Renewable energy sources (wind, solar, biogas) are characterized mainly by the instability of their acquisition, which greatly reduces the quality of production systems producing energy based on them. This leads to the situation that these systems cannot be used as a fully independent source of energy to meet local energy needs. The paper presents various methods of supporting energy systems powered by RES supported by natural gas, LNG or LPG. Simulations were presented of balancing the energy parameters of biogas from agricultural biogas plants and municipal waste used for power cogeneration systems and simulations of operating systems the gas - wind turbines and the gas-solar (photovoltaics) system. As a result of this support, a synergy effect is achieved which, on the one hand, reinforces the market position of energy from renewable sources by increasing the stability and certainty of its delivery; on the other hand, there is the possibility of using fossil gases locally (including the gas that does not meet the quality requirements laid on network gases) in systems where the price of generated energy is lower than in case of stand-alone systems. The article presents exemplary calculations of economic viability for the aforementioned energy systems for different conditions for obtaining renewable energy sources. However, the profitability of the systems consisting of wind farms and gas cogeneration plants is strongly dependent on the working conditions of such systems, thus assisting biogas plants with gas from local sources of gas, whose viability is questioned due to the poor efficiency of the source, and the need to adjust its quality to the network parameters, is fully justified and profitable. The research presented in the article showed that popular home gas appliances can be safely used in a relatively large range of variability of the gas supplying them, which allows the effective use of various biogas mixtures with fossil gases.