This book presents a collection of the materials the authors have published in the past few years and is made up of two parts. The part one is devoted to the new method for energy system evaluation based on the multicriteria assessment. The second part comprises application of the multicriteria method on different energy systems. The focus is on clean air technologies, new and renewable energy systems, hydrogen systems, biomass systems, solar systems and multicriteria evaluation water efficiency, water desalination systems and evaluation of heat sink design for computer systems.