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Large Thermal Energy Storages for District Heating

  • Task 39
  • Currently running
  • Energy storage in energy systems

Institutes/companies and experts

Company name: IF Technology B.V.

IF Technology

IF Technology is a consultant and engineering company that specializes in the development, implementation and exploitation of sustainable underground heating and cooling systems, like low-temperature ATES, HT-ATES and geothermal energy. IF was closely involved in the development of the state-of-the-art HT-ATES of ECW Energy in Middenmeer (feasibility-permitting-design-realization-exploitation), and contributes this valuable knowledge and experience to Task39.

IF Technology-experts

Bas Godschalk, MSc (Business Developer HT-ATES) has been involved in many Dutch heat storage systems in the past, published many articles on this topic and strives for larger scale implementation of HT-ATES in NL, by bringing key players together. Bas leads the HT-ATES team within IF Technology that brings HT-ATES into practice.

Peter Oerlemans, MSc (Hydrogeologist) has specific knowledge and experiences on the subsurface processes and risks around High Temperature ATES like heat transport processes, thermal efficiency, environmental impacts and well design considerations, but also on permitting procedures for these systems.

Nico Franco Pinto, MSc (Mechanical Engineer) is specialized in the design, material selection and the successful operation of HT-ATES systems, from the mechanical point of view. Risks are mitigated in practice by the components in Nico’s well and system design.

Institute name: Technical University of Denmark – DTU



DTU Construct is a department at the Technical University of Denmark. The department carries out research on solar heating. Large solar collectors for solar heating plants have been investigated by the Department since the 1980’ties. DTU will work on Subtask A and C.


Jianhua Fan has more than 19 years of research experience in heat storage and solar heating systems. He has been leading/participating in more than 40 national and international research projects. He has published more than 110 SCI/EI indexed journal articles and 39 conference papers/reports.

Company name: Solmax


Solmax Geosynthetics


Solmax is a leader in sustainable construction solutions for civil and environmental infrastructure. Its products separate, contain, filter and drain essential applications. Founded in 1981, Solmax has grown through acquisition into the world’s largest geosynthetics company, with more than 2,000 employees. 

For district heating, Solmax Geosynthetics GmbH has been successfully sealing Pit Thermal Energy Storages (PTES) for almost a decade. The in-house installation department provides considerable experience in implementing projects in various applications.


Thomas Labda – Key Account Manager Renewable Energy & Leader of the Efficient Pit research and development project – Active member in expert groups: DIN; DGGT 5.1, VDI 4640-3. – Role in Task 39: Subtask B: Expertise in requirements and design of PTES, support specifically to materials and components – Mail: tlabda@solmax.com

Catrin Tarnowski  – Senior Technical Manager @Solmax, expert & consultant for institutions and authorities, international participation in R&D: PFAS, Cold Weather Installation, PTES – Active member in standardization: DIN; CEN and ISO, DVS, ASTM – Role in Task 39 – Subtask B: Expertise in lining materials and its installation, support specifically to materials and components – Mail: ctarnowski@solmax.com

Company name: NewHeat



Newheat is a renewable heat supplier and the leader in solar heat in France. Since 2015, the company has been offering innovative decarbonization solutions for large heat consumers, in particular district heating networks and large industrial sites. Its activity is to develop, design, build, finance and operate projects that can combine waste heat recovery, solar thermal and short and long term thermal storage systems.Based in Bordeaux, Newheat currently owns 6 sites in operation / construction, for a total of 40 MWth. Pierre DELMAS is Subtask A Leader.


Pierre Delmas : Technical Director and co-founder – Pierre started his career in 2011 in Canada with the concentrated solar thermal technology supplier Rackam. In 2014, he joined the French company Exosun to develop products for the solar thermal market, before deciding to create Newheat with Hugues Defreville. – Pierre has been contributing since 2013 to the work of different IEA SHC tasks and AFNOR, he is a graduate of the University of Technology of Compiègne.

Company name: NRCan



Natural Resources Canada (NRCan) develops policies and programs that enhance the contribution of the natural resources sector to the economy, improve the quality of life for all Canadians and conducts innovative science in facilities across Canada to generate ideas and transfer technologies. Natural Resources Canada is committed to improving the quality of life of Canadians by ensuring the country’s abundant natural resources are developed sustainably, competitively, and inclusively.

