Along with growing public interest in alternative energy resources, research and development in electric storage technologies may also hold the key to an energy efficient future. For instance, electric double-layered capacitors, otherwise known as ultracapacitors, are playing an essential role in powering everything from small electronic devices to full-sized automobiles, allowing for fine-tuned precision in the use of the world’s limited energy supply.
The novel design of ultracapacitors gives them many advantages over conventional batteries. Their most notable feature is that they store energy through an electostatic field rather than through chemical reactions, which allows them to charge and discharge energy at a faster rate than batteries do. Whereas batteries tend to lose storage capacity over time, ultracapacitors can handle significantly more wear and tear in the absence of chemical reactions. Ultracapaictors can go through 1000 times the amount of charge/discharge cycles that conventional batteries can, and often outlive the devices they’re meant to power. In addition, they can function within a wide range of temperatures (up to -40C and +50C), and are composed of non-toxic ingredients that make them more environmentally friendly to dispose of than lead-acid or lithium-ion batteries.
What this means in practice is that ultracapacitors are ideal for accepting and/or delivering sudden surges of energy with little to no maintenance during their long life cycle. Such is the case with ultracapacitors used in regenerative braking systems found in today’s hybrid vehicles, which transform a car’s forward motion into additional electricity when the brakes are used. Ultracapacitors are also being utilized in this manner within smart-grid systems to absorb short circuits, provide critical backup power during outages, and to ensure uninterrupted communication to and from the grid during peak hours.
Currently, the majority (70%) of ultracapaictors are found in small electronic devices with low power applications, such as cell phones, digital cameras, and televisions. However, they are also beginning to serve a larger role in alternative energy production through optimizing solar power storage and windmill pitch power. Ultracapacitors have a better performance record than chemical batteries when it comes to delivering reliable power boosts that maximize the output of wind turbines; they are also able to function in extreme temperature conditions. These qualities make ultracapacitors ideal candidates for alternative energy projects located places such as the scorching Mojave Desert, where the Alta Wind Energy Center (AWEC) and the Ivanpah Solar Electric Generating System (ISEGS)–one of the largest solar installations to date–are located.
Although ultracapacitors have been in development since the 1960’s, recent innovations in storage capacity and charging time have made them a more cost-effective technology capable of trumping conventional batteries in various applications. For instance, in 2006, researchers at MIT’s Laboratory for Electromagnetic and Electronic Systems (LEES) developed carbon nanotube structures that increase the surface area of the ultracapacitor’s electrodes, which in turn increases it’s capacitance, or the amount of electric charge that it can store.
Despite these advancements, advantages, and various applications, today’s ultracapacitors still face one major limitation: their energy storage density. While the researchers at MIT are confident that ultracapiactors will have the same energy storage density as chemical batteries sometime in the future, current ultracapiactors can only store approximately 5% of the energy that comparable lithium-ion batteries can, making them unsuitable for applications that require prolonged use.
Although ultracapacitors in the near future will more than likely not be replacing conventional batteries as a whole, they can still work in the present to prolong the life of conventional batteries, saving valuable resources that would go into replacement and maintenance costs. For instance, they are currently used in conjunction with lithium-ion batteries found in electric vehicles (EVs) to provide the sudden bursts of power needed for acceleration.
Yet within the span of decades, it’s possible that the lucrative promise of ultracapacitors may replace lithium-ion batteries in EVs altogether, in that they provide EVs with the fast charging time needed to compete with standard petroleum vehicles at the gas pump.
Overall, the advantages of ultracapacitors far outweigh their costs and shortcomings. They optimize and fit nearly into already existing infrastructure, require little maintenance, and function for long periods of time with minimal environmental side effects. This makes them a viable alternative to other energy-related investments, such as hydrogen and ethanol fuel, which require extensive resources to produce, and/or new technological infrastructure to function.
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