Mallomonas voloshkoae sp. nov. (Synurales, Chrysophyceae) and distribution of M. pechlaneri in mountain lakes of Siberia

Mallomonas voloshkoae sp. nov. was described from Russia based on silica-scale morphology studied by means of transmission and scanning electron microscopy. This species belongs to the section Striatae and is characterised by scales with wide anterior flanges, forming wing-like extensions. This species is most similar in scale ultrastructure to M. pechlaneri. Mallomonas voloshkoae was reported in four mountain lakes of the Transbaikal area and was found in acidic to slightly acidic conditions with very low values of specific conductance. Mallomonas pechlaneri was reported in Russia for the first time. This is the first record of this species after the description of this taxon in Europe. Mallomonas pechlaneri was found in three oligotrophic habitats in the Altay and Sayan Mountain areas.

Mallomonas lusca sp. nov. (Synurales, Chrysophyceae)—a rare species from Southeast Asia

A new species of tropical chrysophyte algae, Mallomonas lusca sp. nov. is described from Vietnam based on silica-scale morphology observed using scanning and transmission electron microscopy. Scales of this species were previously found in Malaysia, but had not yet been described. Mallomonas lusca belongs to section Torquatae and is most similar to M. favosa. Its scales have a unique conspicuous rounded pit with a raised thickened central area, which develops in association with the posterior pore in the angle of the posterior submarginal rib. This rounded pit is surrounded by delicate papillae across the border on the shield. Mallomonas lusca has been observed in six localities in Vietnam and one in Malaysia.

Synthesis of mesoporous silica from geothermal water

Mesoporous silica was successfully synthesized for the first time using geothermal water from the Onuma Geothermal Power Plant, Akita Prefecture, Japan. Cetyltrimethylammonium bromide (CTAB) was used as an organic template for the synthesis. CTAB with a concentration of 2.4 × 10–4 mol/L was reacted for 30 min with geothermal water at a temperature of 90 °C, which had a total silicic acid concentration of 475 mg/L (SiO2), at pH 7.0, pH 8.2 (raw water) and pH 9.0. By calcination of the resulting precipitate at 550 °C, mesoporous silica with a pore size of about 2.8 nm and a specific surface area of > 800 m2/g was formed. The total silicic acid concentration in the solution after formation of the mesoporous precipitates was reduced to < 280 mg/L, indicating efficient recovery of supersaturated silicic acid from geothermal water. The monosilicic acid in geothermal water plays an important role in the formation of mesoporous silica. Production of mesoporous silica by our method will contribute not only to prevention of silica scale formation in the piping systems of geothermal power plants but also to its use as an industrial resource.

Predicting EBC Temperature Limits for Industrial Gas Turbines

Higher turbine inlet temperatures may require the use of ceramic matrix composites (CMC) such as SiC/SIC, which require environmental barrier coatings (EBCs) to protect them against the detrimental effect of water vapor. The goal of this project is to determine the maximum bond coating temperature for EBCs for land-based turbines, where the minimum coating lifetime is 25,000 h. If the temperature exceeds the 1414°C melting point of the Si bond coating, then coatings without a bond coating also need to be evaluated. Thus, current Yb2Si2O7 EBCs with a Si bond coating and next-generation EBCs without a Si bond coating are being evaluated in laboratory testing using 1-h cycles in air+90%H2O. For this initial work, coatings were deposited on CVD SiC coupons. Reaction kinetics at 1250°, 1300° and 1350°C have been evaluated by measuring the thickness of the thermally grown silica scale after 100–500 h exposures. For comparison, scale growth rates for uncoated SiC and Si specimens in dry and wet environments were included as minimum and maximum values, respectively. Based on a critical scale thickness failure criteria, estimated maximum temperatures were calculated for both EBC systems using this initial data.

Mallomonas loricata sp. nov. (Synurales, Chrysophyceae), a new tropical species from section Planae

A new species, Mallomonas loricata sp. nov., is described from Vietnam based on silica-scale morphology studied using transmission and scanning electron microscopy. The species belongs to section Planae and has similar morphology to species from the Mallomonas matvienkoae complex. The new species is characterized by obovoid scales with a thick secondary layer with internal reticulation that covers almost whole surface of the scale. Scales of Mallomonas loricata were found at twenty-four localities of eight provinces in northern, central and southern areas of Vietnam. Scales of this new species have also been previously reported from Singapore and Malaysia. The distribution and habitat conditions of the new species are summarized.

Design of a scaling reduction system for geothermal applications

The aim of the EU 2020 GeoSmart project relies on the demonstration of innovative solutions to improve the flexibility and the efficiency of geothermal heat and power systems. This specific study focuses on issues related to silica scaling and its deposition on the reinjection wells. A limiting constraint for geothermal plants to fully utilize the thermal energy form well fluids is in fact the need to reinject geothermal brine at a high enough temperature to prevent thermodynamic fouling by silica scale deposition. GeoSmart aims to develop a solution based on retention system technology to control and reduce the silica scale formation before re-injection. Lowering reinjection temperature would strongly increase plant efficiency by providing extra useful heat. Based on silica scaling numerical simulation, the effects of parameters like pH, temperature and brine composition on silica polymerization and scaling deposition rates, the design and optimization of the retention system has been developed. The design aims to promote polymerization phenomena inside the tank so that scaling is consequently inhibited in the reinjection well pipes. Chemical additives and specific coatings have also been evaluated to guarantee the optimal required conditions. The case study is based on real-data referred to operational conditions and brine composition of the Zorlu Kizildere plant in Turkey. The economic and environmental impact of the retention system has been evaluated with positive outcomes. The in-site test and validation at industrial level of the above mentioned technology will be provided during the next activities of the GeoSmart project