Reducing the energy consumption of the industrial sector (about one fourth of the total final energy demand in Europe) is critically important to meet the 20-20-20 targets. The industry consumes more heat than electricity and significant energy savings can be expected from efficiently handling thermal energy. Because industrial processes are so diverse a variety of sometimes very specific measures have been proposed for reducing the heat demand in certain industries. A very general approach is to increase the thermal efficiency of the industrial processes by managing the waste heat. Because the processes are dynamic thermal storages are indispensable to meet supply and demand.
Heat demand of industrial sector (EU-27)
Diagram from [Ralf Kuder 2010] Technology orientated analysis of the emission reduction potentials in the industrial sector in the EU-27. Institute of Energy Economics and the Rational Use of Energy. Stockholm. Online available
Thermal Storage with Phase Change Materials
Phase Change Materials (PCM)
The operating range for industrial thermal storages is divided into low (< 100 °C), medium and high (> 300 °C) temperature processes. We focus on the medium temperature range, which includes important industrial sectors (food, pulp and paper, machinery, chemical). The state-of-the-art storage in this temperature range is the steam accumulator, which suffers from several disadvantages: it operates at high pressures, the energy density is only moderate (about 40 kWh/m3 compared to 100 kWh/m3 attainable with PCM storages), and it is rather costly [M. Haider: Neue Aspekte und Perspektiven thermischer Energiespeicher, VDI Forum Österreich, Linz, 2012]. One very important drawback for the state-of-the-art technologies is that the temperature varies upon (dis)charge, although heat at certain well defined temperature levels is required in many industrial processes. PCM storages for industrial applications overcome these problems, because they are able to store and release heat almost isothermally at high energy densities [R. Tamme: Storage Technology for Process Heat Applications, PREHEAT Symposium, Freiburg, 2007.].
Thermal Storage with Thermo Chemical Materials
Thermo Chemical Materials
First sensible energy storage systems in district heating companies are installed, like at Salzburg AG or at Fernwärme Wien. The goal of these storages is to shift waste heat, which is produced in combined heat and power (CHP) plants during a high electricity price level to the times of peak heat demand, during the day. Their storage time is within one day (and their volumes are high (Salzburg AG: Ø 29m, H 44m; 60MW; 1,1GWh, for example). With thermochemical energy storage it could be possible to shift waste heat of those CHP-plants from autumn to winter nearly without any losses, and at theoretically 10 times higher storage capacity.