Abstract

Electricity is a precondition to economic growth and development hence paramount. However, the source for the electricity generation is a strong indicator for sustainability. This paper offers a techno-economic assessment regarding the use of renewable-based electricity in a hybrid, looking at standalone and gridconnected scenario in the Northern Nigerian context for addressing energy deficits. In doing so, physical component modelling and optimization was done for both scenarios in seeing the overall techno-economic and environmental/emissions benefits. The results showed 15% increment in system energy generation, 77% decrement in Net Present Cost (NPC) and Levelized Cost of Energy (LCOE), with avoided emissions all in favor of the grid-connected scenario. Hence, an opportunity for a massive and effective transition if well implemented and especially on a larger scale basis. This is indeed appropriate, provided utility grid security and stability are made certain as well as appropriate policy measures set in place in favor of such energy sector bloom for the case study country in the nearby future.

Abstract

This study presents the hydrogen production from partial oxidation of methanol (POM) under sprays and dual-catalyst bed. In the experiment, two different catalysts of h-BN-Pt/Al2O3 and h-BN-Pd/Al2O3 with low Pt and Pd contents (0.2 wt%) are utilized. The effects of different preheating temperatures (100, 150, 200, 250, 300 °C), O2-to-methanol molar (O2/C) ratios (0.4-0.8), and Pt/Pd ratios (0:1, 1:2, 1:4, 1:9) on POM are also examined. The results show that a preheating temperature as low as at 100 °C can lead the Pd catalyst to trigger a POM reaction. Nevertheless, there is no significant effect on performance with increasing preheating temperature. Because of the autothermal property from the Pt catalyst during POM, it can be used to replace the preheating system in this study. The Pt catalyst is placed as the upper layer to provide heat for the Pd catalyst layer. The maximum H2 yield (1.61 mol (mol methanol)-1 ) is observed at O2/C=0.6. In this study, reducing the amount of the Pt catalyst does not significantly affect POM performance. The methanol conversions are close to 100% and H2 yield is from 1.55 to 1.57 mol (mol methanol)-1 . Overall, POM can be triggered by preheated h-BN-Pd/Al2O3 or by a dualcatalyst bed (h-BN-Pd/Al2O3 and h-BN-Pt/Al2O3) without preheating to produce hydrogen. It is noteworthy that the POM performed by a duel-bed catalyst together with a small amount (3g) of Pt catalyst can achieve a similar CH3OH conversion and hydrogen production to that which use a full Pd catalyst with preheating.

Abstract

Solid oxide cell stacks can be operated in fuel cell and electrolysis modes according to the electricity demand. Dynamic characteristics of the stack in an adiabatic environment undergoing mode step-switching was presented and analyzed in this paper. Stack temperature and its variation rate, and stack voltage and power output are illustrated. The round trip efficiency () of the stack during a switching transient process was calculated and compared when adopting different operational turns. For switching modes, round trip efficiencies of two different processes are 87.4% and 84.6%, respectively.

Abstract

The scientific contribution highlights, first of all, the insurance situation tout court in relation to catastrophic emergencies, outlining a brief framework of the ways in which insurance companies come into contact with the insured parties (contractors), and through which techniques they define, from time to time, specific contractual drafts and cases. Secondly, the text focuses on one of the most important insurance parameters for the determination of the insurance premium and possible indemnity in relation to the risk related to natural hazards, namely the so-called Exceedance Probability (EP) curve. Outlining the first two parts, the article turns to the main one of the analysis, i.e. the legal consequences, both civil and criminal, according to EU and Italian legal system, of the conduct of the insurance company on the stipulation of a contract with the omission and / or commission of a fraudulent determination of the aforementioned curve. In particular, the authors focus on the substantive and procedural determinations of the aforementioned case before the criminal and civil court, highlighting its subsidiarity or alternativeness. The conclusions concern the position of the consumer in the European Union in relation to the conduct of the insurance companies, whose imputation, negligent and / or fraudulent, often determines the stipulation of a contract rather than another about the inherent risk of natural hazards.

