Croatian energy system is currently highly import-dependent and integration of a high share of renewable energy sources needs to be considered. This paper studies eight scenarios; three proposed by the Croatian Energy Strategy, one proposed by the Indicative medium-term development plan of Croatia's Transmission System Operator, and four alternative scenarios that propose extensive construction of hydro, wind and solar power plants in Croatia. Calculations have been conducted in the EnergyPLAN model based on modelled long term energy demand projections in the NeD model, with 2009 as the base year and a scope ranging until the year 2030. Each of the eight proposed scenarios is observed trough different hydrological conditions while analysing import dependency, economic costs and CO2 emissions. After the initial calculations, additional analysis of intensive wind power penetration has been conducted. The Results show that energy systems with a larger share of conventional and nonflexible power plants have more difficulty adjusting to wind power plants production. In case of a high share penetration of wind in a system based upon such power plants, the feasibility of investing in new large combustion plants that will spend most of the time working on minimum capacity is brought into question. INTRODUCTIONGrowing dependency on energy imports, obligation to decrease CO2 emissions, high and unstable energy prices, and increasing age of production facilities are some of the problems European energy systems need to face. In 2010, primary energy import dependency of EU-27 countries amounted to 52.7%, an increase of 22% since 1995, with predictions of reaching 70% in the next 20-30 years [1]. To decrease import dependency, as well as reduce CO2 emissions, European Union is planning increased implementation of renewable energy sources (RES),