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Abstract This study investigates the macroeconomic effects of adverse oil price shocks on a small oil-exporting economy — the Azerbaijan economy. We estimate a recursive (near) VAR model by using monthly macroeconomic data from 2006 to 2018. The results indicate the Azerbaijan economy is adversely influenced by an oil price decline. Specifically, we find that a negative oil price shock deteriorates trade balance, causes a currency depreciation, increases inflation and falls economic activity. Furthermore, our findings imply that the oil price-led devaluation shapes the inflationary and recessionary consequences of this shock.

This paper is concerned with the risk management practices of an electricity retailer motivated by the Dutch electricity market. We examine the effectiveness of the existing base- and peak-load futures contracts as a risk management tool for the electricity retailers. We analytically characterize the retailer’s optimal hedging policy as a function of the serial correlation of the prices and the demand profiles of its customers. We find that the retailer typically over-hedges in the futures market, and the over-hedging amount increases when both base- and peak-load contracts are used. Our findings indicate that although the existing contracts in the futures market are quite efficient to replicate the exposure from profiled customers, when industrial consumers and renewable generation are included to the retailer’s portfolio, the effectiveness of such contracts decreases substantially. In our motivating example, hedging the risk of the profiled customers with base-load contracts, the firm may reduce the variance of its cash flows by 85.9%. In addition to the base-load contracts, including peak-load contracts into the hedging portfolio of the retailer increases the efficiency of hedging to 89.3%. However, when we consider the aggregate portfolio of the retailer including profiled customers, industrial consumers and renewable contracts, the efficiency of hedging through the existing futures contracts goes down as low as 32.8% during certain periods. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

With the increasing need for energy in the world, the demand for renewable energy sources is increasing day by day. This increase in energy need directs governments and private sector investors to renewable energy sources. Wind energy is one of the most important renewable energy resources on earth. In recent years, the share of wind energy in the amount of energy produced by renewable energy sources has been increasing. Wind energy emerges as a sustainable energy source due to its environmental friendliness and ability to renew itself. These features of wind energy have a great effect on the increase of its share in the energy sector. In order to get the highest efficiency from wind energy, the correct positioning of wind farms, that is, the concept of site selection is very important. One of the most important parameters in site selection of wind farms is the wind energy source and the wind speed accordingly. In order to create wind speed maps, wind speed data obtained from a certain number of stations should be interpolated for the study area. In this study, wind speed data obtained from 32 meteorology stations in Balikesir province were used. With the help of these data, wind velocity maps were created with five different interpolation methods, namely IDW, Kriging, Natural Neighbor, Spline and Trend, within the borders of Balikesir province. Finally, the results obtained by these five methods were compared with the real wind speed values according to root mean square error and evaluations were made.

Bioenergy is considered a sustainable substitute to fossil-fuel resources and the development of a prudent combination of renewable and innovative conversion technologies are essential for the valorization and effective conversion of biowaste to value-added commodities. Here, a negative pressure-induced carbonization process was proposed for the valorization of lignin-enriched biowaste precursor to bio-oil and environmental materials (biochar) at various temperatures. The high heating values (HHV) of the as-prepared biochars from the lignin enriched precursor under negative pressure (low-medium vacuum) were within 25.9-31.5 MJ/kg, which matched satisfactorily to the commercial charcoal. Whereas, the bio-oils produced from the lignin enriched precursor under vacuum conditions was a blend of complex aromatic and straight-chain hydro-carbons, including aldehyde, ketone, phenol, and furans, exhibiting ability as potential heating-oil with HHV within 21.2-28.2 MJ/kg. Moreover, the biochars produced under vacuum environments at higher temperature showed greater stability (22.5-35.9%) than those produced under N2 atmosphere.

Abstract In this article, an attempt is made to better understand the contribution of hydropower in meeting electric energy needs of Turkey. Thus, a comparison between Turkey and other countries, which have some similarities with Turkey or which are more developed nations compared to Turkey, for evaluating from different aspects the contribution of hydropower in meeting electric energy needs is performed. The producers of electricity and hydroelectricity in the world, and the electric sectors of all the selected countries are firstly examined. Thereafter, Turkey's water resources and its potential, hydropower potential, and current status of hydropower in Turkey are investigated in detail. A detailed discussion regarding economic and energy indicators, hydroelectricity versus thermal electricity, the contributions of hydroelectricity to the total and renewable electricity generation, and the usage status of hydro potential of each selected nation is also made. Finally, it is found that hydropower is the second largest contributor in meeting Turkey's electric energy needs after thermal, mainly natural gas. It is also estimated that the contribution of hydropower will continue because a vast amount of its economically feasible hydro potential (about 64%) is undeveloped. Besides, it is determined that the contribution of hydropower in the total electricity generation in Turkey is greater than that of China and India, but it is lower than that of Norway, Brazil, and Canada.

