Exergoeconomic and environmental investigation of an innovative poly-generation plant driven by a solid oxide fuel cell for production of electricity,cooling, desalinated water,and hydrogen

Fuel cell and renewable-based poly-generation plants (PGPs) are proven as advanced technologies for multiple generation purposes. To limit the greenhouse gas emissions, an innovative PGP generating electricity, cooling, desalinated water, and hydrogen is proposed in the current study. The system consists of a solid oxide fuel cell as a prime mover integrated with a gas turbine, a biomass combustion chamber, an organic Rankine cycle, an ejector refrigeration cycle, a desalination unit, and a proton exchange membrane electrolyzer integrated with solar collectors. As the most effective tools for performance evaluation, exergoeconomic, and environmental analyses have been applied. The system produces electricity of 4.4 MW, refrigeration capacity of 0.16 MW, and desalinated water of 0.96 kg/s. The attained freshwater enters the electrolyzer during 12 daylight hours, leading to hydrogen and sanitary water generation with the values of 1.55 g/s and 0.94 kg/s, respectively. The cost per unit exergy and the total cost rate of the products are 11.28 $/GJ, 223 $/h, correspondingly. Carbon dioxide emission of the system is estimated to be 10.79 kmol/MWh. According to the evaluation, the total cost rate increases with increasing current density and fuel cell inlet temperature and decreasing fuel utilization factor.     

Prediction of CO<Subscript>2</Subscript> mass transfer parameters to light oil in presence of surfactants and silica nanoparticles synthesized in cationic reverse micellar system

CO₂ miscible injection method combined with surfactants and silica nanoparticles was studied to investigate the effect of these additives on CO₂ mass transfer parameters to the light oil, including diffusion coefficient, mass transfer coefficient and solubility. Silica nanoparticles with controlled size distribution were synthesized in isooctane/1-hexanol/CTAB/ammonium hydroxide, a highly-stable reverse micellar system with w _o =5. The presence of Si-O-Si and Si-O-H bonds in FTIR spectra of the system revealed that silica nanoparticles are formed by partial hydrolysis of TEOS. Results of DLS indicated that the average size and size distribution of the synthesized nanoparticles were 27.6 nm and 13-76 nm, respectively. Diffusion tests were carried out using CO₂ gas and three liquid systems: isooctane/1-hexanol, isooctane/1-hexanol/CTAB reverse micellar system without nanoparticles, and isooctane/1-hexanol/CTAB reverse micellar system with nanoparticles. Results of modeling and optimization of the gas-liquid systems under nonequilibrium interface condition, using pressure decay data show that the presence of surfactants and nanoparticles leads to decreased gas diffusion coefficient; while increased interface mass transfer resistance due to presence of aqueous droplets and nanoparticles as well as lower solubility of CO₂ in the light oil are the results of applying these additives, which limits their application. The obtained CO₂ diffusion coefficients for isooctane/1-hexanol, reverse micellar system without nanoparticles, and reverse micellar system with nanoparticles are 8.5550×10^?8, 8.2216×10^?8, and 8.1114×10^?8 m²/s, respectively.     

Robust control of connected vehicles via V2V communication

This paper introduces a robust controller for connected vehicles which are communicating through dedicated short‐range communication (DSRC) protocol to avoid collision and improve safety. By a comprehensive analysis on both longitudinal and lateral dynamics of the vehicles, the controller covers a wide range of collision avoidance scenarios, such as: Intersection Movement Assistant (IMA), Automatic Emergency Brake (AEB) and Lane Change Warning (LCW). By implementing an advanced Sliding Mode Controller (SMC), the effect of uncertainties will be mitigated for a variety of path plans. It turns out that the proposed control scheme can robustly improve the safety. Finally, we optimize the performance of vehicles in tracking the paths by an MPC controller.     

Synthesis and evaluation of NiO@MCM-41 core–shell nanocomposite in the CO<Subscript>2</Subscript> reforming of methane

In this paper, the synthesis of core shell structured NiO@MCM-41 nanocomposite via vesicles as soft template is reported for the first time. Its catalytic performance was investigated in the CO₂ reforming of methane (CRM) conversion. Stable vesicles first formed with CTAB/SDBS surfactant ratio of 1:2. Nickle nitrate was added to the vesicle mixture followed by addition of the aqueous solution of vesicle containing Ni cations inside to the MCM-41 gel. After high-temperature calcination, NiO@MCM-41 nanocomposite were obtained. The structural symmetry and the surface morphology were characterized by transmission electron microscope (TEM), low angle X-Ray Diffraction (XRD) and N₂ adsorption/desorption analysis. TEM image confirmed core–shell structure and the hexagonally ordered structure of shell of MCM-41 silica. The results indicated that the average diameter of synthesized core–shell NiO@MCM-41 particles is 70–80 nm and the most of them are of spherical shape. The result of small angle XRD and N₂ isotherm adsorption/desorption analyses indicated successfull formation of mesoporous shell. Hydrogen consumption by the catalyst mainly at 700 °C in TPR profile showed the strong interaction of the most of Nickel content with the support. CRM conversion on the prepared catalyst after 245 min of reaction led to H₂ conversion at 42%, CO₂ conversion at 48% with H₂/CO yield ratio of 0.8.     

