The growing need for electricity and other forms of energy such as heating and cooling leads to the development of new and modern technologies. Trigeneration as a solution offers the production of all these forms of energy from one energy source. Trigeneration thus increases the overall efficiency of the energy system, and thus reduces the consumption of primary fuel and reduces costs. The task of this diploma thesis was the project of trigeneration of energy on biogas. We calculated the overall efficiency of the trigeneration plant and the primary energy savings. In the first part, we explained how biogas is created, its characteristics and application as a renewable energy source. After that, the processes in the biogas plant and its components are explained in more detail. Cogeneration and trigeneration are ways of efficient use of energy in biogas plants. The paper will explain the mode of operation, basic parts and types of cogeneration and trigeneration plants. In the final part, there is a calculation of the overall efficiency of the trigeneration system and the savings of primary fuel. At the end of the paper, the efficiency of trigeneration is compared in relation to cogeneration and conventional plants.