Industrial heat demand by temperature range
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The “ECOHEATCOOL” study [3] reports that about 30% of the total industrial heat demand is required at temperatures below 100 °C and 57% at temperatures below 400 °C. Moreover, in several industrial sectors, such as food, wine and beverage, transport equipment, machinery, textile, pulp and paper, the share of heat demand at low and medium temperature (below 250 °C) is about, or even above, 60% of the total figure. However, it should be highlighted that the pulp and paper sector uses primarily heat recovery systems and, therefore, even though the theoretical potential is high, the practical implementation of a solar thermal plant is not convenient in most of the cases. The figures obtained from industry statistics are fully confirmed by the outcomes of the estimates done in the reported potential studies for solar process heat.
Finally, it should be noted that quite often industrial processes exploit medium temperature heat by using steam as a heat carrier even though lower working temperatures would be sufficient.
Therefore, in order to assess correctly the feasibility of the introduction of solar thermal in an industrial process, one should look at the actual temperature needed by the process itself and not at the temperature of the heat carrier being used. Such an approach should be used not only for determining the implementation of solar thermal plants, but also for lowering the current process energy consumption.
