The innovative project of a combined heat-and-power (CHP) plant, which runs with biomethane tries to receive a sustainable solution of generating green power and heat. The plant was started for the first time in 2013 and is located in Münchendorf/Austria at the site of the vegetable producer “Zeiler”. This master thesis investigates the economic, environmental and plant-specific aspects of the combined head-and-power plant. The database of the years 2010 to 2014 shows the differences between the starting point and the final situation, after the plant was implemented, to demonstrate the direct changes triggered by the CHP plant. The Cogeneration plant feeds the annually produced amount of heat of 2,130 MWh in a 700 m3 stratified water storage, which can be also heated by two other CHP plants and a gas boiler. 100 % of the green electricity is supplied to the public electricity grid for a government-sponsored buyback price of 21.02 cents/kWh. The produced amount of electricity of 1,650 MWh, and the thermal energy can be evaluated as CO2 neutral, due to the utilized biomethane. The emissions, which are being released during the combustion of biomethane, are absorbed from the atmosphere in advance by the biomass. The use of the biomethane CHP leads to a reduction in the mileage of the gas boiler and the natural gas CHP plants. Therefore, 12 % of the total heat demand of the company is covered by the biomethane plant. Furthermore, the consumption of fossil natural gas is also reduced by the same amount, which leads to an annual saving of 618 tons CO2e. The efficiency of the CHP was reviewed using investment calculation methods. All of the methods confirm the high profitability and the relatively low investment risk of the eco-project. Ultimately, seen from an economic, environmental and plant-engineering point of view, the usage of biomethane CHP can be evaluated as useful, making the company to fulfil its requirements for sustainable energy production.