Colloquia

Samenvatting

The HERCULES hybrid thermochemical / sensible heat storage system provides a way to store renewable electricity in the form of heat. The storage material which has been investigated is cobalt oxide, Co3O4. The feasibility to integrate a HERCULES system in Steel industry's current hot blast stove process has been assessed from a technical, economic and social point of view. The idea is to create a hybrid hot blast stove process.

For the technical feasibility, a novel Simulink model to capture system level dynamics of the HERCULES system has been set up. When integrating the HERCULES system into hot blast stove process, a hybrid system containing multiple HERCULES systems has been proposed. The four main technical challenges involved are the mass of the system, transportability, charging power and integrating with the current hot blast stove system. The system model predicted an efficiency for a small scale system of 79.8 % and for a large scale system 97.4 %. In the best case of HERCULES integration with the hot blast stove, an autarky of 83.2 % can be achieved.

For the economic feasibility, a comparative techno-economic assessment (TEA) has been performed on the operational expenditure (OPEX) of the proposed system. Based on data from electricity and natural gas prices from 2023, it can be concluded that the average daily OPEX for the HERCULES system over the entire year of 2023 is approximately 50% higher than for natural gas. However, this does not mean that the technology cannot become competitive in the future, depending on markets and policies.

From a social point of view, the main factors influencing the success of a HERCULES system in society are political guidance and global market dynamics. The main bottleneck has been identified to be the utility suppliers, mainly the distribution system operator. This stakeholder will be required to manage and maintain an increase in electricity use on the grid, requiring high sunk costs.

Based on the research and the assumptions taken it can be concluded that the HERCULES system can be integrated quite efficiently from an energy point of view, where there are some technical challenges. Considering the current electricity prices, the heat supplied by the HERCULES system is not cost competitive in comparison to the natural gas based system. Further cost reduction is possible with an expected electricity price reduction due to the increase in the cheap renewable electricity share in the grid.  From a social point of view the main barrier has been identified to be a large dependence on distribution system operators.