The LEI is a technical research centre dealing with energy related research in the analysis of security of energy supply, the development of energy planning methods, fuel cells and hydrogen, renewable energy, thermal physics and fluid mechanics, nuclear safety, structural integrity assessment of components and structures and the simulation of complex energy systems. Furthermore, it has long-term experience in the analysis of energy systems operations as well as the development and mathematical modelling of energy systems development scenarios, environment impact analysis, energy policy, and in the preparation of action plans on the national and municipal level. The Institute has extensive experience in international projects, including work for IAEA, FP5, FP6, FP7, Phare, Intelligent Energy Europe, COST, Eureka, Leonardo da Vinci, INTERREG III, Baltic Sea Region 2007-2013 programme, South Baltic Cross-border Co-operation Programme 2007-2013 and the Nordic Energy Research Programme.

In recent years various research directions were pursued and financed by the Government of Lithuania, such as: the development of energy economy planning methods, investigation of safety and reliability of power plants, their impact on the environment, efficient energy consumption and renewable energy sources.