This thesis investigates the energy situation in Bulgaria, Hungary and Romania from an environmental point of view. The analysis of the three countries' shows that all three countries are below their national CO2-reduction targets for 2020. However, the countries' current energy use is very inefficient with e.g. Bulgaria having the worst energy efficiency within the EU. Therefore, investments into energy efficiency measures as well as increasing the share of renewable energy still makes lot of sense for the countries to benefit economically, socially and environmentally. The countries renewable energy potentials are considerable and varied. Biomass provides the highest potential of renewable energy technologies for all three countries, followed by hydro energy for Bulgaria and Romania. However, when comparing these potentials with the countries' current energy demand (which is order of magnitudes higher), it remains questionable if there is enough availability of renewable energy to substantially reduce and ultimately replace the countries' existing heavy dependence on fossil fuels and nuclear energy. From an environmental perspective, solar and wind energy are generally considered to be the renewable energy technologies with comparatively lower environmental impacts followed by biomass and hydro. As the countries show highest potentials for biomass and hydro energy, the devleopment of "sensitivity maps" is suggested to identify "no go areas" as well as potential sites for such installations to ensure the sustainable extension of renewables. Finally some possibilites for a climate&energy engagement in the three countries are provided. Above all, the development of an "integrated energy vision" is suggested as one respective key element that involves all stakeholders to reflect the current energy demand, define the most sustainable energy mix in the long-term and derive conculsions what needs to be done today to get there.