HISTORY OF THERMAL ENERGY STORAGE

Abstract

This chapter discusses the history of thermal energy storage focusing onnatural energy sources. Links are made to recent trends of usingrenewable energy to achieve greater energy efficiencies in heating,cooling and ventilating buildings. The Deep Lake Water Coolingdevelopment in Toronto is presented as a typical modern interpretationof past practices with an integration of municipal services of watersupply and district cooling. Environmental concerns and restrictionshave also stimulated thermal energy storage developments. Cold storagein aquifers originated in China where excessive groundwater extractionrelated to industrial cooling had resulted in significant landsubsidence. To rectify the subsidence problem, cold surface water wasinjected into the aquifers. Subsequently, it was observed that theinjected and ``stored{''} water had maintained its cool temperature formonths and was suitable for industrial cooling. Thus, aquifer thermalenergy storage (ATES) was born. The Netherlands restricted groundwatermining for industrial cooling but left an exemption if reinjection usingATES for cooling were implemented. This stimulated interest in ATES andled to many implemented projects. In some areas such as Winnipeg,Manitoba, the natural groundwater temperature (6 degrees C) is suitablefor direct cooling. The reinjection of warm waste energy results in agradual warming of the aquifer, ultimately leading to lower systemefficiency for cooling. Using the aquifer for ventilation air preheatingin winter helped the WINPAK plant maintain the natural groundwatertemperature. Ground source technologies combined with undergroundthermal energy storage are seen as the best current method of combiningnatural energy sources with modern energy efficient building design. Thelatest technical findings have been incorporated into codes, standardsand guidelines. Some of these are briefly described. Storing freelyavailable energy to meet the requirements of a later season is``seasonal storage{''}. Three principal stimuli to the development oflarge-scale seasonal energy storage are: (1) the decoupling ofelectricity and heat production in cogeneration plants with heat storageincreasing the fraction of the annual heat demand met by cogeneration;(2) seasonal storage-assisted central solar heating plants to enablesolar energy to supply winter heating demands; (3) the storage ofambient winter air temperatures for summer cooling. Thermal storageassociated with cogeneration and district heating is a standardapplication. Central solar heating plants have been investigated,constructed and monitored as part of the International Energy Agency,Task VII of the Solar Heating and Cooling Implementing Agreement``Central solar heating plants with seasonal storage{''}. The storage ofambient winter air temperature is particularly suited to continentalclimates characterized by long cold winters with brief hot summers. Iceand snow are practical latent energy storage media for cold winter air.Snow and ice may be fabricated or gathered from natural sources. Inlarger commercial buildings, particularly those of energy efficientdesign, the energy expended for cooling can be a major proportion of thetotal energy requirement. This combination of a suitable ice-makingclimate with significant building cooling demands stimulated interest inseasonal thermal energy storage. Various design alternatives wereinvestigated, tested, evaluated and demonstrated. These effortsoriginated in the USA and Canada but now have been applied successfullyin Sweden.