The environmental impact of additional large hydropower plants should be reconsidered, bearing in mind the potentially negative effects of large hydropow er on tourism and the natural environment. Energy security is directly linked to the competitiveness of economies through the strong relationship between economic growth and the reliability of energy sources, including electricity, gas and oil/petroleum products. The trade-off between the short-term social and political need for affordable energy, and the long-term sustainability of pow'er systems, is particularly acute in the six assessed SEE economies where improving energy security will require substantial infrastructure investment.