Starting point / Motivation

In order to transform Europe into a circular, climate-neutral, and sustainable society by 2050, a transformation of the entire energy system across all sectors is required. For the decarbonization of heating (50% of Austria's final energy demand) and electricity supply (25%), not only highly efficient generation technologies are needed, but above all sufficient storage capacities to bridge the temporal asynchrony between supply from fluctuating renewable energy sources and surplus energy potentials, and demand over periods ranging from hours and days to seasonal timescales. Thermal energy storage is therefore essential for phasing out fossil fuels and for achieving a successful heat transition.

However, the construction of storage infrastructure is usually associated with immense investment costs and therefore also with a high investment risk. In addition, the construction of thermal storages generates greenhouse gas emissions itself - also due to the materials used such as concrete and/or steel - and additionally leads to land consumption in case of aboveground systems. Therefore, the dual use of already existing infrastructure of water tanks or basins as thermal energy storage represents a key approach for developing storage capacities in a resource-efficient manner.

One largely untapped thermal energy storage potential lies in fire-fighting water and sprinkler tanks, which provide extinguishing and sprinkler water in the event of a fire for various non-residential buildings such as logistics centers, furniture stores, shopping malls, hotels, office buildings, production facilities, and similar structures.

These sprinkler and fire-fighting water tanks, which typically have a water volume between 400 and 600 m³, are generally constructed either as underground rectangular reinforced-concrete basins or as above-ground cylindrical steel tanks. This water remains unused until a fire breaks out.

If this fire-fighting and sprinkler water were thermally activated (e.g., by increasing its temperature by 25 K from 15 to 40 °C), it would provide an additional energy function alongside its primary function (fire protection), without further land use, major financial expenditures, construction times, or CO₂ emissions from new construction.

The larger the basin or the achievable temperature lift, the greater the storage potential.

Due to the widespread presence of fire-fighting water and sprinkler systems in a wide variety of building types, this concept has a very high potential for replication. It offers opportunities both for tailored energy concepts at the building level (stand-alone solutions) and for use as an energy storage system for district heating network operators (district heating and district cooling solutions) through integration in district heating networks.

Content and goals

Within the DUO-TES project, a novel and particularly cost-efficient storage concept will be developed based on the approach of thermally activating existing fire-fighting water and sprinkler tanks.

To achieve this, adaptation concepts to implement cavitation prevention measures for sprinkler and fire extinguishing water pumps, as well as thermal insulation measures based on detailed simulations and material investigations (durability, vapor diffusion, permeability) will be carried out in order to use these basins as heat storages without any negative impact on fire extinguishing.

A key focus lies on the development of an exergy-optimized concept for the efficient integration of fire-fighting water and sprinkler tanks as thermal energy storage units in district heating and cooling grids. Complementary cost analyses will ensure practical feasibility and demonstrate the economic advantages of dual use.

Methods

Through collaboration with partners from the fields of fire protection, technology development, plant engineering, and energy suppliers and grid operators, the entire value chain will be covered. This ensures the integration of practical experience, research, simulation, standardization, and operational aspects.

Expected results

Within the project, requirement catalogues for fire protection, plant engineering, and structural engineering will be defined. In addition, concrete concepts for integrating fire-fighting water and sprinkler tanks as thermal energy storage systems will be developed, modelled, and simulated. Potential risks will be assessed, and the actual energetic, economic, and ecological savings will be quantified and compared to alternative storage technologies.

Project management

AEE – Institute for Sustainable Technologies

Project or cooperation partners

• GET - Güssing Energy Technologies GmbH
• IBS - Institut für Brandschutztechnik und Sicherheitsforschung m.b.H.
• KGT Gebäudetechnik GmbH
• WIEN ENERGIE GmbH

AEE – Institute for Sustainable Technologies
Gerald Zotter
Feldgasse 19
A-8200 Gleisdorf
Tel.: +43 (664) 187 5608
E-mail: g.zotter@aee.at
Web: www.aee-intec.at