Energy consumption demand, which is still growing along with civilization development facing depletion of traditional resources - mainly fossil fuels (coal, petroleum, natural gas) and accompanying increase of pollution of natural environment result in the increase of interest in the use of energy from renewable sources. The paper presents the significance of renewable energy sources in the energy balance of the country. Special attention was paid to basic sources of renewable energy in Poland, that is to biomass. Types of biomass were described and general energy and physico-chemical properties of basic plant materials obtained for energy purposes were provided. Possibilities of using biomass for production of electric energy and heat and the applied methods of its conversion into biofuels were discussed. Moreover, advantages and threats related to the use of plant biomass for energy purposes were emphasised.