EnergyNest has developed a novel technology for storing thermal energy in solid-state medium that has many advantages over prior art. 

Thermal energy is stored in a state-of-the-art solid-state concrete based storage medium which is named HEATCRETE®. A thermal energy storage system (TES) is made up from a large number of individual elements, connected through pipes in series and parallel. A storage element consists of HEATCRETE® with integrated heat exchanger tubes contained inside a steel casing. Multiple storage elements are placed inside a steel frame structure cassette for easy transport and assembly onsite, allowing also the majority of piping works to be done in a workshop.

Further, multiple cassettes are connected in series through the cassette headers to form a module, and one or more modules can form a block with common piping and valve connections to the main headers. Finally, one or more blocks make up the complete storage system. In addition, the storage requires a thermal foundation, insulation of walls and roof, cladding for weather protection, and necessary interface components (piping and instrumentation, control, electricity, etc) to integrate and operate the system. 

Our approach enables our technology to become a cost-effective, simple, fully modular and scalable system, where commercial sizes range may be from a few MWhth to several GWhth.

HEATCRETE®

EnergyNest has been working together with HeidelbergCement AG since early 2012 to develop a state-of-the-art solid-state storage medium for use in EnergyNests TES system. The focus has been to develop a concrete with superior thermal properties, chemical stability and strength to withstand repeated thermal cycles at high temperatures. The specialized concrete developed by EnergyNest and HC are named HEATCRETE® rather than "concrete".

The thermal and mechanical properties of HEATCRETE® have been tested and verified by independent 3rd party laboratories: such as SP Technical Research Institute of Sweden, the Norwegian University of Science & Technology (NTNU), and Masdar Institute in Abu Dhabi. These laboratories have equipment and competence to measure and compile results for thermal conductivity, heat capacity, coefficient of thermal expansion, compressive and tensile strength. The high heat capacity of HEATCRETE® reduces the required storage volume, and a high thermal conductivity increases the dynamics of the system. 

HEATCRETE® outperforms former state-of-the-art TES concrete in both aspects with 70% higher thermal conductivity and around 15% higher heat capacity. This has a significant impact on thermal performance and necessary amount of storage medium required for a given capacity (MWhth).