4E analysis of a modified multigeneration system designed for power, heating/cooling, and water desalination

ABSTRACTExergo-economic analysis of the pinch point temperature difference (PPTD) in both evaporator and condenser of sub-critical organic Rankine cycle system (ORCs) are performed based on the first and second laws of thermodynamics. Taking mixture R13I1/R601a as a working fluid and the annual total cost per net output power Z as exergo-economic performance evaluation criterion, the effects of PPTD in evaporator ΔTe, and the PPTD ratio of condenser to evaporator y, on the exergo-economic performance of ORCs are analyzed. Moreover, how some other parameters influence the optimal PPTD in evaporator ΔTe,opt and the optimal PPTD ratio of condenser to evaporator yopt are also discussed. It has been found that the exergo-economic performance of ORCs is remarkably influenced by ΔTe and y, and there exists ΔTe,opt and yopt. In addition, ΔTe,opt and yopt are affected by heat transfer coefficient ratio of condenser to evaporator ß, the temperature of working fluid at dew point in condenser T1a, and composition of R13I1/R601a: larger ß and T1a lead to lower ΔTe,opt and yopt; by contraries, larger mass fraction of R13I1 makes ΔTe,opt and yopt increase, and yopt increases linearly. The effects of the temperature of working fluid at bubble point in evaporator T3a, mass flow rate of exhaust flue gas mg, and inlet temperature of exhaust flue gas Tgi on ΔTe,opt and yopt are very slight. For comparison, three additional working fluids, namely R601a, R245fa, and 0.32R245fa/0.68R601a, are also taken into account.

Economical evaluation and optimization of subcritical organic Rankine cycle based on temperature matching analysis

Multi-objective optimization of low temperature cooling water organic Rankine cycle using dual pinch point temperature difference technologies

In this paper, exergy, exergoeconomic, and exergoenvironmental analysis of a gas turbine cycle and its optimization has been carried out by MOPSO algorithm. Three objective functions, namely, total cost rate, exergy efficiency of cycle, and CO2 emission rate have been considered. The design variables considered are: compressor pressure ratio, combustion chamber inlet temperature, gas turbine inlet temperature, compressor, and gas turbine isentropic efficiency. The impact of change in gas turbine inlet temperature and compressor pressure ratio on CO2 emission rate as well as impact of changes in gas turbine inlet temperature on exergy efficiency of the cycle has been investigated in different compressor pressure ratios. The results showed that with increase in compressor pressure ratio and gas turbine inlet temperature, CO2 emission rate decreases, that is this reduction is carried out with a steeper slope at lower pressure compressor ratio and gas turbine inlet temperature. The results showed that exergy efficiency of the cycle increases with increase in gas turbine inlet temperature and compressor pressure ratio. The sensitivity analysis of fuel cost changes was performed on objective functions. The results showed that at higher exergy efficiencies total cost rate is greater, and sensitivity of fuel cost optimum solutions is greater than Pareto curve with lower total cost rate. Also, the results showed that sensitivity of changes in fuel cost rate per unit of energy on total cost rate is greater than the rate of CO2 emission.

In the context of the rapid development of the Belt and Road (B&R) Initiative, the continuous transfer of Sino-US trade to the B&R countries is an important means to mitigate the threat of Sino-US trade, and the environmental impact of this transfer should be considered, so as to provide a scientific basis for China's policy formulation about achieving this possible trade transfer with minimized environmental impacts. This study proposes a multiregional input-output model and analyzes the impact on carbon dioxide (CO2) emissions of transferring the Sino-US trade to the B&R countries for two types of scenarios. The results show the following: (1) A transfer of either the import trade or the export trade increases global and Chinese CO2 emissions by 81.76Mt and 24.84Mt, respectively. When both the import trade and export trade are transferred, the increases in CO2 emissions are only 0.22% and 0.26%, respectively. (2) Globally, the changes in international trade-embodied CO2 emissions are responsible for most of the global emission changes, especially the CO2 emissions exported from Russia, India, and many Southeast Asian countries to China. (3) Different from the impact on global emissions, the increases in Chinese domestic production-based CO2 emissions influence China's total CO2 emissions. Due to the imported CO2 emissions, the consumption-based CO2 emissions are affected to a greater degree and increase by 70.30Mt, accounting for only 0.86% of the CO2 emissions in 2015. Finally, some policy implications are proposed.

