SEA Energia generates energy through three different technologies: cogeneration, simple/combined cycles, and trigeneration.
SEA Energia generates electricity and thermal energy through different technologies, as follows:
The cogeneration combined cycle is a high-yield electricity generation technology with a very low environmental impact.
A cogeneration plant produces electrical and thermal energy at the same time. Thermal energy can be used in a simple cycle to heat or cool water or air (through absorption equipment) or to produce more electricity using the heat generated in a steam turbine. This allows the cogeneration cycle to have a higher energy yield than the separate generation of electricity and heat, as in traditional electrical and thermal production.
The same amount of energy output (45+38) with a conventional plant requires a 48% higher energy input.
The environmental benefits of cogeneration are also related to the type of fuel used, as natural gas consists of 80-99% methane, the “cleanest” of fossil fuels. Its composition, richer in hydrogen and poorer in carbon than other hydrocarbons, produces lower carbon dioxide (CO2) emissions, energy generation being the same. In addition, the fumes contain no sulphur oxides due to virtually total absence of sulphur.
In natural gas combustion, the formation of nitrogen oxides (NOX) is mainly attributable to high temperature oxidation of the nitrogen contained in comburent air.
As an energy user, airports are characterised by simultaneous demand of electricity, heating and cooling; cogeneration is the ideal solution to meet these needs, as among other things it helps to make power supply more reliable, an essential requirement for an airport installation.
There are different cogeneration systems:
- Diesel/gas engines: from which the heat of exhaust fumes and auxiliary circuits (oil, cooling water) is recovered.
- Gas turbines: where a large amount of high temperature exhaust gas is conveyed into a recovery boiler for the production of superheated water or steam.
- Counter-pressure steam team: supplied with superheated steam which is then discharged at low pressure by the turbine to supply thermal energy users.
With regard to gas turbines only, the fuels used are generally liquid and gaseous hydrocarbons like methane. Combustion systems are characterised by high excess of air and by pollutant (NOX) abatement technologies for lower environmental impact. The choice of cogeneration has positive as well as negative effects.
On the positive side:
- High yield, which means lower fuel consumption and therefore lower environmental impact (due to reduced amounts of CO2 in the air) and protection of natural energy resources;
- The possibility of accessing funding provided by the laws regulating the national energy plan, as available to energy generation through wind, solar and geothermal systems.
On the other hand, it must be kept in mind that:
- Thermal energy users must be as close as possible to the production plant to contain distribution network costs, which are generally very high;
- Cost-effective management of the process requires maximum use of heat and electricity, with consistent delivery over time;
- As users, airports fully meets these needs in that their energy demand is high, consistent in time and close to production plants.
A system for the combined generation of electricity, heat and chilled water. The term immediately recalls cogeneration which, as mentioned before, allows the combined production of electricity and thermal energy through the same combustion, by recovering heat which would otherwise be lost downstream of the process. Trigeneration adds air conditioning and cooling to these two functions.
Cooling is produced through the use of the refrigeration cycle which converts thermal energy into cooling energy by transforming the state of the cooling fluid (water) in combination with the substance (lithium bromide).
The chilled water obtained in this way can be used for air conditioning. As with cogeneration systems, trigeneration also ensures significant energy savings due to the combined production of electricity, heat and cooling.
Trigeneration plants find useful application in airports, whose simultaneous demand for electricity, heating and cooling makes them ideal users. Trigeneration does not reduce polluting emissions, but offers three important competitive advantages:
- Higher combustion yield compared to large thermoelectric plants;
- Combined and simultaneous production of three different forms of energy;
- Optimises fumes and exhaust which would otherwise be lost.
The choice of combined electricity and thermal energy production aims to achieve the following objectives:
- Operating safety and continuity by self-producing the entire electricity requirement and using the national grid only to cover peaks of demand or for backup;
- Operating reliability, as the self-production of electricity also provides all heating and cooling energy, thus ensuring optimal management of energy resources;
- Flexible, modular plant configuration able to adjust to current and future operating needs.