Carbon-free chemical energy carriers

Carbon-free energy carriers are studied for storing renewable electrical energy in a circular economy. Here we focus on ammonia, metal borohydride such as KBH₄, and reactive metals such as iron and aluminium. For instance, sun and wind energy can be chemically stored by reducing iron oxides with electrolysis hydrogen in regions of inexpensive renewable energy. The time-flexible energy release through iron oxidation then takes place in regions with high energy demand.

Such seasonal, non-toxic, long-term energy carriers provide energy capacity that is no longer available due to the shutdown of nuclear and coal-fired power plants. They additionally compensate fluctuations in domestic renewable electricity, use existing large-scale infrastructures, and secure a political-independent energy supply.