Supercapacitors Spur Advances in Hybrid Public Transportation

Any driver who has watched walkers or cyclists speeding past his traffic-snarled car knows the benefits of mass transit. When fewer solo travelers take their cars out on the road, everyone gets where they need to go faster — not to mention cheaper and with less pollution. With recent advances in energy storage, the benefits of public transportation are even greater. Around the world, hybridized buses, trains and other mass transit options are making travel cleaner, more efficient and more available. Clean transportation is better for riders, funders and the environment, and it’s on the rise.

What factors are driving adoption of hybrid public transportation? Below are seven of the most significant:

1. Governments are loosening the purse strings to fund energy-efficient transportation projects.

Americans’ love for their own cars affects the environment, but mass transit in this country hasn’t been clean historically, either. To remedy that, the U.S. Department of Transportation has allocated $112 million to support 46 energy-efficient mass transit projects across seven states. And the interest from local governments is keen. Reuters reported that the Transportation Department received 266 funding requests worth $1 billion. The biggest bulk of the money available will go to initiatives in Pennsylvania, where the state is investing in hybrid buses and more vehicles fueled by natural gas. In California, the funding will go to electric, hydrogen fuel cell, hybrid and diesel-hybrid buses that emit fewer pollutants into the air and rely less on oil. Similar projects are underway in Florida, Illinois, Ohio, Texas and Washington.

Internationally, governments in Asia, South America and Europe are funding similar efforts. All of this official support to decrease the environmental impact of mass transit is bolstering the manufacturers and engineers charged with creating hybridized transportation options.

2. Supercapacitors are solving the energy storage problems batteries cannot.

A supercapacitor, also known as an ultracapacitor, can store a high amount of energy in a small container, leading to larger capacitance and longer stretches of time between parts replacement. For these reasons, supercaps are well suited to increase fleet efficiency. Engineers are adopting these components as part of an increased focus on hybridized asymmetric concepts, which combine an ultracapacitor and battery. Together, the battery and the ultracap shrink the carbon footprint of transportation applications such as hybrid buses and light rail trains.

3. Lower equivalent series resistance (ESR) meets the cooling requirements of hybrid buses.

The longer lifespan and higher power of supercaps trumps batteries, but there is another benefit for hybrid bus manufacturers, who have had to grapple with stringent cooling requirements that shorten cell lifespans and increase costs. Ultracaps can increase efficiency and power capabilities of the cell by parallel amounts. The resulting higher performance and reduced cooling requirements lengthen the operating lifespan of cells and reduce environmentally harmful emissions.

4. Advances in regenerative braking help hybrid applications capture, store and apply energy more efficiently.

Regenerative braking solutions harness energy that would otherwise be wasted and use it to re-accelerate. Supercapacitors have become a critical part of that process, providing power that is capable of quickly discharging to get vehicles moving without delay.

5. Supercapacitors are now less expensive and more durable.

The price of ultracaps has fallen by 90 percent in the past decade, while battery prices have fallen by only 30 to 40 percent during the same time. Why is this the case? Supercaps are a relatively new introduction to the industry, and as they are further developed and adopted, their prices are likely to keep dropping. Batteries, though, have been on the market for more than 100 years and their prices are, for the most part, stabilized.