Cost-effectiveness of cogeneration investments depends on the individual conditions in a treatment plant and should be carefully analysed. Analysis should be preceded by an energy audit. However, some characteristics remain unchanged in all installations:

• The possibility of usage in urban areas due to high efficiency, modular design, and low gas and dust emission
• Constant access to ‘free’ biogas from the IFC (Isolated Fermentation Chambers) installations
• Heat production for the needs of the treatment plant – building heating, IFC process heating, sludge drying
• Reduction of energy purchase rates from external sources
• In case of voltage decay in external electricity grid, the possibility to power the plant by using synchronized generators in cogeneration modules
• Lower transmission-caused energy losses
• Rapid cost recovery after the cogeneration investment

The profitability of cogeneration investments depends on specific conditions of a treatment plant and should be subject to analysis preceded by an energy audit. It is assumed that the minimum size of a cogenerator is 100 kWh of electrical power (for a treatment plant of 60 000 PE)

• The usage of biogas created during sludge fermentation may significantly increase the profitability of public utility services
• The usage of biogas as fuel limits CO2 emissions
• Burning biogas in gas engines is considered to be an environmentally friendly technology
• EU support for investments of this kind
• Reduction of the emission of environmentally harmful substances
• Reduction of the amount of energy taken from external electricity grid
• Reduction of greenhouse gases emission by eliminating the usage of torches (torches are used only in emergency states of the system)