The term „trigeneration“ signals a completely new form of efficient use of energy. As a result of trigeneration, it is possible to optimally utilize excess and waste heat from thermal electricity production (or waste incineration) and industrial waste heat all year round. Due to the long practiced process of cogeneration, it has already been possible to use this waste heat for warm water and, in countries with cooler temperatures, heating purposes during the heating periods of the year. If cogeneration is extended to trigeneration, it is additionally possible to use surplus and waste heat for cooling purposes.

The conversion of heat to cold ensues in absorption chillers. These contain a duel solution of solvent and coolant (i.e. water absorbed by ammonia). Both of these components are characterized through varying evaporating temperatures. When heated, both components are separated from each other due to the varying evaporating temperatures. The coolant (ammonia) is then cooled again via a liquid separator and condenser. The next step is to place the coolant in a so-called evaporator, where there is a particularly low level of pressure. As a result of the low level of pressure, the coolant can evaporate at a minimal temperature. Evaporation ensues under absorption of the ambient heat. From that the effect of cooling arises. The warmed coolant is then absorbed again by the solvent (water) in the absorber, and the cycle starts all over again from the beginning.

If the thermal energy required can be extracted from the waste heat produced by other processes, air-conditioning units and other cooling appliances can be operated extremely efficiently. In almost the same manner, regenerative environmentally friendly sources of heat, such as geothermal energy, can also be used. Accordingly, the use of electrical power, which is otherwise needed to operate an air-conditioning system, can be saved on. In times of increasing electricity prices, this can also mean considerable financial savings.