Abstract

In industrial production, a large amount of high temperature waste of dolomite is generated, and it can act as heat source and produce carbon dioxide. Methane reforming is one of typical chemical energy storage reaction to obtain syngas, and it can use heat source and carbon dioxide from high temperature dolomite. In this paper, catalytic activity and methane conversion of methane reforming with high temperature dolomite were studied, and the influence of temperature and inlet reactant flow rate was further analyzed. When bed temperature rose from 950o C to 1150o C, methane conversion can increase to as high as 52%, while it decreased with reactant flow rate increasing. According to Arrhenius empirical formula, the activation energy of methane reforming with high temperature dolomite is obtained as 99.1 kJ•mol-1 .

Abstract

Molten salt and S-CO2 are important high temperature heat transfer media, but molten salt/ SCO2 heat exchanger was seldom reported. In present paper, heat transfer in zigzag printed circuit heat exchanger with molten salt and S-CO2 is simulated and analyzed. Along flow direction, local heat transfer coefficient of S-CO2 first decreases with Richardson number decreasing in inlet region, and then increases with turbulent kinetic energy rising in outlet region. Performance of PCHE is mainly determined by pressure drop in molten salt passage and heat transfer resistance in S-CO2 passage. In order to decrease the pressure drop of molten salt, an optimal structure with “sin” passage is proposed. Results show that molten salt pressure drop significantly decreases in the optimal passage, and overall heat transfer coefficient slightly changes, so comprehensive performance of PCHE is improved.

Abstract

This combined lab-scale and full-scale study investigated how the anaerobic digestion process of sewage sludge was affected in the lower mesophilic temperature range (32°C). The aim of the study was to achieve a more positive heat balance by reducing the operational temperature in the full-scale mesophilic digesters in a Swedish WWTP with a preserved methane production. The effect on methane yield and degradation rate were examined by a BMP-experiment with three different temperatures (32, 34.5, 37.5°C). The BMPexperiment showed no significant difference between 37.5°C and 34.5°C in methane yield or degradation rate. At 32°C the production of biogas was decreased by 11% compared with 37.5°C. Consequently, the temperature in the full-scale digesters was gradually adjusted from 37.5°C to 35°C during two months. The heat balance for the reactors was calculated and revealed that it is possible to save up to 13% in heat consumption per year with an operational temperature of 35°C compared to 37.5°C. No change in the production of biogas could be observed during and after the temperature adjustment.

Abstract

In order to improve the reliability and continuity of smart distribution network, the wavelet neural network (WNN) fault diagnosis method based on distributed phasor measurement units (D-PMU) measurement information has been presented in this paper. Firstly, the D-PMU uploads the collected local data to the main station system, and obtains signals such as voltage and current from the main station, constructed the feature signal after the wavelet packet decomposition and as the input signals of the neural network for algorithm training, and output the training result after satisfying the error requirement, accomplish fault diagnosis. Finally, the effectiveness of the algorithm by simulation analysis using MATLAB software is verified.

Abstract

Nowadays, the fundamental idea of district heating (DH) is to utilize local heat resources to satisfy local heat demands, otherwise those resources would be wasted. However, the mismatch between the achievable resources and fluctuating demand is challenging. This study analyzed the possibilities to solve this problem by introducing a short-term thermal storage and a seasonal thermal storage. A water tank (WT) and a borehole thermal storage (BTS) were chosen as the thermal storages. The DH system of a Norwegian university campus was selected as the case study. A high order system model was built in Modelica language. The results showed that the mismatch might be solved. The BTS brought about 3 GWh annual heat saving, and the WT brought about 110 kW average peak load shaving. However, around 0.8 GWh/year electricity was used by heat pump to recover the stored heat in the ground.

Abstract

Between 1977 and 2017, more than thirty floating production assets were removed, partly due to the high operation & maintenance (O&M) cost. On the other hand, global installations of floating PV have been more than doubled since 2016. Compared with fixed PV systems, floating PV has certain advantages. For instance, seawater can contribute to the cost-effective cooling mechanism of the PV panel. This paper presented a new concept of conveying decommissioned FPSO as a platform for floating PV plant. The proposed PV system is designed to power offshore platforms or drilling rigs. Effects of tilt angle on energy outputs were evaluated through a frequency-domain hydrodynamic analysis of the FPSO. Results showed that roll motion has a larger negative effect on the total radiation on a collector, compared with pitch motion.