Decalcification, especially due to acidity induced by nitrogen (N) fertilization, generates an often-underestimated source of atmospheric CO2 in agroecosystems. Complete soil decalcification intensifies the decomposition of soil organic carbon (SOC) to an extent not yet experimentally demonstrated. Six fertilization management practices including application of urea, urea + superphosphate + potassium chloride, ammonium phosphate, ammonium phosphate + potassium chloride, chicken manure along a control i.e. without fertilization were used to quantify the effects of N fertilization on soil acidification and the contribution of SIC-originated CO2 to total soil CO2 emissions. Gas samples were collected during a 56-day incubation experiment to determine total emitted CO2 and its δ13C value. The presence of soil inorganic carbon (SIC), i.e. carbonates, kept the total CO2 emissions after inorganic fertilization at levels comparable to unfertilized soil and a balanced fertilization reduced carbonate-derived CO2 emissions (15% after NPK vs 35% with N applications) due to better nutrient use efficiency and comparatively less proton generation after nitrification. When inorganic N fertilization led to complete decalcification following the shift is soil pH from circumneutral (pH=7.4) to slightly-moderately acidic pH (pH=6.5 to about 5.8) values, a sudden increase in total CO2 emissions indicated the loss of the protective effects of carbonates, and the extreme decomposition of the indigenous SOC. Complete decalcification activates a negative feedback loop: the more fertilizer is added for more crop production, the more SOC, and soil productivity will be lost. We conclude that balanced fertilization and the use of organic fertilizers not only ensure sustainable productivity, but also significantly reduce CO2 emissions from agroecosystems by preventing soil carbonate loss.

Carbon dioxide (CO₂) emissions are a form of negative externality from economic activity and development, with serious implications for climate stability. Indonesia ranks 9th as the country with the highest carbon dioxide (CO₂) emissions according to the International Energy Agency (IEA) in 2021. Indonesia's total CO₂ emissions in that year will be around 619 Mt CO₂e. The increase in CO₂ emissions in Indonesia is inevitable, as it is influenced by various structural and economic factors. This study aims to identify factors that influence the increase in CO₂ emissions and analyze the long-term influence of the variables GDP per capita, Financial Development Index, Energy Use, and Productive Age Population (15-64 years) on CO₂ emissions in Indonesia. The analysis method used is Fully Modified Ordinary Least Squares (FMOLS). The results showed that all independent variables have a positive and significant effect on CO₂ emissions in the long run. This means that every 1% increase in the independent variables can increase total CO2 emissions in Indonesia. GDP per capita variable can increase by 0.04% CO2 emissions, Energy use contributes 0.68% to CO2 emissions. Productive age population (15-64 years) can affect 0.12%. Meanwhile, Financial Development in scale can have an effect of 0.30% on CO2 emissions. This finding indicates that the policy to reduce CO2 emission.

Driving forces and mitigating strategies of CO2 emissions in China: A decomposition analysis based on 38 industrial sub-sectors

Multi-criteria analysis of a novel biomass-driven multi-generation system including combined cycle power plant integrated with a modified Kalina-LNG subsystem employing thermoelectric generator and PEM electrolyzer

Vietnam’s rapid economic growth has resulted in serious environmental concerns both at local and global scales. In-depth understanding of the key factors behind the rapid growth of CO2 emissions is of great significance in the development of local and global climate policies. Furthermore, this provides insight into how emerging economies can develop a low emission future. Recent works have demonstrated the effectiveness of the input–output model and structural decomposition analysis in analyzing how changes in different socio-economic factors affect energy-based CO2 emissions in the sectoral level using production and consumption-based perspectives. In the context of Vietnam’s economy, such aspects have not been fully explored in previous literature. This study thus analyzes the driving forces responsible for the increase in CO2 emissions in Vietnam from both production and consumption perspective during periods 2000 – 2007 and 2007 - 2011. The results using the production perspective indicate that during 2000 - 2011 the incremental change in CO2 emissions in Vietnam is driven mainly by the consumption structure (100.5%) and consumption volume (219.4%) which are offset by the decline in technology (-132.7%) and production structure (-22.5%). Population (24.1%) had a small effect on total CO2 emissions. Results using the consumption perspective show that even with large variations between the two periods, household, export and investment are the main drivers responsible for the sharp increase in CO2 emissions. This is offset by the decrease in import factor. Policy implications indicate that improving technology, adjusting production and consumption structure, and optimizing international trade are important factors for alleviating CO2 emissions in Vietnam.