Renewable energy transition: a market-driven solution for the energy and environmental concerns in Chile

Chile is undergoing a remarkable energy matrix transition to renewable energy. Renewable energies are expanding extraordinarily fast, exceeding earlier predictions. As a result, the country is expected to meet its 2025 goal of generating 20% of its electricity from renewable energy sources quite before. Chile has become one of the first countries in the world with subsidy-free markets, where renewable projects compete directly with other conventional sources. Favorable market conditions and successful policy reforms were keys to fostering this renewable energy development. Although the country has achieved a substantial growth in renewable energy investment in a relatively short period of time, this optimism should be treated with caution. A successful transition requires a combination of a clear decision making, persistent and consistent government policies, and a clear commitment to tackling challenges to accommodate renewable energy in the power system. In this context, this paper analyses the Chilean renewable industry and the required government policies to succeed in this transition. For this purpose, we identify several critical factors that have attracted and that could attract investment to the renewable energy sector and propose key recommendations to effectively address the major challenges faced for the future development of the industry.     

Synthesis and characterization of some new aromatic polyoxadiazoles through cyclodehydration of polyhydrazides

A series of new polyhydrazides containing pyridine heterocyclic ring, bearing bulky aromatic pendent groups, were synthesized from the reaction of diacid chlorides with dihydrazides via low-temperature solution polycondensation. All the polymers were readily soluble in polar solvents such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), and 1-methyl-2-pyrrolidone (NMP) and showed inherent viscosities equal to 0.38–0.68 dL/g. They indicated glass transition temperatures (T _g) ranging from 190 to 220 °C. Polyhydrazides were subjected to cyclodehydration to prepare poly(1,3,4-oxadiazole)s either by thermally or chemically cyclodehydration approximately in the region of 150–320 °C. The poly(1,3,4-oxadiazole)s, made by chemically cyclodehydration exhibited T _gs of 220–250 °C and inherent viscosities equal to 0.38–0.62 dL/g, while the PODs made via thermally cyclodehydration of polyhydrazides did not show any glass transition and exhibited inherent viscosities equal to 0.39–0.66 dL/g. The former polymers were soluble in conc. H₂SO₄ and partially soluble in hot DMF, NMP, DMSO, and DMAc, and the latter were only soluble in conc. H₂SO₄. They had useful levels of thermal stability and were stable up to 450 °C in nitrogen. The structure of polymers was fully characterized by IR and NMR spectroscopies.     

Comparison of the efficiency of palladium and silver nanoparticles loaded on activated carbon and zinc oxide nanorods loaded on activated carbon as new adsorbents for removal of Congo red from aqueous solution: Kinetic and isotherm study

The adsorption of Congo red (CR) into three new adsorbents including Palladium and silver nanoparticles loaded on activated carbon (Pd NPs-AC, Ag NPs-AC) and zinc oxide nanorods loaded on activated carbon (ZnO-NRs-AC) in a batch method has been studied following the optimization of effective variables including pH, amount of adsorbents and time. The experimental data was fitted to conventional kinetic models including the pseudo first-order and second-order Elovich and intraparticle diffusion model and based on calculated respective parameters such as rate constants, equilibrium adsorption capacities and correlation coefficients. It was found that for all adsorbents the removal process follows the pseudo second other kinetic model with involvement of interparticle diffusion model. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Tempkin and Dubinin and Radushkevich equations and it was found for all adsorbents that the removal process followed the Langmuir isotherm.     

Electrolyzer-fuel cell combination for grid peak load management in a geothermal power plant: Power to hydrogen and hydrogen to power conversion

This study provides comprehensive energy, exergy, and economic evaluations and optimizations of a novel integrated fuel cell/geothermal-based energy system simultaneously generating cooling and electricity. The system is empowered by geothermal energy and the electricity is mainly produced by a dual organic cycle. A proton exchange membrane electrolyzer is employed to generate the oxygen and hydrogen consumed by a proton exchange membrane fuel cell utilized to support the network during consumption peak periods. This fuel cell can be also used for supplying the electricity demanded by the network to satisfy the loads at different times. All the simulations are conducted using Engineering Equation Solver software. To optimize the system, a multi-objective optimization method based on genetic algorithm is applied in MATLAB software. The objective functions are minimized cost rate and maximized exergy efficiency. The optimum values of exergy efficiency and cost rate are found to be 62.19% and 18.55$/h, respectively. Additionally, the results reveal that combining a fuel cell and an electrolyzer can be an effective solution when it comes to electricity consumption management during peak load and low load periods.     

Environmental consequences of tourism: do oil-exporting countries import more CO2 emissions?

ABSTRACT

The study explores the impact of international tourism on consumption-based CO₂ emissions in the case of Azerbaijan for the period of 1995–2013. The results of the long-run estimations revealed that the relationship between CO₂ emissions and international tourism revenues is N-shaped. This finding also indicates that the EKC hypothesis does not hold in the case of Azerbaijan. The found curvature of the relationship and the positive impact of tourism on CO₂ emissions are in line with the expectations, considering the developing path of the country. Moreover, the impacts of imports and exports are found to be positive and negative, respectively, which are in line with the expectations and with the theoretical findings discussed in the theoretical framework section. The positive impact of tourism and the higher impact of imports highlights the importance of utilizing the environmentally friendly policies in tourism activities as well as in international trade relations.