|The Pentadyne high-speed flywheel. Click to enlarge.|
Startup Kinetic Traction Systems, Inc. (KTSi) is launching with proprietary flywheel technology to absorb energy and generate power in rail traction and energy recycling applications. KTSi trackside flywheel systems provide voltage support to overtaxed sections of electric rail systems, eliminating slowdowns, as well as capturing, storing and reusing the regenerative braking energy of rail cars.
Kinetic Traction was formed earlier this year in the wake of the collapse of advanced flywheel energy storage company Pentadyne. Phillips Service Industries acquired the UPS assets of Pentadyne, while the Penetadyne’s shareholders and investment adviser formed Kinetic Traction, funded by the sale of the UPS assets, to continue an existing Pentadyne project with the Long Island Rail Road and to further the development of the rail technology.
|Vacuum cabinet, flywheel cylinder and drive cabinet of Kinetic Energy Storage System (KESS). Click to enlarge.|
Regenerative electric trains convert kinetic energy into electrical energy during braking. Without a load to absorb this—e.g. an accelerating train—the braking energy is dissipated as heat on board the train. By capturing and storing the energy normally wasted to resistor banks, the system cuts energy use both by eliminating unnecessary resistor heat production and the station’s HVAC demands to remove that excess heat. The operator can increase the amount of recovered energy and use the recovered energy to power other trains, saving money on electricity consumption.
The KTSi proprietary flywheel design has already been used to provide clean traction power to subway trains in several of the world’s leading metropolitan transit authorities, including NYC Transit, London Underground and Lyon Metro, France.
Kinetic Traction’s high-speed carbon flywheel systems feature high cycling composite rotors running on magnetic and hydrodynamic bearings at up to 36,000 rpm to provide 200 kW each. The systems are capable of delivering more than 1,000 charge-discharge cycles per day for 20 years with minimal maintenance, the company says.
The KTSi flywheel-based systems offer the benefits of voltage support and recycling of braking energy in rail applications. Instead of drawing more power from the grid, our systems can be installed trackside in a containerized or modular building, or in existing metro transit agency infrastructure to save energy while maintaining optimal rail system performance.—Richard Newark, CEO of KTSi
The flywheel utilizes a fully integrated, permanent magnet, brushless, DC motor generator to provide clean energy capture with lower costs than traditional energy substations. The GTR flywheel technology was introduced nearly 20 years ago and tested in major rail and subway systems in New York, London and Lyon. KTSi builds on this technology, pioneered in the 1990s.
The flywheel systems features an adjustable operating voltage of 570 - 900 VDC, and supports custom-engineered, parallel systems for high power requirements. Input requirements include aminimum under voltage threshold of 450 V DC; a minimum charging current of 5 A DC; and average standby power consumption of less than 400 W.
The normal operating speed range of a unit is from 430 Hz to 630 Hz (25,800 to 37,800 RPM). Usable energy is approximately 6 MJoules or 1.7 kWh. Units are capable of up to 1,150 charge-discharge cycles per day for 20 years. The operating temperature range if from 32 °F to 104 °F (0 °C to 40 °C).
The machine is connected to the traction DC supply system via the constant-voltage inverter drive. Power flow to and from the machine is determined in proportion to the DC voltage characteristic:
- Decreases in the supply voltage below mean DC voltage of the traction supply results in a machine-discharge demand.
- Increases in the dc supply voltage above mean dc voltage results in a machine charge demand.
The KTSi team has more than 40 years combined experience in flywheel technology, and previously manufactured and marketed flywheel systems at Pentadyne Power Corporation and Urenco Power Technologies. KTSi backers include Loudwater Trust, Rustic Canyon Partners and DTE Energy Ventures.