combustion. Decarbonizing the energy sector will require significant financial resources. Therefore, several questions arise: What is the social attitude to the planned changes? How do residents treat the issue of greenhouse gases? Do they perceive the relationship between energy production and the quality of the natural environment? What are their expectations regarding the transformation of the energy sector? The aim of this study was to identify the opinion of the inhabitants of southeastern Poland on changes in the energy sector and its impact on the quality of the natural environment. The study was conducted at the turn of 2020 and 2021. The survey was partial and carried out using the CAWI (Computer Assisted Web Interview) method; 1539 questionnaire forms were filled in and the sample was randomly selected. The study confirms the following research hypotheses: 1. There is social support for the view that climate change is currently one of the greatest threats to modern civilization. 2. There is a social belief that the quality of the natural environment in southeastern Poland is good compared to other regions of Poland and Europe. 3. Increasing the share of energy based on renewable energy sources is socially expected. 4. There is a social expectation of nuclear energy. It can therefore be concluded that the surveyed community accepts the direction of changes in the energy sector.

Permeability effects assessment on recovery performances of small-scale ORC plant

Waste heat recovery (WHR) of internal combustion engine (ICE) exhaust gases through organic Rankine cycle (ORC)-based power units is one of the most effective technological alternatives to increase ICE efficiency, thereby limiting CO2 emissions. Nevertheless, for an optimum design of components and plants, the assessment of intimate ORC-based plant behaviour is a key factor. This is the case of the mass-based permeability of the plant, which represents its attitude to be crossed by the working fluid, defining a specific relation between the mass flow rate and maximum achieved pressure level. Indeed, it was experimentally found that when the pump and expander are volumetric machines, a univocal relation exists between the operating parameters. Thus, the permeability relation defines certain operating paths of the ORC plant, limiting the domain in which the physical quantities can vary and ensuring the prediction of deviations from the ideal design behaviour. The concept of permeability has not been deeply addressed in the literature despite its importance; thus, it was deepened in this study through experimental and theoretical approaches. In particular, the knowledge acquired through a broad experimental campaign allowed us to obtain a physically based relationship, highlighting the main terms which influence this parameter. These terms are then grouped into dimensionless factors that orient the design and outline an easily implementable model-based control of the maximum plant pressure. Theoretical analyses were conducted through a comprehensive mathematical model of the recovery unit validated by an experimental campaign developed on a fully instrumented ORC test bench fed by the exhaust gases of a 3 L turbocharged diesel engine. The results indicate that the maximum values of the recovered power and efficiency are 3 kW and 4.4%, respectively.

Integrated planning of grids and energy conversion units in municipal multi-energy carrier systems

The ongoing energy transition requires the planning of low-emission municipal energy supply systems. These systems comprise distribution grids for electricity, gas, and heat, as well as energy conversion units such as heating systems. This paper presents a linear optimization model considering these elements in order to identify the cost-minimizing system design while achieving a given CO2 emission limit. The model is applied to an exemplary test case comprising 900 buildings. In order to increase scalability of the model to larger system sizes, the effect of reducing the spatial resolution on the optimization results is analyzed. The results show that the effect is small and that spatial aggregation is indeed a valid approach to reduce problem complexity and to allow significant speedups, reaching a factor of 200 for the given case study.

Combination of b-Fuels and e-Fuels—A Technological Feasibility Study

The energy supply in Austria is significantly based on fossil natural gas. Due to the necessary decarbonization of the heat and energy sector, a switch to a green substitute is necessary to limit CO2 emissions. Especially innovative concepts such as power-to-gas establish the connection between the storage of volatile renewable energy and its conversion into green gases. In this paper, different methanation strategies are applied on syngas from biomass gasification. The investigated syngas compositions range from traditional steam gasification, sorption-enhanced reforming to the innovative CO2 gasification. As the producer gases show different compositions regarding the H2/COx ratio, three possible methanation strategies (direct, sub-stoichiometric and over-stoichiometric methanation) are defined and assessed with technological evaluation tools for possible future large-scale set-ups consisting of a gasification, an electrolysis and a methanation unit. Due to its relative high share of hydrogen and the high technical maturity of this gasification mode, syngas from steam gasification represents the most promising gas composition for downstream methanation. Sub-stoichiometric operation of this syngas with limited H2 dosage represents an attractive methanation strategy since the hydrogen utilization is optimized. The overall efficiency of the sub-stoichiometric methanation lies at 59.9%. Determined by laboratory methanation experiments, a share of nearly 17 mol.% of CO2 needs to be separated to make injection into the natural gas grid possible. A technical feasible alternative, avoiding possible carbon formation in the methanation reactor, is the direct methanation of sorption-enhanced reforming syngas, with an overall process efficiency in large-scale applications of 55.9%.

Projected Changes in Climate Extremes Using CMIP6 Simulations Over SREX Regions

This paper presents projected changes in extreme temperature and precipitation events by using Coupled Model Intercomparison Project phase 6 (CMIP6) data for mid-century (2036–2065) and end-century (2070–2099) periods with respect to the reference period (1985–2014). Four indices namely, Annual maximum of maximum temperature (TXx), Extreme heat wave days frequency (HWFI), Annual maximum consecutive 5-day precipitation (RX5day), and Consecutive Dry Days (CDD) were investigated under four socioeconomic scenarios (SSP1-2.6; SSP2-4.5; SSP3-7.0; SSP5-8.5) over the entire globe and its 26 Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate ChangeAdaptation (SREX) regions. The projections show an increase in intensity and frequency of hot temperature and precipitation extremes over land. The intensity of the hottest days (as measured by TXx) is projected to increase more in extratropical regions than in the tropics, while the frequency of extremely hot days (as measured by HWFI) is projected to increase more in the tropics. Drought frequency (as measured by CDD) is projected to increase more over Brazil, the Mediterranean, South Africa, and Australia. Meanwhile, the Asian monsoon regions (i.e., South Asia, East Asia, and Southeast Asia) become more prone to extreme flash flooding events later in the twenty-first century as shown by the higher RX5day index projections. The projected changes in extremes reveal large spatial variability within each SREX region. The spatial variability of the studied extreme events increases with increasing greenhouse gas concentration (GHG) and is higher at the end of the twenty-first century. The projected change in the extremes and the pattern of their spatial variability is minimum under the low-emission scenario SSP1-2.6. Our results indicate that an increased concentration of GHG leads to substantial increases in the extremes and their intensities. Hence, limiting CO2 emissions could substantially limit the risks associated with increases in extreme events in the twenty-first century.

Benchmarking Catalysts for Formic Acid/Formate Electrooxidation.

Energy production and consumption without the use of fossil fuels are amongst the biggest challenges currently facing humankind and the scientific community. Huge efforts have been invested in creating technologies that enable closed carbon or carbon neutral fuel cycles, limiting CO2 emissions into the atmosphere. Formic acid/formate (FA) has attracted intense interest as a liquid fuel over the last half century, giving rise to a plethora of studies on catalysts for its efficient electrocatalytic oxidation for usage in fuel cells. However, new catalysts and catalytic systems are often difficult to compare because of the variability in conditions and catalyst parameters examined. In this review, we discuss the extensive literature on FA electrooxidation using platinum, palladium and non-platinum group metal-based catalysts, the conditions typically employed in formate electrooxidation and the main electrochemical parameters for the comparison of anodic electrocatalysts to be applied in a FA fuel cell. We focused on the electrocatalytic performance in terms of onset potential and peak current density obtained during cyclic voltammetry measurements and on catalyst stability. Moreover, we handpicked a list of the most relevant examples that can be used for benchmarking and referencing future developments in the field.