CanmetENERGY-Ottawa (CE-O) is a NRCan research lab focusing on leading the development of energy science and technology (S&T) solutions for the environmental and economic benefit of Canadians. In pursuit of this mission, we:

  • apply our scientific expertise and leverage our unique pilot-scale facilities
  • accelerate the advancement of clean energy technologies, from the initial research stage through to commercialization
  • collaborate with partners, including manufacturers, academia, planners, builders, and all levels of government
  • research areas: CO2 capture, utilization and storage, transportation, industry, renewables, oil and gas, build environment, bioenergy, norther and remote energy, material characterization


CE-O will be contributing to IEA Task 39: Large Thermal Energy Storages for District Heating subtask C: Round Robin simulation. Lucio Mesquita and Chris McNevin will be participating. Lucio is an expert in solar thermal technology as well as large scale thermal storage and he has been heavily involved in studying the Drake Landings Solar community and its BTES system. Chris McNevin is also knowledgeable in solar thermal technologies as well as energy storage and district energy systems. Jeff Thornton from TESS will be conducting to simulation study on behalf of CE-O. Jeff Thornton is an expert in thermal energy systems design and modelling and has been involved in several studies related to district energy and thermal energy storage.

Institute name: Universität Innsbruck


Universität Innsbruck – Institut für Konstruktion und Materialwissenschaften,  Arbeitsbereich Energieeffizientes Bauen

The unit of Energy Efficient Building of the University of Innsbruck sees its main task in supporting the sustainable renewal process in the building sector. The research covers physics, building physics, thermodynamics, heating, ventilation and air-conditioning technology, building services engineering, renewable energies in buildings and thermal buildings and system simulation, energy concepts in building construction, acoustics and sensor technology.

Based on its experience, UIBK plays a role as a consulting partner in Task 39 in the definition of a guideline for the construction materials (Subtask B) and in the development of reliable numerical models at both system and component levels (Subtask C).

Universität Innsbruck-experts

Fabian Ochs (Dr. -Ing.)  is Assistant Professor at the Unit for Energy Efficient Building. His current research focuses on the transition to a sustainable energy system, energy efficient buildings and districts, HVAC systems, heat pumps and thermal energy storage.

Alice Tosatto (M.Sc.) works as a Scientific Assistant at the Unit of Energy Efficient Building. Her research interests include large-scale thermal energy storage in district heating, hygrothermal performance if construction materials and energy scenarios.

Johann Schroll works as a laboratory technician at the University of Innsbruck. His professional training in mechanical engineering, building energy technology and renewable energy form the basis for his laboratory activities.

Institute name: Austrian Institute of Technology – AIT



The Center for Energy of AIT Austrian Institute of Technology offers innovative and applied research services to its customers and partners such as industrial companies, energy suppliers, technology providers, cities and municipalities as well as research institutions with its high-quality and specific laboratory infrastructure, many years of experience and scientific excellence of AIT experts. The know-how and technological competencies are very diverse and range from the exploitation of scientific findings from co-financed innovation projects, R&D contracts, patents & licenses, scientific consulting, testing for product certification, education & training to technology spin-offs. The AIT Center for Energy is developing solutions designed to ensure an innovative energy supply for the future.

The main contribution will be the participation in the subtask C: Round Robin Simulations in order to provide a benchmark for future models of large-scale thermal energy storage applications. This includes simulations with the following tools: COMSOL Multiphysics, Modelica/Dymola, FEFLOW and Earth Energy Design. The participation will cover LTES applications: tank, pit, boreholes and aquifer TES. Moreover, a participation in subtask B: Materials and components is planned. The goal is to share the knowledge in construction and materials for pit thermal energy storage. Besides, the participants will share their know-how in water quality and corrosion inspection.


Edith Haslinger is a Senior Scientist at the AIT Austrian Institute of Technology. Since 2009 she has been working at the Center for Energy as a project manager on shallow and deep geothermal energy projects. Her focus is on the development of geothermal-based heating and cooling networks and the retrofitting of existing buildings with geothermal energy. She conducts research in the areas of underground thermal storage and the assessment of geofluids when used in technical systems.

Abdulrahman Dahash works as a scientist at the AIT Austrian Institute of Technology GmbH, Center for Energy since September 2021. He is engaged in several national as well as international research projects in the field of efficiency in industrial processes and systems, heat pumps and large-scale thermal energy storage for district heating. He is currently engaged in research fields on the techno-economic analysis of large-scale thermal energy storage with heat pumps, construction of large-scale thermal energy storage and decarbonized energy concepts for industry.

Company name: Vattenfall


Vattenfall is one of Europe‘s largest producers and retailers of electricity and heat, operating the largest DH system of Western Europe in Berlin. We have the vision of a fossil free living within one generation. After shutting down the last lignite fired thermal plant, a complete phase-out from coal is planned for the Berlin DH system until 2030. Long-term thermal energy storage is a key technology for us in this process. In task 39, we contribute by demonstration and testing of LTES models of the open source model library MoSDH (Subtask C) and by our knowledge regarding LTES (A&D).


