Member-only story
One Less Moving Part: Tesla Turbine integrated redox flow batteries and metal-air cells.
A stack of six welding steel discs about 6 inches (15cm) in diameter weighs around 2 pounds (1 kg). If this metal (Fe0 — metallic steel) were completely converted to rust (Fe3+ ; specifically Fe2O3), it would generate around 1200 Watt hours (Wh). That’s enough power to run an LED light bulb for nearly a week. It might run a desktop computer for a few hours, or run your refrigerator for about a day. The problem is controlling that rusting in a way that allows you to extract as much energy as you possibly can, and to prevent it from “leaking” power by rusting when you’re not using it. A simple concept that’s difficult to achieve.
One method of using iron for power storage is called a flow battery. Here, a central electrode system and membrane are used while an external pump pushes the charged/discharged fluid past the electrodes (usually made of carbon, but the anode (the negative side) can also be made of iron. These systems are starting to gain traction for use as grid power storage. The main “battery” is actually quite small, being a stack of cells. The liquids can be stored in massive tanks. Need more capacity/runtime? Bigger…
