The project

Buildings consume most of the world’s electricity and as much as 50% of their consumption is used to cover thermal demands. Some actual developments, such as the growing use of electric vehicles and the usage of heat pumps, are affecting electricity consumption and peak demand, and their impacts will only increase in the future. 

The excessive high energy demand entails significant negative environmental and economic impacts. Consequently, it is imperative to increase the use of demand response strategies that shift electricity use from peak to off-peak periods. 

The BEST-Storage project is an important step to achieve the goal of peak load reduction and shifting, energy saving and energy cost minimization. 

Moreover, technologies for storing renewables for longer time spans of months or seasons are scarce and costly and thus not widely used yet. Large amounts of energy are needed for the heat supply of buildings in cold winter months, when solar energy is scarce and in general when renewable sources cannot cover the demand. Thus, seasonal storage solutions will be a necessary technology for the full decarbonisation of the energy supply system. 

In BEST-Storage, long and short-term high-energy density storage solutions will be developed and demonstrated in four demo cases around Europe. 

A thermo-chemical and loss-free storage technology will be developed as seasonal storage. Two-phase change materials slurry concepts and vacuum-insulated water storage will be developed, for cold and warm applications respectively, with the aim of shifting peak load demands. Finally, storage solutions will be integrated within smart building energy management systems featuring model predictive controls to reduce operating costs for short-term applications.

In a nutshell:

  • Start date: January 2023
  • Duration: 48 months
  • Status: In progress

Expected results:

BEST-Storage aims at having three main impacts:

  1. Develop and demonstrate novel modular, high performance, thermal energy storage solutions (TES) for H/C and domestic hot water (DHW)
  2. Integration of the solution within the energy networks of the building and its system management should allow different functions, such as peak load reduction, energy saving, and energy cost minimization
  3. Develop and demonstrate a novel thermal energy storage system much more compact than state-of-the-art technologies, enabling the storage of heat and cold for domestic applications for periods typically of 4 weeks long

Each of these impacts is interconnected with four objectives:

  1.  Demonstrate high energy density short-term and long-term storage for heating and cooling building applications
  2. Development of long-term thermo-chemical high energy density storage with a capacity of 8kW heating power
  3. Development of a short-term high energy density modular storage for peak load shifting
  4. Development of a model predictive control (MPC) for short-term storage and peak load shifting

The impact:

  1. Develop and demonstrate novel modular, high performance, thermal energy storage solutions (TES) for H/C and domestic hot water (DHW)

Building heating and cooling demands represent a major share of the EU electricity demand with simultaneous consumption and hence high peak loads. Integration of heating, ventilation and air conditioning (HVAC) systems into the smart electricity grid is a key development aspect. Storage devices help to reduce the grid electricity at peak load periods allowing off-peak electricity to be used in the buildings for satisfying space heating (SH) and cooling (SC) as well as DHW demands. 

  1. Integration of the solution within the energy networks of the building and its system management should allow different functions, such as peak load reduction, energy saving, and energy cost minimization

All advanced storage system controls developed within BEST-Storage will be integrated into the building energy management system (BEMS). The smart controls will feature model predictive controls to optimize the operation considering energy efficiency, cost reduction operation as well as peak load shifting or shaving opportunities. The operation cost will be reduced by 15 % compared to rule base controls being able to reach variable electricity prices. Moreover, the optimizer will also consider other target functions such as peak load shifting/shaving and efficiency increase. Since those target functions might be contradictory to the price signals and thus to the operational cost reduction, a multi-objective approach will be used, and a given weight will be decided for each target function depending on the demo case. Both controls, the model predictive controller (MPC) for short-term and the adaptative for thermos-chemical energy storage (TCM) will ensure thermal comfort. The advanced adaptative control of the TCM will adjust flow rates to ensure a proper heat supply temperature and power requirements. The MPC will have a penalizing cost by not providing the required comfort levels.

  1. Develop and demonstrate a novel thermal energy storage system much more compact than state-of-the-art technologies, enabling the storage of heat and cold for domestic applications for periods typically of 4 weeks long

The TCM storage will feature an energy density storage of 350 kWh/m3 which is 5 times larger than state-of-the-art water storage for a temperature difference of 60 K (from 35 °C for SH to 95 °C used as the typical maximum water stored temperature). This massive energy density is achieved thanks to the development of the single vessel that contains the concentrated and diluted NaOH lye which will decrease vessel volumes by 30 % as well as improve heat and mass exchanger rate by 50 % in the A/D unit. These developments will increase the overall energy density of the complete storage (including all internal elements such as A/D, E/C, etc.) by at least 40 % with respect to the current experimentally tested TCM design based on NaOH.


The coordination board with the participants collectively constitutes an experienced consortium capable of achieving the BEST−Storage project objectives. BEST−Storage brings into collaboration diverse expertise, engaging a well-balanced multidisciplinary consortium share of: 

  • Research organizations: TECNALIA, CERTH, TEKNIKER
  • Large Companies: GIR (GIROA/VEOLIA)
  • Universities: OST, TUB, SUPSI
  • Technological specialized small and medium enterprises (SMEs): SOLINTEL, NEWTON, AVAN
  • Non-profit Association: EHPA, TREA 

The consortium is composed of 12 partners from 7 EU countries and associated countries, as reflected in the figure beside. In the following, there is a brief resume of the main involvement of each participant in the project and their respective commitments.


