• Energy Research

Abstract A large amount of low grade heat is wasted at temperatures below 100 °C but its quantity remains mostly unknown. Therefore, the identification and quantitation of low grade heat availability enables further assessments on whether or not the recovery of this fraction of heat is convenient. By considering the countries composing the European Union (EU), this work quantifies the low grade heat from power generation and industrial sectors (mining, minerals, metals, chemicals, pulp and paper, food) with a particular focus on the faction of heat below 100 °C. The analysis shows that, in the year 2018, 8774.4∙106 GJ (2437.3 TWh) of heat was available in the EU below 100 °C, with the power generation sector accounting for 95% of the total low grade heat emitted. In addition, around 96% of the waste heat was in the temperature range from 25 °C to 80 °C, being of ultralow grade. Similar conclusions were obtained in terms of exergy loss, which was essentially from the power generation sector, especially in the range of temperatures between 40 °C and 60 °C. These results suggest that ultralow waste heat is an untapped source of energy which can be conveniently exploited by the same point-source emitters, primarily in the power generation sector or in wider industrial areas where infrastructure is present.