Julian Formhals is a network planning engineer in the system development department of Vattenfall Wärme Berlin. During his academic career, he collected a thorough knowledge on modelling and analysis of LTES and geothermal systems and their integration into district heating systems.

Company name: Aalborg CSP


Aalborg CSP offers a wide variety of renewable energy solutions including high- and low temperature energy storage, solar panels, heat pumps, boilers, integrated energy systems as well as customized Power-to-X solutions. We match individual energy needs with the right systems and technologies and integrates and combines solutions to achieve synergies between both sectors and technologies.

Aalborg CSP A/S contributes to work packages, A, B, C, and D by utilising their experience with construction and knowledge of large thermal storages.

Aalborg CSP-experts

Jonas Ilum Sørensen is a product owner of PTES and materials engineer.

Institute name: Technical University of Ulm (THU)



At the Institute for Energy and Drive Technology (IEA) at the Technical University of Ulm (THU), experts from various fields teach and research thermal and electrical systems, including heat and electricity storage for buildings and neighbourhoods.


Gerhard Mengedoht is involved in Subtask D regarding a Pit Thermal Energy Storage (PTES) with approx. 300,000 m³ in Gräfelfing near Munich that has been planned for 2 years. He is also participating in Subtask A together with Gunter Lindemann, who is providing his approx. 18 years of expertise on the long-term operating behaviour of the Energon Passive House office building. This building has a geothermal probe heat storage system (BTES) with approx. 200,000 m³.

Institute name: Solites


Solites is a Research Institute for Solar and Sustainable Thermal Energy Systems within the Steinbeis Network that investigates and develops solar and sustainable thermal energy systems focusing on innovative and new technologies. Solites’ business activities comprise all project phases ranging from basic research to project development and practical realization of sustainable technologies to accompaniment of plant commissioning, evaluation and optimization. A core competence of Solites is dynamic system simulation of district heating systems including load prediction, renewable and conventional energy production, large-scale thermal energy storage, distribution networks and control system optimization. Solites experts have more than 25 years of experience with the development, realisation an evaluation of large-scale underground thermal energy storage and Solites is head of the German expert’s network for seasonal thermal energy storage.

The main role of Solites in Task 39 is the lead of Subtask C.


Thomas Schmidt has been working in the fields of solar district heating and seasonal thermal energy storage since the mid-1990s. In the context of scientific support for numerous implementation projects for solar district heating with and without seasonal thermal energy storage, he was able to gain extensive implementation experience. His work focuses on the development, design and optimisation of complex heat supply systems.

Company name: PlanEnergi

PlanEnergi is an independent engineering consultancy firm, specialized in renewable energy development and energy efficiency. PlanEnergi has extensive experience with energy planning, district heating networks and is at the forefront of solar district heating systems and thermal energy storages.

PlanEnergi is contributing to all work packages within Task 39, bringing Denmark’s and its own experience with thermal energy storage into play. PlanEnergi is Subtask leader of work package D about dissemination.


Geoffroy Gauthier is contributing to work packages A, C and D, as a project leader and with thorough experience in modelling of LTES.

Hendrik Wetzel is contributing to work package B with experience of large-scale thermal energy storage implementation using geomembranes.

Company name: SOLID


SOLID develops, designs and builds turnkey solar installations based on Engineering – Procurement – Construction (EPC) contracts. In addition to operation and maintenance service we provide Solar Energy Service Contracts (ESCo).


In the numerous Big Solar studies, the solar thermal experts Maria Moser and Hannes Poier have prepared the system integration of large-scale heat storage systems and the loading and unloading strategy as well as the system simulation. With this experience SOLID contributes to work pages A, C and D.

Company name: MuoviTech


MuoviTech is the European leader in products for geothermal energy (ground source heat pump systems), with own factories in Sweden, Finland, Poland, Netherlands, UK and Norway. Complete supplier of ground heat exchangers, manifold chambers, main pipes, backfilling material, casing pipes, and fittings for installation into the heat pump. Although MuoviTech is an international company, meanwhile it stands for speed, informality and innovative. MuoviTech with passionate team is led by experienced professionals and is dedicated to understanding customers’ needs, offer innovative products and solutions to over-deliver on customer expectation. The company was founded in 2002 and since then it has strengthened through innovative products and establishing new business activities in Europe.

