Energy Storage Research & Development

Many governments have committed to reduce CO2 emissions into the atmosphere. They have decided to strengthen their national efforts to increase the deployment of energy conservation technologies and utilization of renewable energy sources. So far in most industrialized countries, renewable energy sources contribute only marginally to satisfy energy demand. This is due to several reasons, in particular because some new energy systems are not yet economically competitive with the combustion of fossil fuels, long term reliability is not yet proven, and there are still some regulatory and market barriers which have to be overcome. Therefore, further attempts are being made to resolve these issues. This is especially true for many new energy storage technologies and concepts that have not yet been implemented on a large scale in the market.

The IEA Implementing Agreement on Energy Conservation through Energy Storage was established in 1978 with the objective to facilitate international cooperation on research, development and demonstration (RD&D) of new, innovative energy storage technologies. Initially, attention was primarily focused on energy storage technologies improving the energy efficiency of energy supply. Generally, with this application much energy has to be stored for longer periods of time. Storage technologies, which can fulfil this requirement, are underground thermal energy storage and technologies, which use phase change materials or chemical reactions.

With Underground Thermal Energy Storage (UTES) soils, bedrock and groundwater are used as a storage medium for thermal energy. At relatively low costs the storage capacity of the underground can be utilized for energy efficiency purposes. Also the use of materials, which show a phase change (e.g. water/ice) or of chemical reactions (e.g. batteries) results in technologies for the storage of considerable amounts of energy for longer periods of time. These technologies require lower storage volumes than UTES. This enables these technologies to be applied in buildings and vehicles.

Over the last few years, the emphasis of the co-operative RD&D efforts has shifted towards storage technologies that improve the manageability of energy systems or facilitate the integration of renewable energy sources. Examples are the short-term (heat) storage in a heat pump system, as a result of which the number of heat pump starts and stops is reduced, and the use of electrical energy storage in an electricity supply system, facilitating the integration of solar photovoltaic panels.