The word “cogeneration” indicates the possibility to exploit one energy resource to produce electrical and thermal energy, with consequent economical and environmental benefits. Natural gas fed cogenerating micro-turbines installed in the SPM allow exploiting the chemical energy of the fuel to produce:
- electrical energy, injected into the distribution grid;
- and thermal energy, used to integrate the boilers’ production during coldest months and as feeding source for the absorption chiller (in order to produce cooling power) during warmer months.
The three micro-turbines have overall electrical and thermal powers of 160 kW and 289 kW respectively, and they are controlled remotely by DEMS (Decentralized Energy Management System), but, if necessary they can be controlled on site.
The turbines are of the type Capstone C65 and C30 CHP (Combined Heat and Power). They are characterized by the performance data reported in Table 1 (at 15 °C ambient temperature and at sea level, considering 60% relative humidity for the C65 model).
The C65 and C30 gas turbines are characterized by compact size, low weight, reduced noise and low maintenance requirements. The electrical energy produced by the machines is used to satisfy the electrical load of the Campus. The gas turbines are also equipped with a by-pass in order to discharge the exhaust gas directly into the atmosphere.
The gas turbine control and data acquisition system is connected to the SPM control room; in particular, the control system is capable of receiving an external set-point of active and reactive power during operation in parallel to the public network and a set point of voltage and frequency during islanding mode.
The micro CHP gas turbine data
Rated electrical power 65 kWe
Rated thermal power 112 kWth
Fuel consumption 23 m3/h
Exhaust gas mass flow rate 0.49 kg/s
Overall efficiency higher than 85 %
Electrical efficiency 29 %
Exhaust gas exit temperature 309 1C