Decentralized energy is in the focus of today's effort of policy-makers and large consumers of energy towards a substantial reduction of energy losses and improved energy efficiency. On the one hand, energy loss is prevented as power is used where it is generated, i.e. on-site, therefore no cables are needed for transmission over a long distance. On the other hand, most on-site power generation technologies deliver several types of energy at once, recovering the waste heat from the engines which is otherwise dissipated in the atmosphere. Modern systems are compact and can be installed both outdoors and indoors, equipped with sufficient noise insulation.