High Temperature Storage in Belgium by Use of Vertical Heat Exchangers: First Experiment―Tessas Project

摘要

Thermal energy storage (TES) is a widely known concept and it is accepted as one of the most economical and practical energy storage techniques. However, the technique is mostly used for cooling. Nevertheless, it is also possible to store heat at temperatures above 40-50℃. Storing heat will be useful in case of CHP, solar collectors, and waste heat, where the availability and demand of heat are not synchronous. By storing and re-using heat at this temperature level, this technique contributes to a more efficient and environment-friendly energy use (reducing the CO_2 emissions by decreasing the use of fossil fuels). Only a few projects (experiments/demonstration) are known in the world with regard to HTES (high temperature energy storage). To fill this gap and to perform a real scale demonstration project, the TESSAS-project has been launched. The Flemish Institute for Technological Research (Vito, Belgium) started in April 2000 with the TESSAS Project (high temperature thermal energy storage in saturated sand layers with vertical heat exchangers) with the support of the European Commission (5th Framework Program). The project will take four years. The general objective of this demonstration project is to study a thermal energy storage system on a real scale. The system is constructed (at Vito) in a water-saturated sand layer and equipped with vertical heat exchangers. The store will be charged during summertime at a temperature of approximately 90℃ by means of a district heating system. During winter, the stored heat will be recovered and used for heating a building of 3.700 m~3. This article gives a general overview of the TESSAS-project including the first results, showing that high temperature storage by use of vertical heat exchangers is indeed an option to reduce CO_2 emissions in the future.