Safety of flywheel energy storage

Flywheel Energy Storage Systems (FESS) play an important role in the energy storage business. Its ability to cycle and deliver high power, as well as, high power gradients makes them superior for storage applications such as frequency regulation, voltage support and power firming.

This project explored flywheel energy storage R&D to reach commercial viability for utility scale energy storage. This required advancing the design, manufacturing capability, system cost, storage capacity, efficiency, reliability, safety, and system level operation of flywheel energy storage technology.

The use of new materials and compact designs will increase the specific energy and energy density to make flywheels more competitive to batteries. Other opportunities are new applications in energy harvest, hybrid energy systems, and flywheel's secondary functionality apart from energy storage.

Robust system design, in combination with the use of certified critical materials, relevant quality control measures and documentation, are the basis for the construction of safe flywheel systems. These can be certified by appropriate independent parties as in the manufacture of many other products.

High-strength steel flywheels have a high energy density (volume-based energy) due to their high mass density. Furthermore, they are superior to composite ones regarding thermal conductivity and design data availability, such as SN curves and fracture toughness.

The safety design criteria were validated though a series of induced failures and overstress events. The flywheels were completely tolerant of a number of fault scenarios such as a loss of vacuum, loss of power, and overspeed; they survived these types of events without damage and were easily put back into service.