Energy market is the sector of the economy which has been given a lot of attention in the last decades. This results not only from a global increase in demand for energy but also from the needs for environmental protection. It should be also noted that modernization of the energy sector is capital-intensive. Therefore, the directions of development in this sector should be driven not only by ecological reasons but also by reasonable economic calculus based on in-depth analysis of operational costs in the next decades. For this reason, an important position in the structure of energy generation is taken by co-combustion of various fuels, with particular focus on coal and biomass. Co-combustion of fuel mixtures, with each fuel having varied properties, often accelerates degradation of the structural components of a boiler.