Estimating the global waste heat potential

The process chain of energy conversion from primary energy carriers to final energy use is subject to several losses. Especially in end use, vast amounts of converted energy occur as waste heat, which is often released to the environment. In terms of raising energy efficiency and reducing the energy consumption, such waste heat needs to be used. To date, some studies or investigations about industrial waste heat of selected countries have been carried out, but other sectors like commerce were not considered. Therefore, this work presents a novel top-down approach for the estimation of waste heat potential of the most common sectors of end use (transportation, industrial, commercial and residential) including electricity generation on a global scale. It also deals with the temperature distribution of this unused energy. The evaluation reveals that 72% of the global primary energy consumption is lost after conversion. In further detail, 63% of the considered waste heat streams arise at a temperature below 100°C in which electricity generation has the largest share followed by transportation and industry.