Hydrogen-based power engineering has great potential for upgrading present and future structures of heat and electricity generation and for decarbonizing industrial technologies. The production of hydrogen and its optimal utilization in the economy and transport for the achievement of ecological and economic goals requires a wide discussion of many technological and operational – related issues as well as intensive scientific research. The introductory section of the paper indicates the main functions of hydrogen in the decarbonization of power energy generation and industrial processes, and discusses selected assumptions and conditions for the implementation of development scenarios outlined by the Hydrogen Council, 2017 and IEA, 2019. The first scenario assumes an 18% share of hydrogen in final energy consumption in 2050 and the elimination 6 Gt of carbon dioxide emissions per year. The second document was prepared in connection with the G20 summit in Japan. It presents the current state of hydrogen technology development and outlines the scenario of their development and significance, in particular until 2030. The second part of the paper presents a description of main hybrid Power-to-Power, Power-to-Gas and Power-to-Liquid technological structures with the electrolytic production of hydrogen from renewable sources. General technological diagrams of the use of water and carbon dioxide coelectrolysis in the production of fuels using F-T synthesis and the methanol production scheme are presented. Methods of integration of renewable energy with electrolytic hydrogen production technologies are indicated, and reliability indicators used in the selection of the principal modules of hybrid systems are discussed. A more detailed description is presented of the optimal method of obtaining a direct coupling of photovoltaic (PV) panels with electrolyzers.

Is hydrogen the answer, and if so, which technologies? Here we present an overview of “everything you need to know” about this promising new global energy source.

The paper discusses a way of choosing the design features (geometry, the rate of grinding and thrust) of ring-ball mills. Various methods of calculating the optimal rate of grinding have been compared. Basing on experimental investigations on the pilot-plant and industrial scale, the influence of the angular velocity and the thrust on the mill have been verified, and the interdependence between the rate of grinding and the thrust of the grinding elements have been explained.

The empirical-analytic model of milling in a ring-ball mill has been presented. It concerns the interaction of the basic design features of the grinding unit (geometry, rate of grinding and thrust of the balls) on the maximum efficiency of the mill. The production of pulverized coal was expressed by the product of the flux of material drawn in by the balls and the so-called "grinding effect of the balls" (defined by the increase of the mass fraction of dust in its flux). The kinematic quantities (among others, the flux of loose material drawn in by the balls) have been calculated on the basis of a simple analytical description of the flow of particles and some parametrical assumptions. The grinding properties of coal have been determined making use of laboratory tests of its cruising by the rollers. Some verifications of the grinding model on the experimental test stand with a ring-ball mill have been presented. The test stand is installed at the Institute of Power Engineering and Turbomachinery of the Silesian University of Technology.

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.

Czy i jakie technologie? Czyli wszystko, co trzeba wiedzieć o nowym globalnym źródle energii.

In the study an accurate energy and economic analysis of the carbon capture installation was carried out. Chemical absorption with the use of monoethanolamine (MEA) and ammonia was adopted as the technology of carbon dioxide (CO2) capture from flue gases. The energy analysis was performed using a commercial software package to analyze the chemical processes. In the case of MEA, the demand for regeneration heat was about 3.5 MJ/kg of CO2, whereas for ammonia it totalled 2 MJ/kg CO2. The economic analysis was based on the net present value (NPV) method. The limit price for CO2emissions allowances at which the investment project becomes profitable (NPV = 0) was more than 160 PLN/Mg for MEA and less than 150 PLN/Mg for ammonia. A sensitivity analysis was also carried out to determine the limit price of CO2emissions allowances depending on electricity generation costs at different values of investment expenditures.

This paper presents a method for assessing the degree of approaching the paper output of the Clausius-Rankine cycle to the Carnot cycle. The computations to illustrate its use were performed for parameters characteristic of the current state of development of condensing power plants as well as in accordance with predicted trends for their further enhancing. Moreover there are presented computations of energy dissipation in the machines and devices working in such a cycle.

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.

The installations of CO2 capture from flue gases using chemical absorption require a supply of large amounts of heat into the system. The most common heating medium is steam extracted from the cycle, which results in a decrease in the power unit efficiency. The use of heat needed for the desorption process from another source could be an option for this configuration. The paper presents an application of gas-air systems for the generation of extra amounts of energy and heat. Gas-air systems, referred to as the air bottoming cycle (ABC), are composed of a gas turbine powered by natural gas, air compressor and air turbine coupled to the system by means of a heat exchanger. Example configurations of gas-air systems are presented. The efficiency and power values, as well as heat fluxes of the systems under consideration are determined. For comparison purposes, the results of modelling a system consisting of a gas turbine and a regenerative exchanger are presented.

The paper presents a description of selected models dedicated to steam condensing flow modelling. The models are implemented into an in-house computational fluid dynamics code that has been successfully applied to wet steam flow calculation for many years now. All models use the same condensation model that has been validated against the majority of available experimental data. The state equations for vapour and liquid water, the physical model as well as the numerical techniques of solution to flow governing equations have been presented. For the single-fluid model, the Reynolds-averaged Navier-Stokes equations for vapour/liquid mixture are solved, whereas the two-fluid model solves separate flow governing equations for the compressible, viscous and turbulent vapour phase and for the compressible and inviscid liquid phase. All described models have been compared with relation to the flow through the Laval nozzle.

A gas turbine air bottoming cycle consists of a gas turbine unit and the air turbine part. The air part includes a compressor, air expander and air heat exchanger. The air heat exchanger couples the gas turbine to the air cycle. Due to the low specific heat of air and of the gas turbine exhaust gases, the air heat exchanger features a considerable size. The bigger the air heat exchanger, the higher its effectiveness, which results in the improvement of the efficiency of the gas turbine air bottoming cycle. On the other hand, a device with large dimensions weighs more, which may limit its use in specific locations, such as oil platforms. The thermodynamic calculations of the air heat exchanger and a preliminary selection of the device are presented. The installation used in the calculation process is a plate heat exchanger, which is characterized by a smaller size and lower values of the pressure drop compared to the shell and tube heat exchanger. Structurally, this type of the heat exchanger is quite similar to the gas turbine regenerator. The method on which the calculation procedure may be based for real installations is also presented, which have to satisfy the economic criteria of financial profitability and cost-effectiveness apart from the thermodynamic criteria.

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.

The introduction highlights the technologies of converting the chemical energy of biomass and municipal waste into various forms of final energy (electricity, heat, cooling, new fuels) as important in the pursuit of a low-carbon economy, especially for energy and transport sector. The work continues to focus mainly on gasification as a process of energy valorization of the initial form of biomass or waste, which does not imply that other methods of biomass energy use are not considered or used. Furthermore, the article presents a general technological flowchart of gasification with a gas purification process developed by Investeko S.A. in the framework of Lifecogeneration.pl. In addition, selected properties of the municipal waste residual fraction are described, which are of key importance when selecting the technology for its energy recovery. Significant quality parameters were identified, which have a significant impact on the production and quality of syngas, hydrogen production and electricity generation capacity in SOFC cells. On the basis of the research on the waste stream, a preliminary qualitative assessment was made in the context of the possibility of using the waste gasification technology, syngas production with a significant share of hydrogen and in combination with the technology of energy production in oxide-ceramic SOFC cells. The article presents configurations of energy systems with a fuel cell, with particular emphasis on oxide fuel cells and their integration with waste gasification process. An important part of the content of the article is also the environmental protection requirements for the proposed solution.

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.