In terms of possible applications, ultracapacitors are versatile energy storage devices. Rapid improvement in ultracapacitor technology enables us to increasingly use them instead of batteries and electrolytic capacitors. Smart implementation of ultracapacitors alone or in combination with batteries may lead to significant economic benefits and increased reliability in many applications. And that’s exactly what has put ultracapacitors in the spotlight.
While most individuals and institutions can handle short power outages without major complications (excluding economic losses), the availability and reliability of power supply at all times is of critical importance for many others, such as hospitals, airports, data and communication centers, just to name a few. For institutions using sensitive electronic equipment, not only a simple outage but also different types power quality disturbances may possess a potential threat to human lives and safety. Thus, there’s a need for backup power to be always available.
Uninterruptible Power Supply (UPS) devices are commonly used for backup power. The simplest UPS devices provide power in case of utility power failure. More advanced devices can also protect against disturbances in power quality. The latter are called on-line (or double-conversion) UPS devices, which draw power from the grid and convert it to high-quality AC power, eliminating disturbances from the voltage sine-wave. Typical UPS devices include batteries as the backup power source, i.e., the source of power in case of utility power failure. However, flywheels and even fuel cells have been used for this purpose. While the majority of UPS systems rely solely on batteries, they are often the most unreliable component of the system. They also have even more disadvantages when looked at closely: high maintenance, replacements, and disposal costs, the need for monitoring/testing, and bulkiness. Nevertheless, the relatively low cost and the storage capacity are what still make batteries an attractive solution in the UPS market.
Ultracapacitors have emerged as a serious alternative for batteries in UPS systems. While ultracapacitors will not provide as long backup times as batteries, they still meet the requirements for most applications, keeping the system less bulky at the same time.
In fact, battery-based UPS systems are often oversized due to the high power requirements, leading to higher than necessary maintenance and replacement costs.
Ultracapacitor energy storage solutions are designed to work in harsh environmental conditions, for example in very low or high temperatures. This will enable the use of ultracapacitor-based UPS systems in extreme environments as well as reduce the need for costly cooling systems.
Ultracapacitor-based UPS will also reduce the maintenance, monitoring, replacement, and disposal costs accompanying battery-based systems. Ultracapacitors offer an extremely long lifetime, require practically no maintenance or monitoring, and contain no toxic chemicals.
In the end – ultracapacitors eliminate the number 1 reason of UPS failures – batteries. Although specific “one-size-fits-all” total cost of ownership (TCO) numbers for different UPS systems are almost impossible to calculate, any analysis is likely to have a similar outcome - for a 15-year period, the TCO for battery-based UPS is the highest. Hence, the investment into an ultracapacitor-based system may be wise despite the higher initial cost. Ultracapacitors are ideal for UPS systems covering short power outages and/or providing bridge power until a generator goes online, offering enhanced reliability and reduced TCO compared to batteries.