The full natural gas combined-cycle cogeneration (GCCC) and trigeneration presents one of the most progressive technologies of the modern energy industry that ensures a high level of fuel efficiency, low emissions and the flexible process of changing the load of a power unit. Within the Doctoral Thesis a special application of the absorption coolers for the transmission of the low potential heat of GCCC to the heat network has been developed. In the result of the study a solution has been found for improving the productivity of the absorption cooler under the conditions of high return temperature. The introduction of district cooling is proposed as a measure for improving the efficiency of GCCC in the Latvian circumstances and a computer simulation has been developed for determining the costs of cold production. For the purpose of determining the heat flow of the absorption cooler integrated within the operation of the GCCC a non-stationary temperature field within the environment covering cylinder type heat pipes has been described by mathematic methods. The Thesis proposes solutions for increasing the total efficiency of GCCC in the countries with temperate climate conditions by utilising the low potential heat of the technological process, which was not utilised before and, which was discharged into the environment without any utilisation until now. The proposed solution allows the increase of the total efficiency of GCCC by at least 2%; the savings of natural gas achieved at the EO amount to 1.4 mill. n.m³ per year. The methodology for introducing the district cooling in compliance with the index of the sustainability of the Latvian energy industry is proposed in the Thesis. The experimental and practical testing of the developed solutions was carried out at the CHP IMANTA of the Joint Stock Company RĪGAS SILTUMS .The gained experience was used for the development of the algorithm of the improvement of the operation of GCCC and the verification of the testing methods. The major results of the Doctoral Thesis have been reported at twelve international conferences and workshops and summarised in 17 publications. The obtained results of the research have been implemented in the study programs of Riga Technical University, they can be used by the producers, designers, planners and developers of the district heating, cooling and electricity for providing additional heat capacities without carrying out major reconstructions of plants, as well as for evaluating the options for the plant expansion. The technological developments of high capacity heat pumps and coolers can be used for the utilisation of low potential heat from geothermal sources and industrial processes.