Dr. Andreas Haselbacher
ETH Zurich
Institute of Energy Technology
ML K 22
Sonneggstr. 3
CH-8092 Zurich
phone +41 44 632 69 05

About 50% of the total energy consumed in Switzerland1 is needed to heat buildings, to provide domestic hot water, and to supply heat to industrial processes. Approximately 86% of the required heat is generated by the burning of fossil fuels, with the remainder produced from electricity. Households and services use about 92% of their total energy needs for heating buildings and water, while industry uses about 92% of their total energy requirement for generating process heat. The center aims to develop and deploy efficient and cost-effective low- and high-temperature storage solutions to help reduce Switzerland’s energy needs and CO2 emissions. We are pursuing several storage technologies and applications for these technologies.

1 Use of Energy in Switzerland 2000 – 2012 , BFE 2013

Building Applications: Heat Storage for Heating, Domestic Hot Water and Industrial Processes
The heating and cooling demands of buildings necessitate storage of thermal energy for the winter and summer. Sensible, latent, and sorption storage technologies can be used to bridge the time shift between the availability of energy (such as solar radiation) and user demand. The application temperature range for heating, ventilation, and air conditioning in buildings will be covered by these storage technologies in the temperature range of about -10°C to 250°C. The experience with the application of sorption materials to seasonal heat storage is being strengthened and expanded with the goal of integrating the improved technology into an actual building.

Advanced Adiabatic Compressed Air Storage (AA-CAES)
Plants based on AA-CAES use electricity during periods of excess power generation to drive a compressor. The heat contained in the compressed air is stored in a Thermal Energy Storage (TES), and the high pressure cooled air is stored confined in a hermetically sealed reservoir. To generate electricity during periods of high demand and low power generation, the air is released from the reservoir, absorbs heat from the storage, and is expanded through a turbine that drives a generator. With an efficient heat-storage design, the efficiency of an AA-CAES plant is projected to reach about 75% and therefore it can approach the typical efficiency of pumped hydro storage (PHS). A heat-storage concept for AA-CAES with temperature and pressure ranges of about 500-600°C and 10-60 bars is considered.
The combination of encapsulated phase-change materials (PCM) with a packed bed of rocks in collaboration with Airlight Energy Ltd and ALACAES SA is developed.

Pumped Heat Electric Storage (PHES)
In PHES, electricity during periods of low demand is used to drive a heat pump. During periods of high demand, a heat engine is used to generate electricity. For PHES, the research is focused on answering several important questions, such as the appropriate combination of working fluid, the temperatures of the lower and upper thermal reservoir, and the accompanying storage media. The pressures and temperatures of the two reservoirs depend on the working fluid and the turbomachinery to be used in the heat pump cycle and the Rankine power cycle.

High-temperature process heat
The storage of thermal energy at temperatures above 400°C is of interest to process-industry applications such as glass recycling, cement production, and metallurgical processing. Accordingly, research is focused on latent and sensible heat storage for these temperature ranges to provide solutions for economic and compact storage of fluctuating sources of high-temperature heat and/or electricity.


Thermo-Mechanical Characterization of Cellular Ceramics in High-Temperature Environments
• G. Zanganeh, P. Good, G. Ambrosetti, S. Zavattoni, M. Barbato, A. Pedretti, A. Haselbacher, A. Steinfeld, «A 3 MWth parabolic trough CSP plant operating with air at up to 650 °C». Industrial High-Temperature Solar Energy, November 6th, Neuchâtel, Switzerland, 2014.
• G. Zanganeh, P. Good, G. Ambrosetti, S. Zavattoni, M. Barbato, A. Pedretti, A. Haselbacher, A. Steinfeld, «A 3 MWth parabolic trough CSP plant operating with air at up to 650 °C». International Renewable and Sus- tainable Energy Conference, October 17–19, Ouarzazate, Morocco, 2014.
• S.A. Zavattoni, M.C. Barbato, A. Pedretti, G. Zanganeh, «Single-tank TES system – Transient evaluation of thermal stratification according to the second-law of thermodynamics». 20th SolarPACES Conference, Sep- tember 16–19, Beijing, China, 2014.
• S.A. Zavattoni, N. Garcia-Polanco, J. Capablo, J.P. Doyle, M.C. Barbato, «Household appliances wasted heat storage by means of a packed bed TES with encapsulated PCM». 13th International Conference on Sustain- able Energy Technologies (SET), August 25–28, Paper ID: E30018, Geneva, Switzerland, 2014.
• S.A. Zavattoni, M.C. Barbato, A. Pedretti, G. Zanganeh, «CFD modeling of a TES system based on a packed bed of natural rocks». 99th Eurotherm Seminar – Advances in Thermal Energy Storage, May 28–30, Paper ID: 02-083, Lleida, Spain, 2014.

Phase Change Material Systems for High Temperature Heat Storage
• D. Perraudin, S. Haussener, «Coupled Radiation-Conduction Heat Transfer in Complex Semitransparent Macroporous Media». International Symposium on Advances in Computational Heat Transfer, Piscataway, May 25–29, 2015.

Thermo-Mechanical Characterization of Cellular Ceramics in High-Temperature Environments
• A. Ortona, E. Rezaei, «Modeling the properties of cellular ceramics: from foams to lattices and back to foams». In: Advances in Science and Technology (2014).
• A. Stamatiou, et al., «Dual Energy Storage and Converter (DESC)». 2nd Swiss Symposium Thermal Energy Storage.

Aqueous Sodium Hydroxide Seasonal Thermal Energy Storage: Reaction Zone Design and Optimization
• X. Daguenet-Frick, P. Gantenbein, E. Frank, B. Fumey, R. Weber, T. Williamson, «Seasonal thermal energy storage with aqueous sodium hydroxide – reaction zone development, manufacturing and first experimental assessments». EuroSun, Aix les bains, France, 2014.
• T.J. Schmidt, «Technical options for energy storage». Studiengruppe Energieperspektiven, Baden, September 3, 2014.