As the Coburg-based compressor specialist Kaeser has now announced, no less than 100 percent of the energy supplied to a compressor is converted into heat. According to Kaeser, air- and fluid-cooled screw compressors are particularly suitable for the most comprehensive recovery and further use of this energy. In these compressors, approximately 76 percent of the energy used is found as heat in the cooling fluid and can be extracted from it in the fluid aftercooler. A further 15 percent of this energy can be recovered as heat via the compressed air aftercooler. The electric motor emits up to five percent as heat loss. Fully enclosed screw compressors even make it possible to recover this energy with targeted cooling. In the ideal case, up to 96 percent of the original drive energy is available for reuse. Only about two percent is lost through heat radiation and another two percent remains as heat in the compressed air.

According to Kaeser, the simplest and most efficient way is to use the cooling air heated by the compressor directly. An air duct system directs the warm air into adjacent storage rooms or workshops. If there is no need for heating air, the heated exhaust air can be directed outside by simply adjusting a swivel flap or blind. A thermostatically controlled blind control system allows the warm air to be regulated so precisely that constant temperatures are achieved. In addition to full or supplementary heating for operating rooms, the warm exhaust air from the compressor can also be used, for example, to support drying processes, to create warm air locks, or to preheat the burner air of heating systems. The corresponding investments often pay for themselves within a year.

Alternatively, the waste heat from the compressor can also be fed into existing hot water heating systems and domestic water systems. The most cost-effective way to do this is with a plate heat exchanger. It is connected to the compressor's cooling fluid circuit and transfers the energy from the heated cooling fluid to the water to be heated. Depending on whether the hot water is to be used in highly sensitive production and cleaning processes, as shower and washing water, or for heating purposes, safety or plate heat exchangers are used. This means that around 70 to 80 percent of the installed compressor power can be used for heating without any additional energy input. This type of heat recovery is also possible with primarily water-cooled screw compressors.

According to Kaeser, heat recovery can therefore significantly increase the efficiency of a compressed air system and reduce the environmental impact by avoiding greenhouse gas emissions. The amount of investment required depends on local conditions, the application and the heat recovery method selected.