• Energy Research

Abstract Zostera marina is an aquatic plant forming wide grasslands and considered as the lungs of the marine ecosystems. However, the residues reaching the coastlines create nuisance and high costs are required for their disposal. The objective was to investigate the potential of Z. marina residues as a source of secondary metabolites and feedstock in order to propose alternative solutions to the landfill. The supercritical CO 2 extract had a total phenol value of 55.4 mg GAE/g extract and a radical scavenging capacity of 71.4%. Considering the raffinate phase, 3% higher hemicellulose content was reached after supercritical CO 2 treatment. Enzymatic hydrolysis revealed 31.45% and the yield of simultaneous saccharification and fermentation was 8.72% corresponding to a productivity of 0.273 kg/(m 3 h). An integrated process is proposed, where supercritical fluid extraction can act both as the main process to obtain solvent-free pharmaceutical compounds and a pretreatment method in order to loosen the lignin structure, thereby liberating some of the hemicellulose in the matrix.

SUMMARY The Turkish wind energy industry is one of the most competitive and fastest growing industries in the energy sector. Industrial energy demands, Kyoto agreement and carbon trade are shown as probable causes. Currently, Turkey has a total installed capacity of about 48.5 GW for electricity from all energy sources. High energy prices and unstable suppliers have stimulated Turkey's growing interest in wind business and wind power. This paper analyzes Turkey's wind energy future perspective and power generation strategy with a view to explaining Delphi approach to wind energy development. In this study, the two-round Delphi survey was conducted by experts to determine and measure the expectations of the sector representatives through online surveys where a total of 70 experts responded from 24 different locations. The majority of the Delphi survey respondents were from 23 different universities (60%), electricity generation industries (21%), two different governmental organizations (11%), nongovernmental organizations (6%) and other institutions (2%). The article discusses not only the expert sights on wind energy technology but also all bibliometrical approaches. The results showed that Turkey's wind power installed capacity is expected to exceed 40 GW by the end of the 2020 s and in the middle of the 2030 s, and Turkey would be the European leading country in the field of electricity generation from the wind. Copyright © 2011 John Wiley & Sons, Ltd.

Abstract Weibull Statistical Distribution is a common method for analyzing wind speed measurements and determining wind energy potential. Weibull probability density function can be used to forecast wind speed, wind density and wind energy potential. In this study a two-parameter Weibull statistical distribution is used to analyze the wind characteristics of Alacati region, located in Cesme, Izmir. The data used in the density function are acquired from a wind measurement station in Alacati. Measurements were gathered on three different heights respectively 70, 50 and 30 m between 10 min intervals for five and half years. As a result of this study; wind speed frequency distribution, wind direction trends, mean wind speed, and the shape and the scale ( k & c ) Weibull parameters have been calculated for the region. Mean wind speed for the entirety of the data set is found to be 8.11 m/s. k&c parameters are found as 2.05 and 9.16 in relative order. Wind direction analysis along with a wind rose graph for the region is also provided with the study. Analysis suggests that higher wind speeds which range from 6–12 m/s are prevalent between the sectors 340–360°. Lower wind speeds, from 3 to 6 m/s occur between sectors 10–29°. Results of this study contribute to the general knowledge about the regions wind energy potential and can be used as a source for investors and academics.

The inevitable transition to a decarbonized society necessitates a widespread utilization of bio-based materials and technologies toward mitigating climate change. In accordance with the European Union's sustainable development strategies, the integration of bioenergy to the existing energy mix is essential for the valorization of energy resources. In this chapter, processes and products contributing to bioenergy are reviewed within the context of biorefinery approach. Economic, ecological, and social impacts of bioenergy are discussed with examples from around the globe. Finally, suggestions to promote and sustain the implementation of bioenergy within the scope of circular bioeconomy are proposed. © 2023 Elsevier Ltd. All rights reserved.

