Large Diameter and Highly Homogenous Homopolar Active Magnetic Bearings for Energy Storage and Aerospace

High-speed Active Magnetic Bearing (AMB) technology can be used to construct a kinetic energy storage device that achieves significantly lower cost per kWh cycled than better-established technologies such as batteries, Pumped Storage Hydro (PSH), and Compressed Air Energy Storage (CAES). The key is to manufacture a large ring that orbits in a homogeneous magnetic field within a toroidally-shaped vacuum chamber. The supporting magnetic fields prevent hoop stresses within the ring from exceeding the tensile strength of the ring material. This allows a ring of sufficient diameter to store much more kinetic energy per unit of mass than is possible with a flywheel. The Levelized Cost of Energy Cycled is calculated and shown to be inversely proportional to the radius of the ring. Rings with a radius of 30m are cost-competitive with the best Li-Ion battery systems. At a radius of 50m, Ring Energy Storage (RES) is cost-competitive with PSH and CAES. At a radius of 120m, RES paired with scalable but intermittent renewable technologies, such as wind and solar, can supply most of the world’s energy grids with reliable power at competitive rates. If this technology is sufficiently matured and de-risked for commercial energy storage applications, there are more advanced applications of the technology that could be game-changing within the aerospace industry. For example, energy storage on the Moon or Mars where the energy storage capacity per unit of mass shipped between planets is a metric of paramount importance. Non-nuclear energy solutions for off-world use are also valuable for environmental and geopolitical reasons.