The present work relates to the investigation of cobalt and manganese oxide based compositions as candidate materials for the storage of surplus energy, available in the form of heat, generated from high temperature concentrated solar power plants (e.g. solar tower, solar dish) via a two-step thermochemical cyclic redox process under air flow. Emphasis is given on the utilization of small structured monolithic bodies (flow-through pellets) made entirely from the two aforementioned oxides. As compared to the respective powders, and in addition to the natural advantage of substantially lower pressure drop that monolithic structures can offer, this study demonstrated that structured bodies can also improve redox kinetics to a measurable extent. Cobalt oxide was found to be superior to manganese oxide both from an estimated energy density and from a redox reactions kinetics point-of-view. Among the redox conditions studied, the optimum reduction-oxidation operating window for the former oxide was determined to be in the range of 1000-800°C, while for the latter material no clear conclusion was drawn with reduction reaching its maximum extent at 1000°C and oxidation occurring in the range of 500-650°C. In both cases, no significant degradation of redox performance was observed upon cyclic operation (up to 10 cycles), however manganese oxide showed notably slower oxidation kinetics

Ce-based materials, that have been extensively investigated for catalytic applications, such as in automotive emission control and more specifically in the oxidation of diesel soot particles, were evaluated with respect to their performance on CO2 splitting. DFT calculations assisted towards the synthesis of two Zr-doped Ce-oxide formulations (Zr content: 20% and 40% respectively) via the LPSHS method. The materials were evaluated with respect to their CO2 splitting activity and compared with other Ce-Zr-based reference oxides. The most active materials were further evaluated under different CO2 splitting temperatures in the range of 800-1480oC in the course of successive redox cycles. The effect of thermal reduction temperature (T: 1480oC and 1600oC) on the most active material was also assessed. The Ce-based oxide formulation with the best performance (Ce0.8Zr0.2O2) was further investigated with respect to its activity towards H2O splitting. In addition, a porous flow-through structure consisting entirely of Ce0.8Zr0.2O2 was manufactured and the resulted body was also evaluated and compared to the respective powder in terms of its CO2 and H2O splitting ability

Olive trees worldwide suffer from a number of devastating fungal diseases that affect production. One such serious disease is olive leaf spot caused by Venturia oleaginea. Recently, we applied magnesium hydroxide porous micron-scale particles (PMPs) on tomatoes and observed potent antimicrobial activity, reducing the fungal load of the treated phyllosphere. To assess the effectiveness of the compound on olive fungal disease, we applied it for two consecutive seasons. One particular olive tree exhibited extreme manifestations of fungal disease and was destined for removal. A single application of Mg(OH)₂ PMP reversed all symptoms of the disease and eliminated the Venturia pathogen, curing the tree of disease. Venturia oleaginea appears to be exceptionally susceptible to treatment compared to other species in the fungal leaf community. The beneficial fungus Aureobasidium pullulans increased in relative abundance in all the sprayed trees. No toxicity and leaf loss were observed, and the compound retention exceeded 47 days. All trees sprayed showed drastic reductions in the total fungal load and compared favorably to the commercial copper compound. Spraying induced a moderate expression of key indicator genes associated with stress responses. No leaf chlorosis or shedding were observed. Overall, Mg(OH)₂ PMP treatment appears to be a highly promising tool for combating plant fungal disease.

The urgent need for sustainable energy supply requires maximum exploitation of renewable energy sources. The latter, being of intermittent nature, need to be coupled with efficient energy storage. Solar-thermal power-plants are inherently compatible with thermal storage, which is a cost-efficient method of storing energy for later use but the field is currently dominated by sensible heat molten salts used as heat storage media but with a maximum operating temperature of about 560oC. Certain ceramic materials, able to induce reversible reduction-oxidation reactions under air flow, are promising alternatives to molten salts because they can withstand much higher temperatures (>1000oC) and thus can be integrated with high-efficiency air-Brayton thermodynamic cycles. At the same time the chemical energy stored/released during such reduction-oxidation reactions can boost energy storage density by up to 10 times cf. sensible only concepts. In this framework, Ca-Mn-based perovskite compositions were demonstrated to function effectively as energy storage materials. The current work offers insights on material synthesis parameters to achieve relatively high purity Ca-Mn-based compositions and subsequently optimize their redox performance in the course of a preliminary 5-cycle campaign. Moreover, the occurring structural transitions and their corresponding heat effects are also discussed and elaborated upon. This study is the first step towards the, currently in progress, process of synthesising – at multi kg scale – and shaping these compositions into extruded honeycomb-like monolithic structures for subsequent future application in lab- and pilot-scale high temperature thermochemical energy storage systems.