Abstract. Fossil-fuel (FF) burning releases carbon dioxide (CO2) together with many other chemical species, some of which, such as nitrogen dioxide (NO2) and carbon monoxide (CO), are routinely monitored from space. This study examines the feasibility of estimation of FF CO2 emissions from large industrial regions by using NO2 and CO column retrievals from satellite measurements in combination with simulations by a mesoscale chemistry transport model (CTM). To this end, an inverse modeling method is developed that allows estimating FF CO2 emissions from different sectors of the economy, as well as the total CO2 emissions, in a given region. The key steps of the method are (1) inferring "top-down" estimates of the regional budget of anthropogenic NOx and CO emissions from satellite measurements of proxy species (NO2 and CO in the case considered) without using formal a priori constraints on these budgets, (2) the application of emission factors (the NOx-to-CO2 and CO-to-CO2 emission ratios in each sector) that relate FF CO2 emissions to the proxy species emissions and are evaluated by using data of "bottom-up" emission inventories, and (3) cross-validation and optimal combination of the estimates of CO2 emission budgets derived from measurements of the different proxy species. Uncertainties in the top-down estimates of the NOx and CO emissions are evaluated and systematic differences between the measured and simulated data are taken into account by using original robust techniques validated with synthetic data. To examine the potential of the method, it was applied to the budget of emissions for a western European region including 12 countries by using NO2 and CO column amounts retrieved from, respectively, the OMI and IASI satellite measurements and simulated by the CHIMERE mesoscale CTM, along with the emission conversion factors based on the EDGAR v4.2 emission inventory. The analysis was focused on evaluation of the uncertainty levels for the top-down NOx and CO emission estimates and "hybrid" estimates (that is, those based on both atmospheric measurements of a given proxy species and respective bottom-up emission inventory data) of FF CO2 emissions, as well as on examining consistency between the FF NO2 emission estimates derived from measurements of the different proxy species. It is found that NO2 measurements can provide much stronger constraints to the total annual FF CO2 emissions in the study region than CO measurements, the accuracy of the NO2-measurement-based CO2 emission estimate being mostly limited by the uncertainty in the top-down NOx emission estimate. Nonetheless, CO measurements are also found to be useful as they provide additional constraints to CO2 emissions and enable evaluation of the hybrid FF CO2 emission estimates obtained from NO2 measurements. Our most reliable estimate for the total annual FF CO2 emissions in the study region in 2008 (2.71 ± 0.30 Pg CO2) is found to be about 11 and 5 % lower than the respective estimates based on the EDGAR v.4.2 (3.03 Pg CO2) and CDIAC (2.86 Pg CO2) emission inventories, with the difference between our estimate and the CDIAC inventory data not being statistically significant. In general, the results of this study indicate that the proposed method has the potential to become a useful tool for identification of possible biases and/or inconsistencies in the bottom-up emission inventory data regarding CO2, NOx, and CO emissions from fossil-fuel burning in different regions of the world.

In this paper, a combined cycle power plant (CCPP) is proposed that comprises of a recuperative gas turbine cycle integrated with a reheat-regenerative steam turbine cycle. The main objective of this study is to carry out the performance assessment of the proposed CCPP based on energy and exergy analyses. The results show that the CCPP yields a net power of 63.59 MW with the energy and exergy efficiency of 49.08% and 47.42%, respectively. It also reveals that the combustion chamber has the highest exergy destruction, accounting 63.30% of the total system irreversibilities, whilst the gas turbine is the most efficient component with the exergy efficiency of 94.91%. Further, a detailed summary of exergy destruction and losses are illustrated using an exergy flow diagram. Besides, a parametric study is also carried out to show the effects of pinch point temperature difference (PPTD), boiler pressure, air preheater (APH) outlet temperature and the gas turbine inlet temperature (GTIT) on the performance of the overall CCPP. It shows that increasing the APH outlet temperature improves the overall performance of the CCPP, whilst with the increase in PPTD, the performance slightly drops. However, with the rise in GTIT and boiler pressure, the energy and exergy efficiency of the CCPP first increases and attains the peak then again reduces.

Impact of economic development on CO2 emission in Africa; the role of BEVs and hydrogen production in renewable energy integration

Performance analysis and multi-objective optimization of organic Rankine cycle for low-grade sinter waste heat recovery

How asymmetric is the response of CO2 emissions to economic restructuring in China? Evidence from NARDL approach