The paper presents a modified algorithm for choosing the optimal coefficient of the share of cogeneration in district heating systems taking into account additional benefits concerning the promotion of highefficiency cogeneration and biomass cofiring. The optimal coefficient of the share of cogeneration depends first of all on the share of the heat required for preparing the hot tap water. The final result of investigations is an empirical equation describing the influence of the ratio of the heat flux for the production of hot tap water to the maximum flux for space heating and ventilation, as well as the share of chemical energy of biomass in the fuel mixture on the optimal value of the share of cogeneration in district heating systems. The approach presented in the paper may be applied both in back-pressure combined heat and power (CHP) plants and in extraction-condensing CHP plants.

A transition from generating electricity from conventional sources to generating it from renewables is one of drivers leading us towards a circular economy. Electricity is a specific product and regardless of where and how it is produced, it takes the same form. A novel aspect of the research is the examination of correlations and relationships between guarantees of origin. The research objective is to analyse the market for the guarantees of origin in the volatile price environment that we had late 2021 and early 2022. Therefore, we analysed demand for the guarantees in January 1, 2020 to June 30, 2022 and the correlation between the price of electricity and guarantees of origin. It was based on the secondary data analysis method and the use of Pearson’s correlation coefficient and a linear regression function. The authors of the study made a hypothesis that the trading volume would increase during the study period and that there would be a positive correlation between the price of energy and the guarantees of origin. A key finding of the study revealed a steady increase in the purchase of guarantees despite the rise in prices. The buying of the guarantees is not a top-down requirement, but rather a bottom-up action, which indicates growing social expectations towards enterprises to consume energy from renewable sources.