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Combining Ultracapacitors, Batteries Helps Auto Makers Meet CAFE Standards

April 16, 2013 By Brendan Andrews

Brendan Andrews

US automotive manufacturers are continually striving to develop new fuel efficiency technologies and measures in order to adhere to domestic regulations that determine the amount of fuel automobiles can use. In the US, the Corporate Average Fuel Economy (CAFE) standards require that new passenger cars and light trucks achieve an average fuel economy of 54.5 miles per gallon (MPG) by 2025, and beginning in 2014, this mandate will expand to heavy duty commercial trucks. In an effort to promote the widespread adoption of renewable fuels, advocates of fuel taxes suggest raising taxes on fossil fuels so that petroleum and cleaner fuels will be similarly priced. When the tax on petroleum goes up, drivers will begin to seek out alternate modes of transportation. Before automotive manufacturers can meet consumer demand for alternative transportation options, they must embrace cleaner, more efficient energy storage and power delivery systems.

Why manufacturers choose batteries

Auto manufacturers are under pressure to increase fuel efficiency to comply with these new standards and to sell vehicles that will appeal to cost-conscious and eco-conscious consumers. In order to do this, some automotive manufacturers choose to implement more efficient battery systems. Batteries are often used in electric and hybrid electric vehicles (HEV) because they provide sustained power at a cheaper cost than gas. Although lead-acid and nickel-metal hydride batteries are more established battery technologies for hybrid and electric vehicles (EV), lithium-ion batteries are becoming an attractive option to automotive manufacturers. Despite their small package, lithium-ion batteries can provide sufficient power to an EV. Since lithium-ion batteries have high energy density but low weight, they can power an EV without hindering its performance by weighing it down. Overall, a lithium-ion battery system helps to make the vehicle lighter, which decreases the amount of energy needed to operate it and results in a more efficient car or truck.

The limitations of batteries

Even though batteries increase fleet efficiency, there are disadvantages to using battery technology. For example, batteries do not have a long lifespan or cycle life, which means users have to put out extra money to replace them. In extreme temperatures, battery performance falters, making battery technology an unreliable energy storage and power delivery option. However, vehicle owners can depend on batteries that are paired with ultracapacitors, which offer high-energy, high-power and efficiency even in extreme environmental conditions. Unlike batteries, ultracapacitors have a long lifespan, which makes them a low-maintenance power delivery and energy storage solution. When ultracapacitors are implemented in automotive applications, costs fall and energy efficiency goes up. During peak power demands, ultracapacitors deliver quick bursts of energy and then immediately store energy and capture excess power that would otherwise be lost. In addition to discharging and recharging quickly, ultracapacitors are also energy-source agnostic. Ultracapacitors are an efficient complement to key energy sources, and manufacturers should strive to achieve the optimal combination of energy storage and power delivery solutions, like batteries and ultracapacitors, in their applications.

How ultracapacitors improve battery performance

When ultracapacitors and batteries are paired together, the ultracapacitor helps the battery perform more efficiently, decreases fuel consumption and increases the hybrid-electric system’s power density. A recent Argonne National Laboratory study concluded that combining an ultracapacitor with a lithium-ion battery system in EVs and plug-in hybrid vehicles (PHEV) decreases the wear on the battery. Since EVs and PHEVs require more of the available energy in the battery, they put more stress on batteries than other applications. If too much stress is placed on a battery, the wear can increase and diminish the lifespan of the battery, resulting in the need for an expensive replacement. By using ultracapacitors in parallel with lithium-ion battery systems, the ultracapacitor can absorb the power peaks, evening out the energy demand.  As a result, the vehicle becomes more energy efficient and the lifespan of the batteries doubles.

Ultracapacitors deliver reliable power and energy storage

Ultracapacitors reliably complete a million or more charge-discharge cycles in all types of weather, without the need for replacement. A hybridized energy storage and power delivery solution comprised of ultracapacitors and batteries improves the performance of hybrid and electric vehicles by meeting the varying electrical power demands of acceleration, power steering, electrical systems, starter systems, start-stop and regenerative braking systems solutions.  Ultracapacitors can absorb and store virtually all the kinetic energy from a braking system. When a vehicle is ready to accelerate, this energy is available and can reduce fuel consumption and related emissions. This regenerative braking technology takes stress off mechanical brakes, which limits the need for brake maintenance and replacement costs. In start-stop applications, ultracapacitors can also be paired with batteries to allow the engine to turn off at a red light or while in traffic. When the vehicle needs to accelerate, the ultracapacitors can deliver a quick burst of energy that restarts the motor.

As the government imposes stricter fuel efficiency regulations and consumers demand cleaner, more efficient vehicles, manufacturers must embrace new approaches. The need for a hybridized energy storage and power delivery solution is even more important as auto manufacturers strive to meet government standards and attract and keep customers. By combining ultracapacitors and batteries, manufacturers can improve fuel economy and reduce harmful emissions.

Brendan Andrews is the senior director of sales global at Maxwell Technologies. He is responsible for the domestic and international growth of the company, specifically in the US, Europe, South America and Asia Pacific.



One comment on “Combining Ultracapacitors, Batteries Helps Auto Makers Meet CAFE Standards

  1. Using Gigacapacitors would give the auto-makers a real advantage over UltraCapacitors, if they would do a holistic design. then they would have energy densities that exceed that of gasoline, and ultimately exceed gas/diesel vehicle ranges.

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