What is it and how does it work the cogeneration?
The definition of cogeneration is very simple. Co - generating means to produce thermal energy and electrical energy simultaneously. The traditional method of producing energy is inconvenient : two separate systems to produce electricity and thermal energy have high installation costs and low efficiency, because most of the fuel energy is lost as heat.
In a typical thermal power plant, in fact, only about 35% of the fuel is converted into electricity, while the remaining 65 % is lost in the form of thermal energy (heat).
With a cogeneration system, however, it is possible to produce at the same time thermal energy and electrical energy from a single plant powered by a single source of primary energy (natural gas, oil, biodiesel and biomass, for example). Almost all thermal energy is not lost in the environment but more is recovered and made available for reuse. This principle makes it possible to achieve energy efficiencies over 80%.
Diagram of a cogeneration plant
The elements of a cogeneration plant are four: the engine, the alternator, the system of heat recovery and the command and control panel. The fuel feeds the engine, the engine activates the alternator which produces electrical energy. Simultaneously, the thermal energy (heat) produced by the engine and by the discharging pipes is recovered and distributed to the users. The control panel on the machine allows to monitor and to adjust services.
High-efficiency cogeneration (CAR)
The definition of High Efficiency Cogeneration, also known by the acronym CAR, is introduced by Rule 2004/8/EC. The Rule was implemented in Italy by Legislative Decree February 8, 2007, n . 20 . The key points are two:
- It has high efficiency when the primary energy savings is equal to or greater than 10%;
- the units of small scale and micro cogeneration units providing primary energy savings (so a value greater than 0), it is similar to the high-efficiency cogeneration.