Abstract This study presents the experimental results for the first time use of Al2O3/ ethylene glycol-water (EG-water) nano-fluid (NF) in ground heat exchangers (GHE) within the ground source heat pump (GSHP) system which is prepared with 8 nm γ -Al2O3 nanoparticles. A test room with an area of 21 m2 was prepared in the cold climate region (39°42’24.8” N, 37°02’01.5” E) of Turkey, and GSHP system was installed into the room. Horizontal GHE designs are preferred as GHE design in order to maintain cost and efficiency balance. Although numerical studies on the use of NF-assisted fluids in GSHP systems are guiding in the literature, these studies have not been supported experimentally. In this study to see performance of NFs in real environment conditions Al2O3 nanoparticles were examined experimentally in horizontal U-type GHE and spiral GHE by adding different volume concentrations (0.1%, 0.2%) to EG-water (25% -75%) base fluid. Our results showed that, with a volume concentration of 0.1%, NF provided a 19% and 22% increase compared to EG-water in U-type GHE and spiral GHE, respectively, concerning GHE output temperatures. In addition, the coefficient of performance (COP) of the system using NF with a volume concentration of 0.1% showed a higher performance of 2.5% in U-type GHE and 3% in spiral GHE compared to EG-water base fluid. On the other hand, in both GHE designs, the NF with a volume concentration of 0.2% did not achieve any performance increase. The NF with a volume concentration of 0.1%, which is the most successful variation of the U-type GHE and spiral GHE systems, showed a 2.7% higher COP value than the spiral GHE in U-type GHE. As a result, it has been determined that the use of low concentration of NF in GHEs for the GSHP system provides performance improvements independent of the GHE design.

AbstractRemittances to the Philippines constitute a prominent part of its economy. However, remittances' effects on its environment have not been researched. In this regard, this research examines the direct and indirect impacts of remittance inflows on the Philippines' environmental sustainability for the 1977–2016 period by proposing a multivariate model, and by utilising the augmented ARDL and VECM methods to estimate this model. Our findings indicate that remittance inflows threaten environmental sustainability in the long‐run both directly and indirectly through boosting income and energy (oil) consumption. The results additionally imply that income and energy consumption also increase the ecological footprint of the Philippines in the long‐run. However, economic globalisation's long‐run impact is insignificant, yet its short‐run impact is significantly negative on the country's level of environmental degradation. Additionally, the findings reveal that the feedback hypothesis is valid between income and energy consumption in the long‐run, but the neutrality hypothesis is valid in the short‐run. This research's findings reveal that remittance inflows' impact on the environment is significant, and can occur through direct and various indirect channels, therefore, these inflows should be an integral part of sustainability policies in the Philippines, as ignoring them could cause further environmental decline.

Abstract One of the most important research areas searches for new sources of energy and for the highest efficiency from existing energy sources. Radio frequency (RF) energy harvesting is a promising alternative to obtain energy for wireless devices directly from RF energy sources in the environment. In this paper, we provide a broad overview of the main blocks of RF energy harvesting systems, which are the wireless transmission medium, the antenna and impedance matching circuit, the rectifier, the voltage multiplier, and the energy storage device or load. The characteristics of these blocks directly affect the performance of an RF energy harvesting system. We mainly focus on the ratio of output and input powers at each block, named as the conversion efficiency and the impedance matching efficiency, which determines the overall efficiency of system. We present detailed information about the system parameters. Thus, we characterize an RF energy harvesting system, which makes the design of system possible to obtain the maximum efficiency and correspondingly the maximum output power, providing the necessary insight about the design of RF energy harvesting systems.

This study searches the impact of tourism growth on emission pollutants in Cyprus (north), which is a small island in the Mediterranean and has shown significant development in hotel and casino sectors in the last two decades. Results from time-series analyses reveal that an inverted U-shaped EKC hypothesis is confirmed for Cyprus with and without tourism development. Tourism also exerts positively significant and long-term effects on the levels of carbon emissions, revealing that growth in the tourism sector causes degradation in the environment.