4/2019
Mercury in the environment, its anthropogenic sources, environmental and health risks
Nord Stream pipeline
Increasing demand for energy has resulted in the requirement of securing the energy situation in the European Union. This problematic situation was partially solved by the construction of the Nord Stream gas pipeline. However, despite its considerable advantage in the form of large supplies of natural gas, especially to Western Europe, it has received many negative responses from the very beginning of the project planning. Despite all criticism the Nord Stream pipeline project, which brings natural gas from Russia to Germany and further to Western Europe, has taken place. A second project, Nord Stream 2, which should guarantee energy stability in Europe, is currently under construction. The paper summarizes the historical development of the Nord Stream project, pointing out the reason for constructing such a conceived gas pipeline. Furthermore economic and environmental aspects are described, which the project, as well as the Nord Stream 2 project, was dealing with during the whole construction. The paper also describes the entire route of both gas pipelines.
Accelerating testing of long-term activity of the HDS catalyst based on Co-Mo
Comparison of the activity of sulphidic Ni-Mo/Al2O3 catalyst in alkyldibenzothiophenes desulfurizati
The goal of this work was to assess the effect of reaction condition on the activity of three commercial hydrodesulfuration catalysts based on Ni-Mo/Al2O3. During hydrodesulfuration, the contents of 4-methyldiben-zothiophene (4-MDBT) and 4,6-dimethyldibenzothio-phene (4,6-DMDBT) was determined. Hydrodesulfuration was carried out in a stirred batch reactor with volume of 0.5 dm3. The catalysts were tested at two different reactions conditions: reaction temperature of 350 °C with hydrogen partial pressure of 6 MPa and reaction temperature of 380 °C with hydrogen partial pressure of 4.5 MPa. For all experiments, 300 cm3 of feedstock, 10 cm3 of catalyst, and constants hydrogen flow 30 dm3∙hod-1 were used. The model feedstocks consisted of hydrogenated gas oil with addition of 500 mg.kg-1 of 4-MDBT and 500 mg∙kg-1 of 4,6-DMDBT. In all the experiments, higher conversion of 4-MDBT compared to 4,6-DMDBT was found. This fact is given by smaller steric shielding of the sulphur atom in the 4 - MDBT molecule by only one methyl group. C catalyst showed the highest activity in 4-MDBT desulfurization at temperature 350 °C and hydrogen partial pressure 6 MPa. At the same reactions condition, catalyst A was the best for elimination of 4,6-DMDBT . This catalyst had the greatest activity in 4-MDBT and 4,6-DMDBT desulfuration at the second reaction condition too (reaction temperature 380 °C, hydrogen partial pressure 4.5 MPa). In the reaction conditions, the decrease of sulphur content bellow 10 mg.kg-1 was achieved with A catalyst after 240 min.
Photovoltaic sources and greenhouse gas emissions
The article presents data documenting the amount of emissions, especially carbon dioxide, emitted into the air from conventional power plants during the periods when they are centrally disconnected from the electricity distribution network, as photovoltaic power sources are preferentially connected to this network. The need to keep conventional fossil fuel power plants in standby is essential so that, according to the regulator instructions, electricity consumption can be quickly covered in the event of sudden and unexpected fluctuations in demand, eg when sunlight is reduced. In the national climate and energy plan, the Czech government expects the share of renewable sources to be increased to 20.8 % by 2030. The European Commission assessed the plan as not ambitious and recommended increasing the share of renewables to 23%. However, this will also be associated with a significant increase in CO2 emissions when putting conventional energy blocks into the socalled “warm reserve”. A successful and usable solution of the discussed problems capable of covering the instability of photovoltaic wind energy sources is the application of gas turbines, resp. cogeneration units burning gas. One example of such a solution is the construction of a new 840 MWe Power plant Počerady. Putting them into full power from the sleep mode is a matter of minutes and, in addition, they can be powered by renewable electricity.