Résumé : Power stations in marine locations cause multi-faceted impact on the environment, man and the economy. There are not many studies devoted to modeling energy benefits for CO2 emissions. The paper presents the issues of assessing the efficiency of offshore wind farms, defined as the ratio of benefits to life cycle inputs. The scientific goal was to develop a mathematical model for efficiency in the design, manufacture, use and management of offshore wind power. The papers practical purpose is the experimental designation of the impact of selected post-use management methods, time of use and maritime location, i.e. average annual productivity of wind power plants on the efficiency of energy benefits from greenhouse gas emissions. The mathematical model of the integrated cost-benefit ratio has been developed for energy use assessment, taking into account the benefits generated by electricity production and the life-cycle CO2 emissions based on the LCA analysis using the CML method. Mathematical model validation was performed by determining the value of the indicator for an existing 2 MW offshore wind farm and comparatively for fossil fuel production: lignite, stone, fuel oil and natural gas. Analytical and research work carried out showed that the higher the efficiency index, the higher the value of the indicator. It has been shown that the location of the power station at sea produces more favorable CO2 elimination rates, due to higher productivity compared to in-land wind power plants. A more favorable form of post-consumer management for CO2 has been determined as recycling. It was found that for electricity generated from offshore wind farms, the value of the energy efficiency benefit from CO2 emissions is higher than for fossil fuel energy production.