Energy storage technologies are a strategic and necessary component for the efficient utilization of renewable energy sources and energy conservation. There is a great technical potential to substitute for burning fossil fuels by using stored heat that would otherwise be wasted and using renewable generation resources. These energy sources can be used more effectively through the addition of short- and long-term energy storage. Thermal and electrical energy storage systems enable greater and more efficient use of these fluctuating energy sources by matching the energy supply with demand. Thermal energy storage can also be used for cooling to reduce or eliminate the demand for electricity, including the most expensive electrical energy that is generated during periods of peak power demand. The overall objective of the Implementing Agreement on Energy Conservation through Energy Storage is to develop and demonstrate various advanced energy storage technologies for application within a variety of energy systems, and to and encourage their use as standard engineering design options. The balance of activities focuses on case studies, demonstrations, deployment measures and design tools. The work programme includes a range of tasks relating to development of underground thermal energy storage systems in the buildings, industrial and agriculture sectors; examination of the potential role of electrical storage technologies in optimising electricity supply and use; examination of the role of phase-change materials and thermo-chemical reactions in energy systems; and development of procedures and screening and decision tools to facilitate the adoption of energy storage in project designs. Most of this activity is undertaken through task-shared projects although some cost-shared work is also undertaken. Work conducted under the programme has influenced many large projects. Several plants using direct cooling and cold storage were built or are under construction in participating countries as a result of programme activities.

21. Thermal Response Test for Underground Thermal Energy Storages
The overall objectives of Annex 21 are to compile TRT experiences worldwide in order to identify problems, carry out further development, disseminate gained knowledge, and promote the technology. Based on the overview, a TRT State of the art, new developments and further work are studied.

23. Applying Energy Storage in Ultra-low Energy Buildings
The general objective of the Annex is to ensure that energy storage techniques are properly applied in ultra-low energy buildings and communities. Applications of these designs are foreseen in a post-Kyoto world where total CO2 reduction is required. Proper application of energy storage is expected to increase the likelihood of sustainable building technologies. Specific objectives include, • assess the potential of harnessing natural energy sources to supply building heating and cooling through energy storage; • assess the use of energy storage (electrical and thermal) to optimize the efficiency of distributed generation; • develop and evaluate energy storage conceptual designs suitable for specific applications.

24. Material Development for Improved Thermal Energy Storage Systems
The overall objective of this task is to develop advanced materials and systems for the compact storage of thermal energy. This can be subdivided into seven specific objectives: - to identify, design and develop new materials and composites for compact thermal energy storage, - to develop measuring and testing procedures to characterise new storage materials reliably and reproducibly, - to improve the performance, stability, and cost-effectiveness of new storage materials, - to develop multi-scale numerical models, describing and predicting the performance of new materials in thermal storage systems, - to develop and demonstrate novel compact thermal energy storage systems employing the advanced materials, - to assess the impact of new materials on the performance of thermal energy storage in the different applications considered, and - to disseminate the knowledge and experience acquired in this task. A secondary objective of this task is to create an active and effective research network in which researchers and industry working in the field of thermal energy storage can collaborate.

26. Electric Energy Storage: Future Energy Storage Demand
The overall objective of this task is to develop a method or approach to calculate the regional energy balancing demand and to derive regional storage demand rasterizing the area and taking into account that there are competitive technical solutions. This objective can be subdivided into ten specific objectives: - to rasterize the whole area to typical small self-similar elements, - to identify and characterize typical fluctuating energy demand for different elements which stands for different regions and grid situations (e.g. intermeshing), - to identify and characterize typical fluctuating energy production (wind, PV) for different elements which stand for different regions and renewable energy potential (e.g. wind velocity), - to identify and characterize typical conventional energy production (gas turbine, nuclear power plant) for different elements which stand for different regions and conventional energy production, - to reduce different grid structures to a fistful typical systems and to simulate their inner intermeshing and their exterior connectivity (transport, import, export), - to derive balancing demand for each typical region, - to derive energy storage demand as a share of the total balancing demand, taken into account that the most successful economic solution will be realized, - to develop a method or model to transfer these results to other countries and regions, - to assess the technical and economical impact of energy storages on the performance of the energy system, and - to disseminate the knowledge and experience acquired in this task. A secondary objective of this task is to create an active and effective research network in which researchers and industry working in the field of electric energy storage can collaborate.

25. Surplus Heat Management using Advanced TES for CO2 mitigation
The general objective of this Annex is to identify and demonstrate cost-effective strategies for waste heat management using advanced TES. New knowledge will be generated with regards to: - The potential for advanced TES to minimize process waste heat through better process integration, enabling the use of waste heat for internal heating demands or cooling demands (via heat driven cooling). - The potential for advanced TES to cost-effectively increase waste heat driven power generation in industrial applications. - The potential for advanced TES to enable external use of heat from industrial-scale processes through effective thermal energy distribution. - The potential for advanced TES to increase the utilization of waste heat in vehicles like on-board cooling and minimization of cold-start. - The potential for advanced TES to increase the use of waste cooling (e.g., the large cooling potential associated with LNG regasification) and free cooling for comfort cooling applications. - Thus, a sub-goal of this proposed annex is to really dig into the waste heat utilization issue from a very broad perspective, and show the great potential for using advanced TES towards reaching a resource efficient energy system where waste heat (and cold) is minimized. This has a good potential for attracting a large number of participants from a variety of disciplines and levels of R&D (basic research to commercial systems).

27. Quality Management in Design Construction and Operation of Borehole Systems
The quality assurance issues included in the strategic plan of ECES is going to be addressed for borehole thermal energy storage systems in this Annex.