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Ultracapacitors in your daily life: Powering your morning subway ride

Ultracapacitors in your daily life: Powering your morning subway ride

| Dennis Flynn, Director of Corporate Marketing

The morning subway commute can be tough, especially when things go wrong. When all you want to do is get from home to work, sitting on a stopped subway is the last issue you want to run into. Believe me, I know, having spent several years commuting on the New York subway system. During those mornings when you’re anxiously waiting for your packed subway car to start up again, have you ever wondered what’s actually inside of the vehicle that you’re stuck on?

The problem that often occurs in light rail vehicles like subways can be traced back to their energy storage devices. Such large vehicles place particular demands on energy storage mechanisms like batteries, adding stress to the device and reducing its operating lifetime. For demanding applications like these, it’s important that energy storage solutions are powerful and reliable, allowing for long operational lifetimes and limited maintenance requirements. Additionally, the storage devices need to perform efficiently even under harsh conditions, including when the system is operating at a high demand and requires maximum power. By choosing a reliable energy storage solution, mass transit applications such as trains and subways can operate dependably by mitigating these added stressors.

In order to meet the demand of light rail vehicles, manufacturers can implement ultracapacitors, a dependable energy storage device. Ultracapacitors, sometimes called supercapacitors, can work alongside batteries in light rail vehicles to deliver power and capture excess energy released during braking. This removes stress from the batteries and can eliminate the need for large, heavy battery-based systems that increase overall application weight. In some cases, the addition of ultracapacitors can also extend the lifespan of the large batteries typically used in rail engine starting applications.

Trains need an incredible amount of energy to start up and accelerate and when they stop, they burn a lot of energy. Ultracapacitors save energy because they can provide the power needed for efficient acceleration within 30 seconds and are able to capture, save and reuse this energy. This specific activity is called "regenerative braking" – as the subway brakes to enter one station, the ultracapacitor captures and stores this energy and then uses it to accelerate out of the station once the passenger drop-off and pick-up is complete.

Additionally, ultracapacitors can eliminate the need for overhead catenary lines which are suspended from poles or towers along the track. This design is very valuable in cities that do not want the lines to visually disrupt skylines. The ultracapacitor-based energy storage systems can be integrated directly into the subway cars, or wayside in the station, to capture and release energy.

Using ultracapacitors for energy-saving regenerative braking improves rail performance by capturing energy and reducing maximum power demand. To learn more about how ultracapacitors are used in rail applications, read about our latest subway project: "A New Destination: Beijing’s Rail Line Sets Model For Ultracapacitor Energy Storage."

Dennis Flynn
Director of Corporate Marketing
About this author

Dennis Flynn has been with Maxwell Technologies, Inc. for four years as Director of Corporate Marketing. Prior to joining Maxwell he authored a book on branding called Brand Clout: Maintaining Relevance & Profitability Amidst Constant Change. He founded two companies focused on strategic marketing and has consulted with prestigious technology firms such as Toshiba and Gateway Computers. He also served as a Senior Fellow at The Media Center in Washington, D.C.

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