The production of lactic acid, a polylactic acid monomer from energy crop Miscanthus × giganteus lignocellulosic biomass cultivated in Izmir was investigated. Liquid hot water (LHW) pretreatment was carried out at a temperature range of 140–200 °C, pressure 100 to 200 bar and reaction time of 15–45 min at a fixed flow rate of 2 mL/min using D-optimal experimental plan. The optimum conditions were elicited as 140 °C, 100 bar and 45 minutes, yielding the highest reducing sugar content of 77.32 mg/g, whereas 1.25 mg/mL arabinose and 1.35 mg/mL xylose as monomeric sugars. Subsequently, the enzymatic hydrolysis was applied to the solid fraction. The optimum conditions for enzymatic hydrolysis were determined as 5% (w/v) solid/liquid ratio, 20 FPU/mL enzyme loading and 72 hours, revealing the highest amount of reducing sugar as 200 mg/mL. LHW hydrolysate was used as a production medium for lactic acid manufacturing in submerged fermentation by Rhizopus oryzae. The maximum lactic acid content was found to be 6.8 g/L at 24 hours, whereas the lactic acid yield was 0.28 g/L.h. The sequential design of LHW, followed by enzymatic hydrolysis and submerged lactic acid fermentation can be utilized in industry, contributing to the bioeconomy.

Olive pomace is a by-product of olive oil production process and has the potential to be a solid biofuel after thermal treatment. In this study, olive pomace was treated by two thermal conversion methods: hydrothermal carbonization (HTC) and torrefaction. Experiments were carried out under the temperature values of 250, 275, 300 and 350°C; reaction times of 10, 20 and 30 minutes for torrefaction and temperature values of 180, 200 and 220°C; reaction time of 2, 3 and 4 hours for HTC. Products with the same energy yield value (62 %) obtained the higher heating values of 23.73 and 25.20 MJ/kg for torrefaction (275°C for 20 minutes) and hydrothermal carbonization (220°C for 2 hours), respectively. Hydrothermal carbonization method has the potential to produce chars at lower temperature values and without a drying process; and obtain products with improved higher heating values, energy yields and atomic O/C and H/C ratios compare to torrefaction products.

Abstract In pursuit of establishing a circular economy, waste-to-energy approach is gaining increasing attention. In this manner valorization of sewage sludge constitutes a critical importance due to generation in high quantities, difficulties in disposal and associating environmental impacts. Hydrothermal carbonization (HTC) is a relatively recent, however acclaimed method for sewage sludge management and valorization due to process compliance with sludge characteristics. In this review, research studies are evaluated under the categorization of application fields of sludge derived HTC products such as solid fuel production, gas production, soil remediation, nutrient recovery, water treatment and energy storage. Research findings are compiled and a network mapping is employed for the visualization of the current situation and correlation in respective fields. The potential of HTC for sewage sludge valorization and future projections concerning available techniques are assessed within the context of circular economy.

In this paper, solar photovoltaic (PV) systems, that play an essential role in reducing fossil energy resources, are considered from a sustainability perspective. Solar PV systems, accounting for a significant capacity share among renewable energy sources, will have environmental and economic repercussions in the future. Despite photovoltaic (PV) modules contributing to the production of renewable energy for an average of 25 to 30 years, they pose a threat to the global environment. Policies should support the significance of initiatives. This will ensure that PV manufacturers, users, governments, and R&D researchers assume responsibility for PV module waste, which is expected to be encountered more frequently and rapidly in the near future. Prioritizing global awareness and policy development in the field of solar PV recycling will inspire future work. Furthermore, the prospect of other solar PV technologies consolidating their market position in the future will necessitate a solar PV recycling industry. This industry should encompass all developing PV technologies.

Due to usage of fossil fuels, the depletion of world crude oil reserves and increased deteriorating climate conditions have reached a high level. These circumstances have led researches to search for alternative and efficient fuels. The main biofuels considered are bioethanol and biodiesel. In this study, ethanol and biodiesel production from cotton stalk and seed were aimed using liquid hot water (LHW) along with consecutive processes, where separate saccharification and fermentation (SHF) process was carried out. The maximum ethanol concentrations of 0.348 g/L and 0.721 g/L were achieved at 24 h and 72 h, respectively. For biodiesel conversion, cottonseed oil was subjected to transesterification, where the main interest was to utilize the by-product, glycerol. Three different glycerol concentrations were investigated in terms of ethanol fermentation using Escherichia coli K1 active culture. The maximum ethanol concentration of 0.415 g/L was achieved at 20 mL glycerol concentration for 48 h. Overall, cotton stalk and seed have the potential to be utilized on an industrial scale.