Iron powder burns readily at high temperatures releasing energy as it oxidizes. This energy can be used to produce steam used in industrial processes or to produce electricity. The burning process emits no carbon, just easily collectable rust. This rust can then be turned back into iron powder with an electrical current (produced from wind or solar) and burnt again. Producing a zero carbon power generation process. Swinkels Family Brewers in the Netherlands has become the first business in the world to put this process to work at an industrial scale.
https://newatlas.com/energy/bavarian-brewery-carbon-free-renewable-iron-fuel/