MuoviTech has its own geoenergy laboratory to do the field test and so far, has been conducting several scientific research and data analyses in the field of geothermal energy, with an emphasis regarding ground heat exchangers . MuoviTech have two test boreholes (200 m depth each) in Sweden and two test boreholes (350 m and 850 m depth) in its facility in Finland just for the R&D activities. Task 39 deals with Large Thermal Energy Storages and one part of that is dealing with borehole thermal energy storage where MuoviTech shares its knowledge with other partners. High Temperature Borehole Thermal Energy Storage (HT-BTES) is a key enabling technology for a realisation of a carbon neutral energy system and at the same time can answer the challenge related to the seasonal mismatch in supply and demand. District heating system is a mature technology for the heating of the built environment, especially in large cities. Large HT-BTES systems are necessary to further decarbonise the district systems and to enable a more flexible operation. MuoviTech is cooperating with all work packages however the most focus of the activities is foe work package B : Components and Materials Database. The activities are subdivided in the following parts:

• Materials database
• Evaluation of the best practice of design, construction, operation and maintenance of Large HTBTES systems
• Data analysis of all subtasks to understand the challenges and mitigate the barriers of Large HTBTES systems.

Institute name: Chalmers University of Technology

Chalmers University of Technology, founded in 1829 in Gothenburg, conducts research and education in a wide range of disciplines in close collaboration with industry and society. Chalmers, one of Sweden’s largest technological universities with about 10,600 students and some 2,200 employees, is involved in approximately 140 industrial and educational projects within the EU programs and has a long reputation as one of Sweden’s best universities. Chalmers has the strongest links to industry of all Swedish universities and one of the strongest in the world.

Department of Architecture and Civil Engineering (ACE), one of 13 departments at Chalmers, represents a broad field of knowledge theory ranging from engineering science to social science to the humanities and design-based, artistic research. Such diverse perspectives enable strong interdisciplinary development and a broader discussion of different aspects of sustainability. The department consists of ten divisions that work with education and research.

Division of Building Technology is divided into four research groups: Building Physics Modelling, Building Materials, Sustainable Building, and Infrastructure Physics. All research groups aim at contributing to a more resource efficient society and to a better environment. The research group of Infrastructure Physics is involved in ANNEX39s. The research of the group covers different components of infrastructures in modern societies and topics, such as advanced materials in infrastructure, innovative designs and materials of roads, district heating systems and urban energy systems buildings and infrastructures. The group tries to use both numerical calculations and experimental test both at laboratory and field.

Chalmers University of Technology-experts

Professor Bijan Adl-Zarrabi is subtask leader in Annex 39 ‘material and componetents’. He initiated a new field ‘Infrastructure Physics’ at the department. His research area deals with heat and moisture transfer in buildings and infrastructure. Furthermore, he has long experience related to characterization of thermal properties of material and components.

Institute name: US Army Engineer Research and Development Center Construction Engineering Research Laboratory (ERDC-CERL)


ERDC-CERL has a diverse team of approximately 300 engineers, scientists, and technical and support staff. CERL’s scientific and engineering efforts fall within six Broad Science and Technology Areas: Materials and Structures, Energy, Engineering Processes, Ecological Processes, Land and Heritage Conservation, and Environmental Processes. The energy-related research focus area includes holistic integrations of power delivery & distribution, energy systems resilience, energy storage, demand-side energy efficiencies, and conservation measures, and energy master planning.

ERDC CERL is contributing to work packages A and D within Task 39, bringing its own experience with energy master planning of public campuses, energy requirements to buildings and energy waste streams, and energy modeling. ERDC CERL is a participant in subtasks A and D.

ERDC CERL-experts

Dr. Alexander Zhivov is contributing to work packages A and D as a team member, and providing results of the US Army-funded project “Public Communities/Military Installations Sustainability and Resilience Enhancement using Thermal Energy Storage” in which he is a project manager.

Institute name: Steinbeis-Innovationszentrum energieplus

Steinbeis-Innovationszentrum energieplus is a non-profit research institution and associated institute of the Technical University of Braunschweig, Germany. SIZ energieplus designs and simulates energy systems for the supply of electricity and heat to buildings and urban districts and accompanies them into implementation. SIZ energieplus participates in Task39 with a focus on the simulations in work package C.

Steinbeis-Innovationszentrum energieplus-experts

The work is being carried out by Joris Zimmermann, who has been working as a research assistant on energy system simulations, including large thermal energy storages, since 2016.

Company name: TESS


TESS is an engineering consulting firm located in Madison WI USA that provides modeling and simulation services to clients in the energy field (www.tess-inc.com).  As a TRNSYS developer and distributor, we will be participating in IEA Task 39 to validate several TRNSYS models that we have developed for BTES, PTES and ATES applications.


The effort will be led by Jeff Thornton, the current President of the company and author of the models to be evaluated.

Institute name: Gazi University



Gazi University is one of the leading universities in Turkiye with more than 60,000 students. It is a research university specializing in additive manufacturing, fuels and combustion, and energy systems. Experimental and numerical thesis studies on sensible energy storage have been carried out. There is cooperation with the Turkish HVAC Engineers Association. On behalf of both, Gazi University takes part in this task as a spectator.