Integration of Renewable Energies by Distributed Energy Storage Systems (Annex 28)

Operating agent:

Dr. Andreas Hauer
Bavarian Center for Applied Energy Research, ZAE Bayern

Dr. Christian Doetsch,
Fraunhofer Institute UMSICHT

Start: January 2014
End: December 2016

The Implementing Agreement “Energy Conservation through Energy Storage” (ECES) approved at the Executive Committee Meeting in 2-3 December 2013 in Ljubljana, Slovenia, the new Annex on the “Integration of Renewable Energies by distributed Energy Storage Systems”. This Annex should focus on the overall storage properties and their impact on the integration of renewable energy rather than the specific challenges of each energy storage technology. Collaboration with other Implementing Agreements (IA) within the IEA Technology Network and other institutions active in the field of distributed energy storage is crucial for this Annex.

The contribution of renewable energy to overall global energy production is expected to grow worldwide. Most renewable energy sources, like wind, PV, and solar-thermal are fluctuating resources. Significant storage capacity is needed to smooth out these fluctuations for reliable future energy systems. At the moment the focus is on large, central energy storage technologies like pumped hydro or the conversion of surplus electricity into fuels such as hydrogen or methane. The potential for small, distributed energy storage technologies remains mostly unexplored. The overall goal of Annex 28 is to foster the role of DES and to better evaluate the potential storage capacities for the integration of renewables at an economical competitive level. To reach this goal, distributed energy storage technologies and their properties will be examined, storage properties requirements depending on the different renewable energy sources will be reviewed and possible control and operation strategies for DES and technologies by smart grids will be studied. Finally the potential of DES systems for the integration of renewable energies based on the actual final energy demand shall be quantified and guidelines for choosing the most suitable DES technology for the actual application will be developed. Best practice and success stories examples will be given. The scope of this Annex includes all energy storage technologies suitable on the consumer side. Three main fields of application – households, trade and commerce and industry – will be investigated. The kick-off workshop and experts meeting will take place in Munich. Germany on April 9-11 2014. If you are interested in more information, please contact Andreas Hauer

Material Research and Development for Improved TES Systems (Annex 29)

Operating agent:

Dr. Andreas Hauer
Bavarian Center for Applied Energy Research, ZAE Bayern

Start: January 2013
End: December 2015

At the Executive Committee Meeting in Auckland, New Zealand, November 2012, this Annex was approved. The objective of this joint Task with the IEA Solar Heating & Cooling Implementing Agreement is to continue the activities started in Annex 24 “Compact Thermal Energy Storage: Material Development for System Integration”.
From the experience of the experts in the first period of the Task, it was concluded that one strong point elaborated is the interaction between the materials experts and the application experts, and the facilitation of this interaction by the division of the work into two subtasks: materials and applications.

The experiences of Annex 24 lead to a structure of the new Annex 29, with three materials working groups, one subtask for applications and one working group on economical evaluation of thermal energy storage (TES) systems. The economical evaluation will be performed by a bottom-up approach (while in Annex 24 a top-down approach was used). A questionnaire was sent out to predict the expected cost of each storage system, including material and other components. Within the material oriented working groups, novel storage materials – phase change materials or working pairs for thermo-chemical reactions – will be developed, tested and characterized. Finally they should be described by multi-scale simulation models in order to predict their performance under the operation conditions given by the application subtask. This subtask is responsible to define reference conditions for relevant application field for TES. Next Experts Meeting and Workshop will be held in Lyon, France, on April 28-30 2014. More information can be found at

Thermal Energy Storage for Cost Effective Energy Management and CO2 Mitigation (Annex 30)

Operating Agent

Antje Woerner

The general objective of Annex 30 is to identify and enable the potential for the implementation of thermal energy storage as a cross-sectoral technology. This will involve improving energy efficiency and process integration, increasing system flexibility as well as expanding utilization of renewable heating and cooling resources.
Ultimately, Annex 30 will create a methodology for characterization and evaluation of thermal energy storage systems. This comprehensive approach will be focused on 4 sectors: industry, power plant applications, non-residential buildings and transport. The methodology will be applied to various case studies originating from demonstration projects where thermal energy storage systems are applied in a real environment. Industrial involvement is critical to this annex and the crucial goal of harmonizing research and industrial needs will be endeavoured.
Annex 30 has been broken down into three phases: definition, methodology and application. The work will begin with the identification of the storage requirements for thermal energy storage systems in the aforementioned sectors, followed by the development of the characterization and evaluation methodology. The third phase applies the methodology to various case studies commonly implemented within industry and then uses industrial feedback to further refine the methodology.
For more detailed information, please refer to the full work program.

Annex workplan is available here

Energy Storage with Energy Efficient Buildings and Districts: Optimization and Automation (Annex 31)

Operating agent

Fariborz Haghighat

Further research is needed to develop efficient and reliable design approaches and operating strategies for storage in conjunction with thermal and electrical energy produced on-site in buildings and districts, and to support intermittency in the external grid. Previous annexes have dealt with some issues in this area. ECES Annex 7 evaluated various strategies for energy storage control and operation for industrial and building applications, but focused only on cold storage. ECES Annex 19 dealt with the optimization and improvement of industrial process heat and power generation with thermal energy storage techniques, but focused only on high temperature applications. ECES Annex 23 deals with the application of energy storage to various types of EEBs, but focused mainly on the development of simulation tools and not on the integration, and development of control strategies. ECES Annex 24 mainly focused on the development of advanced materials and systems for the compact storage of thermal energy.

Research in the area of design and analysis of energy efficient buildings and districts is inherently interdisciplinary. The current research approach to energy efficiency, though multidisciplinary in principle, is hindered by the lack of effective tools, methodologies, and demonstrations that address interdisciplinary aspects of the effective integration of storage in buildings and districts. In addition, the concept of energy use and storage integration with renewable energy technologies for buildings and districts requires not only integration and optimization but also accurate forecasting and controls to predict and react to future energy demand as well. For example, weather forecasts and building dynamics can be integrated into the energy management system to improve predictions of renewable energy generation and expected electrical, heating and cooling demands. This allows an appropriate orchestration of energy conversion systems and storage to maximise overall performance. This objective can be subdivided into five specific objectives: A.To assess the technical potential and total performance of energy storage systems in energy efficient buildings and districts. B.To develop methods and tools to evaluate and optimize the total performance (energy, environmental, and economical) of whole systems. C.To develop efficient and advanced control algorithms and/or strategies for the operation of whole systems, for different climatic conditions and energy markets, D.To develop and provide design guidelines for integrating energy storage into energy efficient buildings and districts, E.To demonstrate and disseminate the knowledge and experience acquired in this Annex through case studies and validated demonstration projects.

Annex Text Proposal is available here