There is a shift afoot in energy storage.

The batteries upon which users rely to power everything from flashlights to cars are -- as it turns out -- inefficient when forced to perform as both energy and power sources. Ultracapacitors, high-energy density components, have emerged as an attractive pairing for batteries, correcting for flaws such as low cycle life, temperature sensitivities and inefficiencies.

The promise of battery-ultracapacitor hybrid energy storage is catching the attention of manufacturers across multiple industries spanning numerous applications. As engineers in these organizations consider hybridized energy storage, they typically weigh factors such as cost, power and performance. On every count, hybridized solutions win, promising greener, more sustainable future products.

Frequently Asked Questions About Hybrid Energy

Manufacturers, regardless of industry, often raise the same questions about hybrid energy components. These are concerns any organization would likely have if faced with calls to alter familiar and long-standing practices such as battery-only energy storage. All of these concerns can be answered by noting the specific and numerous benefits of a hybridized approach.

Concern #1: Cost -- In the past decade, the price of higher performing ultracapacitors has fallen by 99 percent. In the same time period, batteries have become only 30 to 40 percent cheaper. That disparity is likely to continue, since the market is adopting ultracapacitors in greater numbers and the cost of related raw materials is falling. 

Concern #2: Complexity -- A singular energy storage approach might offer simplicity, but its results fail to measure up in almost every way to those of a hybrid component. This is certainly true in regards to power. In most applications, there is a continuous energy demand that is handled by a primary energy source. At times, there are peak power demands. Engineers can either size batteries to handle peak demands or use ultracapacitors to bridge the demand. The latter option has the added benefit of downsizing the primary energy source.

High-power ultracapacitors provide the burst power required by high current demands associated with acceleration, starting, steering and regeneration. Pairing a capacitor with a battery improves the power density of the hybrid supply, which allows the battery to operate without the large current spikes that would exist without the capacitor.

Concern #3: Functionality -- Manufacturers know how a battery performs on its own.  The benefits of a dual-energy solution are less familiar to some. For these organizations, it’s important to note that hybridization does not eliminate the value of the battery. The battery actually performs far better and for longer periods of time when paired with an ultracapacitor. The presence of the ultracapacitor enables the battery to do the job for which it was originally designed: provide high-energy density. One example involves hybrid vehicle acceleration, which creates a significant demand for power in the form of amps.  A hybrid solution directs the ultracapacitor to provide high current, enabling the battery to serve strictly as an energy source, rather than as an energy and power source.

Concern #4: Efficiency and Lifespan -- Ultracapacitors have a much lower internal resistance and, thus, a much faster charge rate than batteries. For this reason, ultracapacitors make battery-powered systems run more efficiently. These components also make batteries last longer because they do the bulk of the work when the load is switched on and allow the battery to pick up load slowly, preventing high current draws. This scenario insulates batteries from high current drains that cause thermal, chemical and mechanical stresses. This reduction of current spikes significantly lowers the internal temperature of batteries, extending their life by as much as 400 percent, depending on the application. Furthermore, while lead-acid batteries offer 70 percent efficiency rates at best, ultracapacitors outshine them with 95 to 98 percent efficiency. 

Batteries rely on a chemical reaction to dissipate stored energy. There is no chemical reaction in ultracapacitors, as they store energy in an electrostatic field. This lack of chemical change enables ultracapacitors to last more than a million cycles, compared to mere hundreds to low thousands of cycles for various batteries. In terms of cycle life, therefore, ultracapacitors deliver greater return than batteries.

Concern #5: Temperature Resistance -- The battery has been asked to perform under extreme temperature conditions, with varying degrees of success. Batteries ostensibly withstand temperatures from +60 C to -20 C, but at 0 degrees and below, they lose most of their available energy. The ultracapacitor is more forgiving at the high and low ends of the temperature spectrum, operating comfortably between +70 C and -40 C. This is particularly important to manufacturers who use these components in applications such as jet engine ignition systems that function at high altitudes and within extreme temperatures.

Creating More Sustainable Energy Storage

With their common concerns addressed, more and more manufacturers are adopting hybrid energy storage. This is increasingly the case in industries such as automotive, wind power, LED lighting and many others. Manufacturers, the gatekeepers to widespread hybrid energy adoption, recognize that the numbers in favor of hybridization are too stark to dismiss. In terms of cost, performance and efficiency, hybrid energy storage outshines battery-only systems. Such hybridizations are more efficient and use fewer materials. By also extending the cycle life of the battery component, the ultracapacitor succeeds in making the whole system greener.

Image CC licensed by Flickr user Audin.