Clean Energy
Presenting a broad survey of the energy problems facing society over the coming decades and the prospects for their solution, this book emphasizes the importance of developing a strategy for the world's future energy supply.
TABLE OF CONTENTS Clean Energy
Chapter 7: Physical Techniques for Storing Energy
The different modes of energy storage have been itemized in Figure 3.14, Chapter 3. Here, we review the major physical modes (as thermal, potential and kinetic energy) and also, for completeness, the electromagnetic and electrostatic forms of energy storage. Storage as chemical energy is treated later, in Chapters 8 and 9.
7.1 Thermal Energy Storage
Thermal energy can be stored in three ways, as follows:
-
Sensible heat storage, in which a substance absorbs heat passively and becomes warm (see, for example, passive solar heating, Section 4.4, Chapter 4).
-
Latent heat storage, which makes use of the energy stored when a substance changes from one state, or 'phase', to another. For example, heat is absorbed when a substance changes from a solid to a liquid, and is released again when changing from a liquid to a solid. There is no temperature change associated with latent heat.
-
Thermochemical storage, which uses the energy stored in reversible chemical reactions.
There are many everyday illustrations of the benefits to be gained by providing the means to store heat (or cold): clothes serve to retain body heat and buildings are thermally insulated to retain or exclude heat; refrigerators are used everywhere to keep food fresh and 'cold storage' is an established industry for the preservation and conveyance of perishable foodstuffs.
Sensible Heat Storage
The storage of sensible heat requires, ideally, materials of high specific heat ( i.e. energy stored per unit weight) and low cost. In practice, it is the latter consideration that prevails...
Copyright The Royal Society of Chemistry 2004 under license agreement with Books24x7
