What is of crucial importance in local conditions as concerns the heat power industry is the use of local biomass, especially waste biomass, as an energy raw material in the existing system of thermal power plants. The purpose of the present study is to assess the possibility of replacing hard coal as an energy raw material with solid biomass. Solid biomass is constituted by: surpluses of cereal straw and rape straw, as well as hay from unused meadows, from the upkeep of roadside trees and from energy crop plantations. The research was conducted on the example of thermal power plants associated in the “Together Warmer” Cluster. This cluster is formed by 10 thermal power plants in small towns in the Warmińsko-Mazurskie Province and the city of Biała Podlaska (Lubelskie Province). All of these are located in north-east Poland. Considering the high transport costs of biomass, a biomass technical potential was accepted within a radius of 30 km from the thermal power plant. The solid biomass potential for each of the ten thermal power plants demonstrates that most of the thermal power plants from the Cluster under examination are able to meet their energy needs with solid biomass from the nearest neighbourhood (replace hard coal). However, when taking a decision on replacing hard coal with local biomass, it is necessary to adequately handle logistics and replace boilers in thermal power plants with special boilers for the combustion of solid biomass.