GM first global automaker to sell 2 million vehicles in China in a year
Report: Mayor of London cutting electric car funding by two-thirds

Kinetic Traction Systems launches with trackside flywheel energy storage technology for rail

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.




"Usable energy is approximately 6 MJoules or 1.7 kWh."

Is this less then 3 hp for a rail system?

Account Deleted

kelly, kWh is a unit of energy and hp is a unit of power as kW is.
1 kW =1.34 hp , if there is 1.7 kwh of energy stored in the flywheel you can drain it at a rate of 1.7kW=2.28hp
for 1 hour or 200kw=268 hp (maximum allowed)in 30 seconds more than enough in accelerations.


This type of (stationary ) application should have many applications including assisting regenerative energy recouperation and storage.
The same machine could see application in all sorts of grid stabilisation and regulation including postponement of expensive upgrades to power handling capacity.

Previous posts on Flybrid storage via the torotrak CVT
seem rather ambitious. Not to say that they would not be a great concept if it can be proven.
they would certainly prove both the CVT and the concept in the city bus application described earlier.

Henry Gibson

There were flywheel electric locomotives on subburban London tracks for freight trains. This allowed the locomotive to pass through the gaps in third rail systems without problems.

Two Parry People Movers are operating with large slow steel flywheels in revenue service.

Many years ago rail transit vehicles in NYC used some on board flywheels and they should become standard.

Capstone microturbines can put out a similar DC voltage and feed the flywheels with electricity produced from natural gas and the wasted heat can be used to heat or cool nearby buildings or the stations. Modern light balasts can be used to light the system from the Direct Current bus. Some NYC tunnels have the remnants of five or six 110 volt bulbs fed in series from the 600 volt DC track bus. These wheels should be augmented with Sodium Sulphur cells from NGK.

On board flywheels should be developed again. They could also be used with small generators for emergency travel to the next station during a power failure.

Capstone turbines operated on jet fuel or diesel can produce low enough emissions to be used in the, tunnels even, for hybrid vehicles to save on costs by turning off the power at night but still provide some service.

A large diameter insulated sodium filled pipe can be used as a cheap high current bus bar for long distance power conveyance for a reliable very low failure rate power supply.

ZEBRA technology batteries can also be used with or without the flywheels when they become cheap through mass manufacturing.

The vanadium flow batteries are also a possible fit for this application. ..HG..

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.


Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)