Maintaining power system security and adequacy has become more and more challenging due to the desire to decarbonize the electricity sector promoting renewable electricity. Power inadequacy occurs when the available production capacity does not suffice the demand. Finland wants to phase out coal by 2030 in a bid to drastically cut greenhouse gas emissions and closures of condensing power plants are expected to affect power adequacy during high demand. The main targets of the work are to find out if the power system of Finland will be reliable by 2030, if the decommission of technologies that use traditional energy sources threat the power balance and what impacts will the introduction of renewable technologies cause on the reliability of the power system. The loss of load probability method using a daily peak load variation curve appears to be the most widely accepted technique and used more often than any other approach, where the criterion of adequacy becomes some acceptable risk level at which the load will exceed the probable available capacity. The development of the tool was made using MATLAB. Once the code was finished, first the reliability of the developed program is evaluated testing historical data of electricity consumption in Finland. The results obtained show that the designed tool is very sensitive to changes in the load duration curve, specifically sensitive to the maximum load peaks. Secondly is made a forecast of the reliability of the Finnish power system in 2030, studying how the installed capacities of each technology will change and setting three different scenarios of electricity consumption represented by different load duration curves. The final evaluation considers three cases, one in which the nuclear power plant of Hanhikivi 1 is commissioned, another in which it is not commissioned and a third one considering the unavailability of wind power installed capacity during peak load demand. First two cases give a reduction of the expected load loss in the power system for year 2030, which in the worst case is a 47% lower than the current value. This could indicate that the Finnish power system will be very reliable in the way that the electricity generating facilities will be sufficient to meet the country's electricity demand during most of the year, but in the third case the risk of power inadequacy increases alarmingly due to the intermittent nature of the renewable technologies and the decommissioning of thermal power plants
