TcET – Thermochemical energy storage unit for thermal power plants and industrial heat

Motivation

In the course of the energy transition towards renewable energies, conventional power plants are facing new challenges. In addition to efficiency and economy, the plant flexibility gets into the focus of operators. Powerful heat storage systems can provide a significant contribution to increase the flexibility of thermal power plants. There are possibilities for using it both for lowering the minimum electrical load of the facility and also to increase load change speed, or to reduce the startup and shutdown times. Additional flexibility options are associated with CHP plants, in which the storage can extend the possibilities for power-controlled operation.

The requirement for the storage system is the storage of large amounts of heat in the temperature range of 300 to 600 °C over a longer period of time. Thermochemical storage units are able to chemically incorporate thermal energy. Thus they combine a very low technical effort for storage with comparatively high storage densities. In contrast to sensitive or latent heat storage systems that are already commercially available, thermochemical storage units are so far only the subject of research.

Objectives

The main objective of the project is the development of performance- and capacity-optimized thermochemical storage systems for various thermal power plants with and without heat extraction.

Like in other thermal storage systems, heat transfer to the storage material is one of the key issues for thermochemical storage. In addition also very good mass transfer is required to maintain good reactivity. The state of the art fixed bed reactors proposed in the literature for thermochemical storage cannot provide these requirements for powerful large scale systems. Therefore, in this project a new fluidized bed process is developed, combining good heat and mass transfer with continuous material handling, thus providing the basics for industry scale use of thermochemical energy storage systems.

The project is dealing with a variety of topics, starting from screening and modification of potential storage materials over reactor design to numerical simulation of the reactor as well as the complete power plant/storage systems.

  • Definition of requirement profiles to the storage system through analysis of power plant processes
  • Screening for suitable storage materials
  • In-depth analysis of suitable materials by thermogravimetry and exploration of catalysis options
  • Numerical simulation of the storage system
  • Construction of a fluidized bed facility plant with realistic conditions (600 °C) on a pilot-plant scale
  • Modeling of the entire system (power plant + storage) for the estimation of economic feasibility