This lecture introduces the concept of Renewable Metal Energy Carriers (ReMECs) as a promising solution for seasonal energy storage.

It explains the mismatch between renewable electricity supply and winter heating demand, and why existing storage options are limited by cost, efficiency, or carbon dependency.

Aluminium, iron, and silicon are presented as candidates that can store electricity through a Power-to-Metal / Metal-to-Energy cycle, offering high energy density, long-term stability, and safe handling.

The session sets the stage for understanding how ReMECs can enable a circular, scalable, and carbon-free energy system. 

CONTENT

1. Motivation 

2. Why Metal Energy Carriers? 

3. Concept and Candidates 

4. Advantages of Metal Energy Carriers 

Main Findings

  • Seasonal storage is essential: renewable supply (summer) and demand (winter) are mismatched, especially in regions with cold winters and a large share of solar energy.

  • Metals (Al, Fe, Si) stand out as viable long-term energy carriers, combining abundance, safety, and high energy density.

  • The Power-to-Metal / Metal-to-Energy cycle enables closed, circular use with zero direct CO₂ emissions if powered by renewables.

  • Compared to hydrogen or hydrocarbons, metals provide superior volumetric energy density and safe, loss-free storage.