Rising fuel prices, new impending corporate average fuel economy (CAFE) regulations and rising consumer demand for fuel-efficient vehicle options mean auto manufacturers are looking for ways to green their products. Auto engineers have looked at options for shifting power and energy storage to greener components and have frequently turned to ultracapacitors.
A manufacturer’s first instinct is often to choose rechargeable batteries as energy storage devices, but using only batteries creates limitations for automotive applications. Alternatively, hybrid energy storage is ready to support advances in electric vehicle production. A hybrid solution pairs ultracapacitors with batteries, resulting in a reduced battery size. The ultracapacitor provides power, which means manufacturers can size the battery for the energy requirements, and use a smaller, high energy density battery. Using a hybridized storage system allows for the strengths and weaknesses of each technology to balance each other out, providing an overall improved system.
More auto engineers and manufacturers are adopting ultracapacitors for several applications. Ultracapacitors improve fuel economy and reduce harmful emissions in hybrid buses. They also redefine the hybrid architecture that enables stop-and-go driving for large vehicles, such as urban transit buses and delivery trucks, which typically rely on diesel engines. By using smaller engines with generators and operating them at constant, efficient RPMs and power output levels, ultracapacitors can increase engine efficiency. Drawing power from the battery and ultracapacitor system helps to meet temporary increases in power demand and to support voltage bus stabilization. Finally, ultracapacitors are commonly used in regenerative braking applications, where the capacitor can recapture energy during deceleration.
In addition to these applications, ultracapacitors ensure reliable functioning of electrical doors, activate the tilting systems of advanced tilting trains, cover the peak power demands and support of switch drives in case of power outage, deliver cold start support and power boost and enhance battery lifetime. Ultracapacitors also provide power bursts required for security applications such as GPS, signal horns and optical warning units.
Here are five reasons ultracapacitors are more beneficial than batteries:
1. Temperature: Ultracapacitors operate in a wide range of temperature conditions — from +70 ° Celsius to –40° Celsius. This is a great improvement over batteries, which do not perform well below 0° Celsius. Even in cold temperatures, ultracapacitors provide high charge acceptance, high-efficiency, cycle stability and excellent performance. In electric vehicles (EVs), this means the capacitors can deliver efficient power to starting and ignition systems in cold weather without relying on batteries.
2. Size: When looking to increase fuel efficiency, the last thing auto engineers want is unnecessary weight. Batteries are large and heavy and offer only a limited charging rate. A hybrid energy storage system pairs ultracapacitors with a considerably smaller battery, thereby achieving the necessary power and performance in a smaller package with reduced weight.
3. Cycle life: Ultracapacitors can handle millions of charge and discharge cycles, which means their lifespan typically lasts throughout the life of the machines into which they are built. Little to no maintenance is required, which is another advantage over batteries. In hybrid vehicle start/stop applications, ultracapacitors can provide the required cycle life.
4. Power and efficiency: Ultracapacitors are more efficient than batteries — up to 95 percent as compared to an average of approximately 70 percent for batteries in automotive applications. When it comes to vehicle acceleration, ultracapacitors provide up to 10 times more power than batteries. And, since ultracapacitors are working along with small batteries, the system can power starting and ignition systems at a lower voltage regulation, which results in more fuel savings.
5. Price: Perhaps one of the most appealing benefits of ultracapacitors is the potential for cost savings. The price of ultracapacitors has fallen by 99 percent in the past decade, compared to only 30 to 40 percent in battery prices. The falling prices can be attributed to several factors. First, the cost of raw materials has dropped due to increased ultracapacitor demand and volume discounts. With increased demand comes cost-reducing competition. Batteries have been on the market for more than 100 years, and their cost has been reduced as much as possible during this time. Ultracapacitors, on the other hand, are a relatively new addition, and prices will continue to fall. In addition to their low cost, ultracapacitors facilitate mass volume savings that batteries cannot match.
For these five reasons, the automotive industry’s interest in ultracapacitors is growing. Green vehicles, whether hybrid or electric, are increasingly more attractive to consumers, and manufacturers need to meet customer demands to extend the longevity of the vehicles and improve performance capabilities. Improving the efficiency of energy storage systems through the use of ultracapacitors is one way to achieve this goal. Ultracapacitor adoption in EVs is still in the early stages, but it is clear that ultracapacitors offer key advantages over batteries. Research into ultracapacitor technology and electronic power supply design will continue, and the results will only intensify the benefits.
Jeff Colton is vice president of sales, North America at Ioxus. He is responsible for managing and growing the company’s North American sales operations in multiple alternative energy sectors. Previously, Jeff held executive roles at companies including General Electric Corporation, Sanyo Electric Corporation, and Saft Battery Corporation.