SOLINTEL is a high-technological SME with more than two decades of experience in the construction and energy sectors developing businesses in the interconnected building-energy value chain. It oversees the coordination of the project and the analysis of the la replication potential of BEST-Storage based on a three-part evaluation approach around the project’s key exploitable results and outcomes from the real, emulated and virtual demo cases.


TECNALIA is the largest centre of applied research and technological development in Spain, a benchmark in Europe and a member of the Basque Research and Technology Alliance. TECNALIA’s work will focus on the development of the thermo-chemical storage system for long-time free-loss storage of thermal energy. 


The Centre for Research and Technology-Hellas (CERTH), founded in 2000, is a leading Research Centre in Greece and in the EU. It is responsible for all fine-tuning of the demo phase of BEST-Storage. In particular, CERTH will be responsible for monitoring & evaluation. 


TUB aims to further develop science and technology for the benefit of society, committed to the principle of sustainable development. TUB is responsible to give the technological frame to the project. It will be responsible for the evaluation of the developed technology in a broader context by mapping the application potential of the system in several territorial clusters in Europe. 


TEKNIKER is a technology centre specialising in Advanced Manufacturing, Surface Engineering, Product Engineering and ICTs technologies, promoting its transfer to companies. TEKNIKER will oversee the development of a novel cold storage system based on phase change material slurry to provide load shifting and peak shaving. 


NEWTON aims to furnish renewable energy and affordable for everyone. For this reason, it is leading the development of sensible heat storage systems that will provide short and mid-term storage capacity for buildings. NEWTON will work on the overall design, manufacturing and integration of the sensible heat storage system with other building systems. 


EHPA represents most of the European heat pump industry. In BESTStorage, EHPA will lead WP7 dedicated to dissemination, communication, and capacity building, leveraging its advocacy and capacity building work for the acknowledgement of heat pumps and the thermal systems associated with them, as a key technology to achieve the European Union’s energy savings and climate protection targets. 


Avanzare provides customers with high-performance nanomaterials and nanotechnology-based solutions. In 2014 Avanzare acquired Ensatec, a European ILAC-ENAC accredited laboratory, which made Avanzare to be specialized in testing, certification and calibration services with the fire testing division, and gave the capacity to issue a wide range of certifications.


TREA will be in charge of the real demo case in Estonia. TREA will take the suitable technical solution and find a household and building to test the solution in real-life TRL7 and provide consultancy to owners. After installation, they contribute to the monitoring of results and evaluate suitability and readiness to use solutions in the Estonian market.


Giroa-Veolia is a specialist energy and environment management services company of Veolia also dedicated to the maintenance, conservation and adaptation of buildings, installations and complexes of different natures to improve their comfort, performance and security. GIR will be responsible for the design, construction, installation and validation of the novel phase change material storage system to be installed in the TEKNIKER building. 


OST is the university of applied sciences for the six cantons of Eastern Switzerland and the Principality of Liechtenstein. OST is the technical coordinator of BEST-Storage and the main developer of two key technologies, the TCM and the PCMSCrys slurry storages. Finally, OST will test the PCM-SCrys slurry system in their concise cycle test emulated demo. 


As a Swiss University of Applied Sciences, SUPSI is an autonomous organization, and it has a university status with a focus on professional training and applied research. SUPSI oversees the design and production of open-cell cellular ceramic structures for the Absorber/desorber unit. 

Work Packages:

The project is designed around seven main work packages:

  • WP1: Project management and coordination

The overall objective of this WP is to coordinate the project and its partners with the aim to comply with the Grant Agreement by ensuring the effective realization of the project objectives as well as the timely production of high-quality deliverables within the resource’s constraints.

  • WP2: Contextualisation, specification and KPIs

This WP will provide a portrait of territorial key aspects (climatic, energetic, environmental, economic and social) needed to assess the sustainability of the proposed storage solutions within the involved countries. The activities conducted in WP2 will allow the development of a solid methodology for the definition of the BEST-Storage solutions, components and configurations that will be developed along the project.

  • WP3: Development of a modular Thermo-Chemical Energy Storage (TCM) system with heating emphasis

The objective of this WP is to develop a modular 8 kW fully functional prototype of a thermo-chemical storage system containing a power & temperature lift unit (heat-and-mass exchanger) and an energy capacity unit (tanks) for at least 4 weeks.

  • WP4: Development of short-term cold and warm storage solutions for peak load shifting

Within WP4, three energy storages to allow peak load shifting with a capacity of 9 kWh will be developed, manufactured, and tested in the laboratory. Two PCM slurries storage will be developed using two different approaches: emulsion and supercooling-crystallizer that will act as cold storages with melting points between 6-12°C.

  • WP5: Demonstration and cost-effectiveness of BEST-Storage solutions

This work package considers the demonstration of the BEST-Storage technologies in the demo cases. The demonstration is done at different levels: i) using one real emulated demo case (hardware-in-the-loop) at TRL 6 and ii) using three real demo cases at TRL 7 and iii) using the virtual demo cases for impact and replication assessment.

  • WP6: Exploitation, business models and marketing strategies

The focus of this WP is to explore and develop innovative business models and market analysis that will effectively support the wide-scale diffusion and replication of the BEST-Storage solutions.

  • WP7: Dissemination and communication

The overall objective of WP7 is to maximise the dissemination and communication activities to achieve an effective promotion, both the project and its progress/ results, as well as on reaching the identified project target groups.

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