## 1 Introduction  
Cogeneration systems based on the production of heat and electricity are standard equipment in biogas installations where, in addition to the production of electricity from biomass, there is also a demand for process heat [1]. In the case of conventional systems producing only electricity, it is only possible to obtain 30-35% of the energy supplied in the fuel. In the case of conventional systems producing only electricity, it is only possible to obtain 30-35% of the energy supplied in the fuel. The Brayton Cycle, also known as the Joule Cycle, was first developed for use in the fuel-injected piston engine around 1870. However, it is currently only widely used in open-cycle and closed-cycle turbine engines. Turbine gas typically operates on an open cycle with fresh air at atmospheric temperatures under the suction condition of the compressor. However, exhaust gases leave (rather than return to) the gas turbine and enter the atmosphere. The open cycle of a gas turbine can be modeled as a closed cycle for a gas turbine, in which the working substance is air sucked into the compressor. The exhaust gases leaving the gas turbine heat the exchanger, where they release heat into the atmospheric air, reach the initial conditions and are reintroduced into circulation in the next cycle. Such an ideal cycle in which the working substance (air) passes in a closed loop is called the ideal Brayton Cycle. Hence, the Brayton Cycle is an ideal power cycle consisting of a gas turbine consisting of two isentropic and two isobaric processes. The Rankine Cycle, on the other hand, is an ideal power cycle consisting of a steam turbine--commonly used in all steam power plants. The cycle uses water as a working substance, changing its phase from liquid to vapor and steam to liquid during the cycle. Therefore, this cycle is also known as the steam feed cycle. The ideal Rankine Cycle system consists of four basic elements (devices): boiler, steam turbine, condenser and pump. The ideal Rankine Cycle consists of four different processes, namely two isentropic processes and two isobaric processes [2; 3; 4; 5]. Heat recovery means that the potential of the system allows for the recovery of 80% of the energy contained in the fuel, 30-35% of electrical energy and 45-50% of thermal energy. Energy losses, in this case, are limited to 15-20%. Electrical efficiency is defined as the quotient of the generated electricity divided by the amount of energy contained in the fuel. In turn, the energy efficiency of a cogeneration system is the quotient of the sum of the amount of electricity and heat produced to the energy contained in the fuel [6]. The heat obtained from the cogeneration installation of the biogas plant is used to maintain the process temperature of the fermenter, but its excess can be used for other processes, such as heating buildings. Another method is to transmit or store heat and produce cold. The new cooling space initiative for useful energy produced by connected energy systems is called Buildings Cooling, Heating and Power (BCHP) [7]. Due to their high efficiency, cogeneration systems play an important role in reducing greenhouse gas emissions, reducing costs and reducing environmental pollution while increasing system reliability and energy quality, reducing network overload and avoiding distribution losses [8]. The cogeneration system primarily consists of an internal combustion engine connected to a generator and a system for receiving heat from the cooling system. Increasingly, cogeneration systems also have heat exchangers used to recover heat from the exhaust system and the oil cooler. In such a case, the maximum heat loss may be 20% [9]. [PERSON] et al. [10] conducted simulations and research on the use of biomass in various types of cogeneration solutions. They considered the following cases: the steam cycle, the Organic Rankine Cycle (ORC) and the use of heat engines such as the Stirling and Ericsson engines.