Inkjet printing of photocatalytically active TiO2 thin films from water based precursor solutions

In this work, aqueous chemical solution deposition route suited for inkjet printing is used for the synthesis of photocatalytically active TiO₂ coatings. Environmentally friendly precursor solutions with electromagnetic ink-jet printing, allows cheap and simple processing of TiO₂ films on glass. The hydrolysis reaction of water sensitive titanium alkoxide (Ti-alkoxide) precursor is controlled by adding complexing agents as citric acid and triethanolamine prior to water addition, and aqueous stable solutions are achieved. The pH of the solutions is brought to neutral to guarantee flexible processing, avoid damage to substrates and equipment. Solution parameters are adapted to obtain optimal gelation conditions and good jettability. The influence of processing parameters on the phase formation and surface morphology is studied by thermogravimetric analysis and differential thermal analysis (TGA/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The photocatalytic activity of the films is evaluated by the degradation of methyl orange.     

An econometric analysis of residential consumption of fuelwood in a mountainous prefecture of Northern Greece

Biomass is a renewable energy source of increasing importance, especially since the energy policies of countries today are largely focused on renewable energy. It is a renewable energy source with significant potential to contribute to the energy needs of modern society, both for developing and developed countries around the world. One very important source of biomass is wood and fuelwood in particular. This article aims at providing an empirical analysis of household fuelwood consumption and the determinants of the choice to use the specific energy for heating and cooking in a district of Northern Greece. In the current empirical analysis several household fuelwood consumption models are employed, such as GLM, Tobit and Heckman regression-based techniques. The results show that household sociological and economical characteristics as well as more general environmental issues are suitable to explain differences towards fuelwood consumption for space heating and cooking. We additionally evaluate the household fuelwood consumption for heating through the statistical analyses conducted.     

Small hydropower stations in Greece: The local people's attitudes in a mountainous prefecture

During the last years, it has become evident that operation of hydropower stations creates discussions and different views on the local communities. Especially, although the issue of operation of small hydropower (SHP) stations or plants is of considerable interest in Greece, almost no study has been conducted to investigate the current status of Greek citizens’ attitudes towards utilization of the available hydropower potential through SHP. The present study, therefore, aims to examine in the prefecture of Ioannina, Greece, the local people's attitudes on operation of SHP stations in connection with the increased public interest for environmental and social dimensions of small hydropower stations, and to determine how these attitudes change with respect to various factors.     

Contribution of SHP Stations to the development of an area and their social acceptance

The global community, but also the European Union particularly, has launched in recent years a series of actions and measures for the promotion of the renewable energy sources (RES) in the context of dealing with the climate change. Small hydropower (SHP) stations can play a vital role in the increasing energy demand, helping to reduce the mankind dependence to the fossil fuels. In addition, SHP stations have significant advantages as they contribute to the development of the local economy and to the reduction of the environmental pollution.Changing the legislative framework in recent years in Greece increased the penetration of RES in the country's energy system and encouraged the private initiative in this area.The study was carried out in an area of Northern Greece (Prefecture of Pella) where the installation of private SHP stations is particularly impressive over the last decade (in relation with other parts of the country). The main conclusions of the study carried out with a questionnaire are that there is an important acceptance of SHP stations from the residents recognizing the role that they play in the regional development and in the protection of the environment making them more attractive to investors.     

Optimum design and operation under uncertainty of power systems using renewable energy sources and hydrogen storage

The presented work addresses the design and optimization under uncertainty of power generation systems using renewable energy sources and hydrogen storage. A systematic design approach is proposed that enables the simultaneous consideration of synergies developed among numerous sub-systems within an integrated power generation system and the uncertainty involved in the system operation. The Stochastic Annealing optimization algorithm is utilized to handle the increased combinatorial complexity and to enable the consideration of different types of uncertainty in the performed optimization. A parallel adaptation of this algorithm is proposed to address the associated computational requirements through execution in a Grid computing environment. The proposed developments are implemented in a system that consists of photovoltaic panels, wind generators, accumulators, an electrolyzer, storage tanks, a compressor, a fuel cell and a diesel generator. Numerous design and operating parameters are considered as decision variables, while uncertain parameters are associated with weather fluctuations and operating efficiency of the employed sub-systems. The obtained results indicate robust performance under realizable system designs, in response to external or internal operating variations.     

Efficient photocatalysts by hydrothermal treatment of TiO2

The aim of this work was to identify the optimum synthesis conditions and the most effective technique for noble metal deposition in a perovskite/palladium-based catalyst for natural gas combustion. The solution combustion synthesis (SCS) of perovskite/zirconia-based materials was investigated, by starting from metal nitrates/glycine mixtures. Characterization and catalytic activity tests were performed on as-prepared powders and then repeated after calcination for 2 h at 900 °C in calm air. Calcination appeared to be beneficial in that, despite lowering the specific surface area, it promoted the simultaneous crystallization of both LaMnO₃ and ZrO₂ and the half-conversion temperature (T₅₀), regarded as an index of catalytic activity, was lowered. Two phases, both active towards methane oxidation – lanthanum manganate and palladium oxide – were combined so as to evaluate their synergism in terms of catalytic activity. Pd was therefore added either via incipient wetness impregnation on LaMnO₃·2ZrO₂ or through a one-step SCS-based route. Characterization and catalytic activity tests followed suit. Optimal composition and preparation routes were found: T₅₀ was lowered from 507 °C – pure LaMnO₃ prepared via SCS – to 432 °C attained with a 2% (w/w) Pd load on pre-calcined LaMnO₃·2ZrO₂.