The invention discloses method and system of drying renewable sources of energy and raw material. The drying process is carried out under partial vacuum conditions and at lower temperatures than conventional dryers. The temperature to dry the material and the rate of water removal are controlled by regulating the degree of vacuum and the intensity of heat input. A method for drying material to moisture content below 10% by weight, comprises introducing into an ejector a stream with a pressure above ambient pressure, creating partial vacuum in a drying chamber through the secondary nozzle of the ejector when the stream enters the ejector and provides the motive pressure to the primary nozzle of the ejector, said drying chamber having an inlet into which a wet material is introduced and an outlet for taking out the dried material after the drying treatment, drying the wet material using low temperature waste heat.