The planned technique of the cogeneration system which are main systems of a local energy system is studied. First, the method of estimating the cooling load, heating load, and electric power load of an area is studied. Next, the feature of a power generator, such as a gas engine and a gas turbine, is studied. Next, the method of a setup of the operating method of a power generator is learned from the balance of heat load and electric power load. Finally, system efficiency is analyzed using the operation data of the example of an advanced system.