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Questions & Answers to understand how Cogeneration works

What effective savings can be obtained from cogeneration in industrial applications?


  • A maximum percentage value can be quantified around 30%, with a pay-back of the investment that can be assumed from 2 to 4 years. These performance values are to be related to three main variables: plant size, effective heat recovery and annual operating hours.

  • The choice of the technological partner is therefore crucial for the success of the project. Feasibility study, product excellence and maintenance service efficiency are the basic ingredients of energy efficiency and therefore of savings.


What are the Authorization Practices necessary for a cogeneration plant powered by natural gas?


  • The administrative procedure to be followed to obtain the necessary permits essentially consists of the following practices:

  • - PROVINCE PRACTICE: used to obtain the Single Authorization for the construction and operation of the system; this request will go to a conference of services

  • - ENEL PRACTICE: allows the signing of the contract for connection to the grid of the electricity production plant;

  • - Firefighters practice (fire brigade): request of the opinion of conformity on the project of the plant and issue of the CPI (fire social security certificates) by the fire brigade.

  • - UTF (Technical Finance Office) PRACTICE: used to request the license of an electrical production and sales workshop; it must be carried out during the installation phases of the machine and carried out before testing the system.

  • - DIA (Declaration of commencement of business): practice for obtaining authorizations and granting building permits. "


What forms of incentives does cogeneration fueled by fossil sources (natural gas) enjoy?


  • White certificates, or more properly Energy Efficiency Certificates (TEE) represent an incentive to install efficient technologies and systems.

  • A certificate corresponds to saving one ton of oil equivalent. They consist of securities that can be purchased and subsequently resalable, the value of which is a function of market trends. They are issued by the Electricity Market Operator (GME) following a verification of the energy savings achieved, for example, through the installation of a cogeneration module with internal combustion engine, compared to traditional electricity production systems (Italian electricity park) and of thermal energy.

  • White certificates cover three types of interventions:

  • 1. Saving electricity.

  • 2. Savings on natural gas.

  • 3. Savings on other fuels


Does a cogeneration plant need a lot of assistance?


  • The assistance theme is fundamental in the choice of a cogeneration plant. We can give a concrete example assuming the use of a system in a company that works on 3 shifts only on weekdays and for 11 months a year. Well, let's imagine how many km the engine of a vehicle would have to travel continuously at 60 km / h for 5 days a week and for 48 weeks: that would be the beauty of 345,600 km per year. We can well understand that the maintenance item is decisive in the choice of a supplier, especially if we consider the cost of downtime as a loss of profit. Given that in a system that makes 1000 kW with current energy tariffs, on average, savings of almost € 1,500 / day can be assumed, one realizes what the cost of downtime is seen as loss of profit!


Is all methane gas destined for cogeneration tax exempted?


  • No, not all gas is tax exempt. To measure the quantity of gas not subject to tax, the UTF (Technical Finance Office) refers to the dedicated electricity meter positioned at the alternator terminals, calculating the consumption of 0.25 mc / kWh. The electrical efficiency of the system is essentially rewarded.


In the production process of my company there is the need to use cold water at 6/7 °. For other phases, a refrigeration temperature with values close to 0 ° is required. is it possible through trigeneration to obtain these temperatures?


  • As for the thermal stage of 7 ° it is possible, through the use of a lithium bromide absorber; for the second need, on the other hand, the use of an ammonia absorber could be envisaged, a solution to be analyzed with extreme detail considering the complexity and the costs of application. Other types of absorbers are appearing on the market, reaching intermediate temperatures between 7 ° and 0 ° C, these technologies to be better explored.


I have a company that has a dynamic painting tunnel at 140 ° where the air is continuously heated by steam and then expelled without thermal recovery: how could I use the water of a cogeneration plant?


  • Since the air is always fresh and is taken from the outside without heat recovery, you can simply think of preheating the air through an air / water coil from the ambient temperature up to the maximum gradient that can be reached due to the quantity of the same. The steam produced by the system through the exhaust fumes would complement / replace that produced by current boilers.

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