The paper looks at an analysis of the tendency of changes in the fuel structure of electricity generation and thus resulting changes in carbon dioxide emissions. Forecasts drawn up by various institutions and organizations were selected for the analysis. Firstly, on the basis of statistical data contained in (IEA 2017a, IEA 2008) and with the use of Kay’s indicators, the impact of changes in energy intensity of the national income and energy mix on changes in carbon dioxide emissions per capita in 2006–2015 for the OECD countries and Poland were analyzed. A small effect of changes was found in the fuel mix in this period of time on the emissions. The main impact was due to changes in the energy intensity of the national income and changes in the national income per capita. Next, selected fuel scenarios for the period up to 2050 (60) were discussed – WEC, IEA, EIA, BP, Shell, with a focus on the WEC scenarios. These have been developed for various assumptions with regard to the pace of economic development, population growth, and developments of the political situation and the situation on the fuel market. For this reason, it is difficult to assess the reliability thereof. The subject of the discussion was mainly the data on the fuel structure of electricity generation and energy intensity of national income and changes in carbon dioxide emissions. The final part of the paper offers a general analysis of forecasts drawn up for Poland. These are quite diverse, with some of them being developed as part of drawing up the Energy Policy for Poland until 2050, and some covering the period up to 2035. An observation has been made that some forecasts render results similar to those characteristic of the WEC Hard Rock scenario.
W ostatnich latach w wielu ośrodkach badawczych skupia uwagę na zagadnieniach energetyki wodorowej. Mimo, że nie wszystkie opinie dotyczące jej potencjału techniczno-ekonomicznego są pozytywne, to wiele przygotowanych prognoz i analiz scenariuszowych pokazuje jej perspektywiczne znaczenie w wielu obszarach gospodarki. Rozwój technologii wodorowej wiąże się z przeprowadzaniem badań i analiz, obejmujących różne obszary technologiczne, w tym wytwarzanie, transport wodoru, jego magazynowanie i zastosowanie w energetyce oraz do napędu środków transportu. Wybór odpowiedniej strategii jest kluczowy dla dalszego spostrzegania szans na rozwój technologii wodorowych. W artykule przedstawiono przegląd zasadniczych problemów dotyczących produkcji wodoru, następnie wskazano na zagadnienia jego transportu i magazynowania. W ostatniej części przedyskutowano zastosowania wodoru w energetyce stacjonarnej i w transporcie samochodowym. Uwagę skupiono na badaniach koniecznych do podjęcia w najbliższej przyszłości. Przedstawiono krótką informację o stanie badań w Polsce.
This article presents changes in the operating parameters of a combined gas-steam cycle with a CO2 capture installation and flue gas recirculation. Parametric equations are solved in a purpose-built mathematical model of the system using the Ebsilon Professional code. Recirculated flue gases from the heat recovery boiler outlet, after being cooled and dried, are fed together with primary air into the mixer and then into the gas turbine compressor. This leads to an increase in carbon dioxide concentration in the flue gases fed into the CO2 capture installation from 7.12 to 15.7%. As a consequence, there is a reduction in the demand for heat in the form of steam extracted from the turbine for the amine solution regeneration in the CO2 capture reactor. In addition, the flue gas recirculation involves a rise in the flue gas temperature (by 18 K) at the heat recovery boiler inlet and makes it possible to produce more steam. These changes contribute to an increase in net electricity generation efficiency by 1%. The proposed model and the obtained results of numerical simulations are useful in the analysis of combined gas-steam cycles integrated with carbon dioxide separation from flue gases.
In this paper, numerical results of modeling of acoustic waves propagation are presented. For calculation of the acoustic fluctuations, a solution of the full non-linear Euler equation is used. The Euler equations are solved with the use of a numerical scheme of third-order accuracy in space and time. The paper shows a validation process of the described method. This method is suitable also for an aerodynamic noise assessment on the basis of unsteady mean flow field data obtained from a CFD calculations. In such case this method is called a hybrid CFD/CAA method. The proposed method is numerically decoupled with CFD solution, therefore the information about the mean unsteady flow field can be obtained using an arbitrary CFD method (solver). The accuracy of the acoustic field assessment depends on the quality of the CFD solutions. This decomposition reduces considerably the computational cost in comparison with direct noise calculations. The presented Euler acoustic postprocessor (EAP) has been used for modeling of the acoustic waves propagation in a cavity and in the flow field around a cylinder and an aerodynamic profile.