The volatility of raw material prices and the rising prices of CO2 emission allowances when using fossil fuels to produce electricity and heat are still relevant problems for owners of generating units. The decision-making tools are used in the fuel purchase process. However, these tools should also consider environmental issues.
The article’s main objective is a quantitative analysis of the potential for reducing costs associated with supplying and using hard coal in public power plants as a result of considering the costs of environmental protection and CO2 emission allowances in the process of planning this fuel supply. A mathematical model was developed to optimize the supply of hard coal for the power industry. The tool and elaborated research scenarios made it possible to calculate and analyze the impact of considering the costs of emissions of harmful substances into the environment and CO2 emission allowances on the planning of coal supplies and the reduction of costs related to acquiring and using coal by public power plants. The calculation results were presented on the example of the Polish power sector.
The model’s results confirm that the appropriate selection of coals, taking into account the quality parameters determining the amount of emissions of harmful substances, reduces the amount of these emissions and the total costs of acquiring and using coal in electricity production. However, depending on the considered scenario, the scale of this impact varies. The results of the optimization of coal supplies to power plants and their proper interpretation may constitute an important contribution to making management decisions in energy companies.

The phenomenon of churching (attendance at churches outside parishes of residence) is associated with socio-economic and cultural transformations of society, including general growth of mobility. In this paper titular issue was described against the background of the concept of the life of a city and according to the concept of place. On the ground of the data gained, the presence of churching in the Old Town area in Poznań and its dimensions were primarily proved. This work is an introduction to an empirical research, concerning spatial behaviour of churching people and possible impact of their decisions on city centre functions.

A meadow, a flowery meadow, a clearing, a lawn – smoothly trimmed, flat and recessed, a grassy pathway – these are elements of gardens that have been known for centuries, used in different styles and different types of gardens, including in public spaces. Pratum commune, commons or grassy mounds are the landmarks of the landscape of many a city, both currently and throughout history. Decorative grasses, such as pampas, Miscanthus or Pennisestum started to be used in garden compositions in XIX-century England. Initially more so due to their peculiarity than beauty. However, it was naturalism that gave rise to the wider use of grasses in gardens and parks in various places of the world and gained many propagators, including W. Robinson, J. Jensen K. Foerster and P. Oudolf.Grasses are currently often designed by landscape architects in urbanised spaces. They are employed both in geometric and freeform compositions. Their texture and delicate colour create a background for more expressive plants. They often constitute the key element of naturalist layouts, and the use of domestic species aids in preserving biodiversity and recreating the domestic landscape. Many of these current projects have been discussed in magazines and subject literature and have received awards in competitions. This review article is devoted to this subject.

In the article, the author analyzes the phenomenon of adapting Bogdan Suchodolski's pedagogy to changing political circumstances several times: from his fascination with mainstream politics in the 1930s, through intensive practice of Marxist and socialist pedagogy after World War II, to universal humanism and tragic humanism in the 1970s and 80s. Following R. Englert, the author calls this adaptability of pedagogy to political changes “pedagogical cairology”.