Los Angeles is the latest US city to experiment with recycled kinetic energy for powering its trains.
Flywheels capture the energy that's created when trains brake and then make that waste energy available for acceleration.
Under a $3.6 million contract, the Los Angeles Country Metropolitan Authority (Metro) is creating a Wayside Energy Storage Substation at the Metro Red Line Westlake/MacArthur Park station.
The facility will use VYCON REGEN storage flywheel technology, which captures and then stores the energy created by braking and returns it to trains as they accelerate. It replaces chemically based batteries with flywheels that are combined with high-speed motors and contact-free magnetic bearings that store energy as a rotating mass.
The city anticipates the new substation will lower demand to the local utility during peak usage periods by up to 2 megawatts (MW) and reduce the cost of the system's peak power, says Metro project manager Frank Castro.
In addition, it will reduce or eliminate train slowdowns and stop/start situations caused by low voltage occurrences, improve system reliability and create a redundant power source that can be used during outages or emergencies.
Metro is already using 2 MW of solar PV to save electricity throughout the transit system.
The project is funded largely by the Federal Transit Administration under the Transit Investments for Greenhouse Gas and Energy Reduction (TIGGER) program.
Over the next year, VYCON has plans for additional demonstration sites at other transit agencies around the world to generate real-world data on the technology's energy savings.
VYCON's technology is designed for high power, short discharge applications. The flywheel can charge and discharge at high rates for hundreds of thousands of cycles making conventional technologies obsolete, the company says.
An innovative pilot project underway in Philadelphia is testing whether trains can send regenerative energy back to the grid. Energy is captured from braking trains, stored in megawatt-scale batteries and then sent to the regional grid.
Besides providing significant energy savings it will be a new source of revenue for SEPTA.
Learn about other train lines that are experimenting with flywheel energy storage: