Under the term cogeneration, it is considered the joint technological process of production of heat and electricity. The reason for the accession of cogeneration powerplants is greater efficiency of production compared to the powerplants with separate energy production. One of the main benefits of cogeneration powerplants is much less gas emissions, better fuel use, more stable contribution to the grid. Existing technologies, and their implementation, have proven to be a very good and efficient factor when choosing cogeneration. Although different renewable or non-renewable sources can be used as a fuel in cogeneration powerplants, biomass is currently shown to be perhaps the best quality renewable source of limited potential. The advantage of biomass is that it is created as an additional product in various industries and economies as waste, and can be used as a fuel by further processing. This final paper describes biomass with its sub-members; then the description of cogeneration, its mode of operation, division and technology used in cogeneration plants. For the end, there are given examples of effective cogeneration (existing and future) in the world, Europe and a little bit more detailed in Croatia.